How To Stop Engine Rod Knocking

Any knocking noise is metal parts hitting each other and is not good, I would stop driving it till you figure what is the problem. I hear some knocking when I start the engine. Ford F-150/F-250: Why is My Truck Knocking? Engine knock is one of those really annoying things that causes much worry with car owners. When the load is taken off the offending cylinder it will stop knocking audibly. the best way to check this is to take out all the plugs and to look in to the combustion chamber. Please also check out the statistics and reliability analysis of the 2012 Kia Motor Sorento based on all problems reported for the 2012 Sorento. I plan to build an upgraded engine down the road, but am not ready to take that step right now. I just pulled the belt off it and it was still knocking so it is definietly something in the engine, its not rod knock for sure its. Does anyone know where that post is ? Or can you tell me if this can be done ? I have a Chevy Box Truck with a 455 engine in it. But again, a knocking still exsist at start up and shut down. 5:1 compression. What do you think it is? This happens in park neutral and in gear. With gas tank at around 1/2 tank, add in the Chevron Techron Engine cleaner. There are two types of 'knocking'. Had a bad knocking noise coming from the engine. Why the engine knock is a problem. The best way to describe car engine knocking is an annoying pinging sound which comes from the engine area. So what exactly is engine knock and how dangerous is it? What causes engine knock and how can it be avoided? You may notice a knocking or rattling noise from your engine or a sudden loss of power under full throttle. When you pull the bad boi, the knock will stop, go away, or get much less pronounced. 7 motor knock IP: Logged Message: I had the exact same issue with a 2001 4. With the motor is running and you will hear a knocking noise. The engine was restarted and moments later smoke and flames was present coming from under the hood of the vehicle. A knocking noise that only happens on engine start up for a few seconds might be a sign that the oil is bad. I loved the car period. I'm told that it is only possible to change rod bearings with the engine in the vehicle if the transmission is out. I'm positive I either spun a rod bearing, I'm getting rod knock, or piston pin is screwed. I replaced the knock sensor but the check engine light is still on. My mechanic said I’m ready to throw a rod. Thus, it is known as external combustion engine. With a different brand filter it wouldn't do it. Other mechanical problems that lead to engine knocking are: Defective main crankshaft bearings. Narrow it down. 566", which produces a very large R / S ratio of 2. com) Its my only vehicle need to fix asap!! Trevor Whiting. It can be serious enough to render the vehicle unusable. Engine knocks during idle? In the past week, my engine has developed a knocking sound while idling. There is another way to remedy this other than installing an idle stop solenoid, which involves the vacuum advance and the ignition timing. Engine knocking / Tapping noise OEM Issues. The connecting rod is the backbone of the engine. Does anyone know where that post is ? Or can you tell me if this can be done ? I have a Chevy Box Truck with a 455 engine in it. The engine starts to use oil so a valve job is performed to correct the problem. How does Lucas oil stabilizer stop engine knock? The reason I ask is because a number of people have suggested I add Lucas oil stabilizer to my car’s crankcase to stop the engine from knocking but I’m a little skeptical. Make sure you communicate to anyone in your home that you are shutting off the valve as it will stop ALL water coming in. A rod knock is as described. The wristpin sounds almost like a rod knockingwhich it is, its just the little end of the rod instead of the big end. The RPMs are staying right at 700 and the car isn't over heating. The knocking was more an updated piston to stop that break-in noise on the '06 models. Re: Knocking or Hard Rattle In Outboard the first thing that i would think of is that one or more of your pistons is loose from the rod or the rod is bent or out of alignment. Chevy Forums FREE technical assistance for your restoration and repair. Ford F-150/F-250: Why is My Truck Knocking? Engine knock is one of those really annoying things that causes much worry with car owners. There are several reasons that your car could be experiencing. + really excellent answer The coolant is probably going out your tail pipe in the form of white smoke. Eliminate engine detonation without retarding the ignition timing or losing engine power, throttle response, or fuel economy - High Performance Pontiac Magazine rings, and rod bearings to. A deep rapping noise from the engine is usually rod knock. Well, the purpose of a lifter is to enhance the performance as well as ensure a long & healthy life of the engine. It did not knock before and it will not stop. ) A very costly oversight!. Rev the engine. You may have to register before you can post: click the register link above to proceed. Although, when I check on the Engineer Mode system I see that the Engine Oil Level is currently at 19%. Hey guys our 2003 ford f 150 with the 5. There are lots of reasons as to why there would be engine knocking. high, or low, in the engine. A rod bearing knocks under acceleration. 9 engine that recently started knocking,like a rod or spun bearing. How to Stop Engine Knocking With Lucas Oil Stabilizer step 1, Buy some oil flush and some Lucas oil stabilizer at your local auto parts store. any time i coast in neutral i have to keep the pedal down so it does stall the entire time there is white smoke coming out of my. No oil now I hear a knocking sound Today my 1998 Volvo s70 ran with very low oil for at least 5 miles. I wonder what kinda of oil pump these have and if it's not the rod knocking due to lack of oil?? Mine also runs great, blows a little oil at start up but fine otherwise. the wierd part is it never does it at a higher rpm. Below that and it feels like it's lugging a bit, which isn't ideal. It's more likely a stuck piston pin. So a lifter tick is what I suspect as #1. AutoEngineLube Engine Oil Pre Lube System will work for all auto, car, truck, marine, motor home, suv, industrial engines, gasoline engines or diesel engines and motors. I do not think any of the dealers in my area have a good understanding about this issue. just enough for the engine to stutter/stumble/miss, usually happens at same time a little fuel comes out, enough to stop the pressure buildup so the injector doesn't pop. If the noise is a steady metallic rap, it may indicate a rod/rod bearing. A damaged or worn connecting rod bearing will produce knock under all speeds. 0L Engine (VIN U - RPO LQ4) Some of the above vehicles may exhibit an engine knock noise that begins in the first several thousand miles/kilometers of use. It is typically heard upon acceleration and is often the result of an irregular combustion process. When you rev up the engine, the pitch and frequency changes. (narrator)>> up next, with a rolling chassis and a cab, the '35 hot rod takes shape! (pat)>> we're back with the first ever factory five hot rod truck build. turn the flywheel till the piston is in the full up position closest to you. My engine isn't making the bbq tick, but something else I don't hear a lot of people mention. Read If Your Engine Ticks/Taps/Pings/Knocks If this is your first visit, be sure to check out the FAQ by clicking the link above. Engine knock is among the most disturbing problems a vehicle can have, but not many people know what it is, or how it is caused. Here's the info - '92 Jeep Cherokee 6cyl, 122000 miles I've been getting a soft knocking noise for a couple of months now. This harmful Engine Bearing Wear and the engine-knocking noise will be eliminated by installing the Insta-Lube Pre-Lube kit to Pressurize the Oil System before Start-ups. Engine knocking / Tapping noise OEM Issues. What is the best oil to use for the rod knock?. To diagnose which rod is bad simply adjust the timing with the engine running to make the knocking noise constant. Rod or wrist pin will though. The engine has to be cold, usually first morning start she will do it. This is often referred to as a "rod knock. But this will require that the engine is pulled from the car. This is brought on by extreme bearing wear or damage. Start the engine, and raise the idle to 2600 RPM. At one point Ford was going to replace the engine but the dealer decided to just do the other cam phaser instead. If it quits knocking with a wire off, you've found which cylinder it is. Start the engine and disconnect the supply hose to the boost controller. A failed rod bearing will end up producing a metallic knocking or rumbling noise from the engine, especially during cold starts. This was the very last thing it did, i havent run the engine for more than 15 seconds total like this, its very noisy and clearly something was wrong, so maybe no permanent damage? So I guess what im asking now, is whats my recovery from this?. Before calling the mechanic there are some steps you can take to. could also be a piston push rod and bad bearings and c-clip check to make sure your using the correct spark plug this will cause knocking,change the oil and look for metal shavings and piece's of metal could be rings are bad. The engine knock may be caused by an interaction between carbon that has formed on the piston, the piston motion, and the cylinder wall. But I could not find the exhaust leak and it sure sounded like the tapping was coming from the manifold. How Do You Make A Connecting Rod Knock Less Noticable In A High Millage Engine. It really didn't sound like a rod knock to me. The car also vibrates while idling. Had a bad knocking noise coming from the engine. and im willing to guess a rod as well. Connecting Rod Noise. You could have spun or worn out a rod bearing, and it is best to have that fixed before it disintegrates and gets into the oil system and damages other parts. My car is making loud knocking noises at idle. Another thing I noticed is that I can only hear the knock inside the vehicle. In modern cars the engine knock is detected by piezoelectric pressure sensors. Have a 2005 Cadillac CTS the engine is knocking when I give it gas and when I let up what can I do to stop it - Answered by a verified Auto Mechanic We use cookies to give you the best possible experience on our website. i have tried different brands/weights of oil with no change in knock. Shake the rods a bit. and drive for miles but when i stop the car. I'd have a mechanic listen to the knocking in your 4. I agree that rod knock seems to be a possibility but it does not follow the pattern. F 150 knocking noise coming from bottom end of engine??? known as a rod knock. Keep the engine slightly lugging or decelerating all the time. If your engine is idling at 600 rpm (and therefore that is the crankshaft rpm), the sound will occur 10 times per second. The truck had 105,000 when I got it. Engine knocking / Tapping noise OEM Issues. Noted below are a few facts about why an engine knocks and what can be done to resolve these issues. This person is a verified professional. Question: My 1989 Mustang’s four-cylinder engine recently began knocking. I wonder what kinda of oil pump these have and if it's not the rod knocking due to lack of oil?? Mine also runs great, blows a little oil at start up but fine otherwise. Fill the reservoir, start and idle the engine. Bringing the revs up will make a wristpin knock droping the revs will make the rod knock. Replace the drained oil with four to five quarts of fresh oil. Doesn't think it's worth replacing whatever part broke, due to possible systemic damages caused by whatever failed. Noisy Valve Lifters!?!?!? a. Localized pressure peaks and the explosion, rather than the burn of the fuel, causes the piston, rings,. At one point Ford was going to replace the engine but the dealer decided to just do the other cam phaser instead. Have a 2005 Cadillac CTS the engine is knocking when I give it gas and when I let up what can I do to stop it - Answered by a verified Auto Mechanic We use cookies to give you the best possible experience on our website. How Do You Make A Connecting Rod Knock Less Noticable In A High Millage Engine. Here’s what we’ll cover: What is an engine. While these steps will help resolve cases of rod knocking caught early enough, however, it is not a remedy for dealing with more serious stages of the problem. Typically a rod will knock louder when the engine is under a load, less at idleuntil it gets pretty bad and the bearing is spit out from under the cap. I had the transmission rebuilt thinking it was the flywheel or torque convertor and wasn't the problem but transmission was in bad shape. Remove the oil pan and check your rod bearings. Just got an 09 Dodge Charger police package and the hemi engine knocking very loud. The result: knocking noises in your engine. if the knocking is on the top ,then i would have the lifters and or. Knock will continue even after driving for while (usually while idling at stop light or RPMs below 1500). if it is spark knock use better gas. I loved the car period. What is the best oil to use for the rod knock?. The engine was restarted and moments later smoke and flames was present coming from under the hood of the vehicle. I spun a bearing in my car but it was making a knocking sound which I figured was a rod and was just going to drive the car until it puked. 566", which produces a very large R / S ratio of 2. The final step is bleeding the trapped air out of the system. What can be done to stop engine knock or pinging? Engine knock or pinging is knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder. A vehicle experiencing a knock should be quickly inspected to avoid any serious damage to the internal components of the engine. A knocking engine rod is a sign of distress from the inner workings of your vehicle. Connecting rod Bearings. The engine was restarted and moments later smoke and flames was present coming from under the hood of the vehicle. Now, flush the lines by opening all of the faucets and flushing your toilets. (Actually the thermostat worked just fine; the stud that holds the thermostat bracket to the engine block came loose, and the thermostat pushed the bracket down instead of pushing the connecting rod up, so the cooling vanes were locked closed. 5:1 compression. The truck had 105,000 when I got it. 0 knocking and clicking noise 2000 ohv- 73000 miles. One half bearings will jump over the other side. Rod knock shouldn't be taken lightly. Manufacturers recommend a certain rating to maintain optimum performance in their. Fill the reservoir, start and idle the engine. Noisy Valve Lifters!?!?!? a. I believe the connecting rod takes more abuse than any other single component in the engine. add a comment. You probably know that detonation is a bad thing, and that by adding a supercharger (or any forced induction power adder), you must take additional measures to avoid detonation, especially if your engine has other modifications. Here's the info - '92 Jeep Cherokee 6cyl, 122000 miles I've been getting a soft knocking noise for a couple of months now. Suggests that we replace the motor with a "junk yard engine". A rod knock is the most notorious of these issues. Lower (or bottom end) noises, generally appear as a knocking sound, deeper in tone than something from the top of the engine. Rod knock occurs when the rod bearing has been partially or completely busted. A rod bearing knocks under acceleration. I am a bit puzzled with a knocking sound seemingly coming from around the top drivers side area of my engine (passengers side US). I loved the car period. The Engine from You won't even get to the point of hearing the "nightmare" engine run. If your car engine sounds like the bottom end is going to fall off, it's probably engine rod knock. any time i coast in neutral i have to keep the pedal down so it does stall the entire time there is white smoke coming out of my. The rod bearing must either be replaced along with fixing associated parts (you don't usually replace just one rod bearing as the entire engine would need rebuilt at that point), or the engine will need to be replaced. Secondly, the knocking noise is not that loud 'as of yet. The more i listen to it, the more it sounds like a lifter knock. Have a 2005 Lasabre 3. 8i with 64k miles N62B48 engine series engine started knocking at 64k???? sounds like a lifter or valve, not from bottom end, engine oil level good, no engine lights, no vehicle info alerts, just sounds like a diesel now. Loud Knocking/Tapping then DEAD! 2nd Gen (93-97) V6 2. A rod knock is as described. if its a rod just drive it easy. 2L EcoTec with 145k on it. Not losing any antifreeze or oil. just enough for the engine to stutter/stumble/miss, usually happens at same time a little fuel comes out, enough to stop the pressure buildup so the injector doesn't pop. The terms valve clatter, pinging, pre-ignition and detonation describe the strange rattle or knock coming from an engine. When you let off the gas, it continues and maybe even gets louder. Because of the diverse causes of knocking sounds, it is difficult to ascertain the severity of the car's problem based on the engine knocking alone, notes HowStuffWorks. The engine was restarted and moments later smoke and flames was present coming from under the hood of the vehicle. 0 ranger, but here goes anyway. An engine compression test shows mid 140’s on all cylinders except one of them which is at 125. October 29, 2019 Categories Articles, Blog and, car knock, engine knock, engine knock noise, Engine Knocking, engine knocking sound, engine noise, engine pinging, engineering explained, how it works, pinging sound from engine, pre-detonation, pre-ignition, the, what is knock, what is the sound coming from my engine, You 100 Comments on Engine. They said since they already inspected my car, to just bring it to them and they will repair the engine. What is Engine Knocking? Knocking in your engine, also described as pinging, can mean one of several problems. Many assume this knocking or ticking noise is the end of their engine and just move on. You may have a vacuum diaphram allowing coolant to be sucked into engine such as heater control valve. I’ve been noticing that my 1994 Ford Ranger 2. A rod bearing knocks under acceleration. I noticed a knocking coming from the engine (closer to bottom of engine than top) on a cold start. At one point, it sounds like the knocking noise nearly disappears. It's not the typical tic tic sound of a bad lifter (though the sound quality of Youtube isn't that great); What I hear is the definite heavy metallic sound of a rod knock. How does Lucas oil stabilizer stop engine knock? The reason I ask is because a number of people have suggested I add Lucas oil stabilizer to my car’s crankcase to stop the engine from knocking but I’m a little skeptical. Connecting rod knock noise increases in volume with engine speed and is at its loudest on deceleration. Serious Avatars of Rod Knocking. Make sure you communicate to anyone in your home that you are shutting off the valve as it will stop ALL water coming in. i have tried different brands/weights of oil with no change in knock. However, the stroke in the F1 engine is in the vicinity of 1. It really didn't sound like a rod knock to me. I've had two cars die rod knock death, one was a Toyota that died very slowly (oil starvation at one point in its life), and took 2000 miles or so before it went altogether. What's actually happening is measured in thousandths of an inch. The IC engine can be further classified as: (i) stationary or mobile, (ii) horizontal or verti-cal and (iii) low, medium or high speed. Someone suggesting a rocker arm. Hi, I'm trying to figure out this loud knocking sound that happens when my Kenmore elite goes in to any spin cycle. Only knocked when you first started it until the oil pressure came up or reving above 2000 rmp. Old Wives Tale number 53. (dave)>> you guys were here for the first hot rod, and here's the big product, hot rod truck. 2004polris sportsman 500 ho engine noise I can hear a steady knockig that seems to be coming from lower engine do not think it is a rod knock but sounds very much like that. True rod knock results when the rod bearing gets wiped out. Rods generally don't knock like this unless they are already problematic - it is rare. if its a rod just drive it easy. The causes of engine knock are many and varied. The mechanic thinks the problem is an upper cam bearing. How to Stop Engine Knocking With Lucas Oil Stabilizer step 1, Buy some oil flush and some Lucas oil stabilizer at your local auto parts store. 1) Sea Foam SF16 Sea Foam is an environmentally friendly oil additive which is registered with the Environmental Protection Agency. A spun rod bearing will tear up the big end bore in the rod, ruin the rod journal on the crankshaft, and sometimes break the connecting rod. Any knocking noise is metal parts hitting each other and is not good, I would stop driving it till you figure what is the problem. It will increase in. mike and i were invited here to get the truck assembled and ready for the sema show. My 2005 Mazda 6 2. Does this really works ? Do I have to drain 1 liter of motor oil before adding it, or I just add it on top of the current oil level ?. A diesel engine can ping, cling, clang and bang, and all the time you are wondering just what is acceptable and what is not. Each term describes a slightly different condition, but the result is usually the same with each, engine damage. Because of the diverse causes of knocking sounds, it is difficult to ascertain the severity of the car's problem based on the engine knocking alone, notes HowStuffWorks. The car is knocking so bad I don't even want to drive it. There are a few reasons engine knock is so confusing. could be internal engine problem, timing chain, crank angle sensor, knock sensor, weak hydralic lifters or bent push rod, and so on. A "knocking" sound is the most typical engine noise indicating a mechanical problem that can be fixed if diagnosed correctly and early. An engine running at a high rpm standing still will benefit from the extra. Misdiagnosis is the norm rather than the exception. It's usually a warning sign that something bad has happened to the bottom end of the engine. Doesn't think it's worth replacing whatever part broke, due to possible systemic damages caused by whatever failed. Roughly a month ago I began hearing a loud knock from the driver's side of the engine bay on my 3. I can only hear the knocking if I am outside of the car, if I am in the car I can't hear it at all. Abnormal combustion, more commonly known as knock or detonation, has been the limiting factor in internal combustion engine power generation since the discovery of the otto cycle itself. My engine isn't making the bbq tick, but something else I don't hear a lot of people mention. Today it started knocking. For example, an engine's air-fuel mixture may ignite too early or spontaneously combust. Rev the engine. A damaged or worn connecting rod bearing will produce knock under all speeds. Low-end knocking always scares me, makes me think there's a bad rod bearing or similar which can be very bad news if allowed to continue. Hyundai and Kia are recalling nearly 1. 3L, 4 banger has a slight knocking sound. Upon driving it to my shop to get the engine overhauled the rod bent, then broke, bent valves and destroyed the block. Had a loud ticking from top of engine. Car has only 62,000 miles. The bottom engine noise will occur once per engine revolution. If the rod breaks while the piston is coming down, the broken rod can pierce a hole right through the engine block (like a compound bone fracture breaking through the skin). Track-rod-end ball joints are not adjustable on later cars. A worn rod sounds more like a knock than a tick - like somebody's hitting the opposite side of the engine block with a soft-faced hammer. , and many of the terms can make the event seem rather innocuous. Have a look - you've got nothing to lose, after all. This is often referred to as a "rod knock. If the knocking or tapping persists, move on to Step 3. The terms valve clatter, pinging, pre-ignition and detonation describe the strange rattle or knock coming from an engine. 4L 3-valve engine may exhibit a ticking and/or knocking noise after reaching normal operating temperature. The noise is unique because you will hear a double knocking sound caused by the lack of oil and excessive clearance between the piston pin and the piston. I can only hear the knocking if I am outside of the car, if I am in the car I can’t hear it at all. It was a slight tick it had at first, but in the end it worked. It does it all the time stationary and when moving. I had the transmission rebuilt thinking it was the flywheel or torque convertor and wasn't the problem but transmission was in bad shape. but all it took was about a week and it was doing it all the time. It did not knock before and it will not stop. It really didn't sound like a rod knock to me. This sounds like someone knocking on the engine with a wrench. If they feel loose that is very bad and everything needs to come out. One half bearings will jump over the other side. beware, an engine with run on can actualy stop then run backwards briefly,you can imagine the conciquences in a marine set up,big gulp!. Not sure if the lifter, valve spring or the rocker arm. So what exactly is engine knock and how dangerous is it? What causes engine knock and how can it be avoided? You may notice a knocking or rattling noise from your engine or a sudden loss of power under full throttle. I just pulled the belt off it and it was still knocking so it is definietly something in the engine, its not rod knock for sure its. I've read all the knocking threads that I can and haven't been able to find anyone who is having a similar problem as what I am so here I am posting a new thread. 1 thing it could be is rod bearings but we still need more info. 5:1 compression. The connecting rod is the backbone of the engine. Pulling plug wire will determine which rod(s) are knocking. Manufacturers recommend a certain rating to maintain optimum performance in their. The noise you hear is like a ball peen hammer tapping on a steel plate repeatedly. It still runs, but sounds horrible and since I don't want to end up broke down on the side of the road in the middle of the night again, it is parked. But it will have to be done sooner or later. Diagnosing Engine Noises can be the most difficult thing a mechanic can do. Re: Engine pinging/knocking after shut off? sounds like diesling or it is sometimes called run on,causes: late timing, to high idle speed,carbon build up, too hot plugs, poor quality fuel. 28 problems related to engine knocking noise have been reported for the 2012 Kia Motor Sorento. GM truck owners complain that piston slap damages the engine and causes excessive oil and fuel consumption. This product is sure to stop your engine knocking problem. When the load is taken off the offending cylinder it will stop knocking audibly. My father's truck started to have a knocking engine so I bought some lucas oil stabilizer to see if it has any effect on the problem I have a side by side comparison so you decide check out the. 3L, 4 banger has a slight knocking sound. Next step in the maintenance process is the fuel injection or the carburettor cleaner and using either will prevent grime from entering your engine. Rod or wrist pin will though. It's easy to misdiagnose the cause of knock, and there might be more than one cause, so you might have to pay a visit to your mechanic. There is a VERY slim chance you may be able to get away with changing the rod bearings. It was a vehicle going by me at about 20-25 MPH and my first thought was rod knocking. I read that from lots of people that it's normal, but I dont believe its normal. Could be a few things. The truck only has 191,000 miles on it, so that is another reason why I am not convinced it is a rod. " Mostly on low end acceleration Could this type of oil change do this? There is no oil seepage at all on the motor and the oil has always been absolutly clear ever since i have owned it. A diesel engine can ping, cling, clang and bang, and all the time you are wondering just what is acceptable and what is not. Replied by EricTheCarGuy on topic Engine knock when accelerating. a tech article on how to prevent detonation, pre-ignition and knock. Just got an 09 Dodge Charger police package and the hemi engine knocking very loud. And this is the reason I bought it even though my wife's don't agree with me. One way to find a bad rod, and which one is to just pull spark plug wires while the engine is running. A friend and I did it in 4 days working on it on and off. Hopefully, your problem is the first type I've listed below! 1. Start the engine, and raise the idle to 2600 RPM. also- driving it around town it clicks sometimes like the ac is on and you can kind of feel the engine bog- bit. It wont take long before the rod separates from the crank and you will be stuck on the road( depends on how bad the knock is, if you baby it who knows it could last a while). 7 motor knock IP: Logged Message: I had the exact same issue with a 2001 4. An electric fan has a sending unit to turn it on Method 2 Increasing the Octane Level in your Fuel. The car is knocking so bad I don't even want to drive it. Hyundai and Kia are recalling nearly 1. As you probably have already figured out, detonation (aka "knock") is a big issue in the world of forced induction. 2 million more cars in the United States for engine failures after customers reported additional failures since the original 2015 recall, according to. Other mechanical problems that lead to engine knocking are: Defective main crankshaft bearings. With a different brand filter it wouldn't do it. I'm guessing it's rod knock. At first I thought it was comin from the top but when i get under it it's alot louder sounds like its comin from the oil pan. It sounds like a rock being knocked against a hard surface. The debris restricts oil flow to the connecting rods. This happens when the hydrodynamic oil wedge is lost between the bearing surface and the connecting rod pin on the crankshaft. i have a 2000 gt and lately i have had a noise coming from my engine that sounds like a rod knocking it does it around 2500 to 3500 rpms. Had a bad knocking noise coming from the engine. GM engineering feels that this engine knock or piston slap is not detrimental to the vehicle. An engine compression test shows mid 140’s on all cylinders except one of them which is at 125. It must be the anti-dieseling mechanism and that mechanism must be functional. Usually when a rod knock first develops it's most noticeable when the engine is first started (before the oil pressure builds) and when the oil is hot. Its not an aggressive knock and must be coming from the back of the engine. Before calling the mechanic there are some steps you can take to. If you’ve got a rod knock, stop driving the vehicle - your engine is on limited time and will need replacement or major repair. Because of this, you may take a little while to pinpoint the exact cause. The car also vibrates while idling. What Is Rod Knock. Each time the piston changes direction, there is a knock from the metal hitting metal.