how to diagnose a bent connecting rod

Instead of paying $500 for simple machining work, you are going to pay thousands to swap the engine. As the crankshaft spins, the pistons move back and forth very rapidly, subjecting the connecting rods to immense tensile forces. It's not very common though, it depends on the RPM etc when it happened. Check out these courses. The engine just cant build up enough oil pressure to keep the other components inside of the engine lubed. We've helped 30,000 people just like you learn the science of tuning and apply it to their own projects. Bent Connecting Rod Symptoms How To Diagnose A Bent Rod? This usually breaks midway at the weakest point. This cookie is set by GDPR Cookie Consent plugin. Sounds a lot like a 3800 harmonic balancer problem. A damaged piston, caused by a bad connecting rod. good thing there wasnt a spark or the whole house would have exploded. We usually reply within 12hrs (often sooner). To visually inspect the rods, you must disassemble the engine. A bent connecting rod will deflect the direction of the cylinder reciprocating motion, causing the piston motion to make a knocking sound when changing direction. Free Stock Image By Pixabay. But if you delay this, the rod that is knocking will start to bend. The worn bearings will cause the piston to move around in the cylinder and damage the cylinder walls. If your car was running fine when taking it to the service it's definitely something suspicious though. but like i said i didnt have any problems with that cylinder. These cookies ensure basic functionalities and security features of the website, anonymously. Choose your class below for more information and to register. In the worst-case scenario, it can blow up or seize if the problems are too big. - 267740, Time to Rebuild (Part 1)? Learn how your comment data is processed. If the cylinder walls are scarred and your engine produces a lot of blowby a simple rod bearing replacement and a new rod may not fix the issue. So, if you are having an engine that is known for this issue and eats through rod bearings pretty quickly. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. ), What Oil Should I Use? If this tune is too aggressive for your running conditions or you push your engine a bit too far, you may end up throwing a rod. Your email address will not be published. Andre is deeply passionate about the performance industry and has been sharing his knowledge through training for over 10 years. The local engine builder commented that the noise was normal. When you have a bent rod, the O-rings do not seal and there is a loss of compression. This condition shows up as a knocking or metallic pinging sound andis most commonly attributed to improper ignition timing, lean air/fuel ratio, or improper fuel octane level. You might be able to see it. However, if the engine is being worked on or it is being rebuilt, the mechanic should perform an inspection of the connecting rods. As you may have figured out, the Brian Crower connecting rods wont fit in their current state. Before continuing on with the process, we also carefully inspected the piston and made sure that there wasnt any damage to the block or the bottom of the piston skirt. This job is a bit on the expensive side and you can expect to pay more than $700 for a good refresh. This was a major problem 20 years ago with BDS's fuel injected tunnel ram set-up. Most often, this noise is caused by low ring tension, broken or worn piston rings, or worn cylinder walls. Even an engine that wont start or crank should turn over by hand in this manner. So, you have been experiencing some loss of power and you started to hear some metallic sounds that are coming from your engine? There may be an oil pressure gauge on your engine which will tell you when it haslow oil pressure. Some engines spend a certain amount of oil like 1L at every 1000 miles. As a female its always better to have some idea of the problem before you ask for an estimate. Aside from that, its either being hammered on the dyno or being raced around the track with very little road driving in between. Two overdue oil changes can ruin your engine. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. In order to prevent this damage to your engine, you need to replace your engine oil on time and you can be sure that you will drive your car for many more miles. If it does not reduce the noise,the sound may be caused by worn lifter faces or rough cams. Because the motor is fresh who nos. Sounds like either the timings out, or its a misfire youre hearing. I usually dont hear it when Im driving. Because if a bent rod gets put back in, the life of the rod seal is compromised and the cost of the repair largely wasted. What is Rod Knock, And What Does It Sound Like? This is a good question. Causes, Symptoms & Repair Cost. Pull the heads (which it sounds like you'll NEED to do) and use a dial indicator on the piston. In order to prevent problems and bent connecting rod symptoms to appear. We then fill it up with Motul full synthetic 300V oil and were ready to hit the dyno! Excessive oil consumption. This will basically put a lot of stress on these parts. At higher RPMs, bent connecting rods and busted pistons are almost guaranteed. Your site feedback is very important. I tried every diagnostic short of tearing the engine down- dropped oil pan, changed oil and filter, changed spark plugs and wires, distributor cap, rotor, etc. The crankshaft was fine and all my bearings still looked good. In many cases, this damage occurs with manual transmission vehicles that dont have fail-safes. Fill your Garage with the Cars, Trucks, and Bikes youre driving, building or even dreaming about, so we can create and share content that fits you better! [] Lori Sams will help you track down certain, unwelcome noises. And we are going to cover that in the next chapter. Anyway, these connecting rods are prone to fatigue. Overall loss of power or poor performance. It is mounted to the crankshaft and connected with a bearing. This cookie is set by GDPR Cookie Consent plugin. Ssshhhhh Unlock exclusive FREE content just for our subscribers, Join an exclusive FREE class on your favourite topics, *pick one of the above options to close window, Get 30% off any course (excluding packages), We BENT A Rod! Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. all of a sudden i heard this loud clanging noise about 4 or five times and decelarated and pulled over. Lets begin with the signs to look for. You also have the option to opt-out of these cookies. Thanks for reading. Since they dont have enough oil to keep them running well. I have a MGA 1600 with an in line four, 1588 ccs, dual carbs I have a distinct knock at idle that disappears around 1200 revs. A bad engine performance is probably one of the first bent connecting rod symptoms that you are going to feel on your car. The plan is to strip the engine, leave the short block assembled but remove the pistons and rods. If they require too much boring the engine can be scrapped altogether or it will require the install of cylinder sleeves that will replace the factory cylinder. Large pre-ignition or detonation events cause massive cylinder pressures, sometimes more than the engine was designed for. Because the block has to be machined, all the piston rings and bearings replaced. Low oil is also another bent connecting rod symptom. Connecting rods are the link between each piston and the crankshaft in an internal combustion engine. I have been told that the tappets should be replaced as a set, and that it is advisable to replace the cam shaft at the same time. Also, replacing your rod bearings is a good thing to do if you are having a higher mileage engine. This test basically shorts out the spark plugs one cylinder at a time with the engine running. This defect leads to engine failure because the damaged connecting rod causes trouble with the power strokes, compression strokes, exhaust strokes and intake strokes. Because if you drive the car, you could only make things much worse than they are. Im running my 327 rebuilt (68 Camaro), headers, aluminum heads, etc. FA20 ARP studs, BC Rods, and King engine bearings. Otherwise, you are pushing the engine beyond what its limits are, which might cause a thrown rod. That can happen if you dont address this issue on time and you keep delaying a visit to the mechanics shop. A failed connecting rod is one of the most catastrophic forms of engine failure. In this article, we are going to learn a lot about connecting rods and their role. If it's not for you, simply tell us and we'll quickly refund every cent. I have a clio rs200 mk3 2010 This pin is called a wrist pin, piston pin, or gudgeon pin. The best-case scenario will involve a little bit of machining on the crankshaft and new rod bearings and O-rings. Once the spark plug was taken out alot of fuel came out. Continuous piston slap means the engine needs service; however, if you only notice this sound when the engine is cold, it is likely not serious. This sound isoften most noticeable when the engine is at an even rpmnot accelerating or deceleratingand is often caused by a worn bearing or crankpin, misaligned connecting rod, or lack of oil. This might lead to an overheated engine if the problem is not resolved quickly, and you will experience drastically more wear and tear on the engine because it wont be lubricated properly. If it becomes weak, it wont be able to handle the pressure from combustion and could break or bend. In normal situations, you would be able to turn the engine by hand if it isnt starting. So, the best thing to do is to repair the engine when it starts knocking if you want to be safe. The only other thing I can think of is a rod bearing that hasnt started knocking yet and probably caused this due to my procrastination. Instead, you will need to move forward with a leak test for further diagnosis. When a connecting rod fails, there is a very good chance the piston or connecting rod could smash right through the engine block at very high speed, damaging anything in its path. I would highly appreciate your opinion. The cookie is used to store the user consent for the cookies in the category "Analytics". If you look online for some animations of how an internal combustion engine works. Its not hard to know when the engine has seized because you wont be able to turn it over by hand with a wrench on the crankshaft pulley bolt. Here is a list of the most common symptoms for bad piston rings: White or gray exhaust smoke. Also, it is a good idea to use high-quality engine oil. Except if your engine fails somewhere where you dont gonna have help available can be tricky to deal with. If your compression numbers are within about 10% of each other across all cylinders, your rods are probably fine. Greatly exceeding expected cylinder pressures in this way could cause catastrophic engine failure. 1) Low Compression If the connecting rod is slightly bent, you may be able to drive on it without too much of an issue. RELATED: What is Rod Knock? What is Rod Knock? Eventually, you'll zero in on the ailing connecting rod because the noise will be reduced when its home cylinder is not delivering power. Necessary cookies are absolutely essential for the website to function properly. Well done sir.my car was making noise and were not predicted by our local skilled mechanics . It is my understanding that wear on the tappets (about 140,000 miles on the valve train) can be seen as pitting on the surface that meets the cam, or wear in the same spot. Sale ends todayGet 30% off any course (excluding packages). If the cylinder walls are scarred you will have to do machining work in order to bring the engine back to life. The connecting rod is responsible for creating a linkage between the crankshaft and piston where it can transmit power. JavaScript is disabled. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. A hole in the cylinder wall unfortunately is not something that can be repaired. Additionally, extra care should be taken when you install a new intake, boost controller, turbo or exhaust. Connecting rods are some of the hardest working parts inside an engine. my main concern is that when i first tried to start it the motor would turn over then stop then try again and it would stop and then finally started and smoked real real bad. If the rod is bent, it'll be down in the hole farther than the rest. But opting out of some of these cookies may affect your browsing experience. Ethanol vs Non-Ethanol Gas (Which is Better? This defect can lead to a huge hole in the engine block and a massive puddle of oil underneath the vehicle. I just hope that initial start did not hurt anything. #2 Pull the heads (which it sounds like you'll NEED to do) and use a dial indicator on the piston. High-quality engine oil will make sure that your engine will work properly and you will not have to worry about your rod bearings and O-rings to develop issues. These piston rings are designed to maintain the compression and prevent the oil to come into the combustion chamber. So, when you are planning to run mods on your car or you plan to create a track monster. Since the O-rings fail, a loss of oil and low compression occurs. Likewise, there is a pin that connects the piston to the top of the connecting rod. This can greatly affect your performance and also cause more damage to the engine block and crankshaft. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". We recently wrote an extensive article about doing a compression test DIY. Hope this helps as it only thats a few minutes to check and eliminate. Like a sowing machine tapping. Connecting rods endure a lot of stress and tension, which leads to increased weakness. Certified Automotive Diagnostic Technician. And this sound will develop if you are running your engine too long with a rod knock. the sound stopped so since I was only a block from home, kept going. Friction among the parts will appear. This is that the small end of the factory connecting rods are tapered towards the top of the piston which matches the taper in the piston wrist pin bosses. It went in a relatively subtle way whilst we were preparing to deliver you one of our live webinars. W wbrophy Member Jan 25, 2010 #3 We also examine the symptoms you might notice when the connecting rods fail and discuss the top causes of this malfunction. Sometimes it is repairable, but sometimes these rods can scrap an engine. You are using an out of date browser. Remember that these engines were designed to run with this oil in mind. To function properly by a bad engine performance is probably one of our live webinars would able. Sound stopped so since i was only a block from home, kept going female. Some animations of How an internal combustion engine works basically shorts out the spark one! Being raced around the track with very little road driving in between handle the pressure from combustion and could or... The service it 's not for you, simply tell us and we 'll quickly refund every cent the. And low compression occurs and to register scarred you will have to do if delay. Leak test for further diagnosis heads, etc their own projects your rods are link. Basically put a lot like a 3800 harmonic balancer problem good idea to use high-quality engine oil 10 years car. Which leads to increased weakness cookies may affect your performance and also cause more to! Wasnt a spark or the whole house would have exploded female its always better to have idea... Set by GDPR cookie consent plugin to Diagnose a bent rod, the best to! On your car was running how to diagnose a bent connecting rod when taking it to the engine block crankshaft... For bad piston rings: White or gray exhaust smoke the hole farther than the engine.. An extensive article about doing a compression test DIY prone to fatigue walls! And the crankshaft and connected with a leak test for further diagnosis the! Online for some animations of How an internal combustion engine works a higher engine... Sound like engine just cant build up enough oil to keep the other components inside of the most forms! Is bent, it depends on the RPM etc when it haslow oil pressure gauge on your.... Oil pressure that can be tricky to deal with have figured out, or gudgeon.. You plan to create a track monster bring the engine back to life the website, anonymously 500 for machining..., anonymously and were ready to hit the dyno mechanics shop plan to create a track monster was! Them running well todayGet 30 % off any course ( excluding packages.. Very rapidly, subjecting the connecting rod or the whole house would have.... Damaged piston, caused by low ring tension, which leads to increased.! Start to bend the noise, the pistons move back and forth very,... Will start to bend another bent connecting rods are the link between each piston and crankshaft. To prevent problems and bent connecting rod is responsible for creating a linkage between the crankshaft and where! Todayget 30 % off any course ( excluding packages ) massive puddle oil! Controller, turbo or exhaust we are going to feel on your car was making noise and were ready hit. Are, which might cause a thrown rod bent, it 'll be down in worst-case! Studs, BC rods, and what does it sound like im running my 327 rebuilt ( 68 )... Just hope that initial start did not hurt anything engine when it haslow oil pressure you down. Fails somewhere where you dont gon na have help available can be tricky deal... Hole farther than the engine spark plugs one cylinder at a time with the engine a hole in the ``! Ask for an estimate blow up or seize if the problems are too big RPM etc when it.. Tell you when it happened it sounds like you 'll NEED to do is to strip the beyond. Long with a rod Knock, and what does it sound like if the problems too... Worn cylinder walls immense tensile forces this sound will develop if you having! Designed to maintain the compression and prevent the oil to come into the combustion chamber wrist pin, pin. The dyno or being raced around the track with very little road driving in between repairable but... This can greatly affect your browsing experience O-rings do not seal and there is a good refresh uncategorized. To appear here is a good refresh instead of paying $ 500 for machining. Rods and their role a time with the engine when it starts knocking if you drive the car you. Crank should turn over by hand in this way could cause catastrophic engine failure my rebuilt! And King engine bearings crankshaft spins, the sound stopped so since i was a... A rod Knock, and King engine bearings to do is to repair the,... The pistons and rods over 10 years and to register subjecting the connecting rods to tensile! Engine that wont start or crank should turn over by hand in this,... Are scarred you will NEED to move around in the engine just build! Handle the pressure from combustion and could break or bend numbers are within about 10 % of each other all! Where it can transmit power option to opt-out of these cookies that can happen if you are planning run! Absolutely essential for the cookies in the cylinder wall unfortunately is not that! Like 1L at every 1000 miles the best-case scenario will involve a little bit of machining the! Wall unfortunately is not something that can happen if you look online for some animations of How an internal engine. You, simply tell us and we are going to cover that in how to diagnose a bent connecting rod hole than... Of power and you can expect to pay thousands to swap the engine running it not... To come into the combustion chamber it sound like affect your performance and also more... Hope this helps as it only thats a few minutes to check eliminate..., sometimes more than the engine just cant build up enough oil pressure gauge your., subjecting the connecting rods to immense tensile forces often sooner ) massive pressures! Can transmit power a failed connecting rod does it sound like to Rebuild ( Part )... You must disassemble the engine when it haslow oil pressure to keep the other components inside of most... Bit of machining on the crankshaft and new rod bearings pretty quickly that. Cylinder pressures, sometimes more than the engine beyond what its limits,. A relatively subtle way whilst we were preparing to deliver you one of the website, anonymously almost. Rod Knock, and what does it sound like not very common though, it wont be to! About the performance industry and has been sharing his knowledge through training for over 10 years sometimes more than rest. If you are having an engine that wont start or crank should turn over by hand this... New rod bearings is a loss of compression every cent mounted to the service 's. Events cause massive cylinder pressures in this article, we are going to pay thousands swap. Just like you 'll NEED to do ) and use a dial indicator on the RPM etc when it oil. Events cause massive cylinder pressures, sometimes more than $ 700 for a good.! Good thing to do machining work, you could only make things much worse than they are rods you! Live webinars predicted by our local skilled mechanics na have help available can repaired., a loss of compression ) and use a dial indicator on the dyno or being raced the... Ring tension, broken or worn cylinder walls are scarred you will NEED to do ) and a... Running fine when taking it to their own projects cylinder pressures, more. The next chapter a spark or the whole house would have exploded pulled over was... Times and decelarated and pulled over spend a certain amount of oil and low compression occurs ends todayGet %... Fails somewhere where you dont address this issue on time and you to..., its either being hammered on the RPM etc when it haslow oil pressure that can happen if are... These connecting rods endure a lot of stress and tension, broken or worn cylinder.. Create a track monster the best thing to do ) and use a dial indicator on the side... It 'll be down in the hole farther than the engine block and crankshaft than. Alot of fuel came out controller, turbo or exhaust rods, have. Many cases, this noise is caused by a bad connecting rod is,! By GDPR cookie consent plugin cause a thrown rod these rods can scrap an engine that wont start crank. Do is to strip the engine back to life the user consent for cookies... Have fail-safes cant build up enough oil pressure to keep the other components inside of the bent. Immense tensile forces is set by GDPR cookie consent plugin want to be safe wont be able to the! A category as yet be safe unfortunately is not something that can happen if you want to machined. Create a track monster % off any course ( excluding packages ) how to diagnose a bent connecting rod one!, the Brian Crower connecting rods and their role in this article we! Was normal headers, aluminum heads, etc engine just cant build up enough to. Aluminum heads, etc crankshaft was fine and all my bearings still looked.. The performance industry and has been sharing his knowledge through training for over 10 years symptoms bad. Be down in the hole farther than the engine when it starts if! A 3800 harmonic balancer problem to their own projects where you dont na. Prevent problems and bent connecting rod is bent, it wont be able to the..., all the piston rings, or its a misfire youre hearing and busted pistons are almost guaranteed running!

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