TC whining and lessons learned
May 21, 2009, 08:07 AM
#1
Evolving Member
Thread Starter
TC whining and lessons learned
I just finished removing and reinstalling a TC on a friend's car. He was getting intermittent whining and there was evidence of leakage going on around the pinion housing. He was afraid that he had a broken TC.
After removing the TC and disassembling it, the culprit was the breather on top of the pinion. Someone had recently did a clutch change on the car before he had bought it. I am a firm believer that things just don't happen, and when they do, they are usually because of the most simplest things.
The reason for the whine was because of the loss of TC gear oil. But how did it lose it? I did a visual inspection around the TC housing and within the perimeter of the TC/gearbox. The gearbox and TC housing containing the diff were completely dry with no evidence of leaks. The pinion housing was wet, as well as the steering rack and the shaft tunnel. I looked at the breather, and sure enough it was damaged. Someone had somehow slammed it into something and caused it to stay shut. With no means of relieving pressure during operation, pressure will try to find the path of least resistance to reach equilibrium. It will blow seals and whatever else it can to get there. With the pressure, you get gear oil to accompany it, in this case. The ring and pinion were in fine working order with no chipping going on. The bearing was fine, too. just the breather needed replacing.
In the place of the breather, I fabbed up a TC oil cooler, since the radiator had access ports for oil cooling (the radiator was from a Lancer with automatic). I just needed to tap an oil return line into the face of the TC differential cover. There is a place for it, since the Mitsubishi Pajero/Montero have similar TC as the Evolution, and they use an oil cooler for the Pajero here in the Middle East, so why not use one for the Evolution? Cooler oil leads to less viscosity breakdown, allowing for things needing lubrication to stay lubricated sufficiently. This is just simple physics.
But while i had the TC out, I took the extra initiative to check the torques for the ring and other periphery items, as well as the differential, differential housing, pinion housing bolts. They were off. I retorqued them and came back 24 hours later to check the torques again to make sure they did not back off (bolts experience a phenomena called "torque shock"; they will relax after time and use). Serviced the TC and the gearbox after reinstalling the TC. Started the car and went out for numerous road checks of loading and unloading. Started mild and ramped up from there. No noises, nothing unusal and definitely, no leaks.
What are the lessons here? Well, firstly, just because your TC whines initially doesn't mean that it is ruined (it's just telling you to come check it out), lack of oil will lead to material failure, cooler gear oil is good, improper torques will lead to improperly balanced moving assemblies, and if there's a lack of oil and improper torques, one is setting themselves up for a broken TC ring/pinion. The cheapest alternative to replacing the TC is to never get to that point in the first place. Check your gear oil regularly, change at regular intervals (more if you are always putting your foot in it), check your torque settings at the same time you are doing a TC inspection, and definitely get in there as soon as you start to experienced any noises coming from the TC, unless one likes to pay big grip for a new or rebuilt TC.
Just food for thought. It works for me, and works for those who have entrusted their Evolutions to me.
After removing the TC and disassembling it, the culprit was the breather on top of the pinion. Someone had recently did a clutch change on the car before he had bought it. I am a firm believer that things just don't happen, and when they do, they are usually because of the most simplest things.
The reason for the whine was because of the loss of TC gear oil. But how did it lose it? I did a visual inspection around the TC housing and within the perimeter of the TC/gearbox. The gearbox and TC housing containing the diff were completely dry with no evidence of leaks. The pinion housing was wet, as well as the steering rack and the shaft tunnel. I looked at the breather, and sure enough it was damaged. Someone had somehow slammed it into something and caused it to stay shut. With no means of relieving pressure during operation, pressure will try to find the path of least resistance to reach equilibrium. It will blow seals and whatever else it can to get there. With the pressure, you get gear oil to accompany it, in this case. The ring and pinion were in fine working order with no chipping going on. The bearing was fine, too. just the breather needed replacing.
In the place of the breather, I fabbed up a TC oil cooler, since the radiator had access ports for oil cooling (the radiator was from a Lancer with automatic). I just needed to tap an oil return line into the face of the TC differential cover. There is a place for it, since the Mitsubishi Pajero/Montero have similar TC as the Evolution, and they use an oil cooler for the Pajero here in the Middle East, so why not use one for the Evolution? Cooler oil leads to less viscosity breakdown, allowing for things needing lubrication to stay lubricated sufficiently. This is just simple physics.
But while i had the TC out, I took the extra initiative to check the torques for the ring and other periphery items, as well as the differential, differential housing, pinion housing bolts. They were off. I retorqued them and came back 24 hours later to check the torques again to make sure they did not back off (bolts experience a phenomena called "torque shock"; they will relax after time and use). Serviced the TC and the gearbox after reinstalling the TC. Started the car and went out for numerous road checks of loading and unloading. Started mild and ramped up from there. No noises, nothing unusal and definitely, no leaks.
What are the lessons here? Well, firstly, just because your TC whines initially doesn't mean that it is ruined (it's just telling you to come check it out), lack of oil will lead to material failure, cooler gear oil is good, improper torques will lead to improperly balanced moving assemblies, and if there's a lack of oil and improper torques, one is setting themselves up for a broken TC ring/pinion. The cheapest alternative to replacing the TC is to never get to that point in the first place. Check your gear oil regularly, change at regular intervals (more if you are always putting your foot in it), check your torque settings at the same time you are doing a TC inspection, and definitely get in there as soon as you start to experienced any noises coming from the TC, unless one likes to pay big grip for a new or rebuilt TC.
Just food for thought. It works for me, and works for those who have entrusted their Evolutions to me.
May 21, 2009, 11:13 AM
#3
Evolving Member
Thread Starter
From the visual inspection of all of the components, there was nothing abnormal. No burns, no unusual wear, and there was nothing wrong with the diff, and no metal shavings on the oil drain plug. Just lack of proper level gear oil, so that would answer the question of singing going on under boost (oil getting thrown, but not enough to keep things well lubed).
The thing I want everyone to walk away from this lesson is that these things work great if there are three things- proper torques, proper gear oil level and regular interval oil change, as well as a properly working vent. Just because someone tells a person they need a new TC, go the extra steps to validate this by opening it up and checking it out. Get an a few unbiased opinions, as well, by a machine shop. What can it hurt, it's already out, and it may be that the TC just needed to be retorqued. Anything off balance is gonna sing for sure.
May 21, 2009, 12:26 PM
#5
Well, that's where one has to take someone's word for it. He said it had been acting strange for a week. He said he put gear oil in and stuff, but it kept leaking, so he parked it until it was time to bring it to me. Under normal driving, the TC didn't make a sound, but under instant punch, it would start to sing.
From the visual inspection of all of the components, there was nothing abnormal. No burns, no unusual wear, and there was nothing wrong with the diff, and no metal shavings on the oil drain plug. Just lack of proper level gear oil, so that would answer the question of singing going on under boost (oil getting thrown, but not enough to keep things well lubed).
The thing I want everyone to walk away from this lesson is that these things work great if there are three things- proper torques, proper gear oil level and regular interval oil change, as well as a properly working vent. Just because someone tells a person they need a new TC, go the extra steps to validate this by opening it up and checking it out. Get an a few unbiased opinions, as well, by a machine shop. What can it hurt, it's already out, and it may be that the TC just needed to be retorqued. Anything off balance is gonna sing for sure.
From the visual inspection of all of the components, there was nothing abnormal. No burns, no unusual wear, and there was nothing wrong with the diff, and no metal shavings on the oil drain plug. Just lack of proper level gear oil, so that would answer the question of singing going on under boost (oil getting thrown, but not enough to keep things well lubed).
The thing I want everyone to walk away from this lesson is that these things work great if there are three things- proper torques, proper gear oil level and regular interval oil change, as well as a properly working vent. Just because someone tells a person they need a new TC, go the extra steps to validate this by opening it up and checking it out. Get an a few unbiased opinions, as well, by a machine shop. What can it hurt, it's already out, and it may be that the TC just needed to be retorqued. Anything off balance is gonna sing for sure.
May 21, 2009, 01:01 PM
#7
Evolving Member
Thread Starter
In the case of my friend's TC, the breather was impacted hard enough to compress the pipe and cap and formed a tight seal.
If your breather is like this, replace it. i do not know if Mitsu in the USA carries the item. If not, do not fear, go to a transmission shop and have one installed. The plate is held down by four bolts. It is easy to remove.
Last edited by dtuned; May 21, 2009 at 03:49 PM.
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May 21, 2009, 01:11 PM
#8
Evolving Member
Thread Starter
Normal breather... The cap on a normal working breather can be removed with your fingers. There's four tiny indentations around the edge of the cap. That is to keep the cap from flying off under pressure. It also spins freely, as I pointed out previously
Your cap... Spin the cap. If it cannot spin or stays depressed with no spring in it or if it is impacted into the plate and won't spin freely, replace the breather assembly. Check your Mitsu parts dept for it or take the breather cap/plate assembly to a transmission shop and have them replace the breather for you.
Last edited by dtuned; May 21, 2009 at 01:14 PM.
May 21, 2009, 01:20 PM
#9
Evolving Member
Thread Starter
he's satisfied, for sure. I'm not the fastest wrench-turner around, for sure, I am actually slow because I am too methodical, but nobody ever has to come back to me for a repeat of the same discrepancy. I don't feel good about my work unless they are completely satisfied with my work and understand the reason things went bad in the first place. I just love go-fast stuff, learning and understanding the mechanics of things.
May 21, 2009, 03:46 PM
#11
Evolving Member
Thread Starter
The pleasure is all mine. Anything I can do to help out the community, and definitely during times like this where everybody needs to stretch their money to the fullest and be armed with as much valid info as possible to make rational decisions when having to spend it. This place has definitely helped me out tremendously, as well, and has saved me a lot of grief and money.
May 22, 2009, 03:41 AM
#13
Evolving Member
Thread Starter
I know you didn't ask, but here's the quickest way to facilitate your job. Jack up the car two-to-two and a half feet level (if you are a jackstand commando like me), remove both front wheels, the half axles, driver's side inner gearbox shaft, drive shaft, downpipe, cat or de-cat, the six 17mm bolts holding the TC to the gearbox and use a portable jack with a block of wood (2x4, 4x4) to take the weight off the TC while you pry and pull the TC off (again, if you are a jackstand commando like me). If you have a friend to help, that's great because you will need to keep the TC balanced while removing and re-installing because it has a tendency to want to fall towards the passenger side (the diff is physically closer to the passenger side; not evenly weighted)
good luck!
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