Hey everyone. Well this really sucks.... When I bought my truck almost 3 years ago the front pinion seal was found to be bad at 12,900 miles. Gear oil at the pinion seal. Had it replaced at a GM dealer. One year and a couple months later it was replaced again along with the yoke and U joint. A few months after that the entire repair was repeated by an independent shop (this was one of the last straw repairs contributing to me essentially firing the local dealership service departments, but that is on another thread) due to another failed pinion seal and U Joint play. Now I have some play again (but very very minimal) and a leaky pinion seal. I have an appointment for a 4th pinion seal repair on Friday with an SKF seal. We already checked the vents. What else could be causing these failures? Are SKF seals good? Thanks
Pinion Seal Repeat Failure
- Thread starter ComputernerdBD
- Start date
Mooseman
Moderator
IIRC, SKF are the suppliers for GM seals. If not, they are still good stuff. Their bearings are at the higher end.
AtlWrk
Member
- Dec 6, 2011
- 674
Is that 12,900 miles or 129,000 miles?
With multiple new seals and a new yoke (does the yoke look new-ish? it sounds like you were dealing with a typical stealership before)...you may be looking at a deeper issue. Worn pinion bearings perhaps, improper setup? If the first seal failed at 129,000 that's not all that unusual and the subsequent failures may be the result of the remove/replace process (damaged housing?), not the seal or differential itself. But, having two different shops do it with the same result makes that less likely. Do you see oil on the yoke itself or just the differential housing? There's a leak path between the pinion and yoke that will allow oil out through the pinion nut if they don't seal it properly like the manual requires.
One thing they might try: pull out the old seal and put everything back together as you normally would (including the drag check) without the seal and dust shield. Check the runout of the seal surface on the yoke. Also, the pinion/yoke should have no movement whatsoever relative to the differential case housing. Crank on the yoke in all directions then back drive the pinion in both directions with the front wheels and make sure the only motion you see is rotation. Before they pull the seal out of the differential inspect for unusual/uneven wear. Any damage on the differential housing itself (like scoring from the first replacement)?
Your comment about the vent line has me thinking: its a little unorthodox but you could try pressurizing the differential through the vent line (like 5psi max as the seals aren't designed for pressure) to see if you can pinpoint the exact location of the leak.
Good luck
With multiple new seals and a new yoke (does the yoke look new-ish? it sounds like you were dealing with a typical stealership before)...you may be looking at a deeper issue. Worn pinion bearings perhaps, improper setup? If the first seal failed at 129,000 that's not all that unusual and the subsequent failures may be the result of the remove/replace process (damaged housing?), not the seal or differential itself. But, having two different shops do it with the same result makes that less likely. Do you see oil on the yoke itself or just the differential housing? There's a leak path between the pinion and yoke that will allow oil out through the pinion nut if they don't seal it properly like the manual requires.
One thing they might try: pull out the old seal and put everything back together as you normally would (including the drag check) without the seal and dust shield. Check the runout of the seal surface on the yoke. Also, the pinion/yoke should have no movement whatsoever relative to the differential case housing. Crank on the yoke in all directions then back drive the pinion in both directions with the front wheels and make sure the only motion you see is rotation. Before they pull the seal out of the differential inspect for unusual/uneven wear. Any damage on the differential housing itself (like scoring from the first replacement)?
Your comment about the vent line has me thinking: its a little unorthodox but you could try pressurizing the differential through the vent line (like 5psi max as the seals aren't designed for pressure) to see if you can pinpoint the exact location of the leak.
Good luck
Sorry, just saw your response now.... Had to revisit this as I had the seal replaced without issue and not seeing much play but now it looks like it is leaking all over again from the bottom of the differential. I even had them put the other yoke back in which also has a clean sealing surface. The tiny amount of play appears to be the U joint but that was also replaced recently. I will have to have them recheck.... Photo attached and the leak is out the bottom of the case. I was able to see the area under the axle is wet.
By the way it was 12.9K miles when I got it and I have 43K on it now. Thanks
EDIT: The bearings in question that could be abusing the seals - how bad are those to replace? Is it something that can be replaced just behind the seal or is that something that the differential has to come off the car to fix?
By the way it was 12.9K miles when I got it and I have 43K on it now. Thanks
EDIT: The bearings in question that could be abusing the seals - how bad are those to replace? Is it something that can be replaced just behind the seal or is that something that the differential has to come off the car to fix?
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Mooseman
Moderator
If the bearing is bad, it has to come out as the case has to be opened up as there are two bearings. At this point, I would just replace the whole diff with a good used unit because of the labour involved.
Oh wow..... How can I tell the axle ratio without using the glove box label? I am concerned now because the rear diff I had to use the oversized 8.6" cover because the one it called for (3.42) the ring gear ate a gouge out of, meaning there is a discrepancy between the label and what is in there.
Mooseman
Moderator
That has nothing to do with what gearing you have. All covers are the same for the same type of differential. GMT360/370 used two sizes of differentials 8.0 and 8.6. Yours probably came with the 8.6 which is kinda strange since the non-EXT/4.2L came with the 8.0 unless they did away with the 8.0 by 2008.
Why won't you use the RPO codes in the glove box? These are the codes:
GU6 - 3.42
GT4 - 3.73
GT5 - 4.10
G80 - locking rear diff
Here's a good thread about info on the diffs:
http://gmtnation.com/forums/threads/rear-diff-upgrade-to-eaton-e-locker.4999/
If your sticker is gone, I found this article that explains how to count turns for the gear ratio: http://www.how-to-build-hotrods.com/gear-ratio.html
Why won't you use the RPO codes in the glove box? These are the codes:
GU6 - 3.42
GT4 - 3.73
GT5 - 4.10
G80 - locking rear diff
Here's a good thread about info on the diffs:
http://gmtnation.com/forums/threads/rear-diff-upgrade-to-eaton-e-locker.4999/
If your sticker is gone, I found this article that explains how to count turns for the gear ratio: http://www.how-to-build-hotrods.com/gear-ratio.html
Mooseman
Moderator
I'm wondering if the case bore where the seal goes into got scored or damaged during seal removal. I always smear a little RTV around there just to be sure. You would have to check for any play at the pinion. There should absolutely no play. No up/down or fore and aft. If there is play, then something is up either with the bearings, the crush sleeve or the torque on the pinion bolt. They might not have replaced the crush sleeve when they replaced the pinion.
Mooseman you called it..... No bearing issue but they found the casing was marred and that was where it was leaking. The seal itself was intact.... They used some silicone to seal it and they said if that doesn't work the housing will need to be replaced. Considering how many times this happened I wonder if it was the original or second time at the dealer this was replaced where this happened. Now I am glad I stopped going to dealers for repairs completely and this seal issue was a big reason. Now I am wondering what to do long term and the implications of this. Thanks
Ok I jinxed myself and sorry to revive this thread but while changing the oil last night I did my normal checks and found gear oil under the pinion seal again meaning 5th or 6th failure..... I called the same shop and they are saying differential will need to be replaced (the sealant was a last ditch before doing this) so I ordered this on Rockauto. I have basically had it with this differential and I know something bigger is wrong as it blew so many pinion seals, damaged a U-joint/yoke and also blew the left seal a couple months ago. I also checked the fluid level and while it was normal and coming out slowly I noticed the fluid was a bit too clear and very thin almost looking watery. I am so tired of differential issues that I feel I will actually save money in the long run by doing this.
Now they are saying 4 hours labor to do this which I find hard to believe as the truck is built around it . Now my questions:
1. I realize that the wheels, steering components, brakes, hubs, CV shafts etc will need to come off but what else needs to come out to get this out? Can it be done without removing the oil pan or engine?
2. With all that has to be removed and getting close to 50k miles, what else that is being removed should I have replaced at this stage while the truck is in pieces?
3. What other parts other than the differential would I need to buy that is required for the job?
Thanks again...
Now they are saying 4 hours labor to do this which I find hard to believe as the truck is built around it . Now my questions:
1. I realize that the wheels, steering components, brakes, hubs, CV shafts etc will need to come off but what else needs to come out to get this out? Can it be done without removing the oil pan or engine?
2. With all that has to be removed and getting close to 50k miles, what else that is being removed should I have replaced at this stage while the truck is in pieces?
3. What other parts other than the differential would I need to buy that is required for the job?
Thanks again...
m.mcmillen
Member
The oil pan has to be removed to get the differential out. Make sure that you use the recommended AC Delco sealant on the oil pan as it doesn't have a gasket. I stopped by my local GM dealer and they had the sealant in stock. I don't recall it being expensive.
You don't have to remove the brakes and hubs and you don't have to remove the CV axle completely. What I do is unbolt the brake hose and the ABS sensor wiring from the frame to give it more slack and then I pop the upper ball joint out from the upper control arm and separate the outer tie rod end and let everything tilt out. This will give you enough room to pop the CV axle out of the differential.
You don't have to remove the brakes and hubs and you don't have to remove the CV axle completely. What I do is unbolt the brake hose and the ABS sensor wiring from the frame to give it more slack and then I pop the upper ball joint out from the upper control arm and separate the outer tie rod end and let everything tilt out. This will give you enough room to pop the CV axle out of the differential.
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
My front diff was swapped and the oil pan sure was not removed. I know most do not remove the oil pan.
m.mcmillen
Member
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
I went from the bottom and pulled the rack out to get it. Most on ORTB are going at it from the top and only remove a couple things and it will pull up and out.
m.mcmillen
Member
Interesting. I'll have to check into that if I have to pull one again. I rebuilt mine while I had it out so it should be good to go for quite some time.
Mooseman
Moderator
Nobody mentioned the disconnect and the half-shaft that goes through the oil pan. That has to come out using an appropriate bolt and slide hammer.
Thanks for the tips.... I asked them about this earlier to see how they are doing it and they are not removing the oil pan to replace it. Wonder if I should proactively buy parts like wheel bearings.... What fails on these just after 50K? I know my old GMC Jimmy is a nightmare when it comes to front end parts.... As the disconnect also has to be removed does that need to be greased? Thanks
Mounce
Member
Disconnect would greatly benefit from new grease.
Usually things on these make it to at least 100k 9/10 times. You just got a bad apple with the diff. I've got a little over 120k, only thing besides normal maintenence I've done is upper control arms, upper ball joints, cpas, and thermostat.
Regular maintenance items I've done is belt (cracked around 115k), air filter, plugs(due at 100k), fuel filter, and trans service(also due at 100k, but 75k wouldn't hurt it as these transmissions tend to be delicate).
Don't forget about your transfer case service due at 50k. GM Autotrac II fluid required.
Usually things on these make it to at least 100k 9/10 times. You just got a bad apple with the diff. I've got a little over 120k, only thing besides normal maintenence I've done is upper control arms, upper ball joints, cpas, and thermostat.
Regular maintenance items I've done is belt (cracked around 115k), air filter, plugs(due at 100k), fuel filter, and trans service(also due at 100k, but 75k wouldn't hurt it as these transmissions tend to be delicate).
Don't forget about your transfer case service due at 50k. GM Autotrac II fluid required.
Ok that is what I thought....
Bad apple? You mean the diff or the dealer tech who damaged it?
Interesting so these have better components than the S10 series? I am on like my 3rd or 4th set of wheel bearings and ball joints on that one.
Already did the belt/tensioner/idler due to noise. Air filter on mine is a K&N and I change all fluids every year. In fact I just had tranny fluid/filter done on both trucks. Transfer case has been done at least twice in the 36k miles I have had this truck. Thanks
Bad apple? You mean the diff or the dealer tech who damaged it?
Interesting so these have better components than the S10 series? I am on like my 3rd or 4th set of wheel bearings and ball joints on that one.
Already did the belt/tensioner/idler due to noise. Air filter on mine is a K&N and I change all fluids every year. In fact I just had tranny fluid/filter done on both trucks. Transfer case has been done at least twice in the 36k miles I have had this truck. Thanks
Ok an update: One thing after another. First I had to get new side seals because the differential weight was on the inner seal during shipping and bent it badly. I get the car there with the new differential, seals and fluid. Show them everything and what happened to the seal at 8AM. I get a call in the afternoon. It wasn't 4 hours.... They had it mostly apart before they called and said it would be 10+ and there was a mistake... I let them continue since that made sense and I had no reason at the time to doubt that (but did have one to question it) with all the work to get it out.
All done now and had to use a ton of orange degreaser to clean it up tonight. I get to the truck, start it and hear a loud noise like the car had no oil or power steering fluid in it. No puddle on the ground or indications of a failure on the dash. I check under the hood and the fan was barely spinning if at all. Thinking the fan clutch is failing but the car is not overheating I drive it a bit as a test to the car wash just down the road where there was better lighting.
I find the power steering hose bracket in the center under the truck pinned against the circular fan rim, jamming the fan. I am not sure if that damaged anything else other than shave it a bit. Since it only touched metal I don't think it compromised the hoses, but could it have damaged the fan clutch? The fan is spinning slowly at idle but when I turn on the AC or rev it the fan does accelerate. With the engine off I can turn it freely with some resistance but it will not freewheel. I can stop it by hand using a towel and after a minute or two it will speed up without the truck ever going above 210 or throwing a code. Am I looking at another fan clutch or do I need to do more troubleshooting? Thanks
All done now and had to use a ton of orange degreaser to clean it up tonight. I get to the truck, start it and hear a loud noise like the car had no oil or power steering fluid in it. No puddle on the ground or indications of a failure on the dash. I check under the hood and the fan was barely spinning if at all. Thinking the fan clutch is failing but the car is not overheating I drive it a bit as a test to the car wash just down the road where there was better lighting.
I find the power steering hose bracket in the center under the truck pinned against the circular fan rim, jamming the fan. I am not sure if that damaged anything else other than shave it a bit. Since it only touched metal I don't think it compromised the hoses, but could it have damaged the fan clutch? The fan is spinning slowly at idle but when I turn on the AC or rev it the fan does accelerate. With the engine off I can turn it freely with some resistance but it will not freewheel. I can stop it by hand using a towel and after a minute or two it will speed up without the truck ever going above 210 or throwing a code. Am I looking at another fan clutch or do I need to do more troubleshooting? Thanks
Mooseman
Moderator
It sounds like it's working fine. Your tests seem to prove that.
How to test the electro-viscous fan clutch
How to test the electro-viscous fan clutch
Ok perfect on that part but found another problem tonight.... I was driving on the highway and noticed I have to keep the wheel turned left about 10-20 degrees to keep it tracking straight. I put it straight and the yaw input was enough to cause the car to make a quick lane change. I just had this car aligned during the summer and I knew it was driving well before this.... Looks like this caused alot more problems than it fixed and maybe I should have just lived with a leak...
m.mcmillen
Member
I would be back at the shop that did the work and make them fix it right. They screwed something up.
Just did about an hour ago to check the fan and steering wheel.... I wonder if they put the steering shaft in wrong. They did an alignment a few months ago and it was perfect before this.
Fixed, no damage to the fan and alignment was WAY off for some reason.... Going to test it on the highway later to verify but hopefully I can consider this case closed...
Alignment was good the whole weekend (800 miles of driving) but noticed when I was replacing a power steering hose (rubber part of the line between the return line from the rack to the cooler, started dripping on the ground on the last leg of the trip. One I replaced before for leaking at the opposite end of it) that there was a drop of gear oil under the front end directly below the differential and wiped that part. I went out this morning and saw the same thing. I cannot find any leaks from the side seals or the pinion seal (as far as I can see) but it feels like it is coming from behind that spot. I am hoping not the case sealant since this is a reman differential and they used plenty of sealant. I sprayed the exposed part of the differential the same night I got the truck back with orange degreaser and hosed it down so maybe I missed a spot (hopefully) and this is residual oil flowing downward from when it was handled? I made an appointment to recheck it.
EDIT: They hosed the whole thing down with brake cleaner yesterday and I rechecked today. Same thing.... Where else could this be leaking from?
EDIT: They hosed the whole thing down with brake cleaner yesterday and I rechecked today. Same thing.... Where else could this be leaking from?
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Ok worst fear realized in this case.... The differential case halves are leaking. Whole thing has to be redone with a replacement part so I am out alot more $$$ now.... Not sure I want to do that from the same place considering the quality of the part I was sent but use their refund policy. Anyone have a suggestion of where I can get a better remanufactured differential?
I just don't want to go through this again.... I just want this issue fixed so I am not topping up fluids or dripping gear oil the ground. Enough of a headache as is and another concrete lesson on the importance of using local independent repair shops in my personal opinion...
EDIT: If I have to go through this again, how much more work would it be if I bought another diff with 3.73 or 4.10 gears and had the rear differential regeared in the process? Especially if I eventually plan to lift this truck and put larger tires on it. Thanks
I just don't want to go through this again.... I just want this issue fixed so I am not topping up fluids or dripping gear oil the ground. Enough of a headache as is and another concrete lesson on the importance of using local independent repair shops in my personal opinion...
EDIT: If I have to go through this again, how much more work would it be if I bought another diff with 3.73 or 4.10 gears and had the rear differential regeared in the process? Especially if I eventually plan to lift this truck and put larger tires on it. Thanks
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Mooseman
Moderator
That sucks big time. The case itself is probably fine. Just needs to be cracked open and re-sealed. I know the first year there were issues with the front diff case leaking due to a mounting bolt shim issue (there was a TSB on it) but by '07 should not be an issue unless they used an '02 case if it was replaced. There was a mounting bolt case design change at some point, either late '02 or in '03 where they added a bolt hole below the pinion.
Well, if you want to change gears, this would be an opportune time to do it. 4.10 gears are harder to find but 3.73 should be fairly common. Reprogramming the PCM for the gearing and speedo change is possible.
Well, if you want to change gears, this would be an opportune time to do it. 4.10 gears are harder to find but 3.73 should be fairly common. Reprogramming the PCM for the gearing and speedo change is possible.
Wait a minute.... is this the one vs two bolt hole design change? Mine had two but one was filled with junk so I did not see it and I ended up getting the one hole model. When I get the replacement should I get the two hole?
In terms of regearing if I am going to lift this truck and oversize the tires a bit which one would be best without killing my gas mileage more and still work great at high speeds? Provided that the PCM is adjusted, what other implications are there with regearing? Thanks
In terms of regearing if I am going to lift this truck and oversize the tires a bit which one would be best without killing my gas mileage more and still work great at high speeds? Provided that the PCM is adjusted, what other implications are there with regearing? Thanks
Mooseman
Moderator
Yes. The one hole is the one with the leak issues.
I am not well versed on this so I will defer to @HARDTRAILZ since he's more into that.
Ok, after talking with the local shop not only are the parts not easily available for this it is more work and expense than it is worth for what I am doing. As I am planning on putting 31.56" tires (265/65R18) on it eventually it still fits the gear ratio chart on OffroadTB but in the pink range. As I have a transmission cooler there are no negative implications, correct? If not, I am just going to leave it the same for now and fix the leak..... Thanks all for the tips anyway. I ordered the two bolt hole part today so hopefully this finally brings closure to this.
It doesn't end, does it? I received the new part today and I was not a fan of how it was packaged. While it does not appear to have any damage other than the inner seal getting bent again, I noticed that the pinion yoke is a bit difficult to turn by hand. At first it felt like there was a hard spot but I cannot find it now. Is that just because it was just rebuilt and there is no oil in it or could there have been internal damage during shipping?
m.mcmillen
Member
From the manual:
The rotating torque of the pinion and differential assembly should be 3.4-6.2 Nm (30-55 lb in) for new bearings or 2.8-5.1 Nm (25-45 lb in) for used bearings.
The rotating torque of the pinion and differential assembly should be 3.4-6.2 Nm (30-55 lb in) for new bearings or 2.8-5.1 Nm (25-45 lb in) for used bearings.
Ok so revisiting again..... During an oil change I found a drop of gear oil on the same place (just under pinion seal) again on the second replacement differential... I wiped it down but I have not been under the truck since it was replaced so possible residual a month later even after washing the undercarriage? Shop could not find anything but this housing cannot be scored in the same manner right?
I feel like its one of those items that are going to be constantly leaking on all of our vehicles just like the inner axle seals at one point or another. From the picture shown above, it looks like there is oil coating other areas as well on the side there maybe from where you sprayed? Or is the drip coming from above there and settling down to the bottom of the case. I have dealt with the same issue as well and it ended up being a simple seal. I'd hate to see the diff taken out again, but the shop should do it all for free if you covered the diff or just a reseal
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At the moment there is oil all under the diff but that was from a diff fluid change on Wednesday and they could not find the leak I found because it was wet out but I see that same drop again at the very back of the differential as before.... I noticed that the vent hose migrated to being stuck between the power steering lines in the wheelwell so is it possible dirt got in it and blocked it causing the pinion seal to leak again? How much pressure does it really take? What does it take to clean the vent out or should I replace it? Thanks
AWD V8
Member
- Jan 12, 2015
- 463
It don't know how much pressure it takes, but if the diff can't breath it will blow oil out somewhere, axle seals or pinion seal.
Remove the fill plug. Remove the vent hose from where it is attached to the chassis. Blow into the vent hose. It should be clear. If you can't blow through it, that is your problem.
Remove the fill plug. Remove the vent hose from where it is attached to the chassis. Blow into the vent hose. It should be clear. If you can't blow through it, that is your problem.
Ok thanks. I am going to make a followup appointment to check that since I can't get in there easily. If it is clogged and can be cleared what is next? Another pinion seal?
I did a thorough degrease with orange degreaser at the car wash and used the low setting on the pressure washer. Drove the car to let it dry and rechecked. Confirmed it is from the bottom of unit. Another wet gear oil drop formed. How easy is it for water to enter the vent using a pressure washer? I noticed that the whole wheelwell and the vent hose all the way to the cap was wet when I was done.... Thanks
I did a thorough degrease with orange degreaser at the car wash and used the low setting on the pressure washer. Drove the car to let it dry and rechecked. Confirmed it is from the bottom of unit. Another wet gear oil drop formed. How easy is it for water to enter the vent using a pressure washer? I noticed that the whole wheelwell and the vent hose all the way to the cap was wet when I was done.... Thanks