Stubborn RMS leak...'91 964 Turbo

[yasir]

I started a similar thread in the Turbo section as well but thought It won't hurt to ask in this section too.


Is there a protocol procedure of diagnosing a recurring RMS oil leak? Shop installed RMS twice and both time it leaked.

1)- Shop thought that both times the seals were installed correctly yet it leaked?

2)- Should they not have checked the thrust bearing end play/crank play to see if that's the culprit?

I was talking to a local friend who builds motors and was told, regardless of the cause, when they were changing the RMS with the motor out, they should have checked the thrust bearings/camshaft/crank play (sorry for my ignorance here but that's what I understood)?

Shop refused to drop the motor second time around to see if there was any other issue causing the leak

They advised ase be split open to see where the problem is?

Please advice?

[DSPTurtle]

Well, if I were you, I'd bring it to your "local friend" who can measure camshaft play, back at the RMS. Clearly that dude is a magician!
Seriously though, why didn't you just get your friend to fix the problem? (You've posted this question all over the Internet so maybe I'm asking you this question on the wrong thread)

[yasir]

It's technical question and I need to know what the accurate answer is?

[911nut]

It's going to require another engine-out inspection, I'm afraid.
Until then we are all just guessing.

[KTL]

Rear main seal leaks are not that common on these engines. So it should be a straightforward repair if it is indeed the rear main seal leaking.

Ask the shop if they noticed the crank had excessive wear on the seal contact surface. If so, the new seal should be installed at a different depth to avoid riding on the area where the groove occurs.

Did they use any sort of lubricant on the seal perimeter to ease its installation? If so, often times this lube can allow the seal to walk out and leak.

The crank end play is not adjustable. The #1 main bearing has thrust surfaces on it to contain the crank's thrust movement. Plus, the seal is installed quite deep into the bore such that any crank movement, if present, would still be captured by the seal.

Are they certain its the crankshaft seal and not the transmission input shaft seal? Sounds ridiculous to say this, but you never know. As long as you're certain the oil leak you're finding is not gear oil, then its not the transmission input shaft seal. Gear oil has a distinct smell to it.

[zelrik911]

Perhaps the crankshaft has a groove worn into it where the oil seal tip makes contact? If new seals are put back into exactly the same position, then the leak will reoccur.
Kevin is correct in that the new seal may be able to be moved slightly so it touches an unworn part of the shaft. In very bad cases a thin sleeve is pushed onto the shaft and the seal tip will rub on this.

Is it a high mileage motor?

[yasir]

Originally Posted by zelrik911

Perhaps the crankshaft has a groove worn into it where the oil seal tip makes contact? If new seals are put back into exactly the same position, then the leak will reoccur.
Kevin is correct in that the new seal may be able to be moved slightly so it touches an unworn part of the shaft. In very bad cases a thin sleeve is pushed onto the shaft and the seal tip will rub on this.

Is it a high mileage motor?

40,000 leisure miles

In all honesty, I am not too sure how it was all done.

Shop told me, the seal was installed correctly and that was it

[AlfonsoR]

Crank seals, especially in these engines, can be finicky. They shouldn't be, but they can be.

Best case, it's simply a matter of installing the seal at a different depth than original. On my wife's e39, I installed a front crank seal. I had assumed that the seal or garter spring was simply worn since I could detect no worn area on the crank. A couple of days after installation, checking to make sure everything is good, I discovered the leak, about a drop every 5 seconds or so. I thought, hmmm I must have just missed some worn spot obviously. I got all the tools and a new seal ready to go, ready to do the job about 2 weeks after discovering it was leaking, then I noticed it leaked no more. Now 10,000 miles later, still no leak.

Worst case, you have excessive radial runout or possibly thrust or a combination of the two. In that case, yes, it will mean splitting the case to repair.

So, your engine has 40,000 miles since rebuild, then you got a RMS leak. You had the shop replace the seal, but it still leaks. Is that the correct sequence?

[yasir]

Car currently has 40,000. Was sent to the shop 1000 miles away for nagging slight RMS oil leak along with an engine out service.

Shop does an engine out service and 6 months later sends the car back.

First drive and the oil leak is back.

Shop picls up the car and finds out it is the RMS

Replaces the RMS seal with out dropping the motor.

I was told I now have two issues and mind it, this is after they have the car for almost 10 months.


1)- There's a slight leak coming from the front of the motor and it is the case and needs to be split open

2)- The RMS still persists and it is something inside the case that's causing it and once again the case needs to be split open.

Why did they not diagnose the case leaking the first time when the motor was out?

Should they not have dropped the motor the second time when they had the car to diagnose it more appropriately?

[KTL]

Originally Posted by yasir

Replaces the RMS seal with out dropping the motor.

I was told I now have two issues and mind it, this is after they have the car for almost 10 months.


1)- There's a slight leak coming from the front of the motor and it is the case and needs to be split open

2)- The RMS still persists and it is something inside the case that's causing it and once again the case needs to be split open.

Why did they not diagnose the case leaking the first time when the motor was out?

Should they not have dropped the motor the second time when they had the car to diagnose it more appropriately?

You need to find a new shop if they claim to have replaced the crank seal at the flywheel end w/out dropping the motor. Either they did it by taking out the trans instead (not easy to do with a G50 trans, but it can be done) or they're not telling you the truth, or you've got your information/parts mixed up.

The other seal is at the pulley end of the engine. That one can indeed be replaced with the engine still in place. But if they did replace it and a leak still exists, they can indeed be correct that something else inside the engine is amiss. The crankshaft seal at the pulley end is often thought to be leaking when in fact it is the engine case itself leaking due to the o-ring around the number 8 crankshaft main bearing that leaks. Only way to fix that o-ring is by splitting the engine case.

If it is indeed the #8 o-ring leaking, I don't fault them too much for thinking it was the crank end seal. It's a very common assumption for people to tackle the crank end seal. The challenge is that it is hard to test the seal after replacing it. One should really run the engine before putting all of the surrounding parts (engine support structure and exhaust system) but that's just not easy to do because you need that stuff in place to run the engine.

So my opinion is they're not being off-base telling you there's another source of the leak. But 10 months to diagnose the issue is unacceptable and I would find another shop for future work.

[royjeep98]

Yasir its roy following this to

[yasir]

Hey Roy,

Good to see you on the site

Originally Posted by KTL

You need to find a new shop if they claim to have replaced the crank seal at the flywheel end w/out dropping the motor. Either they did it by taking out the trans instead (not easy to do with a G50 trans, but it can be done) or they're not telling you the truth, or you've got your information/parts mixed up.

The other seal is at the pulley end of the engine. That one can indeed be replaced with the engine still in place. But if they did replace it and a leak still exists, they can indeed be correct that something else inside the engine is amiss. The crankshaft seal at the pulley end is often thought to be leaking when in fact it is the engine case itself leaking due to the o-ring around the number 8 crankshaft main bearing that leaks. Only way to fix that o-ring is by splitting the engine case.

If it is indeed the #8 o-ring leaking, I don't fault them too much for thinking it was the crank end seal. It's a very common assumption for people to tackle the crank end seal. The challenge is that it is hard to test the seal after replacing it. One should really run the engine before putting all of the surrounding parts (engine support structure and exhaust system) but that's just not easy to do because you need that stuff in place to run the engine.

So my opinion is they're not being off-base telling you there's another source of the leak. But 10 months to diagnose the issue is unacceptable and I would find another shop for future work.

Going over the emails I realized that he did indeed removed the transmission and re-positioned the seal but It's still leaking.

Towards the tail end of the repairs (after 10 months), I was told that there's now a small oil leak on the pulley end (opposite to RMS?) but I was told the dye test showed coming from a case itself, so no repairs were mentioned besides splitting the case open.

My gripe is, when I got the car after 6 months and before they took the car back, I noticed there's oil leak on both ends of the motor. Infact, I even have an estimate from Porsche from even prior to sending them the car with leak on both ends.

I am surprised why they did not look into it until the very end.

[AlfonsoR]

It's a tough call. You may want to have another shop try a new seal once more, but it is obviously no guarantee that the leak will be fixed.

There is also this... SKF SPEEDI-SLEEVE - SKF.com/Products

I have not used this, but I have seen it mentioned here.

Good luck