Crank seal loose - sticking out a few mm
 

I'm in the process of replacing the belts and I knew my upper balance shaft seal was leaking, but when I pulled the crank pulleys I found that the crank seal was protruding quite a bit. I can't tell if it was leaking because the area is coveted in oil anyway from the BS leak. I nudged it with a pick and it was very loose. After removing the oil pump drive gear, the seal came out effortlessly. It's the right size: 38x52x7 mm. Is it supposed to be that loose? I seem to remember it wasn't that easy to get it in there when I installed it 3 1/2 years ago. Obviously I'll replace it now but I wonder if the fact that it's loose is going to be a problem.


https://cimg6.ibsrv.net/gimg/rennlis...5a1d094ee3.jpg

it takes some force to press it in. You need to replace the seal before you button the car up, and also inspect the oil pump drive gear for any wear marks. Be sure and order a new green O-ring too for the crankshaft. No way I'd try and reuse that seal, it's obviously shrunk from age and more than likely leaking way more than you realize.

In my experience, when one of the front end seals start to leak, the other's all need replacement too. Sounds like it's a good time to do a new water pump and also do the cam seals and the other balance shaft.

I didn't think it would have shrunk after this long. I mean, this is pretty much the recommended belt interval, maybe a little longer, but I wasn't expecting to have to do the whole re-seal that often.

I've been wondering if there could be a difference between the aftermarket seal and the OEM ones. And then I came across this!

https://rennlist.com/forums/924-931-...ket-seals.html

Apparently the OEM one is marked as 52.2. I think I will get one from my local Porsche dealer and compare with a digital caliper, although I don't have a new aftermarket one to hand, only this old one.

Now I'm worried about the aftermarket balance shaft seals I was going to install too. They're Reinz, but I can't remember what brand the crank seal I used last time was.

I just did mine a few weeks ago, I used kaco for the front crank seal. when was the last time you did front seals? if the job was done right they should last at least 8 years at a minimum in my opinion.

3 and a half years ago.

Was the front seal hard to press in? They really shouldn't go in easy, I've done front reseal jobs on several cars and I've always had to tap the seal in with a piece of wood and a hammer. The balance shaft and cam seals are the same way. Remember that they have to seal oil at 75+ psi.

Early oil pumps take the smaller 52mm OD seal I believe, later gets the larger 55mm OD. There should be a date stamp on the front of the oil pump or just measure.

Right idea but you have it backwards.

-84 is the 38 x 55 x 7

The others are 38 x 52 x 7

In regards to the Victor Reinz gaskets, tons of people use those engine reseal kits from them (I know I have). Perhaps that specific case the seal was slightly damaged when it was installed, mating surface was not clean or it was a quality control problem. Of course it stinks to have to do the process again but since you were already digging around doing the belts it was worth the extra little effort.

Same here and the oil pump sleeve gets changed every other time. Not that it has a "fingernail" groove but because it just is not perfectly smooth and a few drops of oil appear on the front of the oil pan.

J_AZ

Yeah it's definitely the 52 according to the PET catalog. I just ordered a new one (and the o-ring too) from the local dealer. I thought about the balance shaft seals but the dealer prices are nuts so I'll take my chances with the Victor Reinz ones I have. I don't know what brand the crank seal I used last time was so maybe it was something else.

Up until today I had no idea there were two different size crank seals. I used the 38 x 55 x 7 on my 83 engine so I got that right and it was a snug fit. Was a change in the oil pump dimensions what caused this? is the oil pump drive sleeve interchangeable for all years? For the drive gear, The PET shows #944-107-161-02 for 83, and 944-107-161-03 for 84 onward. That doesnt match up with the cutoff for the different crank seal so what's going on? I used an oil pump drive gear from an 86 on my 83 pump and I want to be sure it will be ok.

My understanding is that main oil pump difference is the offset between the driven gear within the pump and the back of the housing. The drive sleeve should be the same. I would think you'd instantly know if you weren't engaging the driven gear splines, or not having it recessed enough against the crank.

That's pretty much the conclusion I came to as well, but from what I can gather the drive sleeves did undergo a slight revision in mid 84, though it seems they are compatible for all years.

With respect to the change in the gear offset of the pump: oil pumps are a constant volume pump like a supercharger, they displace the same volume of fluid with each revolution and rely on rotational speed to change volumetric flow/time. Did the increase in gear offset essentially increase the volume flow of the pump? I know you know way more about our pumps than I do from that project you did ;)

So basically what happened is in 9/1984 Porsche changed the mounting boss size on the oil pump to 30mm from 43mm for the stud and collar nut resulting in better belt alignment. At the same time they modified the design to increase delivery rate, and the intake bore in the crankcase lower section diameter was increased.

Just got the OEM seal today. It is marked 52.2 just like the other thread said. I measure them at 51.9 (old one) and 52.2 (new one). But the old one tapers a bit more towards the rear.

The only other difference I can see is that the OEM one is mostly metal with rubber or whatever it is covering only the front and halfway along the edge. The one I removed from the car has no exposed metal and I'm not sure if it is made of metal at all inside.


Old one:


https://cimg1.ibsrv.net/gimg/rennlis...a0d8961deb.jpg


OEM one:

https://cimg2.ibsrv.net/gimg/rennlis...3463f274d0.jpg