Nagging oil leak at front seal

[AndreasLanghoff]

Have a look at an older thread, I had the same oil seal problem:

nose 8 bearing o-ring leak

Good luck
Andreas

[Rob 930]

I finally have my engine home after tuning and am now going to get serious about finding and fixing the oil leak at the crankshaft seal. I did some more diagnosis, but I still can't find the source of the leak -- even with 15 psi of air in the crankcase and a spray bottle of soapy water. My suspicion is that it is indeed the crankshaft seal, and that the oil is getting past the seal lip where it contacts the crank. I believe this is true because during one of the seal installations, red assembly lube was used on the crank at that location, and the first oil to drip on the pan was red in color.

I removed the seal and looked carefully at the cranshaft surface. There is a small groove in it, likely where the seal had previously been running. I hadn't noticed this before. I believe (read: hope) this surface may be the culprit. However, I really can't explain why a) it didn't leak before this build, b) it did leak on this build even after three different seal installations locations, c) it didn't leak until hot and d) I couldn't find it with air pressure and soap.

Nevertheless, I'm likely to try the Speedi Sleeve, as suggested by Tristan and Jim Sims (thanks, guys), in conjunction with a new seal. The seal this time was ordered from the dealer; I don't yet know the color or brand.

Question: Does anyone have first-hand experience with the use of a Speedi Sleeve on a 9 bolt crankshaft? I'd like to know exactly what part number is appropriate. Based on my measurements, it looks like part number 99353 is the right one. Is it okay to just install it and leave the installation flange attached to the sleeve (with the installation flange facing toward the engine case)? It looks like that should work. Jim, I didn't understand why Ted would have to cut clearance counterbore on the flywheel to make it work -- it seems to me that the flywheel should fit around the end of the crankshaft and sleeve, but I haven't measured to confirm. The sleeve is only 0.011 in. thick. Is the flywheel/crankshaft fit so accurate that it can't accommodate the thin sleeve?

Rob

[Jim Sims]

"Is the flywheel/crankshaft fit so accurate that it can't accommodate the thin sleeve?"

On the five-bolt crank/flywheel joint it was; the other possibility was trimming back the sleeve with a knife but Ted was uncomfortable about what kind of edge this would leave. So he decided to counter-bore the flywheel in addition to the usual flywheel re-facing.

I simply followed the CR Speedi- sleeve directions and selected the best size sleeve for the dimensions of the crank seal land. What are the dimensions (diameter and length) of your crank rear main seal land? I'll check the sleeve number you selected.

[Rob 930]

Jim,

The diameter is 3.540 - 3.541 in.; the length is about 0.72 in. The length is a bit harder to measure, because it requires some guesswork, since I'm measuring "down a hole" of sorts. The distance from the flywheel face of the crank to the surface on engine case directly behind the crank is 0.82 in. That's a number I'm more certain of.

Do you know if Ted left the installation flange on the Speedi-sleeve, or did he somehow remove it? With the crank installed in the engine, it will be nearly impossible to remove it. Do you see a problem with leaving the installation flange on the sleeve?

Thanks for your thoughts on this.

Rob

[Jim Sims]

I don't remember if he left the flange or not. I don't see a problem leaving it in place; it will simply be in against the oil slinger. A more significant question regarding an in-situ installation is whether there is clearance for the 4.000" outside diameter of the flange and the installation tool? 99353 looks like it's okay provided it projects far enough to cover the location where the oil seal will run; don't forget to include the .125 radius of the flange in the projection calculations. If this works, it may clear the flywheel counter-bore. If you need a longer sleeve surface (more projection) then 99351 could be considered.

[Rob 930]

Hi Jim,

I think I'll be okay from the standpoint of the 4.000 in. flange OD. The seal bore ID is 4.27 in., so the flange should clear, though barely. The shorter sleeve (99353) should be long enough to cover the affected area. The problem with the 99351 is that it's too long, and when installed to the correct depth, the end of the sleeve will overhang the end of the crank. I don't know how to safely trim it. It's thin (0.011 in.), but it's stainless steel, so I probably can't just use a knife. I sure hate to go hacking at it with a Dremel tool or some other power tool. Ideally, the crank would be out of the engine, then it could be neatly trimmed off on a crankshaft lathe. But I don't have that luxury. So, I'm thinking the shorter 99353 sleeve will work okay. It's long enough.

But here's the scary part, and it may cause me to rethink this. To install that sleeve, it has to get hammered on with a pipe-like installation tool. If I hammer it on too far, the flange will contact the engine case. That would be disastrous. There's no oil slinger on the crank. And because I need to have the crankshaft seal ride on the flat portion of the sleeve, I'd have to drive that sleeve (and flange) very close to the engine case. To fix it, I'd have to disassemble the engine, because that sleeve is a press fit, and it isn't just going to slide back off. Furthermore, it's really hard to see where you are once you start installing it. The more I think about it, the less sure I am that this is a good idea on an assembled engine...

The other option I'm considering is to "tighten" the spring on the factory crank seal by removing the spring from it, "unscrewing" it where it is joined, cutting off 4 mm of the spring, and reinstalling it. I hear that's a trick that has been used with success in similar situations. If I do that, I'll work to make sure that the sealing lip is not riding anywhere near the existing "groove" I already have in the crank.

[briankeithsmith]

Good luck Rob!

Its kinda funny how so many of us have trouble with the flywheel seal. Its like there is some special way of doing it that noone has shown us yet.

Brian

[Rob 930]

Brian,

What's strange is how so many experienced machinists and engine builders have said they *never* have problems with the seal on 9 bolt crankshafts. My problem is that I'm not absolutely sure that the crank/seal interface is leaking. There are other possibilities. But none seem as likely, given the symptoms I've experienced. It's a particularly difficult area to assess, because it's hidden from view during operation, and the proximity of a spinning flyweel tends to redistribute oil and obscure the real source of the leak. The leak on my engine only occurs when the engine has run for a while, so it apparently has to be warm. To re-create those conditions with the engine out is not easy. And each iteration to test a solution is a big deal -- it means installing the engine, hooking everything up, filling with oil, and running it. If the fix isn't successful, you have to start over. Even worse than that is the thought that I might resort to disassembling the engine to "reseal" it, only to find after reassembly that I still have a leak! I don't want to disassemble, and at this point I don't think I need to, but I'm certainly not going to do so until I'm sure what's causing the leak.

[Rob 930]

Folks,

My oil leak problem has been resolved. I installed a new seal from the dealer (black, made by KACO), but I first shortened the spring in the seal 4 mm. This is done by removing the spring, from the seal "unscrewing" the point where the straight spring is joined to make it a circle, and by cutting off a length of the spring. I used a diamond cutoff wheel used for metallurgical specimen preparation. It's important to cut off the "open" end of the spring (not the conical end), so it can be "threaded" back together. In addition, I made sure the case surfaces were clean and smooth. There were a couple burrs that needed attention. And I sparingly used a green Wurth sealer, not too different from Loctite 574, around the seal perimeter. The seal was installed using a hammer, gently, and placing the outboard edge of the seal flush with the flange on the case.

After this fix, not a drop of oil is leaking. I really don't know why it leaked before; that's the big mystery. But hey, I'll take this as success and move on.

[briankeithsmith]

Congrats! We have a winner! Way to go Rob! Seems like you are the first one I've talked to that's had success in this area!!!

Brian

[adomakin]

at last!

[sand_man]

Glad it's fixed, Rob!!!! Here's to hoping it stays that way!