Nagging oil leak at front seal

[Rob 930]

Thanks cgarr. That aluminum plug even *looks* suspect from your photo (even though it may be fine). There's certainly no harm in putting some sealer over it. I'm surprised to see that roll pin in the crank bolt circle; I don't recall that on my engine.

I'll let you know the results of my oil leak situation once we have some to share.

[len911]

When I did my son's 944, and installed the seal flush with the edge of the case, it leaked. Ended up having to go in and redo. On my last eng a 3.2, I decided to do the same thing as the 944. Well, I screwed up! Had a massive leak as soon as I turned the engine on after the rebuild. Had to go in and install a new seal flush with the case. Holding up nicely now... Learned my lesson... Pictures included... Lou

[MBEngineering]

HI you need the seal in the poss' in the above photo, flush with the case, if it is in to far the oil return holes in the crankcase are ristricted buy the back of the oil seal and the oil pressure will pop the seal lip, if the plug in the crank is leaking the flywheel will be wet?? also if the plug has been damaged in the cleaning prosess i would not give much hope for the rest of the plugs in the crank. good luck

regards mike

[cgarr]

Any luck with it Rob? What kind of crank case venting do you have, If I close my case Vent/Vacuum line off I can get mine to leak, they dont pull much but it must be enough so there is not any pressure..

[briankeithsmith]

FWIW: I've rebuilt my engine 3 times, and every time, my flywheel seal has leaked. After the first time rebuilding, we almost immediately pulled the engine to fix the flywheel seal, found nothing wrong, installed new seal with different sealants, and same problem. I think each time we've tried something different according to different recommendations, and each time we've had the same result. Also, mine doesn't leak once the engine gets good and warm.

Brian

[Rob 930]

Hmmm. This isn't looking good. The crankshaft plug was covered with silicone sealer and the flywheel was bolted on. Everything was cleaned up, and it was run on the dyno stand. The engine was run for 10 to 15 minutes, at revs of 2000 RPM or less. Oil temp got to 150 deg F at least. At the end of the run, there was a 2 in. dia spot on the pan just below the crankshaft seal.

I'm not sure what to do. We may pressurize it with air and look for bubbles somewhere.

Cgarr, my venting is stock -- out the breather cover. That's all. I haven't experimented with anything else. Did you find that if you had positive crankcase pressure (i.e., inadequate venting), that yours would leak? How much did it leak, do you recall? I can accept a drop every day or two, but a drop or two every minute is not acceptable!

Brian, I think I remember hearing you had trouble with your seal(s). Did you ever solve the problem? What suggestions did you try? Which ones seemed to work? Mine seems not to abate at higher temps. If anything, it gets worse. I'm not sure where this is going...

[briankeithsmith]

Rob:

Here are the different methods I used:
1. Curil-T on the outside edge of the seal- recessed a little below the case
2. Aviation Sealant on the outside edge of the seal - installed flush with the case
3. Curil-T again, pressing the seal in so that it is flush with the case.

Neither one worked. They all leaked, and still leak today.

I guess the engine knows now that it's a race engine and believes that it has the right to leak....

Brian

[sand_man]

You guys are really freaking me out! I'm due to start assembly on my engine next week! I DO NOT WANT OIL LEAKS!!!! FWIW, I've heard that oil leaks from the crank main seal on the 9-bolt cranks are rare! Something is not right...obviously! Please keep us posted, Rob. If I stumble onto anything, I'll be sure to notify you.

Jeff

[briankeithsmith]

Not rare to me. I'm 3 for 3.

Brian

[sand_man]

Originally posted by briankeithsmith
Not rare to me. I'm 3 for 3.

Brian

Race cars don't count! That's a special "oil slick" feature to keep your competitors from closing in on you

[briankeithsmith]

My leak isn't that bad in reality. Now when it sits in the shop or driveway and warms up it will leave a few drips. After the first session of the day though, its dry. Mine just has to get good and warm, and I guess the seal/crank have to expand a little.

Brian

[adomakin]

any news rob? good to hear you finally got your engine together but what a nitemare with the leak. hope this isn't taking it too off topic but have you got any pics of the engine complete but out of the car?

[Ho Hum 74]

I had this issue with my 2.7. I replaced the seal 3 times then gave it to a "pro". He also replaced it more than once and each time it leaked. It's an issue because it leaks over the heat exchangers and starts pluming smoke on the track - not good.

My guy then took a closer look at the surface of the crank (it was a different crank than the original) and noticed a small groove. I never saw it and the crank was polished by a machine shop. He played around with various locations of the seal on the crank and eventually found one that worked. It has not leaked since.

Now there is another way: Apparently you can buy a small, super thin sleeve that fits over the crank and creates a new mating surface. You can then buy slightly enlarged seal and that should create a perfect mating surface. I'm not sure where you get these but they are available.

I sure hope you get it fixed, I know how frustrated you must be.

Best of luck
Tristan

[Rob 930]

Guys,

No progress yet. The engine is out of my hands right now on the dynamometer. It needs another day on the dyno. The tuner has been trying to help diagnose the oil leak problem too. All I know is that the problem was not the crankshaft oil gallery plug. There are a number of other possibilities, including the seal itself, a couple of crankcase gallery plugs, and of course, the case sealing surfaces. I'm hoping it's not the latter. But I'll find the problem and fix it, wherever it is. Just another bump in this long journey.

Tristan, I haven't heard of a sleeve option on the end of the crank. I assume this is something that is done with the engine apart? The crank and case were professionally prepared and assembled, so I have a hard time believing there is anything seriously wrong with the crank and case in that area. But it is what it is, and I'll deal with it after the tuning is complete. If it means taking it down to the crank again, much as I don't want to do that, so be it.

Andy, you asked for pictures. Here are a couple -- one on the stand, and one on the dyno.

Rob

[Ho Hum 74]

I was told it could be done with the engine in 1 piece...

[Jim Sims]

If the the crankshaft sealing surface is grooved/worn/cracked under the seal location then the below repair sleeves can be used without a change in seal size. Ted Robinson of German Precision installed one on a 2.4l crankshaft he had polished/repaired for me. The sleeve can usually be installed in situ and the kit comes with the installation tool. Rather than trim the excess speedi-sleeve per the usual installation method Ted elected to do a minor clearance counter-bore on the flywheel. I ordered the speed-sleeve through the local NAPA store.


http://www2.chicago-rawhide.com/speedi_sleeves.htm

[Ho Hum 74]

There you go! Thanks Jim, that's what I was thinking of.

[CBRacerX]

Wow. The speedi-sleeve is an excellent option!

[adomakin]

great looking engine rob, can't remember the spec, could you give me a quick run down? also, wheres the intercooler from?

[Rob 930]

Andy,

The engine is a 3.4 liter, with 7.33:1 Mahle p/cs, extensively ported and modified heads, Holcombe exhaust, Garrett T-66 by Kevin, GT2 Evo cams, flowed Carrera manifolds, 70 mm throttle body, DTA ECU, and all the usual mods for longevity. We've so far seen 600 ft-lb on the dyno and 600 hp, but we're not done yet. The IC was made by Joe Essa's shop a number of years ago.

Rob