roco16

Some of you may have read the thread Beautiful Saturday gone bad describing my costly ruptured oil pan incident, and all the legal stuff that ensued. Well, this is a continuation of my plight, but under a different pretense.

After the accident, I replaced the oil pan, op gasket, motor mounts, rod bearings, rod nuts, intake manifold gaskets, updated windage tray, updated idle octopus, bypassed the cycling valve, new spark plugs, all bolts replaced with brand new 10.9 grade bolts, installed LR vacuum lines, and wrapped the cross-over pipe with Thermotec exhaust wrap. Big thanks to Ian at 944Online and Dave at Lindsey Racing.

The car was running like a top for about 120 miles while I was taking it easy to break in the rod bearings (no more than 3psi of boost), before the oil pan gasket blew and started a small fire on my crossover pipe. Thankfully I was able to put it out quickly and clean off the corrosive powder before any permanent damage occured. So, I ordered another gasket, and the EuroParts ETC oil pan gasket retention rail for fixing this weekend(very nice piece, I might add).

The blown gasket bothered me, as this was the second time I replaced the op gasket, and the workmanship being far more shoddy the first time. As per the wonderful thread "Dreaded oil pan gasket bulge", I used the 3M spray to seat the gasket onto both completely dry surfaces. The gasket installed beautifully, with minimal swelling as the pan was torqued to 3, then 6 ftlbs.

After blowing the gasket I checked my compression (first time) : 140, 145, 140, 130. Also, each removed spark plug was nicely blackened, way more so than the old plugs I removed when I was replacing the pan.

Why did my gasket blow on a textbook operation? Are they that finicky? The low compression on #4 certainly was there before the accident.

The only culprit I can think of is my Air/Oil seperator unit (which was working fine before, I assume), because when I installed the new hoses, I ran a line from the black fitting on the valve to the ~J boot on my MAF pipe. See pic.

Thanks for the tips, and forgive me for the lengthy post.

Robert Combier

B951S

Good question Robert, as you probably know from the thread you mentioned, I tried all kinds of glues etc. Right now I use the dowl pins and a gasket retainer and its tight as a drum after a few throusand miles and 18psi boost. The last install was bone dry. My compression was good also but there was a few people insisting I was building crank case pressure which I am sure I was not. I guess they are just finicky. Hope this one lasts for you.

Peckster

Who's selling those retainer brackets? I just saw them last week.

roco16

Steven Wistuba sells them (Steven.Wistuba@ypg.com, Europarts ETC) for 65.00 including shipping. I have the pieces here on my desk and the workmanship is dandy. There is a big post on it for more info.

B951S-
How can I build crankcase pressure with the air/oil seperator? Isnt that analogous to a PCV valve?

Is having 130psi on #4 low enough to indicate significant blowby to push out an oil pan gasket?

Back to the garage.....
-Robert

roco16

I checked my MAF elbow and the section aft of the Air/Oil Seperator is really oily. Is this an indication that my AOS is functioning well?

B951S

Not necessarily. That is just oil carry over from the seprator. Take your hose off where is comes from the oil separator to the inlet boot and blow down it with the oil filler cap off. It should be easy to blow air through it into the crankase and out of the oil filler. If it is not, then there is a restriction. A restiction is bad in that under boost the entire crankase will pressurize and the weakest seal with give. I have always been astounded that the oil pan gasket which is under compression would give before the rear main lip seal. 951's dont have a PCV as such but the crakcase gasses are constantly run through the separator to knock out the oil and then fed back into the intake to burn. I use an additional separator after the factory one before plumbing my vent line back to the intake, and also 'T' in vent points from the cam housing as belt and braces against positive crankcase pressure.

roco16

I checked the AOS, and everything was dandy. I still think that it would be to my advantage to get an additional seperator. Who other than LR makes one, and could it be hand made for less?

Also, when I pulled the pan last night, it took me and my 2 buds about an HOUR to pull the adhered pan off the block. The 3M adhesive we used previously is no joke. Finally we had to pull the gasket out around the pan to get it off.... only worrying me more that I had substantial positive crankcase pressure.

Anyway, the pan is on, the retainer in place... back to the garage to wrap things up.

-robert

dmoffitt

LR sells one from Kokeln as well (it's quite pricey iirc but has an included cooler and lines too). something tells me tho that that's not the source of your problem, are you abolutely sure you aren't routing a vac. line wrong? ever have the dip-stick rocket out of it's tube / find it loose or popped up?

roco16

As far as routing a vac line wrong, I cant find any errors. The current setup is what Tony G recommended:
-Brake booster line straight off the intake manifold (incl the blue check valve) and into the brake drum,
-idle stabliser line between the intake and intercooler pipe,
-replaced 3 piece hard lines with new hoses and removed the cycling valve: Air oil seperator to j-boot, plugged cycling valve return, straight hose from intercooler pipe to wastegate

Those are the big vacuum line changes that I made... is there any chance that crankcase pressure can be caused by a misconnected small vacuum line? I am confused as to what the two vacuum lines do that goto the fuel vapor purge system.

dmoffitt

the fuel vapor ones go into the port under the throttle body.

Danno

"when I pulled the pan last night, it took me and my 2 buds about an HOUR to pull the adhered pan off the block. The 3M adhesive we used previously is no joke."

What about the part of the gasket that blew out? Did the adhesive fail? Or it wasn't sticking there in the 1st place? I've found out after doing the oil-pan gasket 3x in one month what the cause of my problem was, oil dripping down the sides of the block. I made sure to clean up the mating surfaces with acetone to remove all oil residue. And on the block, I wiped up the insides as far as I could go.

After my last install, with 3M weatherstripping adhesive, I removed the bolts and actually drove around without the oil-pan bolts to test (just two installed finger tight to hang onto the oil-pan just in case the gasket went). And it held just fine with no bolts installed. When I blew up the engine at the OTC, I had two cylinders with cracked rings at 79 & 85psi compression, lots of blow-by, but the oil-pan held just fine for 30-minutes at full-throttle under those conditions. I actually poured out about 1oz of oil from turbo's compressor housing and about a quart from the intercooler when I disassembled the engine.

I've also found on installing the pan, that not disturbing the gasket and its still-wet adhesive helped as well. This means getting around the oil-pickup tube without touching the gasket. Method that worked for me was holding the fan tilted at 45-degrees and sliding it sideways from the driver's side. Once the baffle cleared the oil-pickup strainer and the pan was centered underneath the block, I rotated the pan so it was parallel with the block's bottom surface. Raise up and that's it. Also I only installed the pan to 3-lb•ft and let it sit for a couple hours to allow the adhesive to set. Then went back and torqued to full specs.

Good luck with our next install . Did the Exxon guys pay up yet?

roco16

I think I was victim to the same thing that blew your gasket all those times. The spot where it blew was the lowest point of the jacked engine block, and when I went to clean the mating surfaces, the fresh oil would appeared where the gasket blew first.

B951S

Ditto.
When mine blew out the area was void of adhesive and oily.

RajDatta

So what is the consensus, use a sealer or not? and if one should use a sealer, which is the best one that does not cost over $100 for a small tube like the Porsche recommended one.
TIA.