oil pan leak after rebuild

[nickferguson08]

ok so i have rebuilt my 7 bolt engine and its been leaking oil out of the pan ever since, 400 miles on the engine and the oil leak seems to be getting worse. Chrome Moly Topline rings, all necessary machine work, had to take off the head since rebuild and re-do the headgasket because it didn't seal, pulled the pistons out to check ring gap since I didnt the first time luckily they were in spec, then put it back together, slight bubbles out of water outlet neck, overheats while driving and oil is all over my firewall and under the whole car. Am i looking at blow-by and need to re-ring the engine again??

Compression test:
#1 - 150psi
#2 - 147psi
#3 - 132psi
#4 - 150psi

Leak Down Test: heard through oil cap/dip stick
#1 - 15%
#2 - 15%
#3 - 25 ~ 30%
#4 - 15%

Thanks guys

 

[kawboy]

This is why I always bore over used motors.. they never seal 100% when just re-ringed.

If you scrape your oil pan clean (all grooves etc) then apply a bead of Permatex Ultra Gray, you won't have anymore oil pan leaks. Make sure the block is free of oil also. Sealant doesn't seal on oil.

 

[nickferguson08]

The engine was at .020 over now its at .040, i've tried 2 cork gaskets, no gasket just RTV (Right Stuff) and a different oil pan, on dry surfaces, same problem every time...

 

[lacroixdp]

Those compression figures are simply unacceptable for a rebuilt engine. 178PSi is what your engine calls for stock - your #3 is a pound lower than the service limit. At 400 Mi. your rings should be sufficiently broke in by now to get within 5% of standard compression - you're nearly 16% out of spec on your good cylinders after only 400 Mi. As for you blowing your head gaskets did you check your deck for flatness with a straight edge and a feeler gauge (or did your machinist check the block)? Did you have the block magnafluxed when you had it bored over? Also did you check the head for cracks and warpage? Did you happen to get your block shaved while it was being bored and did your machinist use a torque plate when he bored out your cylinders? What are you torquing your head bolts down to - 85FT/LBS? If you're using a MLS, did you get a head gasket the proper size to compensate for your bore size? To me it sounds like your machine work is out of spec, your head is warped, or there is an assembly error. I hate to give a laundry list of things like this, but there's just quite a bit that if not done correctly during a rebuild that can cause problems. Also, when your machinist honed out your cylinders did you tell him you were going to use chrome rings? They need a rougher hone to aid during break-in.

 

[rush2252]

chrome moly rings sometimes take awhile to break in as well but it doesnt sound right. Did you have the head/block decked? I wouldnt spend the time/money and rebuild the bottom end if the head isnt true. If you had to "redo" the headgasket and now your seeing bubbles with those compression numbers and leaking oil something definately isnt right.

Try running ATF through the intake at idle and see if it changes up your compression numbers after the smoke clears up.

Kolby

 

[nickferguson08]

The head and block were both machined flat, i dont know if it was magnafluxed or if a torque plate was used. Me and my instructor at school resurfaced the head when i tore it apart again, i did a pressure test to check for cracks, none found and we made sure it was flat...ARP head studs are at 30-60-90FT-LBS. Cometic head gasket is make for 86mm (40 over).

 

[nickferguson08]

Should I buy another cometic head gasket and total seal rings, rehone it and go from there or what?

 

[lacroixdp]

Cosmetic MLS's are reusable - you should be able to reuse it with no consequence as long as it's not damaged. However, with you on your second head gasket leak, I'd probably bite the bullet and replace it just in case yours is damaged. Just as a note, MLS are very sensitive to the flatness of the mating surfaces. If you have 1-thousandths of an inch or more of warping they will most likely leak. They are also very sensitive to the quality of the finish on the mating surfaces - your block and head need to be perfectly smooth with no residue present. I would take out your pistons and double-check your bores to make sure there isn't any deformities - I'm honestly not sure how out of whack your cylinder bores would be without a torque plate being used - I've never done it without one before Definitely rehone your cylinders using a coarse pattern so your chrome rings break in properly. I believe that's what is causing your low compression in your other cylinders. You could try reusing your rings if they spec out, personally I'd buy new ones though. When you break in your engine, break it in like this:
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power
Double-check your deck and your head for flatness and for cracks one more time before you reassemble it all.

 

[nickferguson08]

Vacuum is at 18 - 20 InHg and the engine runs greaaat no sputtering, no knock counts, i dunno. The Compression test was done with the throttle closed...i forgot about that part, but i don't think that would raise the numbers too much anyway. But I guess i'm gonna tear it apart a 3rd time and re-do it again...thanks guys..

 

[lacroixdp]

Good luck to you man!