Pressurized Oil Leak - Need a Little Help

[JimCT]

blowing oil

I hate to say it but I bet you have a hole in one piston. Been there and done that and it did just what you are describing. Check your compression. Jim

[Bostonian1976]

I hate to say it but I bet you have a hole in one piston. Been there and done that and it did just what you are describing. Check your compression. Jim

how does that happen? I don't lug the engine. I don't run the engine too hot (okay my temp gauge doesn't work but it never exhibits symptoms of being too hot), timing was pretty accurate......

[Terrys]

Anything which would cause the pressure relief valve on the oil pump to open will only bypass pump output back to pump input.
Check the oil feed tube which runs from the block to the head. Don't put a close system cap on your oil fill pipe till you plumb up the breather line, or you'll very likely blow your front seal. If you had holed a piston, you would have noticed it in both performance, and laying down a smoke screen, not to mention plenty of pissed off people behind you.

[daveb]

I was talking about this with one of the folks who tried to help at the event.
It is crankcase pressure, not oil pressure. It is blowing out of the nipple at the bottom of the oil fill tube straight into the air current from the fan.

He is using a SIII filler neck with the top cut off to allow fitting of a breather style cap. The bolt/hose plug on the filler neck degraded and cracked.

It could be a hole in the piston or it could be a bad ring or rings. You might not notice the perfromance drop. Most likely it is a probem that has existed and was only noticed because the makeshift plug one the breather nipple failed.

You can lose a cylinder completely on a 2.25 and barely notice, so it isn't a stretch to say that a hole in the piston would go unnoticed, especially if it formed gradually. That said, i don't think that is the problem here. In any case, a compression check is easy and will tell the whole story.

The 2.25 on my last 88 had quite a bit of blowby, but ran great 62-65 mph all day long, made a few long trips in it that way sans difficulty.

If the engine is providing sufficient power, it is well to leave it alone and simply fit a decent PCV system to keep the engine bay a bit cleaner. It ain't rocket science, folks.

Anything which would cause the pressure relief valve on the oil pump to open will only bypass pump output back to pump input.
Check the oil feed tube which runs from the block to the head. Don't put a close system cap on your oil fill pipe till you plumb up the breather line, or you'll very likely blow your front seal. If you had holed a piston, you would have noticed it in both performance, and laying down a smoke screen, not to mention plenty of pissed off people behind you.

[daveb]

got the cork gasket on that dizzy?

nothing whatsoever, except I think I checked the oil on the way down and added a quart (it was fine at that point, but not fine 20 miles later). I've been driving it all summer exactly as is - put a new distributor in last February that needs a few shims in between it and the block (it's Pertronix and there is a slight gap for some reason), but that has been completely dry all summer too

[Bostonian1976]

per my other post - I finally checked compression and it was 135-145 on each cylinder. If I had to guess, oil seems to be coming from the breather cap on top of the valve cover and being blown back by the fan. Why would that happen?

[Donnie]

per my other post - I finally checked compression and it was 135-145 on each cylinder. If I had to guess, oil seems to be coming from the breather cap on top of the valve cover and being blown back by the fan. Why would that happen?

Bad oel rings can give you a false comp reading as the oel leaking by them can actually seal the upper comp rings, thus raising, not lowering your comp test results..........

[Bostonian1976]

Is that common?

[Bostonian1976]

all plugs were dry if that makes any difference

[Donnie]

Is that common?

what can happen to rings: they can wear prematurely from dust entering the engine through a neglected air filtration system, they also can sieze in the piston grooves, usually from using inexpensive oel or infrequent oel changes..the top comp ring, not the oel ring can break either from preignition, lugging the engine or over reving, advanced timing or low quality gas....faulty oel rings usually are indicated by excessive oel consumption, exhaust smoking when decending a long grade, foot off the throttle..this is only a touch on the subject & by no means a complete diagnosis of worn rings....Best to get you a manual and study....Oh yea, U did say that your PCV system was XXXXXXXXX....toss that into the mix...

[Bostonian1976]

so uh - where to begin? sounds fun

someone at the metal dash event did notice that, after a long descent in first and low, when I hit the gas I smoked a bit (from the tailpipe). Normally though there is ZERO smoke....just a bit of black exhaust from probably running too rich.

I pulled the plugs too and they were all black (but dry)

The third plug had a pool of oil below it

[Bostonian1976]

I think I finally narrowed this down. I had a steady drip today from the top of the oil filter canister (where it comes apart) after driving at 55 or so for 10 mins. Is it at all conceivable that a leak from there would spray up onto the oil fill tube and onto the bulkhead? Thanks

[graniterover]

It drips down onto the driveshaft and sprays back up.

[Bostonian1976]

It drips down onto the driveshaft and sprays back up.

this would be awesome if this is it. No blowby would obviously be a good thing.

is this a common occurrence? does the seal for the oil filter just blow?

[sven]

Most oil leaks Ive delt with always leaked down not up. Not sure of a spinning driveshaft would make oil spray upwards like that. That seal is probably just leaking because of the excess blowby pressure.