Oil Leak and Smoke under Boost

[BennyBuick]

Recently bought highly modified 87 GN. Leaked oil all over driver side engine compartment... steering linkage, headers, dipstick sleeve, under carriage, etc... just fresh oil all over. Also, under heavier boost, smoke just pours out the back. So first, I wanted to eliminate the valve cover gasket, so I replaced that. The one on there was a metal one with the blue rubber on each side. Possibly not the best gasket selection as the head and valve cover both have rough cast finish and are not machined smooth, so I thought it best with an old fashioned cork gasket to form more to the rough casting finish. Cleaned up oil a bit best I could and went for a ride. Again, under boost, smoke pours out the back. I don't know if its oil spraying out somewhere onto exhaust and that is causing the smoke or if it is actually coming out of pipes.. Anyways, I check under the hood and of course there is fresh oil all over again. I'm super bummed. My brother points out that the dipstick cap is covered in oil and suggests taht is the root. So I put a rubber cap on it instead of the loose fitting dipstick head. This is how hte previous owner had it, anyhow, cleaned up oil, went for a ride and got on it quite a bit. No smoke even under full boost, I get back home and no fresh oil in engine bay. So maybe that solved the problem.. Any thoughts? If it is coming out of the dipstick sleeve, does that indicate excessive crank pressure. If so, is this bad, or indicative of a bigger problem? Also, I do get a bit of knock here and there under boost. the worst I saw was on the last ride and it pegged at 4.7 degrees. Do I need to be worried? I've also been told not to freak out that false knock is common with the headers being bigger than stock and so close to block in the close quarters of the engine bay. I'm not educated on such things and just learning. Other times knock registered, I think the most I saw was 3.4, other wise it was 1.2 and 2.3 I think. Any thoughts or advice?

 

[BMR]

My old sbc would do that on 15 psi. It was not that excessive though. Sounds to me like it could very well have some damaged rings or a cracked piston. My first thing to do would be a compression test. Every time i have damaged a piston it would blow oil everywhere.

 

[BennyBuick]

Will do compression test tomorrow. Thanks for thoroughly freaking me out though. Lol. I hope that is not the case. That would be heart breaking. It sure runs good, I would think it would be running poorly if that were the case.

 

[BennyBuick]

Btw, what's an sbc?

 

[BMR]

Small Block Chevrolet

 

[bogies87]

Make sure the valve cover breathers do not have baffled rubber grommets. In other words if there are baffles of any kind on the breathers do away with them.

 

[BARRACUDA1968]

Make sure the valve cover breathers do not have baffled rubber grommets. In other words if there are baffles of any kind on the breathers do away with them.

Reason?

 

[SHADOWII]

Pushing oil out the dipstick tube is indicative of a pressurized crankcase. The compression test should reveal any weak cylinder/s. Do you have valve cover breathers to allow the pressure to escape? You want the block to breath.

 

[BennyBuick]

Yes, I have tall breathers on both sides. The valve covers have rubber grommets that angle into the breather filters. Compression test coming soon.

 

[BennyBuick]

And again, there is no oil leaking anymore since capping the dipstick sleeve, and smokes no longer an issue. I hope compression test goes fine to put me at ease. Motor, rear end, and tranny were all freshly rebuilt so I can't imagine there are problems already...

I also forgot to mention, at the time of valve cover gasket replacement, I had to tighten down all the bolts in the oil pan and transmission pan as they were ALL loose. Some of them I got a full turn out of without cranking hard on em. Snug and tight, not cranked down power tightened.

 

[earlbrown]

Pinch off the PCV line and run the test with the dipstick installed. If it stops, you were blowing boost into your crankcase.....


BE CAREFUL when doing that test. If that is the problem, you might have more boost than you want if the PO tuned around a large leak.


Also, be careful tightening the crap out of the pan gasket. They like to split on the rear and dump oil all over the crossover pipe.

 

[BennyBuick]

Pinch off the PCV line and run the test with the dipstick installed. If it stops, you were blowing boost into your crankcase.....


BE CAREFUL when doing that test. If that is the problem, you might have more boost than you want if the PO tuned around a large leak.


Also, be careful tightening the crap out of the pan gasket. They like to split on the rear and dump oil all over the crossover pipe.

Ok, I also have a "turbo saver" oil catch can... Which part of the Pcv line do I pinch? And do I just pinch it with a vise grip or something with padded jaws? Sorry for the ignorant questions here, I'm definitely a noob and my brother is the mechanic in the family. Also, if oil stops coming up the dipstick sleeve with Pcv line pinched off, could I buy one of those rjc pcv valves I read about on these forums to remedy the problem? Hope this would be a simple answer as to why I'm getting crankcase pressure...

 

[bogies87]

Reason is, under boost the baffled grommets dont allow enough pressure to escape. My experience is just that. I had baffled grommets and breathers, found they were closing under boost, lifting the dipstick and smoking like crazy. I thought mine was smoking out the tail pipes but it was actually burning off the cross over. Cut the baffles off and all was good. Zero smoke, zero oil leak.

 

[BARRACUDA1968]

Reason is, under boost the baffled grommets dont allow enough pressure to escape. My experience is just that. I had baffled grommets and breathers, found they were closing under boost, lifting the dipstick and smoking like crazy. I thought mine was smoking out the tail pipes but it was actually burning off the cross over. Cut the baffles off and all was good. Zero smoke, zero oil leak.

Makes sense, not sure how much oil splash the breathers will see but definitely need ventilation under boost. Could just build extensions for the breathers to keep them out of the oil.

 

[BennyBuick]

Reason is, under boost the baffled grommets dont allow enough pressure to escape. My experience is just that. I had baffled grommets and breathers, found they were closing under boost, lifting the dipstick and smoking like crazy. I thought mine was smoking out the tail pipes but it was actually burning off the cross over. Cut the baffles off and all was good. Zero smoke, zero oil leak.[/QUOTE
Hmmm, that does make sense. Thanks

 

[BennyBuick]

I just went ahead and replaced pcv valve. Old one was bad and it was only $2 from auto zone. Haven't done compression test yet. Car goes in Friday to be dynoed and the tune checked. Will also have engine checked over. I will have compression test done then, but I'm really not worried about compression at all. If that was an issue it wouldn't go like it does

 

[earlbrown]

There's a good chance that $2 autozone PCV is garbage. If it stops smoking though, you've started to isolate the problem.

 

[BMR]

My old SBC would run mid 6s in the 1/8 whether it had a cracked piston or not. It would just fog the world up when it was hurt. But these baby Buick motors are different animals.

 

[BennyBuick]

It hasn't smoked since I put the rubber cap on the dipstick sleeve. At this point I'm just wondering why I'm getting excessive crank case pressure. That valve may have had something to do with it. I also believe it has just a bit too much oil in it to begin with as it reads pretty high on the dipstick. I think maybe the previous owner just over filled it a little so maybe that is coming into play.

 

[earlbrown]

If you've been running with it overfilled, you need to chance the oil NOW. These engines make a bunch of torque down low and the last thing you need keeping the rods off the crank are air bubbles.

I just mentioned the PCV because it's a quick and easy test that can be done in minutes with no disassembly.