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| bam | excessive oil consuption | ||
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Senior Guru
 
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Since putting a hot cam, 1.6rrs, LT4 valve springs in my 93 LT1 it is using about a quart of oil every 100 miles. There is a puddle of oil on top of each closed valve. There is also oil running down the air foil on the throttle body. The whole inside of the intake is black and wet with oil. Also the last time I drove it oil started blowing out the oil pan where it meets the block. The whole back of the car underneath is coated with oil. It's leaking out the front of the pan and the back too. Also oil is dripping out of the exhaust. I am totally baffled, any thoughts?
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Posted on: 2011/7/26 20:11
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| bogus | Re: excessive oil consuption | ||
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Grand Imperial Pooh-Bah
 
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PCV valve stuck? That would be my first thought.
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Posted on: 2011/7/26 20:15
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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I checked the PCV valve, it moves freely up and down, it seems to be ok, but I will replace it anyway.
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Posted on: 2011/7/26 23:00
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| BrianCunningham | Re: excessive oil consuption | ||
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Senior Guru
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you pull the heads or just the intake?
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Posted on: 2011/7/26 23:12
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Just the intake. I am wondering with all that oil on top the valves that there must also be oil on top the pistons too which would be a very bad thing. With the LT1 small combustion chamber it could build up enough to bend a rod.
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Posted on: 2011/7/27 2:19
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| bogus | Re: excessive oil consuption | ||
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Grand Imperial Pooh-Bah
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you would need a lot of fluid to hydrolock the engine...
What happens if you disconnect the pcv line? I wonder if the hose is blocked? |
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Posted on: 2011/7/27 5:34
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Am on the road traveling now, will be home in a week +. I blew compressed air through the PCV line, not plugged. I am wondering if a broken ring would let that much oil to the top of the motor, is that even possible? Would a compression check tell me if an oil ring is broken?
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Posted on: 2011/8/2 16:27
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| bogus | Re: excessive oil consuption | ||
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Grand Imperial Pooh-Bah
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Well, to put it into perspective, when Ford 302's and 351W wear out their rings, the intake gets full of oil.
Very common problem with those engines... somewhere north of 175k miles and more prone on pre-1990's engines. So, yes, a bad ring is very possibly causing this. Excess combustion pressures blow into the crankcase and that's that. I would do a leak down test to confirm. |
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Posted on: 2011/8/2 23:28
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Well I am back home and working on the motor. Now that I think of it when it was last running I disconnected the hose that runs from the TB to the passenger side valve cover and smoke was coming out, a lot of it. That shouldn't be, right? There should be enough vacuum thru the PCV to make it pull air and not blow smoke on that side right? I am going to buy a leak down tester and test the cyl. pressure leak down next week. Any ideas would be appreciated.
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Posted on: 2011/8/16 22:10
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| JeffK | Re: excessive oil consuption | ||
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Elite Guru
 
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Sounds like it could be blowby. Hopefully it is something simpler than that. I ended up with a new shortblock when mine did that.
Doing the leakdown test should tell all though. |
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Posted on: 2011/8/16 23:46
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| rklessdriver | Re: excessive oil consuption | ||
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Senior Guru
 
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With that much pressure comming out of the PCV hose something is bad wrong.
Collasped rings or a burned piston. Leak down all 8 cyls and see what you get. Will |
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Posted on: 2011/8/17 0:12
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| flyboy | Re: excessive oil consuption | ||
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Elite Guru
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...but this oil problem started after the cam swap?
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Posted on: 2011/8/17 0:16
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Yes it started after the cam swap, didn't burn any oil before that (1/4 qt. in a 3000mi oil change). When I was replacing the springs I used compressed air. Had read to use 20-30psi, but couldn't get the keepers free with that little air pressure. I ended up using 100psi and putting the tranny in gear then putting air in the cylinder at TDC. I forgot to put it in gear on one cyl, when I connected the air to the cyl. the piston obviously slammed to the bottom of the stroke, I could hear it bang. I am thinking I might of broke a piston or ring when that happened. I ordered a leak down tester from Amazon today, should be here in a week, hopefully that will tell me something.
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Posted on: 2011/8/17 1:53
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Quote:
It's not coming out of the PCV hose, it's the other side of the engine (pass side) where the hose runs to the TB to get filtered air for the crank case, make sense? |
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Posted on: 2011/8/17 1:53
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| flyboy | Re: excessive oil consuption | ||
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Elite Guru
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The compression stroke is more than 100 psi and I can't picture a piston "slamming" to the bottom of the stroke and breaking something from air pressure....
What could cause enough excess oil pressure to force oil through the pan gasket? |
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Posted on: 2011/8/17 3:16
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Quote:
My compressor is a commercial air compressor, the tank on it is huge, it could easily drive the piston to the bottom of the stoke and not register any less air pressure than 100 psi (the compressor cuts off at 120psi, I had the line pressure set at 100). But that said, I sure hope you are right. As to the pan gasket leaking yesterday I was under the car and I can see the oil is leaking around the oil filter adapter where it meets the block. I took if off and the o ring is blown??!! Anyway that is where the oil came from, now I don't think the pan gasket is leaking. I ordered a new o ring seal for the filter adapter and hope to start it up in a week. Thanks guys for all the helpful comments. |
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Posted on: 2011/8/17 13:16
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| BillH | Re: excessive oil consuption | ||
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The Stig Moderator
 
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Quote:
No way. 100 psi is nothing compared to compression. And 100 psi is what you use to do a leakdown unless you want to mess around with a conversion chart. I've spun engines with that pressure at least 100 times doing leakdowns and missing TDC by a hair. I can almost guarantee that you'll spin the motor a couple of times doing the leakdown especially since you have no timing mark to work with. |
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Posted on: 2011/8/17 13:26
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| bam | Re: excessive oil consuption | ||
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Senior Guru
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Quote:
Not to argue but the motor won't "spin" with compressed air introduced into the cylinder, it instead moves the piston from TDC to the bottom of the stroke and then stops, it is impossible for the piston to move after that, that is what I simply mean that the piston hit the bottom of the stroke with a "bang". When an engine is running the piston does not stop at the bottom of the stroke but keeps spinning on past. Still I hope you are right that no harm was done. Also I have been thinking, I have a puddle of oil on each closed intake valve. Now it seems to me that oil must be leaking down the valve stem for that to happen, it could not get there any other way, am I right? May be it is the guides or seals? What valve seals are you all using with stock LT1 heads? I used felpro viton. |
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Posted on: 2011/8/17 19:55
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