When I shoot the nitrous at the track I seem to be low on oil after two runs or so. Could this mean something bad for my engine??? Rings gone? seals somewhere? It seems to be running fine, but then again I could be missing something. Thanks.

 

I would do a compression leak down test. Sounds like you have a possible blown ring or two and the pressure is venting right into the crankcase sending the oil out through the PCV.

 

Would white smoke on startup be another sign of this??? I've been noticing it more and more lately. I cought a compression tester lastnight. Do I just put it in for a spark plug, pull the rest of the wires and crank it over?? or is there something more scientific I've gotta do?

 

Smoke on startup is associated with valve guides usually.

 

Well, there are two different tests you should perform. One is a compression test (probably what you bought) and the other is a leak down test (different tool and you need an air compressor). The more important of the two test is the second one. You can try doing the compression test to see if one cylinder is not making the same compression as the other cylinders, but this will not always show you a bad ring or pinpoint the problem. To do the compression test, install the tester in the first spark plug hole. Crank over the engine for at least 3 rotations, preferably four. Each stroke, the compression tester will get higher and higher and will even out by the third or fourth stroke. Jot the number down. I would expect it to be about 155-165psi. Move on the the next cylinder and do all 8 in this same fashion. All of the cylinders should be within 10 percent of each other. If 7 are between 150-165 and one is in the 140 range, then that cylinder has some kind of problem. Could be anything from bad rings, to burnt exhaust valve, bad valve seats, etc.

The leak down test is a similar process as you have to install the tool into each of the cylinders. But it will show you the percentage of "leak down" that each cylinder has when idle (still). For this test the cylinder needs to be at TDC or BDC, preferable TDC (top dead center). Then you hook the tool up to 100 psi of air, and the one gauge shows you the incoming air supply pressure, the second gauge shows you the amount of air pressure that the cylinder is maintaining. Generally the cylinder will maintain between 94-98% of the air pressure if all is well. I did this test on a friends 95 with 60K miles on it (stock short block with heads and cam) and he had 2% leak down in each cylinder which was perfect. This test will allow you to also pinpoint where the air is escaping and you can find out if the rings are bad, or if the air is getting out past the valves. You just listen to the motor to determine where the air is escaping.

I posted a couple months ago how to build your own leak down tester for under $30 from Autozone parts. Had a diagram and all. May be worth the search.

Chris


[Modified by Vette92, 9:55 AM 4/2/2003]

 

I returned the $30 compression gauge and called up my local small town mechanic/speedshop. He said he'd charge me $20 to do a leakdown test if I helped him pull the plugs. I'm going there friday after work. I'll have to let you guys know what happens. I was thinking about getting a setup and doing it myself, but if I do it three times that $60 and the cost of the tool and an aircompressor way out does that.


[Modified by mn_vette, 9:05 PM 4/2/2003]

 

$20! Has he ever tried doing it on a Vette?! LOL. Takes me at least an hour to do it myself.

 

like I said, this guy is a small town mechanic, the population of the town is about 500 or so. But they've got business from all over the place. The guy has been building engines for a long time and does good work, they've got an engine dyno in the back too. I think he's more doing it as a favor as he knows I get my stuff there and plan on having my engine redone there if it does need a rebuild. And if I'm pulling the plugs it shouldn't take him very long to do the actual test.

 

The verdict is in, we tested 4 cylenders
1.) 80%
2.) 50%
3.) 90%
4.) 80%

I'm in the process of pulling the engine right now. Perhaps this is why my car wasn't as fast as it should have been. Time for a rebuild. 383 here I come! :D


[Modified by mn_vette, 10:31 PM 4/7/2003]

 

I would be willing to bet it is that 150 shot that did it. When you pull the heads I bet it all looks fine and your rings are just not holding the pressure. Wehn I blew a stock ring on a 150 shot, everything "looked" good, but the ring was bad. I just put a new stock ring in it and all was well after that.

Since you are doing the turbo thing, might as well build it for it now though.