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So my 355 rebuild has about 1000 miles on it and it is going through oil like crazy. It does not burn oil that you can notice out the tail pipe. Had it out yesterday, drove 158 miles and it is down almost a quart of oil. I am running Bard Penn 20W 50. Are the rings still seating? I have noticed oil in the PCV hose and there seems to be a lot of blow by. Any thoughts on what might be going on?

Thanks
Pat
 

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What Valve covers do you have on the Engine? Are they baffled below the PCV Valve?

Go to the tail pipes and run your finger around the INSIDE of the pipe...is it wet?

You may be sucking the oil right out the exhaust from the PCV valve.

Dave
67 Nova Boy
 

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I just went through a similar head scratcher, with my fresh engine consuming about one quart of oil/100 miles. I had a set of valve covers with no baffles, so I used grommets with baffles built in. When I pulled my PCV valve to test it, thinking it might be the cause of my oil, I saw oil drops spattering on top of my valve cover around the grommet.

I replaced those valve covers with some chromed Chevy valve covers with the factory-type oil baffles and my oil consumption problem disappeared. When I started to suspect the PCV valve I read some very informative posts here on SNS about PCV valve selection.

If your problem isn't the baffles (or absence thereof) in your valve covers, you might look into testing your PCV valve and replacing it with one that is properly matched to the amount of vacuum that your engine produces.
 

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Not an expert but, my issue was about same. I was using oil and found my intake gasket was leaking by. Replaced the intake gasket and problem solved. Check your plugs if you haven't already. Any loss of oil from the intake and or vlv seals will show on the plugs. By the way, I never saw any smoke out the exhaust either.
 

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I was having an oil consumption problem with a 327 I built for my 66. I found that the PCV valve (L79 design) was hanging open. I bought an NOS one but it still used oil. Another problem was the intake wasn't completely sealing so I fixed that problem. Still used oil. I finally figured out it was the valve seals on the new heads I put on the engine. It had the standard umbrella seals and oil was being sucked by those down through the guides. I switched them out for some of the good Fel Pro push on kind and haven't had a problem since.
 

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Hard to believe if you're using 1 quart in a hundred miles you can't see it somewhere. I suppose it could be the pcv valve or intake gaskets, but I'd be doing a leakdown test, not a compression test, and see what I found. I know I put a second compression ring on upside down on one cylinder once, and it pumped oil into the combustion chamber, plug was soaked in oil, had to pull the motor apart to figure it out. I make sure I've got the rings in right since then.
 

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I had a head scratcher once on a new motor. Took me awhile, but I figured out I forgot to put the front seal in the timing cover - duhhhhh. It only used oil when I was beating on it and I couldn't find the source of the leak. It would only sling up when the crank was really moving!

Kev
 

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KINDA LOOKS LIKE THE GROOVS IN THE RINGS ARNT OPPOSITE sorry wasn't yelling rings didn't seat or rings wernt put in with the correct spacing by the look of the plugs
 

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If you have a lot of blow-by, you are going to have some oil getting into the PCV hose, that's a given. The blow-by means that the rings aren't seated.

The only causes for this are defective rings (doubtful, but possible), engine overheated and took the tension out of the rings (did it get hot a some point?), improperly installed rings (oi rings upside down or broken, maybe bad expanders) or wrong size rings (who installed them?), or improper finish on the cylinder walls (was the block bored, or was it a re-ring job?).

If it was a re-ring job and the cylinders weren't deglazed, or if there is too much taper, ring step, or the cylinders are out of round the rings won't seat.

If you can do a leak down test, I'll bet it isn't going to be good.

I know it's a pain, but if you have a lot of blow-by, the rings aren't seated and the heads need to be pulled to determine the problem.
 

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Pulled the plugs, from left to right cylinder #7, 5,3 and 1. Oil or running to rich or both? The other side is no better. Keep in mind no more than 1000 miles, more like 750. Plugs are NGK FR5 and running Edelbrock e-street heads.

That is definitely an oil issue, my plugs looked the same but, not on all cyl's. You need to tell us more about the build or talk to the person who did the build. Pulling the intake and heads will reveal the problem or you may get lucky and find it's just an intake leak (bad gasket seal). Was the intake torqued correctly?
 

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Were the heads, block or intake milled? If you deck the block or mill the heads and don't cut the intake to match often intake gaskets will not seal along the bottom edge of the intake in the lifter gallery. That lets the intake vacuum suck oil into the intake manifold. That will cause high oil consumption and often the engine will foul plugs like yours has and when its running the oil will cause the engine to spark knock really bad.
 

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Discussion Starter #17
The deck was machined, 9.010 and the heads are new. It recently started to run on after I shut it down. It does look like the intake manifold is touching or almost touching the heads. I have talked to my engine builder and he is not sure what could be going on. I know I need to change the power vavle to a lower one like a 5.0 or 4.5 as my vacuum is only 10 inches. I am going to show him the plugs tomorrow and see what he thinks, also find out if he machined the the intake as well. Someone asked if the engine ever over heated and the answer is no, as matter of fact it runs cool 185. The cam is a comp cam 12-4338, should it have a stronger vacuum signal and if the intake gaskets are leaking would that effect/reduce the vacuum signal?
 

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The deck was machined, 9.010 and the heads are new. It recently started to run on after I shut it down. It does look like the intake manifold is touching or almost touching the heads. I have talked to my engine builder and he is not sure what could be going on. I know I need to change the power vavle to a lower one like a 5.0 or 4.5 as my vacuum is only 10 inches. I am going to show him the plugs tomorrow and see what he thinks, also find out if he machined the the intake as well. Someone asked if the engine ever over heated and the answer is no, as matter of fact it runs cool 185. The cam is a comp cam 12-4338, should it have a stronger vacuum signal and if the intake gaskets are leaking would that effect/reduce the vacuum signal?
If the intake is leaking it could cause a lower vacuum at idle. The greatest vacuum that will cause this issue will be when your going down the road and when the most oil is moving in the engine.
 

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If you suspect the intake is leaking block one valve cover solid(what ever holes exist in it) and check for pressure or vacuum on the other cover. I had a poor fitting Victor Jr years ago that used oil like yours. With the breather hole plugged on one valve cover is would suck a piece of paper to the hole in the other valve cover at idle:eek:
 

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number three looks the best out of all of them but you can tell heavy oil useage has been going on in the rest of them. How was the engine broken in? Is there moly or cast rings in the engine? what were the end gaps? If isn't the intake causing the problem your going to have to take it back down and see whats going on. Intake will be the easiest to spot as the runners should have oil in them. If you can do a leak down test that will prove out rings or not.Also if the heads are new and not reworked you should be fine there,I have seen some redone heads the guides were looser than they were before being redone! You should also run the spring shields if your able the help keep oil off the guide area.
 
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