Oil consumption with no blue exhaust ?

[superdave]

On the noise at start up, search for piston slap on this website. Many of us have the same thing for a couple of seconds and it doesn't seem to have any adverse effects.

The PCV valve was a good check. They can certainly cause this issue. Stuck rings is another thing that can cause a problem. There are lots of methods/ideas/snake oil ways of trying to unstick those. Valve seals is another heavy contributor. If these or leaks aren't the issue, plain old wear and tear is the killer.

You need to do a compression test first, which is like going to the doctor and getting your vitals taken.

 

[DerekTheGreat]

My dead 350 which burns 2/3qt in 180 miles does not smoke on start-up or when cold. Won't smoke on the highway at 80mph doing ~2300 rip 'ems but will smoke if I drag race it. So I think the rings are shot. Why I just discounted a valve job and am going with a different motor altogether.

 

[AlexHawk94]

That isn't going to fix anything. 50wt oil hot might not be such a bad thing but when its @60 degrees F or less it's going to flow like honey, and starve your worn out bearings even more. The engine is on borrowed time. Try throwing a can of Restore at it. Didn't do much with our truck but it helped with my Town Car. Oil consumption with that is non-existent now. It used to chug about 1/8-1/2 a qt of oil every 250 miles. With this past oil change, I haven't had to add a drop and I'm ~1,800 miles into it, not to mention it quieted down my noisy valvetrain.

Could you make a pic of Restore can? It's a bit difficult with such stuff in Russia to buy

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[AlexHawk94]

You don't get a puff of smoke on startup, so that eliminates the valve seals/guides. Also since you don't get fogged out by blue smoke when the engine and catalytic converter is cold, it's not the piston rings.

I suspect what's going on here is all is fine till the engine gets up to temp. Then the intake seals start allowing oil to get drawn in past minor leaks in the valley. At the very least put a torque wrench on the bolts that clamp it down and see if you can get it clamped down more. Pretty common problem on Gen I sbc to have internally leaking intake manifold gaskets when the engine comes up to full temp. Mine has that very issue right now and it's on my "'round to it" list. That situation is compounded if the heads have ever been shaved more than .010" and the intake manifold didn't get the proper milling to match.

In regards to the knocking on hot startup, is the oil filter in the stock location or remotely mounted? If it's in stock location and you are already using a good quality oil filter with anti-drain back check valve then sadly, the engines life is probably limited from here on out due to excessive wear throughout.

well, before installing engine to my truck I replaced intake manifold gaskets did it with correct torque...at least I hope so... I used Fel Pro gasket kit. Also, I replace valve cover gaskets, installed new pcv valve.

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Adding a pic from Mitchell to show what specs I used.

Oil filter is AcDelco PF52 and it's located on standart place I believe. However, I have oil filter adapter for cooling lines but I think it doesn't matter.

 

[Shaun Anderson]

The torque values you used were 100% correct. Were the bolts you used to install the intake oem original, or something purchased in the local hardware store? Reason I ask is because if they are not originals, perhaps they are just a tiny bit to long and are shanking out prior to full clamp up of the intake manifold to heads.

On a side note I see you are working on a 97' model Vortec 5.7 liter. That era of Gen I SBC cylinder heads have a notorious reputation for developing cracks due to thin castings in critical areas. More so than any other SBC cylinder head. Weight savings efforts by GM. Something to consider. A crack in just the right spot would fit your symptoms exactly.

As I said earlier, bad rings/guides/guide seals would all produce blue smoke upon cold start up. Smoke that would go away once the catalytic converter comes up to temp and effectively begins burning it away.

 

[AlexHawk94]

The torque values you used were 100% correct. Were the bolts you used to install the intake oem original, or something purchased in the local hardware store? Reason I ask is because if they are not originals, perhaps they are just a tiny bit to long and are shanking out prior to full clamp up of the intake manifold to heads.

On a side note I see you are working on a 97' model Vortec 5.7 liter. That era of Gen I SBC cylinder heads have a notorious reputation for developing cracks due to thin castings in critical areas. More so than any other SBC cylinder head. Weight savings efforts by GM. Something to consider. A crack in just the right spot would fit your symptoms exactly.

As I said earlier, bad rings/guides/guide seals would all produce blue smoke upon cold start up. Smoke that would go away once the catalytic converter comes up to temp and effectively begins burning it away.

Used original bolts

That's an interesting version, thank you for advice about cracks. I will think about this when I decide what to do with truck - rebuild engine or make one more swap

Well, I have no catalyc converter

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[AlexHawk94]

On the noise at start up, search for piston slap on this website. Many of us have the same thing for a couple of seconds and it doesn't seem to have any adverse effects.

The PCV valve was a good check. They can certainly cause this issue. Stuck rings is another thing that can cause a problem. There are lots of methods/ideas/snake oil ways of trying to unstick those. Valve seals is another heavy contributor. If these or leaks aren't the issue, plain old wear and tear is the killer.

You need to do a compression test first, which is like going to the doctor and getting your vitals taken.

I searched the forum and youtube for piston slap, that seems like my situation.
Also I think it could explain oil consumption i think, if the piston is a bit damaged there is no guarantee that rings are fine. Also I've been told that this engine was overheated once, so I think rings are dead

 

[TylerZ281500]

if the engine was overheated, has low oil PSI etc its probably pretty sad, a compression check and leak down will help. for future reference, 10-40 mobile is probably a waste of money, 10-40 rotella T or defy is likely better, thicken weight (40) will fill some of the loose bearing tolerance, and the higher zinc content will prevent some further wear. now overheating can warp and change material characteristics, the engines likely not happy, could explain lifters ticks, oil deposits, pistons slap, whole bunch of things. Heat is the devil in any situation.

 

[AlexHawk94]

if the engine was overheated, has low oil PSI etc its probably pretty sad, a compression check and leak down will help. for future reference, 10-40 mobile is probably a waste of money, 10-40 rotella T or defy is likely better, thicken weight (40) will fill some of the loose bearing tolerance, and the higher zinc content will prevent some further wear. now overheating can warp and change material characteristics, the engines likely not happy, could explain lifters ticks, oil deposits, pistons slap, whole bunch of things. Heat is the devil in any situation.

Compression test is OK,
every cylinder has similar compression without big difference (dispersion between higher and lower value is less than 5%)
But I didn't add oil and didn't test it again

What's for oil, it's difficult to buy American oil in Russia. We have mobil as the most popular, also we use liqui moly, elf, shell, mannol and some Russian brends.
Ah, petro Canada is the one oil from North America brends here, but quite expensive.

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[Shaun Anderson]

I searched the forum and youtube for piston slap, that seems like my situation.
Also I think it could explain oil consumption i think, if the piston is a bit damaged there is no guarantee that rings are fine. Also I've been told that this engine was overheated once, so I think rings are dead

Piston slap does not happen for a few seconds at start up and then go silent, as you previously described. Piston slap is a sound like a diesel engine makes idling, a chattering and it gradually lessens as the engine warms up to full temp, pistons fit the bores better. What you are hearing is most definitely bearing noise, specifically rod bearing noise. My truck does it to, very slightly. It has 250K miles on it, so it doesn't owe me anything. I'm content with it till it makes that noise continuously. Then I'll just yank it out and put a crate engine in it's place and motor on.

If your rings were truly bad you'd be fogged out by blue smoke, 'specially since you said there's no catalytic converter.

If your engine was overheated it is very likely the heads, or a head is cracked. Those heads don't fair well when overheated.