Oil consumption, valve seals or rings, both?

[samsterman99]

86' K5, what looks to be the stock 350, with the CCC Q-jet, california emissions and all. 170K miles, if I let it sit for 1 hour, it will blow a plume of smoke out on startup. So the valve seals are shot. I know I need to replace those. I still burn, or somehow loose 1 quart every 300-500 miles. No smoke at the exhaust any other time. THere is some smoke coming out the valve cover breather, and it will spit out oil from the breather after long highway runs, so it just soaks my air filter and my air filter housing with a few ounces of oil. I dont have a compression tester with me here at school, and I am deciding betweeen replacing the seals with the engine in the car, or just waiting to rebuild the entire thing. I dont want to have to keep worrying about running out of oil, this engine is strong and runs great besides this one problem. But it really is a problem when I want to drive 3+ hours to a trail, camp and drive back. Any ideas, any experience with just replacing the valve seals? If I can reduce this to a Qt every 1-2K miles, I will be happy. I dont really have the money or time to do a rebuild this year, so I want to make this last as long as possible.

Edit: I guess a main question I have is : can bad valve seals cause a rise in crankcase pressure, or will they just leak oil into the CC. Also how much oil consumption can really be caused by bad valve seals.

 

[4X4HIGH]

First explain to me how your PCV system is hooked up. That will determine if it could be the source of your problem. Basically bad rings and the engine will smoke ALL the time and bad seals or valve guides it will usually smoke upon start up then clear away and also on acceleration then clear away. A bad PCV valve or a system that is not hooked up correctly will allow too much crankcase pressure and start pushing oil out of seals and or burning it.

 

[samsterman99]

^^ I have tried two different setups. In both scenarios my pass side breather tube is the factory style that goes into the air cleaner housing and has the filter on it.
1. I bought it used with no pcv valve, so I went out and bought a breather filter. just ran a valve cover breather in place of the pcv.
2. Now I have tried to hook up the emissions lines again so I can pass smog when i need to, so it goes to a "T" fitting, which go to the charcoal canister and the intake and its just a cluster bomb of tubles and lines. I wish I had a diagram of it, but thats how it stands today. In both cases, it would smoke out of the valve covers.

 

[samsterman99]

First explain to me how your PCV system is hooked up. That will determine if it could be the source of your problem. Basically bad rings and the engine will smoke ALL the time and bad seals or valve guides it will usually smoke upon start up then clear away and also on acceleration then clear away. A bad PCV valve or a system that is not hooked up correctly will allow too much crankcase pressure and start pushing oil out of seals and or burning it.

I should also add that I replaced the valve cover gaskets, and there was some sludge present in the heads. I was thinking of running some seafoam or ATF for 10 min before I change the oil next. Also was considering checking out the oil pickup screen and making sure that was clear. I would ideally love to get this motor back to where I can drive it for more than 2 tanks of gas without having to add oil.

 

[bigred81]

Did you check the holes at the back of the heads if they are plugged that would be one source for your oil consumption due to the oil running down the valve stems. They may look clean but near the bottom it may be plugged so use a screw driver to loosen the junk than blow out with air.

 

[samsterman99]

Did you check the holes at the back of the heads if they are plugged that would be one source for your oil consumption due to the oil running down the valve stems. They may look clean but near the bottom it may be plugged so use a screw driver to loosen the junk than blow out with air.

Your talking about the oil drain holes that allow the oil to flow back down into the pan?
I never did check those out, I will probablly do that tomorrow, and use a pick or something to clean it out. The heads did have a few pieces of gunk, sludge, whatever crap was in there. but I didn't notice oil pooling up there anymore than normal. This is why i was thinking ATF or seafoam in the oil would either help clear it out, or just clog a passage and fry the engine for good. If it was lacking power I would have ordered a crate engine already, but it just sounds so good and runs so well otherwise, I hate to scrap or tear into a solid piece.

 

[79bonanza]

man i have a 1995 toyota corrola as a dd for gas milage and stuff and that thing takes about a quart or oil every 20 bucks or so in gas lol i usually end up putting in on average about a quart and a half every week but i am driving around 700 miles a week. sorry for the highjack good luck with your truck

 

[trustyrusty]

Yup, sure sounds like worn out valve seals and clogged drain galleys.
Are you hearing any noises coming from the internals? (noisy rods, etc.)
If not, I would pop the heads and have them serviced. IE: cleaned and a valve job$$ or just seals.
DO NOT attempt to clean the drain holes while they are on the engine, you will drop crap down the holes and screw the pooch.

 

[diesel4me]

I've used a shop vac to suck out sludge and on one enginre,about 100 aluminum foil discs they put on platic oil can spouts for a gasket!--evidently the former owner just squeezed the bottle without tearing off that "gasket" first,probably to avoid spillage,and they ended up in the heads,clogging the return holes...after removing them all it no longer smoked or used oil..

The suggestion to ensure your PCV valve is hooked up correctly and working is a good one,I've bought good running trucks cheap beacuse someone put "hot rod" aftermarket valve covers on them that lacked a place for a PCV valve or a breather,and they either jerry rigged one or left it off entirely,which led to excessive blowby and oil consumption...it could be the source of your woes as well..

Just about every engine I tried being frugal with and did only the heads over,ended up smoking or consuming more oil than ever after just a valve job--tighten up the valves,and those pistons & rings still have all the wear they ever had,and compression will sneak by them more than ever now that the valves seat tightly again...so if you end up pulling the heads,you might as well do the rings too...

A quart of LUCAS will probably go a long way to reduce oil consumption if it is excessive blow by or worn rings,it'll help reduce the leakage past the valve stems too..

 

[samsterman99]

I've used a shop vac to suck out sludge and on one enginre,about 100 aluminum foil discs they put on platic oil can spouts for a gasket!--evidently the former owner just squeezed the bottle without tearing off that "gasket" first,probably to avoid spillage,and they ended up in the heads,clogging the return holes...after removing them all it no longer smoked or used oil..

The suggestion to ensure your PCV valve is hooked up correctly and working is a good one,I've bought good running trucks cheap beacuse someone put "hot rod" aftermarket valve covers on them that lacked a place for a PCV valve or a breather,and they either jerry rigged one or left it off entirely,which led to excessive blowby and oil consumption...it could be the source of your woes as well..

Just about every engine I tried being frugal with and did only the heads over,ended up smoking or consuming more oil than ever after just a valve job--tighten up the valves,and those pistons & rings still have all the wear they ever had,and compression will sneak by them more than ever now that the valves seat tightly again...so if you end up pulling the heads,you might as well do the rings too...

A quart of LUCAS will probably go a long way to reduce oil consumption if it is excessive blow by or worn rings,it'll help reduce the leakage past the valve stems too..

Ok, quick update:
I had the PCV valve hooked up to the charcoal canister, but at idle, the line i had it hooked up to had 0 vacuum. So I am now going to go on a search for the one emission line that does pull a vacuum and hook it up to there. Could that really be causing this many problems? I assume i still have bad valves and maybe plugged return ports. I dont want to have to take the heads off while I am up here at school. All I have is a tool set, nothing fancy to work with. Opinions on using atf or seafoam to try and break loose the crud? do that about 3 times and then clean the oil pickup?

 

[samsterman99]

Daily Update #2,
Fixxed PCV valve, no longer smoking out of valve cover breather on passenger side. I dumped a bottle of engine clean/sluge remover in the crankcase, and changed the oil. I still assume my valve seats are shot, but I am hoping this will band aid my problem a bit.

 

[4X4HIGH]

Daily Update #2,
Fixxed PCV valve, no longer smoking out of valve cover breather on passenger side. I dumped a bottle of engine clean/sluge remover in the crankcase, and changed the oil. I still assume my valve seats are shot, but I am hoping this will band aid my problem a bit.

Worst thing in the world you could have ever done.

Any sludge that is in the engine won't hurt a thing as long as it's just sitting there as long as the oil passages aren't clogged. The minute you try to "clean" the sludge is when the problems start as the sludge starts to break up it will now clog oil passages, oil return holes, lifters, push rods, oil filters.

 

[K5_Fla]

+1 .... put the sludge back in there...... not really but there is alot of truth to that

 

[trustyrusty]

Worst thing in the world you could have ever done.

Any sludge that is in the engine won't hurt a thing as long as it's just sitting there as long as the oil passages aren't clogged. The minute you try to "clean" the sludge is when the problems start as the sludge starts to break up it will now clog oil passages, oil return holes, lifters, push rods, oil filters.

Yup that's where I was going when I said to remove the heads to clean/rebuild them.
I've seen 2 vehicles (1truck 1 car) where they cleaned the gunk with the heads on and in one case (truck-Ford) he ended up having to buy a new engine as the oil pump pickup got clogged and sent a rod through the block and lodged it in his tire. Don't know the fate of the car but I would suspect a similar effect as there was some pretty hard chunks he was clearing out of the heads. That one was so bad that there was a wall of tar that was about 1" high near the rear of the head.

 

[samsterman99]

Yup that's where I was going when I said to remove the heads to clean/rebuild them.
I've seen 2 vehicles (1truck 1 car) where they cleaned the gunk with the heads on and in one case (truck-Ford) he ended up having to buy a new engine as the oil pump pickup got clogged and sent a rod through the block and lodged it in his tire. Don't know the fate of the car but I would suspect a similar effect as there was some pretty hard chunks he was clearing out of the heads. That one was so bad that there was a wall of tar that was about 1" high near the rear of the head.

Haha, well whats done is done now. I am keeping my eye fixxed on the oil gauge, and as soon as I have a day, I will rip off the oil pan and inspect it/clean the pickup. Hopefully I am lucky, and all the loose gunk was drained out or trapped in the filter. I will have to take a long highway drive and see if the PCV valve relocation has fixxed some of my problems.