yotasound

There is blue smoke coming out of my exhaust. We ran a compression test and the compression in all cylinders was fine. Anyone have a clue of what it could be.

jimbo74

blue smoke is burning oil......

Rivalred

Valve guides or rings are worn out and your burning oil like Bean said.

kyle_22r

good compression might indicate valve seals need replacing.

yotasound

My compression ratio for all the cylinders was 190. Every one I have spoken to said they thought it might have been rings or seals until we ran the compression test. Blue smoke indicates rich fuel. Black smoke is burninig oil. My gas mileage has gone to ÅÅÅÅ and is about 5-10 mpg. leaning more towards the 5 mark. I changed my oxygen sensor but that didn't help.

DudeBud

uh i think your a little mixed up blue smoke can mean its rich but usally means is burning oil. black smoke is fuel

tabb

A compression check only checks the 2 top rings (compression rings) it does not check the oil control rings (bottom one). You are definitly burning oil. Make sure your PCV system isn't plugged. Depending on mileage, probably a combo of worn valve seals/guides and/or seized oil control rings.

91RN81

you really need to do a leakdown test, that will tell you the condition of the oil rings.

tabb

Leakdown tests only pinpoint the source of cylinder leaks ie: valves, head, head gasket or compression rings..... Since the oil control rings don't seal (they only scrape the excess oil off the cylinder walls) and the valve seals and valve guides are not located inside the combustion chamber, neither a compression or leakdown test will diagnose oil burning.

I think the only thing/tool that can diagnose oil burning is a vacuum gauge. Don't ask me how 'cause I can't remember. I've heard of old school guys doning it but have never done it myself. Like I said before, depending on mileage it may be several things.

From past experience, unless you've got the tools to replace the valve seals "head on car", then you will be ripping the head(s) off and tearing the head down on the bench. In this case it's really only a little more work to pull the oil pan and pistons to replace the rings and hone (deglaze) the cylinders. You can leave the block and crank in the car. Just make sure to do a very good job cleaning.

If you want to go all out, you can re&re the entire engine and get it bored to the next oversized spec and install oversized pistons. In this case I would recommend you have the cylinders machined as close to the min spec of the next oversize as possible (closer oil control ring clearances). If when you replace the valve seals and they do not seem to be very hard or brittle, then I would have a look at the guides. They may be excessivly worn.

On a low mileage engine you can get away with only valve seals. On a high milege motor, doing both rings and seals is advisable. The rule of thumb is when you fix the weakest point, the next weakest part is not far behind to go.

Check your PCV system to start , make sure it's not plugged and make sure your oil level is not overfilled before you spend any money on more costly repairs. Also have a look at your airbox and intake air tube for oil/blow-by.

94x4

Bad valve seals or guides, though more likely the seals as you've not posted anything about hearing any "rattling" from the top end of your engine.

Rivalred

AMSOILKing

First off, what kind of engine oil are you using? Second of all, how often are you changing your oil? Third have you ever considered using AMSOIL products. I ususally get around 20,000 to 30,000 miles on 1 oil change and I am covered by a warranty. My truck gets around 27-29mpg and it has 156,100 miles on it. What kind of truck do you have and what year is it?

Bob_98SR5

amsoilking,

i would say that the vast, vast majority of the forum member are aware and knowledgable about amsoil products, so you can chill out with the hard sales pitch. in fact, there are other independent amsoil dealers (which is the correct way to present yourself to customers, per amsoil terms of agreement) on the forum too.

bob

JamesD

Huh? It can't? Actually it can. Using the tester you can see the percentage of leakage from where the air is coming from. If you have a lot of air coming out of the dipstick or the crankcase, over 10%, then you have worn rings. If you have very little leakage, say around 5%, then this is normal. Cylinder leakage test is the BEST tool out there. If you have under 10% leakage on all cylinders and you are still burning oil then odds are the valve seals and valve guides. It can still be oil rings but you would most likely have low compression cause usually oil rings wear at the same rate as the piston rings do.

James

CynicX

Yeah, thats his problem. Hes not running Amsoil!! We are so dumb not to have thought of that /sarcasm off. Post like this is why i'll never fall into this amsoil hype. Seems like everyone who swears by it is either selling it or very unknowledgeable

.....

Anyway, when does it blow the blue smoke? If its only on start up chances are its the seals.

nachoman

Wow old thread. First time poster long time reader. I have a 86 22re I'm having similar issues and waiting for a leak down test. Does anyone know how it turned out for these guys. A re-ring kit from engnbldr is only like a 100 bucks could this work if its not to bad. I appreciate all coments

Yotamobbin

I only ask because I had blush smoke coming out as I down shifted going up a hill I thought it might have been a piston ring going out.

thefishguy77

iTrader: (1)

Very old thread. Do what others in the previous replays have said. Run a compression test. Also check your ecu for codes. Might be something easy to diagnose. How much oil are you going through per oil change? How many miles are on the truck?

Yotamobbin

Super old thread lol, yea I was looking for my compression tester. I'm going through about a half quart of oil evert couple days. It hasn't been smoking lately but running a little rough. There are 267,xxx miles I also noticed that I had oil coming from the top of the engine replace pcv value thinking it was clogged. I noticed it's will smoke from the pcv value in between the gasket and pcv. Thanks for the reply brotha.

thefishguy77

iTrader: (1)

Here is a link for checking the ecu for codes if you have an fuel injected motor
http://www.4crawler.com/4x4/CheapTricks/TroubleCodes/