alex_johnson2

The 3VZE in my '94 pickup with 101,000 miles (salvaged at 5000 miles & mostly a weekend truck since then) has been burning oil and barely passed emissions, so I decided to do a compression check and take a look at the plugs.

Compression was:
Cylinder 1 = 165 psi
Cylinder 2 = 175
Cylinder 3 = 130
Cylinder 4 = 165
Cylinder 5 = 152
Cylinder 6 = 175

My compression tester allows for hand-tight connections at best so some variability could be in the test, but I checked cylinder 3 twice.

The plugs were also showing signs of deposits, although oddly the worst deposits were on cylinder 6 (see the picture - plugs are 1,3,5 on the left 2,4,6 on the right).

The engine had cooled down by the time I continued, but I remeasured cylinder 3 (cold) and got 125 psi, then I added about a tablespoon of oil and read 185 psi.

I also noticed a film of oil in the intake manifold when I reached in past the throttle plate.

So am I correct in diagnosing that cyl 3 & probably 5 have worn rings? How about the oil film in the intake and deposits on the other cylinders? I have used Mobil 1 synthetic for many years and never ran it dry, and the oil pressure gauge still indicates the same pressure ranges as always. The PCV valve was replaced about 2 years ago.

I want to make sure I know what's going on before making any decisions, since it sure looks like the engine is due for a rebuild or replacement (or perhaps replacing the entire truck).

85toyman

iTrader: (2)

You should not trust a comp tester that you cant trust all the way. However from looking at the plugs you have shown us, you have an engine in need of a rebuild. The blow by in the intake chamber is most likely from a bad set of rings and a pcv valve that is malfunctioning from oil saturation from the blow by. Your best bet if your able is to pull the heads off and inspect the block and heads, with the realisation that you will most likely pull the block and have the block honed and put some new rings on the pistons. I had the same thing about 2 years ago on a 1994 pickup I had and ended up rebuilding the motor top to bottom.

Did you pull all the plugs when your did your comp test. The head gaskets are also notorious for failure. Pulling all the plugs is one way to make sure you don't have bleed over to another intake chamber and giving you false reading for comp as well. You could have an internal head gasket failure that is allowing oil to mix in the combustion chamber and giving you the false comp reading as well. Either way you rebuilding. Question is whether it is the top end only or the complete thing. The engine I rebuilt useing stock specs cost me about $2000. Now I did the complete thing, you will spend less just doing the top end.

If you have any other questions don't hesitate to ask. If you love the truck and don't want to sell then its crunch time and decision making time. If your not so in love with this truck and it runs at all, I would put new plugs back in and try to sell it for what ever you can get out of it.

MudHippy

Yes, it's most likely the rings and/or scored cylinder walls.

I've heard that a bad PCV valve will lead to oil in the intake. And the plugs do show some oil fouling.

For shame!!! That's not a very nice thing to do AT ALL!!!

You deserve a spanking!!!
A good whack on the noggin!!!

And, in my opinion, a

alex_johnson2

Thanks for the responses guys. Don't worry, I'm disgustingly honest - If I sell it, the buyer will be aware of the engine issue!