Burning Oil

[PlumCrazy]

I have a 1994 2.3, it burns oil at start up, and after it has been sitting at an idle for a while. but not during hard acceleration. I was thinking valve seals, but i put a new head on it less than 3,000 miles ago. It didn't seem to do it before putting the new head on it. I had the intake manifold off recently and was coated with oil inside, and i had already replaced the PCV valve.
I would pull the head and check it but then i have to buy bolts and a head gasket, there is 120 dollars even if that isn't the problem. Is there any way to check the head seals with out removing it? also, why is there so much oil in the intake? the motor has over 150,000 miles on it, it has decent compression that holds, would excessive blow by cause the oil in the intake?

 

[mikepotts]

to your final question... yes. sounds like piston issue, cracked, broken or bad rings. you say decent compression... what were the readings?

 

[Mark_88]

Yes...excessive blow-by is usually the cause of oil in the intake...

Blow-by can also be caused by bad or worn rings where part of the combustion is blowing through to the oil below...so a new head is not necessarily going to correct it...if the valves are bad then you get blow-by through them into the top end and this can result in oil being forced out the top end...piston blow-by can also result in it coming out the dipstick and possibly plug up the pcv system...or it can create enough force to blow pressure through the oil passages into the top end...

Some people put a little filter on the top hose so the oil doesn't end up in the intake (like mine was setup) or breather on a carbed engine...but that is only a temporary fix and eventually you get oil everywhere...or engine failure like my 2.0 after I went through all the oil in a twenty minute drive...

Sounds like maybe you should do a compression and/or leak down test if you haven't already done so...

 

[PlumCrazy]

i have already done a leak down test and it passed, i know that a new head won't solve piston blow by. When i had the head off i made sure the cylinder walls were ok and the pistons didn't rock. I am assuming that tightning up the top end with the new head just forced the already worn bottom end to go out faster.

Ill have to find the compression test results, what should it be?

 

[Mark_88]

Above 115 - 125 is average...but all should be within 10% of the others

 

[mikepotts]

Above 115 - 125 is average...but all should be within 10% of the others

exactly! and the 10% is improtant! that is the cut off, you want them to be closer.

 

[PlumCrazy]

Checked compression again

I checked the compression agian today and this is what i got:

1- 131
2- 139
3- 138
4- 135

 

[mikepotts]

good numbers! well that in mind, i would have to think the problem is not the bottom end. since the head has been taken care of, i can assume it is cool also. you replaced the PCV valve, did you happen to disconnect it while the motor is running to make sure it is sucking? these motors have a funny little box thingey which it get its vaccum from under the intake manifold. the one on the 2.3 i am rebuilding right now was completely stopped up and wouldnt let it pull vaccum, thus NOT evacuating the crankcase, creating blow-by.

 

[mikepotts]

i cant think of anything else, just make sure the lines for the PCV valve are clear and unobstructed.