Oil Dipstick pops out!?

[DTT92LX]

Hey,

Someone's giving me a standard output 5.0 from an '89 Lincoln town car. He says the oil dipstick pops out when the engine is run. Says he changed head gaskets but it's still doing it. He thinks its a blown piston ring.

Do you guys think he's right? Or could it be something simpler like clogged pcv or something? Obviously there's pressure in the crankcase that isn't getting vented properly but what are some of the other things I could check without having to do a full rebuild?

I'm gonna take the engine any way just to tinker with, maybe convert to HO 5.0 or just practice rebuilding (never did it before) but I though if I could get it running easily, without rebuild, then I could drop it in this '87 3.8L cougar I found for cheap and have myself a nice little ride.

Thanks for any and all input!

Dave

 

[Michael Yount]

You're on the right track - excess crankcase pressure. I'd run cranking compression checks and see what the numbers look like. If one cylinder in particular is bad it should show up. And, it could be as simple as a problem with the pcv system not ventilating the crankcase like it should.

 

[DTT92LX]

Can I run cranking compression checks with the engine out of the car? Not sure I'll get to work on the motor until he has it out of the vehicle and I take it home...

 

[mackey]

I blocked off my oil filler vent. I am too cheap to put a breather on, so a little rubber cap fits. I have only seen my dipstick out once, and I do not know if i may have left it out on accident.

 

[Michael Yount]

Yes you can run cranking compression checks with the engine out of the car - just leave the bell housing/starter attached; set it on the floor with the cherry picker and strap it to the leg of the picker so it doesn't move around when cranking. Take all plugs out to ease the strain on the starter and battery.

Capping off the oil filler vent accomplishes nothing performance-wise, and it can cause two problems. First, that line lets metered make-up air INTO the crankcase when vacuum is pulling on the pcv - so capping it causes un-metered air to enter the engine, and hurts the seals - that's usually the weak point where the engine will 'suck' air into the crankcase. Second, under heavy throttle, you've removed an additional vent that for crankcase pressure making the pcv line do all the venting work. The air in the line is bi-directional - flows into the engine under vacuum; flows out of the engine under heavy throttle.

Why did you choose to cap it off when there's only downside?

 

[ratrapp]

michael is right,it will only cause more problems later down the road.my non ho motor does the same thing.i replaced the pcv valve,screen and grommet but it did nothing to help my problem.my engine is just plain worn out as yours may be.i'm going to continue to run mine until she gives out.