Did I get ripped off? I'm thinking so!

[bruceb58]

Dodge minivans are known for oil consumption issues. Watch your oil level like a hawk so you don't get too low. I would have the valve seals replaced. Seems to be a common problem.

 

[fhhuber]

For what the compression value SHOULD be:

Look up the compression ratio. (should be able to look yup your exact engine's ratio) Multiply by 14.7 You should be pretty close to that result. I'd generally expect a minimum compression ratio of about 8:1 or a bit under 120psi. Then make allowance for the valves being open a bit into the stroke... and there you are ... appx 100 to 120 psi range.

190 psi would have you near a 13:1 compression ratio That's a bit high...

Higher compression ratio needs higher octane fuel.

Above 13:1 I'd expect it to be a diesel.

 

[bruceb58]

You can't multiply by the compression ratio and get that calculated pressure unless the temperature remains constant which it doesn't. That's why a SBC with 8.5:1 compression ration will yield over 150 PSI.

High School chemistry pv=nrt. Also entropy, specific heat ratios, heat transfer, and volumetric efficiency.
http://www.corvetteforum.com/forums...-compression-ratio-from-compression-test.html

​

 

[tpenfield]

At least you know why this car was for sale. It could be that the rings are sticky or worn. You could try an engine oil treatment to see if you can get any build-up or sludge out.

 

[fhhuber]

You might get away with.... Slick 50.
(people love to hate this stuff...)

I call it a cheap rebuild in a can.
It either works really well, or it does no good at all.

 

[bruceb58]

Do a compression test and post your values in this thread.

If they look ok, valve seals will need to be replaced. No mechanic in a can(snake oil) is going to help compression or valve seals so save your money.

 

[boatman37]

compression ratio is the ratio of cylinder volume at BDC divided by the cylinder volume at TDC. engine compression is the pressure created when the piston cycles through the compression stroke. there may be some correlation but it can't be used to calculate cylinder compression engine compression can vary depending on camshaft overlap, air getting past the valves or rings, etc. whereas compression ratio doesn't take those things into account, which is why it is referred to as 'static' compression

 

[Chad Flaugher]

I started a new job yesterday, and I wont be getting home until after dark this week... I'm going to try and do a compression test this weekend. I will post results! Thanks for the help guys!

 

[bigdee]

Do a compression test and post your values in this thread.

If they look ok, valve seals will need to be replaced. No mechanic in a can(snake oil) is going to help compression or valve seals so save your money.

^^^x2^^^ If compression checks OK it sounds like valve stem seals to me. If the exhaust valve stem seals (usually first to go) are leaking it WILL clear up after engine runs for a bit because there isn't any vacuum to pull more oil in. The intake seals if worn will cause oil to be drawn in while running.

 

[Chad Flaugher]

Yeah, I'm going to test compression and replace the PCV valve this weekend... Also hoping to pass emissions soon as well. I really hope it's just valve guide seals, but It'll just have to wait! I will post results after that!

 

[dolluper]

Do yourself a favour do an oil change replace one quart of oil with trannie oil ,as trannie oil contains lanolin this will soften the valve seals if run enough ,if its guides no help.....one other problem can be oil gallery's are blocked with sledge not allowing oil back into the crankcase and staying in the heads

 

[dwco5051]

Bad valve stem seals will show a cloud of blue smoke after descending a long grade when the engine is braking. That cause a high vacuum and when you hit the gas at the bottom the oil burns out all at once. I had several 1970's GM 350 V8's that I had to replace them on and that was one of the first indications. Still have the adapter I made from a spark plug body with an air hose adapter brazed into it to make changing them a simple job. Some guys used to stuff the cylinder full of sash cord and turn it by hand to hold the valves up.

 

[bruceb58]

trannie oil contains lanolin this will soften the valve seals if run enough

ATF does NOT contain lanolin. It will also not help soften valve seals. Don't believe these old wives tales.

 

[bigdee]

ATF does NOT contain lanolin. It will also not help soften valve seals. Don't believe these old wives tales.

Correct. There is no salvation for worn/hardened/cracked valve stem seals. Now for a ray of hope, seals are cheap and if you can DYI it is a rather simple fix.

 

[gm280]

I would certainly try and replace the valve seals. After all it really isn't that hard to do. However, just hope that the valve guides are still good. JMHO!

 

[DeepCMark58A]

I thought it was good that it was leaking oil because that way you know the critical components are getting oil, oh wait that is old aircraft engines not mini vans.

 

[bruceb58]

I would certainly try and replace the valve seals. After all it really isn't that hard to do. However, just hope that the valve guides are still good. JMHO!

This is true. If the valve guides are worn, the valve will slightly wobble and replacing the seals won't do much for long.

 

[Volphin]

This is true. If the valve guides are worn, the valve will slightly wobble and replacing the seals won't do much for long.

It's not the guides that you have to worry about on these heads, it's their tendency to crack. FWIW, heads ending in casting number 88AA tend to crack more often than castings with the 49AA designation.

 

[Chad Flaugher]

Weather set in over the weekend... Looking at 14" by Monday night. Wasn't able to perform tests. It did finally throw a PO420 code. (catalytic converter) I cleared the code. I still plan on checking a few things out, but it turns out the van is smaller than the Grand Caravan (my wife's current van). She runs a daycare, and although it does seat 7, it does not have room for as many car seats. That being said, I think that this new van is going on the chopping block for a loss. I'm going to sell it honestly, stating that it smokes when you first start it. I don't really have time for another project that doesn't float!

 

[bruceb58]

That code is probably being set because the oil has caused an O2 sensor to fail.