so i took the van in for snow tires the other day and the mechanic figures it has weak compression so I had them test it and it was quite bad (35 on the second stroke) on 2 cylinders (318 sm block) , though they dont fire together. He said this indicates that the rings are bad from overheating of high revving, as the engine doesnt burn oil and isnt particularly high mileage to my knowledge. So now I have a supposedly dead engine, trying to figure if I should unload it while im ahead or try and drive it. The mechanic said you can typically get 6mths to a year out of an engine in this condition.... what should I do?? Drive and rebuild or drop in another engine when the time comes or scrap and sell while ive got the chance? Is there anything else that could fix this type of compression problem such as a top end only rebuild or something? Thanks again

 

If the two questionable cylinders are next to each other you might just have a head gasket leak between the two. You can tell if it's the rings by pulling out the dipstick (engine running) and see if compression is being force out of the hole. If not, it's not the rings.

 

Alloro has some great points there. Give them a try.

Also, have you tried the on-off key trick to get any engine codes?

Plus, check to see if any oil has leaked past the plenum gasket into the intake manifold. There are postings on how to check for this in many of the Dodge forums out there.

 

so i just checked the dip engine running and there wasnt really any compression coming out so if it is the rings, is that something that needs overhaul to fix or could i just spot fix the problem? thanks a million

 

If there's no compression coming out then it's highly unlikely a ring problem. But to answer your question, if you do one cylinder you do them all, or else your engine will never run smooth.

 

[hr]Ok so i have had the van out and its running fine while driving but rough idle from those 2 bad cylinders...mechanic said it isnt too bad since the bad 2 dont fire in unison with each other. Two more questions for you experts: 1. What is the average cost of a home rebuild, and is it practical to do if you have little experience with vehicles? and 2. will any carbureted dodge 5.2 318 drop right in? I am talking with a guy right now who is selling an 88 carvavelle 318 on propane, was wondering if it could be a donor engine or would all the mounts for external stuff, manifolds etc be different on these cars? thanks a million, r

 

The cost of the rebuild depends on how far your going to take it. Are you doing just rings, or are you planning on doing a reground crank and bearings, valve job (are the heads okay), oversized pistons or cylinder sleeves, camshaft and bearings, lifters and pushrods, having the block dipped, new freeze plugs, balanced, honing, head and block planing, etc.

To the best of my knowledge, the 318 block hasn't changed since 88.

 

so that would mean i could drop in th engine out of a caravelle then?

 

Since the donner is a propane burner, you'll have to swap parts on your bummed engine to make it run on gas again.

 

What do you mean by compression coming out of the dipstick water, steam, exaust or something else?