Good morning I’ve done a compression test on an engine I bought and get the following 2 cylinders between 95 / 100 one at 65 and one at 15??? the engine was bought knowing it had been lying and at first wouldn’t even turn over freely but after a bit of oil down the plug holes and working it back and forward it “freed up” well enough to get a starter to spin it for comp test my question is before I go into uncharted Territory for me and undertake full strip down (scary lol) is there anything else I should do which could improve the compression or is a full strip and rebuild inevitable now?
You already did. I thought you'd answered your own question. Likely the rings are gummed up/barrels rusty from sitting. D you know it's recent history?
Strip it down , check and clean everything re- assemble and try again, if it’s the same - time to start buying new stuff . Don’t be daunted it is quite easy and there’s always someone to re-assure you on here
Cheers Dazza it’s the first time doing anything like this There’s no rush cause I have a couple of good engines and this one was actually bought thinking it’d need stripped down as a sort of “teaching” engine so I’m happy to try it and see how it goes
Off with the heads and see what you can see? The 10 years in a shed isn't ideal because some of the valve springs will have been compressed all that time...but we bought a beetle that had sat in a dryish shed for 12 years, ungummed the carb, changed the oil and ran it for several years before divorce caused sale.
Is it type 1 or type 4 engine? I’ve got some type 4 barrels & pistons 1800cc which have only done 3k miles if you’re interested. I Will be putting them on flebay later.
I’ve got the heads off so do I need to remove the jugs to check the rings now or is that not the way to go Hear a lot about sticking rings so how would I identify this and if that’s the reason for low compression?
Rings should compress a couple of mm by finger pressure and follow the curve of the piston all the way around . If they`re not `springy` or won`t spin on the piston they`re gummed up .
Cheers Lasty once I’ve got the jugs off and if the rings are “gummed up” are they possible to be saved or is it new rings required?
Jugs ?? Barrels It really depends on how bad or worn they are - are the barrels scored ?? - anything broken ?? - how worn are pistons ?? You may need a vernier and feeler guages to take some measurements ... All this is available in a Haynes manual , as well as a very easy to follow sequence .
Exactly. With heads off first you can see if water got in there. No? Great, not that problem so look at the piston crowns. Burnt at the edges?;No? Great, hasn't been detonating. Pull off the barrels and see if the rings stick, check for wear, piston sides scuffed, barrel cross hatching, ridge at top of top ring stroke.
