no compression in a cyl

A

A Rookie

Member
239 In 49 car sealed up (air cleaner on, Breather cap on, Dipstick in, hoses intact,) so no rodent issues. Motor was rebuilt in 1966, Receipt from a rebuilder found in the glove box. Sat ever since w roughly 2000ish mi. Oiled the cyls down w M. Mystery oil to keep from breaking rings. Spins well, but no compression in a couple cyl's. No compression pressure coming out of the dipstick or oil filler tube. Now what ???? rings lose tension? Valve stuck open?
 
Last edited:
I would bet on stuck valves. I pulled a car out of storage in he early 90's that had sat since 1954. It had 6 cylinders with 110 lbs and 2 with 0. When I pulled the plugs, I could see that it was two exhaust valves that were stuck. I probably shouldn't have done it, but I put some MMO in the offending cylinders and gently tapped the valves down with a drift. They "clicked" back down. I then turned the engine until they were up. I repeated this cycles 3 or 4 times and they freed up. The engine started easily. It smoked like crazy for a while and then ran fine. This was not the right way to do it, but probably the only way short of pulling the heads.
 
Thank you, Pulled the Champion plugs they were brand new a LONG time ago, Logo's were faded, LOL, Showing no use other than some light tan discoloration on the porcelain. I'll try some light tapping and see where it goes.
 
Please keep us posted as you proceed with your testing. My two bits is on stuck valves too.
Squirt a lot of MMO in the cylinders aiming at the valves and crank her over with the key off.
I had that with my car when I first got it. Lots of info on this subject. Try using the search function at the top of the page.
I think if the engine will start, I'd try running it a little to warm it up a bit.
 
Just saw a video on penetrating oil. Liquid wrench out performed them all including acetone transmission fluid.it was second
 
If you are tapping on the valve ( the exhaust valve is what you see through the plug hole), be sure to tap in the center of the valve. You don't want to break one.
 
I have had the same experience and did the same thing as tubman, with good results. A word of warning:if you find that the valves are stuck open tap gently.If they don't come loose on the 1st or2nd tap pull the head and find out why.
 
If you are going to go the "tapping" route, make sure that you watch through the plug holes while turning the engine over so that you can determine which valves are stuck and which are not. You won't see the stuck ones move; those are the ones to work on. If they don't move on the first tap, rotate the engine a half turn and try again. No sense tapping on a valve that's on the cam lobe. Again, easy does it. Luckily, it's usually the exhaust valves that stick because they run hotter with less lubrication.
 
SUCCESS! Thanks guys ,LW and a light tap and I have compression in all 8. I have 1 more question I will ask in a separate post. Thanks again.
 
You must log in or register to reply here.
Back
Top