My son and I are trying to get his 74 mav up and running. We ran a compression test last night on the 250 cid. Cylinders 1,2,and 6 read 150 but cylinders 3,4,and 5 read zero. Can someone give me an idea why I am getting these readings and what my next step would be?
Take the valve cover off and make sure the valves are opening and closing .. perhaps the timing chain slipped or broke .... With readings like that it must be valve train/timing issue
Is it possible that the head gasket is blown? I am talking with a friend and this is his thought on the lack of compression issue
Thank you for your input The car hasn't run for the last 4 years or so. We just replaced the gas tank and the fuel pump due to bad (sitting) gas and rust issues. We don't have the carb on the car yet. We were just checking the cylinders to see if the engine was in good condition before we started and drove the car. Does this give you any better insight as to where we are on this project?
I have never seen a quick fix for stuck valves, you will likely have to pull the head and send it to a machine shop for a complete valve job.
Would this be a short term fix? In that will I have problems with the bottom half down the road(rings etc.) if I dont rebuild the whole engine now? Lack of money is the issue right now. I'd like to get the car running for now so my son has transportation.
Unknown. If the valves are stuck open, the cylinder has greater exposure to the outside atmosphere. Although your in Arizona, rust can form in the cylinders. I would suggest doing like Dan Hines said and remove the valve cover and check each of the valves to make they are opening and closing. If you have a stuck valve the valve springs will remain compressed regardless of cam position. The rockers on these valves will also have lots of play in them. If they are stuck, then you can remove the head inspect the internals of the engine and proceed from there. Don't know of a way to check the rings with a good valve seal other than pulling it apart. Anyone else have any ideas!
If not the valves themselves it could be the lifters stuck in the bores. I would try spraying valves, lifters, etc. with Liquid Wrench, WD40 or something like that and let it soak in. Then turn the engine over by hand and see what moves and what doesn't. Before you try to start it again do an oil change and prelube using a drill.
Not sure how your 250 is but on a V8 you can pull out the distributor, put an old distributor shaft in a drill, turn it counter-clockwise to run the oil pump and send oil throughout the engine. You keep turning it until you see oil at the rocker arms, the fartherest point from the pump. Then you know everything in between is lubed. Only takes a few minutes.
Sounds like your timing was interrupted at some time and bent some valves. I don't know how it happened, but 3 of my valves were bent a little and were not sealing. This was my wife's great grandmother's car, and I have no idea what she did to it. Took the heads in, had them cleaned and 3 new valves. About $80 for the cleaning, extra for new valves and seals. Runs great now.
i had a valve stuck once and did the wd40 thing. then took a rubber hammer and taped the top of the valve stem that was stuck . your case tap all of the valve stems . chances are the valve guide seals are shot ...frank...
