No Compression!!!!!!!!!!

[maxb45678]

I'm building a 360 in my garage and we just put the heads and valvetrain together. We were putting it at TDC on the #1 piston before droping the oil pump drive gear in and we didnt feel any compression on the number one piston by plugging the spark plug hole with our thumbs, and the compression tester had no reading when we hooked it up. Also, sometime during the cycle a puff of air is blowing out the exhaust valve.?.?. We tested this on the number 1 and number 3 cylinders with the same results?? I'm very confused and dont know what is going on. What are the possiblities? Any suggestions would help. Thanks again guys.

[sixpackgut]

something is holding the valves open. wrong pushrods maybe. were the heads milled? are the rockers on right? are they adjustable rockers?

[MoparMarcIdaho]

New lifters freshly installed after soaking in oil?Need more info.

[rumblefish360]

No rings on the pistons! LOL!

Only kidding.

[bbeckwith]

I would guess one of two things, either you weren't on the compression stroke, or your valves are being kept open by improper valvetrain geometry.

[jslikness]

My guess would be in the valvetrain, if it's old lifters, sometimes they need to be bled down...

[maxb45678]

i didnt have any work done to the heads when i rebuilt the engine. I'm using the same lifters (not terribly old and I primed them before i put them in), same pushrods, and the rocker assembly seems to be just fine. It is adjustable rockers. How much would it be to take the heads to a shop and get them looked at and adjusted, considering they dont have to do any extensive work on them?

[rusty duster]

try loosening the adjusters on number one cyclinder until you have a little play.Then see if you have compression.Did you mill the block or put new pistons in?

[A3404SPD]

I know this may sound obvious,but are you sure that the timing chain is correctly aligned?Thats what it sounds like you are describing.I've seen this more than a few times.

[MoparMarcIdaho]

Heck,I dont know,if those same parts were on that motor before,they should work again.As in previose post make sure there is some slack in the pushrods and at that time,double check timing gear and chain setup.If there is no compression then,either oil up the cylinders or pull the heads to make sure stuff is assembled correctly.Its something simple thats why you cant find it.

[DanL]

You said you primed the lifters. Are you running hydraulic lifters with adjustable rockers? If so, seems like the lifters would pump up and hold the valves open.

[maxb45678]

i can see the valves closing, it has to be a very small gap because some pressure does build up. It comes out as a little puff, so its building up and letting go. My thought is that the valves that i'm having a problem with were open wheni decided to rebuild the engine and that carbon has built up at the seal, causing it to have a poor seal. A mechanic I talked to said that he recommended lightly rapping on the spring end of the valve with a rubber or plastic mallet to try to loosen the carbon and that when i fire it up it should clear the rest out pretty easily. Another problem that I failed to post is a gurgling air sound that sounds like air is pushing past the rings. This mechanic said that was alright too because the cylinders havent been honed or rebored. He said that it will just take a little longer for the rings to fully seat. What are yall's opinions on this.

[23T]

Are you putting heads on a fresh rebuild without having them checked and a valve job done? Exactly what all have you done in this rebuild? NO just trying to get a handel on this

[maxb45678]

It's not really a rebuild, i just call it that for lack of a better term, it had a cracked crank in it. I tore the engine apart, replaced the crank, bearings, and rings, everything else is the same parts that were on it before and havent been changed in the slightest.

[satelliteply65]

Originally posted by rusty duster
try loosening the adjusters on number one cyclinder until you have a little play.Then see if you have compression.Did you mill the block or put new pistons in?

Rusty may have a simple solutions. About 20 yrs ago, I had some oil seals put on a set of Olds. heads. Engine would not start after a simple process.

After a few days of trying everything by the manual, I loosened the adjusters until the valves were close and got compression. Once I saw that it worked on one cylinder, I loosened all of the adjusters. The engine fired right up and the lifters started clanging. I adjusted them according to the book after it started.

On a side note is there any chance that the rings are dry and there is no oil between the ring and cylinder wall? Dumping some oil in the spark plug hole would ensure this was not the problem.

[maxb45678]

well, i've decided that the gurgling sound of air pushing past the cylinders was just because the new rings havent completly seated because the bores werent honed. Everyone i've talked to said that they will seat just fine, it may just take a lil longer. As for the air pushing past the exhaust valves, I think its just carbon buildup at the valve seat. A trusty mechanic I talked to said that I could use a mallet to tap the spring side of the valve to try to clear some of the carbon. He also said that there is a chance that it will clear itself out when i fire up the engine. If it doesnt clear it up I will just pull the heads and take them to the shop to get them cleaned up and inspected. Any comments on this stuff.

[23T]

Originally posted by maxb45678
well, i've decided that the gurgling sound of air pushing past the cylinders was just because the new rings havent completly seated because the bores werent honed. Everyone i've talked to said that they will seat just fine, it may just take a lil longer. As for the air pushing past the exhaust valves, I think its just carbon buildup at the valve seat. A trusty mechanic I talked to said that I could use a mallet to tap the spring side of the valve to try to clear some of the carbon. He also said that there is a chance that it will clear itself out when i fire up the engine. If it doesnt clear it up I will just pull the heads and take them to the shop to get them cleaned up and inspected. Any comments on this stuff.

It's your $, car, engine & time, but it seems like a lot of maybe's if's & hope to not find the problem and fix it now before you waste $ on parts that will need to be replaced if another tear down has to be done. Good luck hope it works for the best