I have a b16 head that was just vaccum tested and it checked out fine. how possible is it that my rings are the prob...I just installed them. and cyllinders 1,2,3, are all fine and hold perfect compression well anyway what all is involved in a leak down test? I will try this tonight and see what happens let me know ideas and information...thanks for your time...k

 

usually teh the rings or the valves. what was the conclusion of the comp test.

 

cyllinder 123 tested @ 210 cyll 4 was at 60+-

 

sounds like a headgasket prob to me.

 

I thought of that too but the gasket is brand new and seated correctly

 

Hmm.
Didnt i just read in another post that you were having problems with you valves tapping your pistons?

With such extreme deviation in your compression numbers, I would bet on bent valves. Time for a leakdown test.

 

ok, take a teaspoon of regular motor oil, pour it down into the bad cylinder, and redo the compression test. this should seal the rings, so if the numbers are still low, chances are its the valves, if the numbers shoot up, then you have bad rings. im pretty sure thats how its done, ill go read up a little to make sure.

 

The problem with that plan, is that the numbers will ALWAYS shoot up after adding
oil whether the rings are good or not.

But the chances are that the rings arent sealing in that cylinder.

 

but if it shoots up alot, it points to rings right? where as a small increment points more tword valves? just curious because im about to do a leakdown. 100/200/200/200 for me today.

 

thanks for the info guys but when i took off the head I did notice a chiped valve and had it replaced...I watched the machinest perform the vac test on every chamber(intake&exhaust) and everything tested fine. Last night I took out the piston in cyll 4 and it is possible that the 1st 2 compression rings were to closley aligned (the may have been 2-3 inches from the gap in the top ring to the gap in the 2nd ring) so we shifted the top two rings to off set a little more and maybe that will help...I just ordered a new head gasket today and should be reassembling things around tues. night and wed....wish me luck...later

oh yeah...I did to the comp test again last night. 1st with no oil in the cyll comp was 50psi...tried again with oil in cyll. comp was 60 psi so hopefully it was the rings tomorrow i will take the head to the shop and get it vac tested again and surfaced just to eliminate those probs...later


[Modified by lsvtec42, 11:50 AM 12/3/2001]

 

I know this topic has been dead for a couple of days but I just wanted the people who helped me to know the outcome.

I took the head back off again and took it back to the machine shop for a vaccum test again...and once again it held perfect pressure on every chamber (intake/exhaust) I also had it checked for any type of warpage on #4 chamber of the head but again it checked out fine...I then eliminated the head from the mix...i then checked the block for warpage around the #4 cyllinder but it too was fine. so I gave up I knew I was loosing over 200psi of pressure out of #4 but I had no idea where it was coming from...even if the head gasket was bad the rings were bad and the head was warped there had to be a huge gaping whole somewhere to loose that much pressure so where could it be??? I almost gave up when my friend realized that maybe the valves were either bent or just not completely shutting. we then thought the valves would be too loose...so i measured with the feeler gauge and the valve was too tight so it couldnt be staying open but then I thought that since i have CTR cams which are way bigger than stock b16's so maybe the rocker arms were riding too tightly on the cam and staying open all the time or atleast before they were supposed too. anyway i loosend them up some on cylllinder 4 and re did the compression test and low and behold the compression shot up to 242psi. so anyway problem solved the motor ran for about 30 mins last night w/o a problem so as long as i can make it through the break in process with no problems everything will be alright!...thanks for all the helpful input!...later

 

CONGRATS!!!! Isn't it great when you discover a problem and fix it your self when the mechs can't!?!

 

so all you needed to do was a valve adjustment?