Compression

[abelh7]

Recently My 91 Honda's Timing Belt Broke And I Was Stranded. I Finally Got It To My Mechanic And He Replaced The Belt And I Prayed That The Valves Were Not Bent And Thank God That They Wern't. But One Thing That My Mechanic Said Once It Was All Put Together Was That 2 Cylinders Were Running At About 130lbs And The Other 2 At About 200lbs. My Question Is What Does That Mean In The Long Run And How Long A Run. I Dont Race Or Anything Its Just A Daily Driver To Work And A Couple Out Of Town Trips. What Can You Tell Me?

[deevergote]

Compression is best to be the same across the board. Usually the higher, the better. Those two low cylinders are beginning to fail. They may last for a while, but the motor isn't in top condition. It's hard to say how long it will last, because that depends largely on how well you maintain it, and how you drive it. It's not on its deathbed, but it's not healthy. Don't beat on it, take good care of it, and it'll probably still last a long while. For all you know, it may have been running like that for years already!

Also, please don't type in all caps. The software corrects it... but it's still not fun to read the first letter of every word capitalized. People see that and they don't want to help.

[10thcb7]

a stock rebuild of the bottom end should be good for another 150K plus. Just get oem seals oem bearings and oem gaskets. Oh and piston rings too. Thats all you really need for the build up. Under 500 bux

[Djmoua]

Also, please don't type in all caps. The software corrects it... but it's still not fun to read the first letter of every word capitalized. People see that and they don't want to help.

lol so picky deeve tahaha...at least he didn't go something like:
"Mah kompreshun" or "mY cOmpReSsIOn"..

thank god he didn't do that..AND didn't say it like usher: "These are my Compressions, blah blah" however the song goes lol.

[deevergote]

a stock rebuild of the bottom end should be good for another 150K plus. Just get oem seals oem bearings and oem gaskets. Oh and piston rings too. Thats all you really need for the build up. Under 500 bux

plus another $700 for labor. The guy didn't do his own timing belt... I doubt he's going to do a bottom end rebuild by himself.

[bcjammerx]

bad rings...bad bad rings...nooo...nnnooo!

[chrischhorn]

yeah youve got bad rings comin and since practically the whole motor will already be apart u might as well rebuild....the only thing u will start to notices is loss of power or if ur rings go out completely u will start misfiring and u will tear apart ur cylinder walls. Its best to do it now since u caught it early.

[johnl]

The rings may be on their last legs, but they may also just be stuck in the ring grooves by gummy deposits (effectively gluing then in place and preventing them from being adequately pressed againsr the bore by compression pressure acting behind the rings). You might try something like Seafoam or Auto-RX or a similar product designed to help clean deposits from rings (etc etc). If you want to read up on such products check out the 'Bobistheoilguy' website.

Also, please don't type in all caps. The software corrects it... but it's still not fun to read the first letter of every word capitalized. People see that and they don't want to help.

X2, though it's not quite as bad as posts written with no punctuation, paragraphs and / or in 'textese'!

[Cb_JoeyG]

i just seafoamed my car cuz i noticed a loss in power and i reciently did my valve lash and i noticed it was dirrty in there alot of coking.. also i think my car is going to have low compression (havent checked yet) because im getting alot of blowby i kno this cuz i made a oil catch can off of my pcv valve and i have already filled half the canister and its only been about a week.. so im thinkin ima have to do a complete engine rebuild soon too =D good luck to ya man

[MRX]

are you sure some valves weren't bent? It'd explain the loss of compression in two cyliners more than likely it was either cylinders 1&4 or 2&3, huh?

[Fake Thug]

Sounds like bent valves to me.. One way to check is to pull the plugs, . set the #1 cylinder at top dead center. Use a compression tester hose with spark plug adapter and an air compressor. Push compressed air(90psi) thru that cylinder and listen.

Air hissing by the exhaust manifold or blowing out the tailpipe = bent valves. Do that for all four cylinders. Another way to "eliminate" the rings is to do a wet compression test. Pour a tablespoon or 1/4 cup of oil into the bad cylinder and crank. If compression goes up, compression rings are screwed. If compression stays the same then you have a valve/seat/guide problem.

[musteredonme]

thoes PSI's are better than mine with out a broken t belt

[HondaFan81]

are you sure some valves weren't bent? It'd explain the loss of compression in two cyliners more than likely it was either cylinders 1&4 or 2&3, huh?

Yes, I agree with MRX, how were valves not being bent verified? This could be the issue, especially if your car ran fine beforehand. Time for a reconditioned head, your mechanic should have checked all the valves before reinstalling it.

[deevergote]

What would cause slight damage to the valves, though? Contact would do more than a slight loss of compression, I would think...

Still, if the low compression is in 1&4 or 2&3, then that is a very likely answer.

[MRX]

What would cause slight damage to the valves, though? Contact would do more than a slight loss of compression, I would think...

Not necessarily, depends on how much contact and force there was. When i bent valves on my head you could only visibly tell that 2 valves were bent. Took it to a shop and it turned out that about 6 were actually bent.