I just checked my compression on my 97 civic with D16Y7 and its giving 210psi on 3 cylinders and 175 on 1 cylinder.I think the normal values should be around 135psi?the car has 190k kms on itand its total stock engine. Its lacking power and giving bad gas mileage.i just bought this car few months ago and replaced cracked exhaust manifold.It was giving really bad gas mileage before and after changing exhaust manifold,it improved a lot but still not good.Could the high readings be due to carbon in the combustion chamber due to the engine was running rich all the time bcoz of cracked manifold? also my coolant level goes down very slowly. any suggestions please? thanks in advance.

135 would be scary low.

I expect 180-220 psi from most of Hondas engines.

Why is your #1 lower than the rest?

Got codes?
Got datalist?

Thanks for the reply. I think i read somewhere nominal 135psi but i could be wrong.where i can find exact nominal value for d16y7 engine? i am suspecting head gasket bcoz of 2 reasons.first i can smell combustion and gas from the coolant reservoir and second it looses coolant slowly and there is no visible leak anywhere.but there is no coolant in oil and no oil in coolant. and there are no codes .thx

I doubt you will ever find a real spec. You may find a minimum number, but it isn't worth much. In your case, if you found a minimum spec of only (example) 135 PSI and adhered to that and that only, that would make for a very sick engine.

I wouldn't worry about the 210 at all. I wonder about the low one.

A compression test is a relative evaluation between all of the cylinders. It determines pumping ability along with sealing (to a certain extent).
Experience says a compression test should show 180PSI or above on that engine.
Industry standard says no more than 10% variation between cylinders.
I might check valve clearances, see if there is a tight valve on the low cylinder.
I might run a wet test and see what the low cylinder comes up to.
I might do a leakdown test, depending on the results of the other tests.

If I think I have a head gasket blown and leaking into the cooling system, I use a fun-l-fill in the radiator, and apply shop air (150+ psi) to each cylinder. If the coolant level rises, then there is a breach. And I know which cylinder to be looking at when it comes apart.

If it is blown really bad and the leakage is severe, cranking the engine and selectively removing and installing spark plugs can lead to the same conclusions. It has to be in really bad shape to do this though.

HTH

thanks ezone for the detailed reply.i will take it to the mechanic as i dont have leak down tester and air supply.and they can do pressure test for cooling as well.another thing i noticed it that when the engine is hot at running temp and if i shut down the engine for 5-6 mins then it hesitates to run for the first 2-3 secs and then it runs just fine and smooth.it doesnt do when its cold. thx

Another idea, now that you mention this (or something else to check):
I would make the engine run bad for a few seconds, then shut it off, and immediately pull the plugs out. See if they are fouled or wet with coolant, or what have you.
You have to do this while it is running bad, because once it clears up the plugs will look fine.

great idea..i will check it tomorrow as my car will be at home tomorrow and will let you know.thanks again...