Compression Test

[Blackbird_]

Does anyone have the numbers for a comp. test on a cold engine? I think hot is 160 - 180 psi with 10% max variance between all if I remember correctly? Also, if someone wants to share the correct procedure for doing a compression test, please share :)

[Civic Accord Honda]

i belive 180 is good and 160 is service limit but im not sure
and do to the test you

remove the fuel pump fuse
remove all the plugs
install compression tester in cylinder 1 crank car over about 5 times with WOT
check the number right it down then move on to cylinder 2 3 4

[Dr_Snooz]

There are threads on this already.

178 is new for an FI engine
171 is new for a carbed engine

135 is the service limit with no more than 28 psi between any two cylinders.

The correct way to do a compression test is to warm the engine up first. Of course, if the engine is not running, or out of the care, you can't do that so much. I used a leak down tester when I did my swap. I looked for the same amount of leakage from all cylinders at a given psi, air exiting from the same places at roughly the same rate, etc. Basically, you want consistency and it seemed to be pretty accurate for me. The engine turned out to be rubbish for other reasons (oil pressure) which I won't get into here.

What's going on that you need to do a test cold?

[Blackbird_]

I mentioned this in the last thread I made but my car suddenly lost power while driving and wouldn't start back up. Been to two mechanics, and was told two different things: 1) Bent valves + broken timing belt 2) Electrical problem. I'm not sure how the first one checked this other than when I saw him take the oil cap off and see that the camshaft wasn't rotating. The second mechanic tried different things like a reman'd dizzy (he said there wasn't a spark but good tension on the belt). Not knocking either one but sometimes things can be overlooked. I want to do a comp test to see if something really is wrong with the valves. The car cranks but just won't turn over (so it seems it has compression...). If the psi is fine then I figure I'll take down the fuses and check the main relay, check engine grounds, dizzy, firing order, and starter.

[Civic Accord Honda]

if it sounds like this when it cranks over you got bad compression
http://www.youtube.com/watch?v=Zq5GmplkrBo&feature=player_embedded

[Jared]

I'm guessing you've figured out the problem, but you got me thinking of a familiar situation I dealt with when you said the mechanic "took the oil cap off to see the cam wasn't rotating". I have an 89 LXi and before I took ownership of the car, it belonged to a friend of mine who probably shouldn't have had it. His mother bought it brand new and always serviced it, unfortunately he didn't have the same foresight.

What happened was he spun out the camshaft. I remember trying to help him figure out what was wrong because the car would try and crank over with no success. We checked everything. Had no idea till we removed the valve cover and noticed the cam had twisted and snapped just above the first cylinder closest to the timing belt. Had to get a new head and camshaft machined. Unfortunately, he chose not to have a mechanic put it all back together so we did it in the garage. After all was said and done the car started up and ran like a dream. I finally took it off his hands and while driving it the cam seized in the head.........spun the bearings. Turned out there was an oil valve that was not replaced and oil wasn't staying in the top end. Needless to say I had to replace the engine. The engine I got had 190lbs of compression straight across. I called Honda cause I thought something was wrong, to high maybe, but I was assured average was 160-180lbs and some made it off the production line with a higher output.

If you haven't figured out what the problem is, and the cam isn't spinning, pop off the valve cover and take a look.

[1987AccordLx-i]

I mentioned this in the last thread I made but my car suddenly lost power while driving and wouldn't start back up. Been to two mechanics, and was told two different things: 1) Bent valves + broken timing belt 2) Electrical problem. I'm not sure how the first one checked this other than when I saw him take the oil cap off and see that the camshaft wasn't rotating. The second mechanic tried different things like a reman'd dizzy (he said there wasn't a spark but good tension on the belt). Not knocking either one but sometimes things can be overlooked. I want to do a comp test to see if something really is wrong with the valves. The car cranks but just won't turn over (so it seems it has compression...). If the psi is fine then I figure I'll take down the fuses and check the main relay, check engine grounds, dizzy, firing order, and starter.

i think our engines are non-interference engines meaning the valves wont hit the pistons if the t-belt snaps... someone correct me if im wrong.... also! check your main relay... mine did kinda the same thing and when i replaced the main relay she started right up

[AZmike]

Frequently rather than breaking, the the timing belt loses its teeth on the crank pulley. It still has good tension, but does move when the starter turns the crank.

It should just take a few minutes to pull the upper timing belt cover (two 6 mm bolts), make a small mark on the belt and run the starter for a second or two to see if it moves. Either you've found the problem, or you have proof the the timing belt really is ok.