Mechanics

TIMING/COMPRESSION

1992 Honda Prelude

Engine Mechanical problem
1992 Honda Prelude 4 cyl Front Wheel Drive Automatic 170000 miles

I recently had a timing belt break while driving about 45 mph on a '92 Honda Prelude Si, engine type H23A1. I replaced the timing belt, along with water pump, timing balancer belt, both serpentine belts, as well as any involved gaskets/seals. The #1 piston was set at TDC and both camshaft gears are set with up marks pointing up and all notches lining up with the cylinder head. The replacement was done exactly according to the service manual. After replacing, the engine will not fire. The crank turns when the car is attempted to be started, and the spark plugs are indeed firing. I manually turned the crankshaft by the pulley bolt and verified all four strokes with respective intake/exhaust valves closed or open. Starting with #1 piston at TDC; piston #1 moves down (ignition stroke) with all valves closed, piston #1 then returns upwards with exhaust valves open (exhaust stroke), then piston #1 moves downward with intake valves open (intake stroke), then returns to the top with all valves closed (compression stroke). Upon removing the spark plug and doing a compression test (both with a meter and feeling by hand), there does not seem to be any compression during the compression stroke. I performed this same compression test on piston #2 and got the same result. I know the timing is exact (as described above) as you can watch the valves opening and closing as you see the piston moving up and down through all four strokes. I do not know what would cause a loss of compression like this, and think that might be the problem of the engine not firing. What might be the problem as to why the engine will not fire? Why might there not be compression in the cylinder during the compression stroke even though all valves are closed, considering this is happening in more than one cylinder? Any ideas on what to check or what is the problem? Thanks.
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Rswain
October 24, 2010.



Well. I would have to say 4 bent valves. The valves will still move up and down but bent just enough to cause no compression. Another possibility out of time.

I would put the eng on tdc pressurize the number one cylinder see where you are losing pressure. If the cyl is not losing pressure with all valves on that cyl are closed then the valves are sealing.

As far as spark, this could be related could be another prob. But you have to find the comp prob first if you are unable to pinpoint it only other way remove cyl head.

Billymac
Oct 24, 2010.
Check the valve clearances, if they are excessive, that would mean bent valves and cylinder head have to come off.

KHLow2008
Oct 25, 2010.
Would bent valves cause the engine not start at all, or would they just cause it to run rough? The engine will not fire. I am going to do a leak-down test as well as check the valve clearances to see if this will unveil the problem.

Tiny
Rswain
Oct 25, 2010.
Bent valves would result in no compression and that would not allow the engine to start.

KHLow2008
Oct 25, 2010.
Yes the leakdown test will tell you what you need to know

Billymac
Oct 25, 2010.
Also, is there any timing adjustment that needs to be done to the distributor? It is a distributor with an internal rotor like seen on most older models, not a COS system or anything of the such. Just curious if the timing of the distributor is controlled by the camshaft that it is connected to, and therefore would be in time as long as the camshaft is in time, or if there are extra steps that need to be taken to get the distributor in time? Thanks again for all the help.

Tiny
Rswain
Oct 25, 2010.
The distributor would be in time as long as the camshaft is in time but the ignition timing can be too advanced or retarded depending on the position it is bolted on. Igniton timing can be adjusted.

KHLow2008
Oct 26, 2010.
I did a leak-down test and was leaking air out of the exhaust. There was no compression in the cylinder. I even rotated through all four strokes to be double sure it was not a timing issue. I take it this means the exhaust valves are bent and the head needs to be taken in to a machine shop for a valve job. If I remove and reinstall the head myself, how much should I expect to pay for a job like this? It is DOC with four valves per cylinder. The engine type is H23A1 made by Honda in a '92 Prelude, if that helps for specifications.

Tiny
Rswain
Oct 26, 2010.
Well this could vary from one shop to the next find one that will work with you or just replace the bent valves yourself. If you have a machine shop do it most will want to do a complete valve job. But some will check and replace the bent ones. Most likely they do it min 500 dollars you do it 200. Hope this helps

Billymac
Oct 26, 2010.