Timing belt repair

[jrickyk]

I own a 1.6 litre, single overhead cam, 1987 Nissan Pulsar. The timing belt
broke recently and I purchased a replacement.

I set the no. 1 cylinder to top dead center (looking in the spark plug hole
when the cylinder is at the top of the stroke) with the no. 1 cylinder being
the one nearest the timing belt. I then set the valve cam to the position
that the no. 1 contact on the distributor was in the correct position
(according to my service manual). I then installed the belt with the
indicator marks lining up properly (again according to my service manual).

after installation, I have little compression, if any and the engine will
cough as if to crank, but it will not. I have been told this is an
interference engine, which would indicate I might have damaged or bent valve
stems. However, I have also been told that the engine should still start,
even if it runs rough, but it will not.

My service manual is not very forthcoming on this issue and the
illustrations are not very helpful and at times are rather confusing. When
you turn the engine over with the starter, you do not get the characteristic
whop, whop sound you would indicating compression, but rather only a the
whine of the starter motor. The crank is turning and the pistons are moving
as I can see them with the spark plugs out. In addition, I have sufficient
spark on the plugs as well.

Can you make a recommendation on the problem and the requisite fix. I know
it must be something simple that I have over looked.

Thanks for any help you can give. I can be reached at
wsidcj@mindspring.com.

Rick Kelley

[ivymike1031]

Little compression on a single cylinder, or on all four?

If you're curious as to whether the information you have is correct, you can verify that it's an interference engine by turning the cam until a valve is fully open, and then turning the crank (by hand) until the piston either reaches TDC or contacts the valve.

If you've got no compression on any of the cylinders, but the cam is phased properly, then off the top of my head I don't know what to tell you (except to double check everything).

If the compression is only bad on one or two cylinders, and it's pretty bad on those two, then perhaps you have bashed a valve (there are other possibilities as well). Check the valve lash (clearance) and see how it compares to spec.

[jrickyk]

Hello,
it appears that all the cylinders are not compressing, which would seem to indicate that the timing is off. However, I have followed the directions to the T as indicated in my tech manuals. I cannot believe that valves on all four cylinders or indeed more than one of them was damaged by the failed belt. the valves would have remained in their last position prior to failure even if the crank shaft and pistons continued to move with the momentum of the vehicle while in gear. When I first put it back together, the engine tried to start with a pop and blue flames coming out of the exhaust header (I have a small leak here which I also need to repair). WHen I checked my fix I found that the timing was 180 degrees out and made the corrections accordingly if the prime cylinder is the one nearest the timing belt. IN addition, if the spark plug wires are oriented correctly then prime cylinder or No. 1 is as follows on the distributor
Top of Head
X
X X (this is no. 1 )
X

I just think that I must have something just out of whack either 90 or 180 degrees out of sinc.