Engine has a miss......or two, maybe another issue.

[Ring84]

So I bought a MH55 a while back. The engine was loose and I was told it hadn't run in 6 years. I got it running and using spark detectors on each cylinder it shows its firing on all cylinders. However, it has an audible miss-fire. I took the plug wire off of each spark plug to listen for a change and there was no change on cylinders 1 or 2 and the miss-fire got worse on cylinders 3 and 4.

I've tried to adjust the timing, the miss-fire only stopped until I drove the tractor then it started again. I also put new plug wires on with no change. Anyone have any thoughts on what the issue could be or something to check next? Thanks

 

[joeysmith]

Compression would be the next thing I checked

 

[Ring84]

Compression would be the next thing I checked

Thanks

 

[centash]

So I bought a MH55 a while back. The engine was loose and I was told it hadn't run in 6 years. I got it running and using spark detectors on each cylinder it shows its firing on all cylinders. However, it has an audible miss-fire. I took the plug wire off of each spark plug to listen for a change and there was no change on cylinders 1 or 2 and the miss-fire got worse on cylinders 3 and 4.

I've tried to adjust the timing, the miss-fire only stopped until I drove the tractor then it started again. I also put new plug wires on with no change. Anyone have any thoughts on what the issue could be or something to check next? Thanks

Check the intake manifold runners for cracks. Over time they can crack resulting in a lean mixture to the cylinder affected, a weak or miss fire and eventually a burned valve due to a too lean mixture.

 

[Ring84]

Check the intake manifold runners for cracks. Over time they can crack resulting in a lean mixture to the cylinder affected, a weak or miss fire and eventually a burned valve due to a too lean mixture.

Ok thank you. I will say it is a homemade welded manifold and not a factory cast one.