AC5050 will only start with ether, please advise- we need this thing to run.

[Jerry/MT]

I would venture to say that the compression test is ok. Compression tests are supposed to be done on warm engines. Since the OP couldn't get the engine running it was done cold. Therefor low compression. If the tractor started right up like he said the compression is good enough.

Engines I am familiar with have to eventually start with a cold block.

If the op's compression measured 250 psig and he's not at high altitude, he has low compression. His saving grace maybe a high ambient temperature that will help with low compression pressure to get started. But 250 psi compression pressure on a 17.1 compression ratio engine says the there is a problem with the mechanical condition of the engine. It might be rings or it might be valves, but it has a problem.

 

[Mike1955]

Engines I am familiar with have to eventually start with a cold block.

If the op's compression measured 250 psig and he's not at high altitude, he has low compression. His saving grace maybe a high ambient temperature that will help with low compression pressure to get started. But 250 psi compression pressure on a 17.1 compression ratio engine says the there is a problem with the mechanical condition of the engine. It might be rings or it might be valves, but it has a problem.

Jerry the fact that you build the pressure assures me that all that you mentioned are all good. So that leaves the injectors, providing air and fuel are there. I would have to be there On another subject I have an old 1979 Massey 80hp that starts in less than threee turns even at 10 degrees. Some start easy I can’t explain

 

[UrbannGuerilla]

I've been thinking about this some more. If you cranked the engine a lot previous to finding out the timing problem there could be some diesel in the bowl of the piston. That would increase the compression to help with the immediate start. It'll be interesting to hear how it starts cold after sitting idle for a few days.

Also: What is your location? If you're deep south and the engine is always relatively warm compared to where I live in Canada then low compression would be less of an issue.

I would say it wasn't excessively cranked, but that is just my opinion. We certainly didn't continue to crank and crank and crank when the engine didn't even attempt to start. It started right up yesterday morning, first try again. Pop drove it around a while, about 45 minutes at varying RPMs- probably trying to hear or feel anything out of the ordinary. I asked him what he heard or felt yesterday evening, he said he didn't feel or hear anything abnormal. I know there could still be an issue, but I am happy at the moment that its running so we can at least (hopefully) complete this season and have the luxury of dealing with it in the offseason. When it started right up the "first" time -2 days ago, it had not ran in a month. (Had the issue right after planting, so I'm pretty sure that's accurate bc the peas are almost ready to pick) 85% of the times we spent attempting to crank it was before we found the fuel obstruction, so the fuel flow was still severely restricted, and it probably still had some air in the lines. (I'm just assuming on the air, because we unhooked a lot of connections trying to find the issue) When we did attempt to crank it (before it would start), it was for 2-3 seconds per try, and we might try it twice before returning to troubleshooting.

We are indeed in the deep south, in south GA. It was probably around 90ºF outside temp when it started again, after we corrected the injection timing.

 

[pmsmechanic]

I'm glad the tractor started right up for you and I'm hoping that you don't have any more issues. It would be nice to see a warm engine compression test but as far as I'm concerned it isn't worth pulling the injectors to do it again. Obviously if the tractor starts right up the compression is good enough.

 

[UrbannGuerilla]

I'm glad the tractor started right up for you and I'm hoping that you don't have any more issues. It would be nice to see a warm engine compression test but as far as I'm concerned it isn't worth pulling the injectors to do it again. Obviously if the tractor starts right up the compression is good enough.

That makes two of us that are glad its running and hoping for no more issues, at least until the season ends. I thought about proposing a warm compression test to my father yesterday when he was riding around on it, but I didn't because the tractor was together and running for the first time in a month. I am curious what the warm compression PSI is myself though. Even though I'm not in Canada, I would have to imagine that a 90ºF "cold" test and 200ºF warm test would have different PSI, even if it is less dramatic than a colder climate would have. How much, I really don't know, but I am curious. Maybe after we turn everything under we can find out what the difference in pressure is.