John Deere 420 Timing Issues

[EHuffman]

I am working on a 420 crawler that my brother picked up a few days ago and it is only running on one cylinder. I am getting spark out of both out of both spark plug wires but it is only running on one cylinder I have new plugs and my spark is good. I think I have timing issues. If I rotate the distributor 180 degrees it starts to run on the opposite cylinder. I am puzzled as to what is going on and if you guys have any ideas that would be great! I have about a hundred and twenty pounds of compression on each cylinder. Thanks!

 

[Jim.ME]

That can be a symptom of putting a Waterloo 2 cylinder distributor cap on a Dubuque 2 cylinder engine. Something to check.

 

[Hayfarmer]

My guess would be either cap or rotor. check that rotor is on tightly and that the little plastic piece that fits on slot on shaft isn't damaged so it is loose on shaft. Timing marks are on back of flywheel, toward front of tractor, accessable through hole with cover on it on same side as distributor.

 

[EHuffman]

Thanks, the distributor and cap are fine, we even switched them from another tractor and it didn't make any difference. It is converted to 12v, is it possible that it need a different cap? Also it possible that the oil pump off 180?

 

[Glen D Anderson]

As Jim mentioned, there may be issues as a result of the wrong distributor cap being installed or possibly the oil pump out of time as you suggested.

A quick way to confirm would be to roll the engine over in the direction of normal rotation with the spark plugs removed feeling for compression with your finger or thumb. As you start to feel compression pay attention to the location of the rotor and if it is not close to lining up with the corresponding cylinder on the distributor cap, you've found your problem.

 

[Gene Davis (Ga.)]

Most likely the cause is the oil pump is not timed. There was a special tool for that job that came with the OTC
set Deere sold to the dealers when the Dubuque engines came out. I made the mistake of loaning mine out and it
never came back. It has a place on it that reads this side out when the oil pump drive is correctly installed.

Gene Davis Tennille, Ga.

 

[sm420]

I have wondered why no one has made a reproduction of that tool it doesn't look that would that difficult to make ?

 

[Jim.ME]

In case he doesn't get back here. The oil pump was out of time. He posted on jdcrawlers he turned it 180 and runs fine now.

 

[Jim.ME]

Search John Deere tool AM450T. There are reproductions available.

 

[Hay maker2]

(quoted from post at 16:02:01 11/17/20) Most likely the cause is the oil pump is not timed. There was a special tool for that job that came with the OTC
set Deere sold to the dealers when the Dubuque engines came out. I made the mistake of loaning mine out and it
never came back. It has a place on it that reads this side out when the oil pump drive is correctly installed.

Gene Davis Tennille, Ga.

It easy enough to time it with the naked eye, a flashlight, and the service manual.

 

[EHuffman]

Yep that was the issue. I just turned the drive cog on the distributor shaft 180 for now. Looking in the spark plug hole, there is a pretty good gouge in the cylinder wall that is now leaking coolant. I'm thinking that it threw a rod and the previous owner tried to fix it and never got it right. It will probably need a new block if we can find one. Except for the fact that it is burning oil and coolant, it runs very well now. I appreciate your help guys! Thanks!