4020 has me stumped

mattroh

Member
We overhauled our ‘67 4020D, had the injector pump worked on, and all new injectors. We only partially have gotten the engine broken in, because of a weak clutch on the pto when we dynoed it (forgetting that we could adjust the clutch linkage to tighten it) and now we’re too busy with harvest to dyno it right now.

If you let the engine idle warm or cold under 1000rpm for a while then sped it up over 1400rpm, it will miss for a while pretty bad, blowing out a lot of raw fuel. However, if you don’t idle it any slower than 1200rpm, it doesn’t ever do that, but it still doesn’t sound like the engine is running quite right.

Any thoughts?
Matt
 
Synthetic oil will bypass rings on an overhaul.
Could be your slobber.
Did you check cam for wear? Many people don't.
I have replaced worn cams on every engine I've
overhauled for years now. I'm talking about lobe
wear not just 4020 tooth wear. If your tooth wear
is bad you might be out of time.
 
Forgot to mention, the tractor was overhauled because of excessive blow by that turned out to be from the number 6 piston having broken rings and so the piston was cut as well.

We did not work on cam, a friend that has redone tractors thought the cam and cam gear were fine.

It has had JD break-in oil in it since overhaul, is that synthetic?

At one point, we readjusted the valves and that lessened the problem. Before that, when cold started (outside temperature wise) it would sometimes ehauxt raw fuel and miss when you first brought the rpms above 1200-1400, even if done right after starting.

Thanks,
Matt
 
I bet you have a bad new injector-it is sticking.Determine which cylinder the miss is on,crack each injector line while the miss is occurring,until you find the miss.Then do not run the engine any more !! That raw fuel will wash out your rings on that new piston! Pull that injector and replace it.Mark
 
We took the injector that we figured was causing the miss (cylinder 1) and swapped it to a different cylinder, and the issue stayed with cylinder 1.

The local diesel shop thinks it may have something to do with a broken ring or poor ring seal.

So we are thinking running it on the dyno again needs to be done before we do anything else

Matt
 
If the problem is a piston ring or something else in that cylinder, you will need to pull the head to fix it. At this point a compression test or leak down test should tell you more than running it on a dynamometer.
 
To be sure its no 1 cylinder check the temperature of the exhaust manifold on the port coming out of each cylinder right after you fire it up from dead cold. The cold port is the missing cylinder.
 
Check injector pump timing (TDC) then check the speed advance to see if its moving 6* wide open . Sounds like you have been doing light work and/or idling since overhaul . Put this on a big disk or plow and put her to work to help get the rings seated . Takes 500 hours to do the job . This is assuming none of the rings were broken due to improper installation on the pistons and the sleeves.
 
We are wanting to run it on the dyno again in order to seat the rings because we were unable to do it before.

We did check temps on exhaust manifold, and the number 1 cylinder runs about 150-160*F and the others are around 200*F.

Matt
 
At the recommendation of a friend, we did not remove the pistons from the sleeves, we only pulled them out the bottom enough to put the connecting rods on.

Matt
 
That is the recommended method for John Deere parts. Not sure what aftermarket recommends ? What brand did you use ?
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top