JD lost power after warming up good.

RalphVa · Oct 5, 2004

I went over to the widow's place and replaced the fuel filters on her old JD diesel (4 cyl direct injection). Checked the air filter. Looks as though somone put a new one in.

Started right up. Decided to run the bush hog for a little bit to check it out. After about 5-10 minutes running, it wouldn't go above idle. Had to creep it back up near the house in 1st or 2nd gear.

I'm betting the valves are too tight. The clearances aren't there. After the valves warm up, they don't seal good and yield low compression.

Forgot to look at the model number. Did it a couple years ago. It's about a 1957 vintage.

Wonder how easy it is to turn this engine over by hand, and how? Suspect may need two people, one to turn while the other watches the valve positions.

Help.

Ralph

Kyle_in_Tex · Oct 5, 2004

It could be tight valves, but it might also be starving for fuel.

jd110 · Oct 5, 2004

Its hard to give a definite answer without the model number, but I doubt that the valve clearance is the problem. It sounds as if the injection pump may be the problem. There is a rubber ring inside the pump that deteriorates over time that clogs the fuel return circuit between the pump and the tank. I am guessing you have a Roosa Master pump. On the side of the pump facing the outside should be a rectangular plate secured with two small screws. That is the timing window. remove that plate and if you see black particles in there similar to coffee grounds, the pump will need to be rebuilt. If you run it long enough to loose power again, loosen those two screws while it is running to let out fuel pressure and it will probably speed back up again. Let me know if you need any more advice and get the model number.

RalphVa · Oct 6, 2004

It's a JD 820.

Does this injector problem only show up after it's fully warmed up? It starts and runs fine until fully warmed up. The exhaust is a bit smoky after it warms up and won't go past idle speed.

Ralph

RalphVa · Oct 6, 2004

I may be wrong about the 4 cylinders. Didn't count the number of injector lines. Found a picture of a JD 820 3 cylinder diesel that looks just like it on the web.

Ralph

jd110 · Oct 6, 2004

The injection pump problem doesn't really have anything to do with engine temperature, but usually a certain amount of time of running. If you shut it down for a couple of minutes it will probably rev up for a short time until the pressure builds up in the pump housing again. There were two versions of the pump on these tractors.The earlier version was a smaller pump that did not have the problem I am talking about. The later ones with the larger pump did have this possibility. The 820 three cylinder was built from 1968-1973. There was also a 2 cylinder 820 model that was built from 1956-1958. Something else you may want to check is the flow of fuel from the tank. A restricted fuel line or filter could give similar symptoms. I am attempting to post a link that shows the pump I am refering to. The timing window plate is item #13.

jd110 · Oct 6, 2004

I'll try the link again. Sorry if it doesn't work.

RalphVa · Oct 7, 2004

Thanks.

Makes sense now that it's probably a 1968-1973 820. That's about the time that they came here from Texas. That was my own bum research from a couple years ago where I concluded that it was a 1957.

He died about 3 years ago from an illness that lingered for 4 years.

I've changed the filters, and fuel pumped fine via the hand pump to bleed air from the filters. Probably pumped far more doing that than it did in 10 minutes or so of running.

Ralph

RalphVa · Oct 7, 2004

I went over this afternoon and fired up the JD 820. It didn't take it but 2 or 3 minutes before it slowed down this time. Never really got fully warmed up. Shut it off for 2 minutes. Started back up fine and revved up for a minute or so. So, I think it definitely points toward an injector problem as it follows the symptoms mentioned.

Will call the local JD dealer for an estimate for them to replace the injector and the cost of a rebuilt or new injector. There's a mechanic who has been doing work for her. He might have the knowhow or might have done one of these before. I COULD do it IF I could get the timing requirements, etc.

She can't seem to locate her owner's manual. She lost her purse for 2 weeks and found it on the living room sofa.

Say, where might the serial number for this beast be? I've the web site that has the SNs by model and year. It is a 3 cylinder and likely bought new around 1970.

Ralph

jd110 · Oct 7, 2004

The serial number should be on an aluminum plate That should be on the right front side on the casting under the grille screen I think. If there is no plate there, check on the right side of the transmission case under where your right thigh would be if you were sitting in the seat. Good luck!