John Deere 450

[rbp]

This message is a reply to an archived post by oneliner on August 30, 2019 at 10:42:50.
The original subject was Re: John Deere 450.

Could you explain more about the check valve and where you put it? Thanks. I'm having trouble with diesel
getting into the oil.

 

[Jim.ME]

The check valve in his post is the one right at the top of the pump where the excess fuel return line to the fuel tank attaches, your injection pump should have one already on it. If it plugs it can produce the symptoms he described. I don't see that check valve having any relationship to getting fuel into the engine oil. The two likely suspects, in order of likely hood of being the cause of in getting fuel in the engine oil are: 1. the fuel transfer (lift) pump or, 2. the umbrella seals on the injection pump drive shaft.

After a look back at your previous posts on this problem, did you replace the lift/transfer pump as suggest to you in a previous post?

This post was edited by Jim.ME on 10/05/2021 at 04:09 pm.

 

[rbp]

Yes I replaced the lift pump. We think now that the return fuel line to the tank may be problem. Thanks!

 

[rustred]

that is the shaft seals. check valve has nothing to do with it.

 

[rustred]

well if the return line would plug the engine would stop.

 

[Jim.ME]

You had posted previously about the seals: They seem to give out on me and leak fuel into engine." What did the lips of the failed seals look like when removed? Rolled back? Are you installing them with the lip facing into the pump on the inner one and out on the one facing the engine? Is there a wear ridge or other roughness in the bore of the tube the seals run in? If so the tube needs to be replaced.

If the check valve is plugged or restricted, it can/will cause the engine to quit, due to holding pressure inside the injection pump. Is your engine quitting and refusing to start until after it sets for several hours?

And, while not as likely, it is possible the lift pump you got is defective.

 

[rbp]

We think the fuel return line is clogged.

 

[Jim.ME]

(quoted from post at 07:22:39 10/06/21) We think the fuel return line is clogged.

You have not answered: Does your 450 stall out and not restart without setting for a time?

Remove the return line, going back to the tank, from the back of the tee connector on the #4 injection nozzle and use an air hose/nozzle to blow the line out (take the cap off the tank) to the tank. Blow the return lines on the engine out separately. Doing this should answer the question as to if the return line is plugged.

 

[rbp]

the dozer does start , but it doesn't run very long

 

[Jim.ME]

(quoted from post at 08:00:52 10/06/21) the dozer does start , but it doesn't run very long

Ok, now with that answer. That can be a sign the pellethane ring in the injection pump is breaking up. Pieces of it can plug the check valve which is located in the fitting, the return line connects at the injection pump. While it can be a temporary fix; just cleaning or replacing the check valve will not cure the root problem.

A test to see if that may be the problem is to clean around the small metal plate on the side of the injection pump. Loosen the two screws that hold the little plate on the side of the pump enough to let some fuel leak out. Try running it with that plate loose and fuel leaking. If it stays running, while leaking fuel, it is a sign your injection pump needs a rebuild. If you carefully remove the plate, while keeping a clean white rag below the plate, you may find pieces of the ring (often described as mouse turds) behind the plate.

 

[rbp]

Thanks for info. My dozer had a major rebuild which took about a year. Would those umbrella seals be ok
after sitting for so long?

 

[Jim.ME]

(quoted from post at 08:27:30 10/06/21) Thanks for info. My dozer had a major rebuild which took about a year. Would those umbrella seals be ok
after sitting for so long?

Was it started even briefly at times during the rebuild? Likely they would be, always an outside chance they were stuck and damaged when they turned. I would expect more problems with pump internals being stuck from setting. Getting fuel in the engine oil is one thing, they usually run even if the seals leak. A plugged check valve or return line is another, those often will start run a bit and quit, then have to sit a while before they will start again. As for stuck internals in the IP; I would expect the engine would not start and run.

 

[rbp]

I don't know if they started the machine when working on it or not. I think they would have but I really
don't know.

The dozer runs well. I use it for about 5 hours at a time and then it shows about 1 quart of diesel in the
oil. I drain the oil / diesel mix and we try something other fix.

 

[Jim.ME]

(quoted from post at 08:44:55 10/06/21) I don't know if they started the machine when working on it or not. I think they would have but I really
don't know.

The dozer runs well. I use it for about 5 hours at a time and then it shows about 1 quart of diesel in the
oil. I drain the oil / diesel mix and we try something other fix.

If it will run 5 hours, not quit, and you have to shut it off, I would say the plugged check valve or return line is not your problem. Fuel can get into the crankcase from a bad lift pump or failing umbrella seals. A dead cylinder with fuel being sprayed in and not burning could put fuel in the base, but I would think you would know if it was running on just 3 cylinders, so don't see that as a cause here.

Is the lift pump new since the rebuild? When did you last put umbrella seals on the drive shaft? Did you check the inside of the tube before putting the pump on? Are you sure the inner seal didn't roll when you installed the pump?

 

[rbp]

I run it 5 hours and I shut it off. It has new lift pump. Lots of power, I think. The umbrella seals are
over 1 year old . We took our time installing umbrella seals to make sure they didn't roll. I have special
tool. Maybe the shaft is worn and fuel leaks there?

 

[Jim.ME]

(quoted from post at 09:22:07 10/06/21) I run it 5 hours and I shut it off. It has new lift pump. Lots of power, I think. The umbrella seals are
over 1 year old . We took our time installing umbrella seals to make sure they didn't roll. I have special
tool. Maybe the shaft is worn and fuel leaks there?

More likely the tube in the pump the lips of the seals run against.

 

[rbp]

Ok. Thanks.