JD 450C Transmission Pump pressure

[mskovira]

Transmission pump pressure is only 40 psi. Could anything but a faulty pump be the cause?
Machine runs and works fine except for low power when moving.

[Jim B]

Welcome to the Board. Your posts related to a 450 model should be on the Late Models Board and this post will likely get moved over there soon.
Short answer to your question is, there are a number of things it might be other than the pump, but us just firing off possible things is a good way to waste your money. Some background history of your machine is needed to help you the best.

First question is are you sure it is a C series by serial number verification? Decals don't tell the whole story, more than one has had the wrong decals installed on them. There are differences between the series, so answers will be different depending on the series. It is best to know for certain we are discussing the right series (we've been down the wrong road before). Next question is do you have the right John Deere technical manual (or copy of the right one) for it (different series, different manual in most cases)? That manual is needed as there are a number of diagnostic tests to be done before condemning a pump or anything else. You are going to have to do those, we aren't there to do them. If you don't have the right manual, send Lavoy an email and I expect you will be able to purchase one from him, again you need to confirm you have the right series to get the right manual. Once you have the manual and go through the procedures the guys can answer questions on things that aren't clear.

How long have you owned it? If you just got it do you have any history from the prior owner? If you have had it a while, did this happen all at once or develop over time. Have you changed the transmission oil, cleaned the sump screen and changed the transmission filter? What are you running for oil in it?

This likely isn't what you wanted for an answer but these things will all be asked so it is best to get them out up front so people are working with complete and proper info.
Jim

[mskovira]

SN# on tag is 450CA 312228T. Pretty sure 1978. It is a crawler loader.
My manual is a technical manual for JD 450c crawler.
Manual says there should be 180 psi at port on transmission.
I am only getting 40 - 60 psi at any rpm.
Tried adding multiple shims with no change in pressure at all.
Hoping a bypass valve is stuck open if that is even possible.
Have owned for 6 months. It has gotten worse since I have owned it but
I don't use it everyday so it is hard to say for sure.
Spent time replacing rollers & misc.
Probably only have 10 -20 hrs on it. Primary use is for cleaning up around property.
I have changed filter but have not cleaned screen or changed fluid.
Was planning to change fluid with JD HY-gard, just haven't yet.

[mskovira]

Finally replaced filters & fluid.
No surprise that pressure did not increase at all.
Starting to remove engine to check pump, unless someone has a better idea.

[JWB Contracting]

Check your pressure with both steering clutches pulled back and check for improvement. If you have a steering clutch leak it will cause pressure loss. We have recent had a few machines with clutch vs pump issues.

[mskovira]

Pulling both steering clutches did not change pressure at all.
I am going to pull transmission cover off. Maybe I will get lucky and find something obvious.

[Riley99]

I had the same issue yesterday, i would suggest doin both clutch adjustments, the recheck the pressures.i ended up not needing shims.

[Riley99]

I had the same issue yesterday, i would suggest doin both clutch adjustments, then recheck the pressures.i ended up not needing shims.