case 1150c trans pressure problems

[dmoore1979]

hello im new to this sight I have a 1150c dozer and having trans pressure problems I put a gage in the main line on the fitting on control valve wen its cold it runs around 300psi and everything works great after it warms up it goes down and stays around 200psi then the right track only in forward takes for ever to kick in once it starts pulling it dosnt slip or stop until u try to steer then u have to wait to it catches back up charge pump filters and oil is all new any ideas on what to check first ?

 

[mikebramel]

Does it use charge pressure for pilot or is there a seperate pump for pilot pressure. When did the problem start? hose blow?

 

[dmoore1979]

Does it use charge pressure for pilot or is there a seperate pump for pilot pressure. When did the problem start? hose blow?

As far as I know it’s all worked off trans pump The only other pump is the regular hydraulic pump It just started all at once

 

[alrman]

If the problem "started all at once" - can you explain that more clearly?
Were you operating the machine & did the pressure just drop?
Was it working fine one day, then you parked it up, next day pressure was low?

Pressure should be 250 - 310psi at operating temp

 

[dmoore1979]

If the problem "started all at once" - can you explain that more clearly?
Were you operating the machine & did the pressure just drop?
Was it working fine one day, then you parked it up, next day pressure was low?

Pressure should be 250 - 310psi at operating temp

I’ve been using it pretty much all winter dragging logs and about 2 weeks ago I took it back up on the hill and after the temp came up I noticed it was getting slow kicking in on the right side (forward gear) The more I used it the longer it took to kick in so then I put a new trans pump on and change filters and oil other than a little silicone the filters didn’t look that bad Ever sence I’ve had the dozer on dash gage it’s always ran right at the Btm of the green but still worked good it’s still running in the same spot on gage now to Even with new pump

 

[alrman]

Your pressure is low at 200psi, especially with a new pump fitted - is that at full RPM?
Does the pressure drop off more when you apply the brakes?

They can have issues with blowing gaskets in the transmission control valve - that's where I would look.
I would strip, clean, & reseal the entire valve.

Sometimes you can actually hear the oil escaping the broken gasket area if you put your ears close to the control valve - like a hissing / buzzing noise.

 

[dmoore1979]

Your pressure is low at 200psi, especially with a new pump fitted - is that at full RPM?
Does the pressure drop off more when you apply the brakes?

They can have issues with blowing gaskets in the transmission control valve - that's where I would look.
I would strip, clean, & reseal the entire valve.

Sometimes you can actually hear the oil escaping the broken gasket area if you put your ears close to the control valve - like a hissing / buzzing noise.

Yes the 200 psi is at full throttle. And it stays right there around 200 psi wen using breaks

 

[alrman]

And it stays right there around 200 psi wen using breaks

Sometimes the brakes can affect it sometimes not ...... I still be looking inside the control valve.

 

[dmoore1979]

Sometimes the brakes can affect it sometimes not ...... I still be looking inside the control valve.

I’ve got all new gaskets seals and any springs that was still available coming in a few days for the valve body that’s what I was gonna try next Thanks

 

[alrman]

Let us know how you go & what you find - fingers crossed

 

[dmoore1979]

Sure will probably with some more questions lol thanks again

 

[miller125]

Not trying to hijack your post but alrman
what cause pressure to drop when braking or is it supposed too

 

[alrman]

@miller125
When you apply the brakes, transmission modulation is also activated.
Depending on where the gasket is blown, sometimes applying the brakes causes more pressure to be lost.
I've seen this occur a couple of times while doing diagnostic tests on machines that had blown gaskets.

Under normal operation, applying the brakes is just like engaging a any gear selection - showing a momentary loss of pressure then return to system pressure.

In saying that, as long as the seals in the brake piston housing are in good order - while the plates are the same as a gear range clutch pack, the brake piston seals are different (& more efficient) to the gear range clutch packs, but, eventually they do leak some pressure when they start to click up some big hours.

 

[miller125]

Thank you alrman that’s what mine does lose it momentarily than returns. I didn’t know if that was correct or not .

 

[dmoore1979]

i finally got it to my shop and got the valve off and apart the only thing i found was a broken range orifice spool spring would that cause any of my pressure problems ? still waiting on parts to come in from my case dealer

 

[alrman]

the only thing i found was a broken range orifice spool spring would that cause any of my pressure problems ?

Absolutely! Most times when that spring breaks, they lose pressure/drive all together.

 

[dmoore1979]

I couldn’t take it since I’m waiting on parts I decided to pull winch off and back of trans Going to go ahead and freshen transmission up while I got it in the shop found a few future problems in there one clutch pack was wore down and 2 of the metal seal ring locks was worn out