C4 not moving fluid to cooler! HELP (2024)

I just rebuilt my C4 myself, got it installed and all the cooling lines plumbed to the cooler. Took it for a drive and everything seemed fine, shifted all gears, didn't slip. Drove it to work the next day, about 9 miles, started smelling something hot, figured I got something on the exhaust pipes. Popped the hood to look, didn't smell anything but noticed the aux cooler I installed was cool, like ambient temp, not good. Worried about it all day while I was at work then drove it home slowly.

Today I pulled the line off at the cooler that comes from the forward port on the trans. Hooked a hose to it and started the Bronco, no fluid came out. Ran it for about 10 seconds like that.
I then pulled both lines from the trans and put a hose on one and blew thru it, air came out the other so the radiator and cooler path are clear. That leaves the trans itself. I must have done something wrong when I rebuilt it.
Any ideas what would cause no fluid to come out the port but still shift and drive fine?
Do I need to pull the trans or can it be repaired in place?
Thanks
Dan

Could be some dirt or gunk in the passage in the stator support. On a stock c4 that passage has two check balls and a spring that can easily get jammed up. I always remove them during a rebuild. You can try putting some air pressure into that front port to try to clear it out.

Other than that maybe the pump gasket is slightly out of place.

It's not good to drive like that because that rear return port lubes the entire rear half of the transmission.

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Thanks Viper, I'll shoot some air at it and report back.

I didn't intend to drive it like that it just turned out that way. I really hope I didn't ruin anything. It was my first attempt at rebuilding an auto tranny.

Dan

I don't remember two check balls and a spring. I'll look back at the Haynes manual I used.

Ok, I blew 90psi air into the output line. It didn't seem to blow thru the trans, it just pressurized the line. I gave it 4 or 5 shots each time holding it for 10 seconds.
I started the truck and still no fluid comes out the line.

I really hate the idea of pulling the trans again.

Well I pulled the trans today. pulled the front off and removed the pump assembly. I checked the ports for obstructions and the gasket for misalignment. Nothing. I can't find anything wrong, but I don't really know what I'm doing so that doesn't help.

I'm about to remove the ball and spring as Viperwolf1 suggested. Is there a way of testing for fluid flow without installing the trans in the truck and starting it?

I'll post some pics I took today, maybe someone here can spot something not right. The last photo is the bearing I replaced.

Viperwolf1 said:

.... The spring/balls are under an aluminum ball plug on the edge. You would have to remove the ball plug to get the balls/spring out. Then you can tap it for 3/8"-24 plug.

Click to expand...

I got the outer aluminum plug drilled out and removed a spring and one steel ball. There appears to be another deeper in the hole. I banged it on the workbench and picked at it but it's stuck. Any ideas how to get it out?

Yea, I think that's the root cause of no fluid flow. Thanks Viperwolf1, you were right on the money.

Thanks Dbarnes72, I really hope it got that bearing in correctly because it was a bear to install.

Try to seal up the ends of the stator (where the input shaft goes) and blow some high pressure air into it. Don't point the ball at anything you like.

When you tap the hole go slowly. You don't want the plug to block the that other hole.

You want the front bushing oriented so the reservoir is at the bottom like this. This is a C6 bushing, its wider.

Dan74Bronc said:

Thanks Dbarnes72, I really hope it got that bearing in correctly because it was a bear to install.

Click to expand...

Take a look at Viperwolf's picture. I don't know how much of an issue it is, but it looks like the two are oriented differently.

Viperwolf1 said:

Try to seal up the ends of the stator (where the input shaft goes) and blow some high pressure air into it. Don't point the ball at anything you like.

When you tap the hole go slowly. You don't want the plug to block the that other hole.

You want the front bushing oriented so the reservoir is at the bottom like this. This is a C6 bushing, its wider.

Click to expand...

Thanks for all your help Viper.
I have one more question I would like your opinion on. I have about 50 miles on this rebuilt trans and the fluid smells really burnt and there are black particles in it. Should I replace the clutches and bands or can I get away with flushing and cleaning it thoroughly.

Thanks.