(New guy) 1990 Ranger front of transmission heavy leak ONLY when A/C on

[90XLT4_0]

Hey guys. New here. Had a rude awakening yesterday with an otherwise nice Ranger I just got!

Picked up for dad a couple weeks ago. 1990, 4.0 V6, Auto, 2WD, reg cab, XLT. It replaces a 1982 Datsun that we got our money out of, to put it lightly.

I got it from the original owner who bought new in January 1990. On the plus side, truck is extremely original, clean, runs great, drives great. 143k. Paid $2000.

We put a can of r134a in yesterday. Truck has not had running A/C in 25 years. 15 minutes later we got out of the truck and saw the transmission dumping lots of ATF out from between engine and bellhousing. Long story short, AC on causes the transmission to spew like a geyser. Like nothing I’ve ever seen before. Let it cool down and run it with the AC off, dry as a bone. Not a drop.

Basically I assume this means that the torque converter bushing and/or front pump seal are marginal, and the added heat from the AC is just enough to push them over the edge. Does this sound right?

Note that the condenser is right next to the trans cooler and got extremely hot with the AC on—to the point that the hood prop rod was unusually scalding.

Note that engine does not overheat with OR without AC on. Runs at low end of normal on gage, temps as shot with IR gun (AC off): 202 at hot side of rad, 172 at cold side of rad, 185 at water pump/engine block.

Note that rear transmission seal just replaced very shortly before I got the truck. It had sprung a sudden, massive leak itself. You can still see the aftermath on the floor pan.

Note this is in Georgia, July so hot ambient temps.

Without running the AC, we used the truck for moving furniture today and had no problem. At the end of the day I sent dad home with it and told him to keep an eye on it. AC is a moot point now anyways since a can only lasts 24 hours in it and it's now second in line for issues needing resolution.

 

[90XLT4_0]

Sorry, another note, transmission rebuilt in 1998 or 1999 at I think 131k so only has about 12k miles on it. Works great aside from leak. Very strong, quick firm shifts feels like a really healthy automatic.

 

[90XLT4_0]

Update. Dad drove the truck around town this week with no issues. Totally dry. So today we decided to take a load of furniture to my sister's house in west GA about over an hour and half away, almost 100 miles each way. We had the bed loaded and a small trailer as well. Truck drove great, 4.0 very strong. We stopped at the halfway point, it was dry. Got to my sister's house, did see a couple drips but level had not gone down. On the way home, stopped at the halfway point and checked again. All good. But at the end of the day when we got back to my house the transmission was leaking significantly again. Again, where the bellhousing meets the engine. With the truck still running I took the following temperatures with the IR gun: 185 at the water pump. 190 at the radiator. 190 at the hottest point on the transmission cooler. Those temperatures don't seem out of line to me. I don't think the truck has a cooling issue. Temp gage stays at the N or O in normal. I think the tranmission needs a front seal/bushing. I did speak with one transmission shop a few days ago. He offered to rebuild the transmission but did not seem keen on just replacing the seal and bushing as I suggested. He didn't say he wouldn't, he just didn't seem enthusiastic about it. I think we need to look around and find someone to reseal the front of the tranmission.

 

[bobbywalter]

its a shit seal or bushing alignment issue....or both.

there is an elastomer seal that was around for a bit....during that time period.... that is really sensitive to heat and movement under load....i had them in my e4od and aod and seen them in rebuilt 4 whizzer mustangs and some aerostars and rangers. no rhyme or reason...some would do it instantly and others 2 years later.


not saying this is the case, but something i have experienced.

 

[RonD]

Welcome to TRS

Reads like front transmission seal is bad, of course , or is now
Could be flex plate has a crack or something inside torque converter is broken
When it starts to wobble the seal leaks, a lot

You would expect the wobble and leak all the time, intermittent doesn't seem to fit
I am sure you would have mentioned it but have you ever notice any on/off vibrations?

 

[bobbywalter]

bad bushing alignment and old crank spacers definitely kill flexplates. not a good idea to reuse the crank spacers....they will be flush fit...but are soft and will distort and lead to cracks...

 

[RonD]

AC on, wonder if crank pulley balancer is bad, causes a vibration with the extra load


And just as a thought....................
Top rear of main transmission housing has a Vent, image here: https://www.therangerstation.com/wp-content/uploads/2017/06/4R55E_top.jpg

4R and 5R have same setup as the A4LD's

You said rear seal also showed leaking from before
Wonder if Vent is somehow partially blocked
When any fluid is heated up it MUST expand in volume, that's the point of the vent, it allows the pressure from the expansion of the fluid to vent, otherwise............excess pressure inside transmission

 

[90XLT4_0]

Thanks for the input guys. I should also add, we have not had the A/C running in the truck since the original ATF leak about a week ago. So yesterday when we got it to leak, that was without A/C. I guess just driving it 200 miles on a hot day heated the transmission up enough to leak by the end. I just think the transmission doesn't leak unless it's good and warm and the A/C caused the overall heat load on the condensor/radiator/trans cooler area to increase quickly that day.

So the leak is very heat dependent. In normal driving with no A/C, it's dry as a bone. It's only when the trans its very warm that it lets loose.

Another note, we ran the truck with O/D locked out on the trip out since we were loaded and ran with O/D on on the way back. I suspect if we had made the trip home with O/D locked out we might have kept the trans cool enough not to leak, but it's designed to run in O/D unloaded and needs to be able to.

I have considered the possibility of vent blockage. When you consider that the rear seal just went a month or two ago right before I bought the truck (and it went catastrophically, according to previous owner and fluid on floor pan) that would suggest the possibility that the vent is blocked. I have felt the end of the vent with my finger when I was under the truck, and the end itself does not seem blocked, but that doesn't mean the tube isn't somewhere. Tube blockage may be hard to troubleshoot based on accessibility. I have seen pictures of tranmissions similar to this where there are 2 anti-siphoning holes punched in the vent line around where it makes a u-turn at the top of the bellhousing. Would my 1990 A4LD have those?

By on/off vibrations do you mean on/off throttle (accel/decel)? I have not experienced any kind of vibrations, including on/off throttle. In fact the truck drives really, really well.

I will keep the flex plate, TC, and crank spacers in mind and possible collateral issues going forward. Thanks

 

[bobbywalter]

AC on, wonder if crank pulley balancer is bad, causes a vibration with the extra load


And just as a thought....................
Top rear of main transmission housing has a Vent, image here: https://www.therangerstation.com/wp-content/uploads/2017/06/4R55E_top.jpg

4R and 5R have same setup as the A4LD's

You said rear seal also showed leaking from before
Wonder if Vent is somehow partially blocked
When any fluid is heated up it MUST expand in volume, that's the point of the vent, it allows the pressure from the expansion of the fluid to vent, otherwise............excess pressure inside transmission

damn dirty mud dobber could have got em for sure.... though they have the 3 slits to combat that.....it could happen.

 

[RonD]

Well if there was ATF coming out the rear seal, and the front seal, but nothing ever came out of the vent pipe........................................

Then either its not an internal pressure issue or vent is plugged up

 

[90XLT4_0]

Given the symptoms and the possibility of a bad/plugged vent I advised dad to see if he could blow bubbles in the pan by blowing into the dip stick tube with a hose. I tried it this morning on my own car and was able to blow bubbles. Dad said he was able to blow bubbles easily. That to me probably eliminates the bad/plugged vent theory and indicates bad front seal.

So, dad called a tranmission place this afternoon. Like the first transmission shop, the guy essentially said he could not guarantee replacing the seal would fix anything and offered to rebuild the transmission for more than we paid for the truck.

We will likely move forward by offering the truck for sale, disclosing the issue. Hopefully we can recoup some of our losses. It's a shame, it seemed like a really nice truck, but I'm afraid we got royally screwed on this deal. This was my first time trying my luck on an American vehicle in probably 10 years and while this thing drives a lot smoother than a Toyota, I think I'll be going back to Japanese from here on out. Hate to say it because I really did like this thing.