Alison transmission Leak

[For Wheelin]

Greetings, a short while ago we had the radiator replaced under a purchased extended warranty.  The radiator had a slow antifreeze leak during summer months.  We had it replaced the week before a planned work related 800 mile round trip.

Before the new radiator the transmission ran at about 140 degrees with or without a 5k pound jeep behind it, and as warm as 190 with a jeep attached in 100 degree summer days.

After the new radiator, the trans ran at 220 degrees on the way to Vegas in 65 degree weather, and is now blowing transmission fluid all over the exhaust.

Especially going up any grade, essentially causing the coach to shift down from drive - RPM above 3k, transmission fluid is leaking near the transmission pan, or rear seal, or tail shaft seal, not sure, and blowing onto the the exhaust pipes and cat converter producing lots of pretty blue smoke. It appears that the amount of oil leaked depends somewhat on the RPM.  We nursed it to Vegas and went to a local reputable RV repair shop.  They said it was the rear seal, but was a week away, and I had to be on the road.  So I nursed it on keeping an eye on it and the following week and returned it to the shop that fixed the radiator.

I was advised Friday that it was the transmission pan gasket.  This Allison trans has 11,000 miles on it!  Why is leaking in the first place?

Question: 

Could the transmission leak for wherever it is, been caused by a botched radiator replacement?

Am I not crazy for noticing more fluid leaks at higher RPM?

Since no fluid has come up and out of the dip stick tube, can I assume it is not overfilled, and if it was overfilled, could that have caused some over pressurization of the trans blowing out a seal?

I brought it back today...I was hoping to get an opinion on this.

Thanks,

Steve

 

[Cyril]

My trans was accidently overfilled and trans fluid covered the transmission after driving a short distance. There is evidently a relief hole or valve on top of the transmission and that is where the fluid was coming from. After draining and refilling with correct amount of fluid the problem went away.
In your case, did they add fluid after your repair and if so, how much?  Hopefully the trans cooler was hooked up correctly.
Cyril Flammang

 

[driftless shifter]

Might be an external cooler in tandem with internal radiator cooler. Was it eliminated, never put back in, plumbed wrong? Wouldn't surprise me if it was eliminated by lazy apes with wrenches.
Nearly every heat shield was eliminated by whoever swapped a new engine into mine. 2 years later PO gave up because of continuous problems with drivability due to things melting. Google your chassis cooling system for radiator and related parts. Look for a schematic of your radiator and associated parts under images and parts house websites.
Oil leaks almost never travel up or forward. So leaks are generally foward of the oil stream, and no higher than the beginning of if. Think gravity and wind pushing, down and back.

Bill

 

[driftless shifter]

Went and got on the real computer so I could link.
If you have the GM Kodiak 5500 0r 6500 chassis you should have an external tranny cooler.
Here is a link to the plumbing schematic.
I'm suspicious of any shop that creates a new problem, whether due to incompetence or a malicious returning customer policy.
Your pan gasket leak may be one of those fittings improperly connected or tightened.

http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=370125

Bill

 

[For Wheelin]

Thanks guys,

Bill, good point..."Oil leaks almost never travel up or forward. So leaks are generally foward of the oil stream, and no higher than the beginning of if. Think gravity and wind pushing, down and back."  I did wonder if the tranny does have a relief somewhere high, naturally, the fluid would end up where it is, and if so did they simply overfill it, cause the flow and replace the pan gasket to cover up the overfill.

So they did repair it again...They said the trans fluid pan gasket they replaced was defective, and was the cause of the leak after the repair! Will be flat towing again this weekend will see if it is truly fixed.

BTW, I was told that the Ally trans does not have a relief outlet, but wouldn't be surprised if that incorrect.  I was also told that the trans, now running warmer than it ever did, albeit not in the caution zone, is a result of the new thermostat they replaced when they replaced the radiator. WHY?!  The engine is running no hotter than  before!

Long story short, they probably caused the trans fluid leak in the first place when replacing the radiator, too much a coincidence, and botched the repair, and then did it again.  If the topped off the trans fluid after the radiator change and the leak was extra fluid coming out of a designated relief, there is a third issue.  If that was the issue and the pan gasket didn't need replaced - a fourth. 

To top of the experience, he did not arrange this job through the extended warranty because it was supposed to less than my deductable, and it turned out to be $150 bucks more than the deductable.  now i need to deal with reimbursement for the difference.  I gotta agree with my wife; trailers dont have a motor and trans!

 

[donn]

With an Allison I have to assume your MH is a GM based?  If so, GM has had a lot of problems with transmission coolant line failures.  Check them first before some "tech", and I use that term very loosely anymore, gets you for unnecessary parts.

 

[For Wheelin]

With an Allison I have to assume your MH is a GM based?  If so, GM has had a lot of problems with transmission coolant line failures.  Check them first before some "tech", and I use that term very loosely anymore, gets you for unnecessary parts.

It is a GM...and not going back to this shop.

 

[driftless shifter]

Automatics vent through the dipstick tube. Manuals, with no dipstick, have a vent hole.
The shop is blowing smoke up your aah. Study the schematic in the link. Pipe seven, the one closer to the middle of the tranny goes to the bottom fitting of the radiator. Pipe one comes out the top fitting and goes to the external cooler in front of the radiator, on passenger side. Pipe eight comes out on drivers side of cooler, all cooled off and returns to the tranny. If the external cooler has been eliminated or plumbed backwards your tranny, with 11,000 miles will be junk soon.

Heat destroys automatics.

Plumbed backwards means pipe seven goes to the external cooler first, then pipe one goes to the radiator cooler, where it is heated back up by the 200? plus radiator coolant and sent back to the tranny thru pipe eight. I used the schematic pipe numbers for clarity, could be as simple as # seven and # eight were reconnected to the tranny in the wrong ports of the tranny. That would flow backwards through the coolers and explain a leak because the pipes would have been unhappy being bent to fit in the wrong ports and there's the leak.

One question. Has your engine temp changed at all since the work? If not they didn't change the thermostat they're BS'ing you hoping you'll blow up several states away. The shop that did the engine swap for my PO went out of business shortly after the swap. PO is a clerk in the county courthouse. I wonder if he had anything to do with it.

Your pan leak is probably pipe seven or eight, where they connect to the tranny, right in front of the pan and slightly above it.

Bill

 

[Mark R.]

Someone may have pointed this out but, the new radiator trany tube could be kinked or plugged internally, could be a cheap china radiator, plumbing backwards is almost impossible if lines are factory, and if reversed they will make a difference but a small one. Simple test, bypass radiator and plumb to a decent oil cooler mounted if front of radiator, should see a dramatic heat reduction. Good luck

 

[driftless shifter]

If they are reversed the tranny oil WILL be heated up by the hot radiator after cooling by the external cooler. Instead of being cooled further, in the external cooler AFTER passing through the hot radiator. It will make a huge diference if it's backwards. If the engine is running 220? pulling a hill and the cooler is plumbed wrong the tranny oil temp will be close to engine temp in the return line instead of under 200?, which is where auto trannies want to be.

To the OP you only have 11,000 miles on this. It's too hot at 65? without a toad something is wrong with their work. I wouldn't take a trip without figuring it out. The consequences will hurt. A pan gasket  won't fix the high temps.

Bill

 

[For Wheelin]

Thanks for the responses all...I have followed the trans lines from tranny to radiator and external cooler and can say the lines and connections are good.  The leak is definitely coming from the rear seal as advised by the first tech that looked at it when we first discovered the leak.  Unfortunately, I was not in a position to leave the coach there for repair and ended up returning to home area. 

I am going to bring it in to a GM heavy truck repair shop, and try to get my money back from the "specialist" who tried but failed. 

Thanks again.

 

[driftless shifter]

That there is the best thing you can do.

Bill