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choctawmel 03-31-2010 04:01 PM

tranny burn!
I got a question for all those (almost everyone) smarter than me.
My Silver Bullet has a Allison 545 4 speed tranny. I changed the oil and filter at 74k, it has 82k on it now.
Now for the problem: I'm going up I-49 after driving around 300 miles today and I look in the rear view mirror to see a smoke screen that would made the Battle Ship Missouri vanish. Look at the tranny temp gauge and it's reading about 200 degrees (usually runs a little over 100), I shoulder her, crawl under to the sight of oil dripping/burning off the exhaust. I check the cooler and it's clean. Start her back up, the temp goes back to 110 and I drive another 200 miles. I'm driving 60 mph without the toad in 75 degree weather. This isn't the first time. It just does it.
Any ideas?

DaveFL 03-31-2010 04:25 PM

Did you check transmission level when it was hot? You didn't say where the oil dripping on exhaust was coming from.

Diesel1 03-31-2010 04:29 PM

Maybe a thermostat in the cooler line sticking shut and allowing the trans to overheat, causing the fluid to expand and blow out the trans vent. Adios, John

choctawmel 03-31-2010 06:31 PM

Fluid level never looks low (or high) It don't take a lot of oil to make a lot of smoke. It's coming from somewhere close to the front of the transmission. I think it blows out the front seal, but can't tell.

I didn't know a thermostat was in the cooling line. Is that internal? That could answer the question.

DaveFL 03-31-2010 06:44 PM

When I had a leaking transmission pan, gasket was placed with a wrinkle doubling a corner, only way to find it was removing the pan, but you could see the clean track from the area back, also had a leak when the seal of the dipstick tube loosened. both dripped down onto the ground. It would have to be higher to hit the muffler, so your front seal guess is as good as any so far. Can you see a drop on a bolt head after driving, red vs. clear to dark for reg oil. I placed cardboard under transmission area finding a puddle one time and a drop the next, when it was the dipstick tube.

choctawmel 03-31-2010 06:58 PM

It don't leak. No regular drip or anything. Just every once in a while, while driving, it dumps some oil on the hot exhaust and smokes. It hasn't done it more than 6-8 times in the 50,000 I've had her, but I'm concerned for her health. When it does, she wont cool down till after I stop, look and then she's good to go again.
If the 454 would start using/leaking oil, I'd think about a transplant, but that 454 engine just keeps going like the Energizer Bunny at 6 to 6.5 mpg.

ROBERTSUNRUS 04-01-2010 12:47 AM

:) Hi, it is/was very common for GM vehicles to spit trans fluid out of the dip stick tube; Especially while going up a hill. The additional heat caused the trans fluid to expand, and overflow onto the exhaust system. We, at the Chevrolet dealer, would fill the trans to the middle of the safe area on the dip stick. Or for sure, not above the full mark, when hot. Do not fill to the full mark while cold. The trans in most cases was not overheated and nothing was damaged. [over filled] Only a few drops of trans fluid on a hot exhaust manifold or "Y" pipe will make quite a smoke sceen.

choctawmel 04-07-2010 05:25 PM

The dip stick is at the rear of the 545.
Another odd thing: Ever since I installed (in '94) EFI, when the tranny does it's smoke screen trick the check computer light comes on. Usually as the rpm's drop. Does that for a 100 miles or so. Can't remember for sure, like I said, it's maybe done this 3-4 times after the EFI installation. May throw some oil up on top of the motor into one of the EFI sensors.
I talked to one of my racing friends, he said, "The 545 Allison is a #%* weak tranny, put and diesel in it." Story of my life. Need a wrecked Dodge Cummins with automatic.

choctawmel 07-06-2010 12:37 PM

Here's an update on my tranny problem: Talked with a 'medium truck' tranny guy who said, "The torque converter's bad."
I call up United Engine of Okla City (the Allison dealer) give them the serial number off the 'Allison tag' and was told it's not a good s/n. They can't tell me anything. Think I'm feeling some smoke on my back side.
It I pull this transmission I would like to go back with one with overdrive, but there again United Engines can't tell me squat.

r carl 07-06-2010 01:08 PM

I think you better call a different dealer.

choctawmel 07-06-2010 04:46 PM


Originally Posted by r carl (Post 868441)

I have. Pulled out my stack of papers from the PO. Found the bill for the installation. It was done by Covington in Greensboro, NC.
I called some other transmission shops and found a guy at ATS in Arlington ,TX that was happy to talk and I guess I need a rebuild. After I get back from my bicycle tour of the west coast in October I'll pull it and call them with the details of what I need and they will build me one for $1650. Without a total transplant I guess that's better than walking.
I'm still thinking about a diesel swap though. Just need someone to drive a later model Isuzu 4-series truck with a 4H 5.2 diesel in it in my yard and forget where they left it. Just may not be on my bucket list though.

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