View Full Version : Shade Tree Mech's: any reason transmission shop would have drained my coolant?

2009-Dec-10, 10:26 PM
I know there's some talented shade-tree mechanics here; so the question's not so oddball as it may sound.

I just had my transmission rebuilt & a few days later the engine overheats. Once it cools down, I discover there's no measurable amount of coolant in the radiator. I've not seen any leaks & it wasn't overheating before that.

Would there be any reason for the tech's to drain the coolant on a 97 GMC Yukon (4WD) while doing transmission work?

2009-Dec-10, 10:45 PM
Some automatics have a heat exchanger that cools the gear box, IN the engine radiator. But that's not a reason for not refilling the engine coolant.


mike alexander
2009-Dec-11, 02:29 AM
Being serious, could they have taken out the wrong drain plug?

I realize coolant and transmission fluid should look and smell quite different, but have you checked the tranny fluid to see if it's overfilled or still dirty?

2009-Dec-11, 02:46 AM
[...] while doing transmission work?

What transmission work? Rebuilt? Brought out of the vehicle?

2009-Dec-11, 04:30 AM
My speculation: Perhaps they had to disconnect a hose in order to get the transmission out or get to what they needed to service. So they drained the coolant and forgot to refill it.

On my 1990's car, the service manual says that the first step in removing the transmission from the car is to remove the engine. That would certainly require disconnecting coolant hoses.

2009-Dec-11, 04:32 AM
If the shop drained any fluids, its their responsibility to top them back up.

I can't think of any reason off-hand to drain the radiator. Usually the transmission oil cooler carries the transmission fluid to the radiator for cooling.

If it was a leak, depending on when it started leaking there may or may not be a puddle under the vehicle.

Check around the bottom of the radiator and look for any tubes that go back to the transmission--the seal around the tubes may have been damaged when the transmission was being worked on.

Or it could be a coincidence that something went wrong with the cooling system after the transmission was repaired....

2009-Dec-11, 05:49 AM
Hummmm.... "They 'forgot' to refill and check the coolant' ? Yeah.... sure.
That's a third grade excuse for a third rate mechanic. It sounds like a $3500
or more repair,as well. If you "forget" to replace the oil in an aircraft engine,
you just cooked a $28,000 certificated aircraft engine. I guess we know why that guy doesn't work on aircraft. Even rookie mechanics know enough to make complete checks of all fluids before running a vehicle. It's your reputation,
and you will be held responsible ..financially.

2009-Dec-11, 09:24 AM
Agreeing on the "it's their mess to clean up" front.
It sounds like they had to disconnect it for some reason or other. And then maybe it ran out when they forgot to reconnect it and you drove out and dislocated the hose.


2009-Dec-11, 01:35 PM
check your engine oil to see if it is full of coolant- it's a good possibility that an intake manifold gasket went bad. it is a common problem with the "vortec" engines from that era, due mostly to the craptastic coolant they used eating away the plastic in the gaskets. it could be just a coincidence that it happened after having transmission work done.
if the oil is about a gallon overfull, DO NOT run the engine.. the Dexcool will tear things up in a hurry.
for more info, google "dexcool problems" and do some reading..

2009-Dec-11, 09:22 PM
Avoid shops with younger folks, or very old people. Middle age ASE folks are best. I am in hock with car repairs from not learning that lesson.

2009-Dec-11, 10:33 PM
If there was no coolant at all, then how did you notice that the engine was overheating? The temperature sensor would normally take a reading from the coolant, so no coolant would mean negligible reading, you'd probably only notice when it all went very wrong.

2009-Dec-11, 11:58 PM
The death light comes on, followed by a tape recorded voice that says...
" Good morning, Mr Phelps. Your engine light has just come on.
This engine will self destruct in five seconds. Good luck, Jim. "

2009-Dec-12, 08:55 PM
also, you might now have a cracked head- if it wasn't the cause of the initial overheating, it could be a result. the head castings are a bit on the thin side and don't take heat too well..

2009-Dec-13, 08:20 AM
Would there be any reason for the tech's to drain the coolant on a 97 GMC Yukon (4WD) while doing transmission work?

To get you to go back to them on account of the fact they did such a durned good job on your transmission?

Common modus operandi. Beware the mechanic!

Seriously - I've rebuilt my share of engines (including two entire cars), and I once took one into a dealer, pretending to be a dumbass. They found more than 30 things "wrong" with the vehicle.

100% of their "findings" were utterly bogus, but would have cost me more than $6k to "fix."

Beware the mechanic!!!

captain swoop
2009-Dec-13, 06:49 PM
If it's a modern engine (well in the UK) it will be all alloy, prob won't have cracked it but might have warped the head. Ford Mondeo 'Zetek' engine was bad for that, I had one warp and it had to be skimmed and that wasn't even a 'bad' overheat. If it didn't actualy 'boil' you will prob be ok.. At the least check the head gasket.

2009-Dec-27, 10:49 PM
It has been a while since I've worked on a Yukon - so I may be incorrect. But by memory I would say that no, there isn't a reason to drain the coolant. As a note however - the transmission fluid lines and cooler should have been flushed out as part of the rebuild process. This is to get any contaminants (mostly clutch pack material but also possibly metals) out of the system to protect your newly rebuilt tranny.

It is possible that they decided to remove the radiator for some reason. Perhaps they even replaced it if the cooler was bad or clogged. But draining it would not be required if flushing the tranny cooler.

Larry Jacks
2009-Dec-28, 05:01 PM
I just had my transmission rebuilt & a few days later the engine overheats. Once it cools down, I discover there's no measurable amount of coolant in the radiator. I've not seen any leaks & it wasn't overheating before that.

If they drained the engine coolant, your engine would've overheated within a matter of minutes, not days. If you hadn't seen any sign of leaking or overheating right after the repair, I'd wager you had another cause for the overheating that may not have had anything to do with your mechanic's actions.

2009-Dec-30, 05:23 AM
Hi, Tell me Jack, have you pressure tested the motor yet? Warm and cold?
Not to be paranoid, but it has happened that some dingaling decides to make a little business for himself and pierces a hose. Under pressure, it will
spit your coolant in a couple days or less. These guys generally get run out of business... and out of town. I don't know... it's possible.
Did you find a leak? Hmmm...