Transmission fluid temps

[NMBurb02]

The transmission fluid temps in the GP seemed to normally hover in the 195-200F range under a variety of driving conditions, including highway and city driving, and the owner's manual states that the normal operating temps are 180-200F. However, I noticed yesterday that the temps were reaching 210-230F under the same type of driving conditions and ambient temps were 75-80F with relative humidity probably in the 70-80% range. My shop just replaced one of the transmission cooler line fittings two weeks ago and the entire other hose four months ago. Lubegard Red was added at the time of the hose replacement and the tranny fluid was last changed about 22k miles and 2 1/2 years ago by the PO.

Should I be concerned with these temps? If they are too high, how should I address it? Do a drain and fill of the fluid (replaces about 7.5 quarts/50% capacity), use an aftermarket aluminum transmission pan with cooling fins and built in drain plug, replace the stock cooler with a high performance transmission cooler (thinking the stacked plate MSP Desert Fox), or add the aftermarket cooler inline with the stock setup?

 

[RF Overlord]

If you're transaxle temps have been consistent until recently, then I would be concerned.
Originally Posted By: NMBurb02
My shop just replaced one of the transmission cooler line fittings two weeks ago
Start there.

 

[NMBurb02]

I had thought about that but wasn't sure why that may have caused a problem.

 

[dgsbikes]

Make sure the internal diameters on all the fittings and any new hoses are spec and no kinks...

I would suggest doing a ATF flush or at least a couple of drain and refill before trying any of the other cooling mods.

 

[PhillyJoe]

Check the level and make sure you don't have a leak and the level is low. Sounds like a flow problem. I have the same car ('07 GT)and my trans temp is consistent in the 180-200 range. I've never seen mine go over 210 degrees.

 

[demarpaint]

Originally Posted By: dgsbikes
Make sure the internal diameters on all the fittings and any new hoses are spec and no kinks...



+1 and make sure they filled the unit to the proper level and it is leak free. Sounds to me like they might have screwed up somewhere along the line.

 

[NMBurb02]

The reason for the fitting replacement was that the old ones was leaking. I checked the fluid level yesterday and it is on the very bottom of the checked area on the dipstick so I will add a pint of Dexron VI but I doubt that will have much of an effect.

 

[LeakySeals]

When was coolant last flushed/drained? Dex?

 

[SHOZ]

If you replace the factory fittings with regular hose barbs then use 3/8" hose there will be a lot better flow. This with a good aux cooler should eliminate the problems.

Most steel lines are reduced to 1/4" or less internally somewhere in the system.

 

[NMBurb02]

Originally Posted By: LeakySeals
When was coolant last flushed/drained? Dex?

4 months/5,000 miles ago. Yes on Dex.

 

[Trav]

Originally Posted By: NMBurb02
The reason for the fitting replacement was that the old ones was leaking. I checked the fluid level yesterday and it is on the very bottom of the checked area on the dipstick so I will add a pint of Dexron VI but I doubt that will have much of an effect.


I wonder what they used for a fitting. GM uses a push in fitting with an o ring and small E clip on these, the fittings are threaded on the other end to screw into the radiator and tranny.

If they used one of these for the replacement there should be no issue but if they used flared line with a threaded fitting and a compression union it may be restricted.
You can see the stock fitting in this thread. Look for kinks in the line as someone posted.

https://bobistheoilguy.com/forums/threads/gm-push-fit-connectors-junkyard-jewels.68850/

 

[NMBurb02]

Originally Posted By: Trav
Originally Posted By: NMBurb02
The reason for the fitting replacement was that the old ones was leaking. I checked the fluid level yesterday and it is on the very bottom of the checked area on the dipstick so I will add a pint of Dexron VI but I doubt that will have much of an effect.


I wonder what they used for a fitting. GM uses a push in fitting with an o ring and small E clip on these, the fittings are threaded on the other end to screw into the radiator and tranny.

If they used one of these for the replacement there should be no issue but if they used flared line with a threaded fitting and a compression union it may be restricted.
You can see the stock fitting in this thread. Look for kinks in the line as someone posted.

https://bobistheoilguy.com/forums/threads/gm-push-fit-connectors-junkyard-jewels.68850/

Thanks, Trav. I'll have a look at that. With the couple other pieces of advice you have given me in regards to the 3800 I was hoping you would chime in. Maybe next time I will save space on the forum and PM you.

 

[NMBurb02]

I did a line off fluid exchange, pan drop, and filter change on Saturday (http://www.bobistheoilguy.com/forums/ubb...314#Post3071314) but that has not fixed the problem. In fact, it seems to be running hotter than ever!

I drove the car around a bit to get the temps to 180F to check the hot fluid level, topped it off with about 8 oz and then headed to the nearest dealership to get a replacement fitting due to a new leak in one fitting I removed for the flush during the work that day. It is about a 20 mile drive, mostly highway. There was some traffic on the way there and the temps got up to about 195F by the time I got there. On trip back they climbed over the course of 5-10 minutes to 221F and stayed there during the remaining 25-30 minute drive home (more traffic) while cruising on the freeway at 65 mph, while on side streets to avoid the worst of the freeway congestion, and during the short trip from the freeway to my driveway. Ambient temps were right around 70F and the humidity was a little high as it rained a bit that day.

The cooler line fitting replaced by my mechanic a few weeks back is on the cooler return line and is the OEM style push-in connector (aftermarket - not ACDelco) and the line they replaced a few months back is an ACDelco OEM style with rigid metal sections and rubber hose at certain flex points. I did not remove the new fitting to check the internal diameter but will be under the car later today to replace or try to fix the other cooler line fitting on the tranny and while down there will pull the fitting replaced by my mechanic and compare against the ACDelco unit I picked up on Saturday at the dealership. I will also double-check for any kinks in the cooler lines, but did not notice any on Saturday and there seemed to be a pretty good flow rate during the fluid exchange and flush.

Barring any discoveries involving the fitting replaced by my mechanic, where do I go from here? The auxiliary cooler is still an option, but I would rather not spend the money and have to cut up the cooler line most recently replaced by my mechanic.

 

[Trav]

Any idea what the engine coolant temp is when it climbs up to 221f?
With the stock cooler its pretty much normal that the tranny fluid will mirror coolant temps.

All fans working and coming on the at correct temp? If the mechanic used an OEM style fitting it should fine they are all pretty much the same. I just wondered if had cut the line to use a non oem threaded flair.

 

[NMBurb02]

Pulled the two tranny-side cooler line connectors and compared them to each other and the ACDelco replacement connector I picked up on Saturday from the dealer. From left to right: OEM (tranny out to cooler), replacement installed by mechanic (tranny return), ACDelco from dealer (to replace tranny out).

All had the same inside diameter and internal design (flaring, o-rings, etc.). The biggest differences are clear: thread and coupling depths. The dealer part is needed for the tranny out connection due to the connector depth but I am a bit baffled by the differences in thread depths. Both holes are deep enough for the longer threads, have slight inward flares at the holes' bases, and it looks like the threads would seat perfectly if as long as the OEM. Could the short threads interfere with the flow and be the cause of the high heat? If so, I'm not sure where to get units with the longer thread section.

 

[NMBurb02]

Originally Posted By: Trav
Any idea what the engine coolant temp is when it climbs up to 221f?
With the stock cooler its pretty much normal that the tranny fluid will mirror coolant temps.

All fans working and coming on the at correct temp? If the mechanic used an OEM style fitting it should fine they are all pretty much the same. I just wondered if had cut the line to use a non oem threaded flair.

Coolant fluctuated between 205 and 219, per my OBDII scanner. From feedback I got on a previous thread I started on the topic of coolant fans (http://www.bobistheoilguy.com/forums/ubb...905#Post2901905) and watching the needle gauge I figure all is well there. I could try putting in a 180F thermostat if you think that will help. It would be cheap and easy enough! Maybe get a tune to activate the fans sooner?

 

[NMBurb02]

Many of the fins on the bottom few rows of the radiator are bent and there is some debris between some (most look like grains of sand - maybe from passing through a windy desert area during the PO's move from IA to CA a few years ago?). However, 75%+ of the fins look fine as they are higher than the openings in the bumper where the damage is and there is not much debris in those. I will straighten the fins, pick out the larger debris, and hose the radiator from the engine bay out in the hopes that will do something positive.

 

[Trav]

The tranny temps seem to be mirroring the coolant temp which is to be expected.
Being an 06 they may have it running a little hotter than older cars.

I think i misunderstood. I was under the impression that it ran lower tranny temps then for some some reason started running hot.
The temps you have are a lot higher than my two but they are older and have coolers.
Still i don't like tranny temps that high OEM or not. 06 IIRC was the introduction of Dex VI a synthetic or semi synthetic fluid able to handle higher temps.

Lowering the thermostat 180f wont help much as in traffic it will just climb anyway to the fan on point.
I would probably do a cooler after the radiator, one from a car that had it OEM like the 9C1 Police package W body.

These are not like the cheesy aftermarket stuff, they use proper lines and mounting brackets.
Let me see if i can dig up some info.

 

[SteveSRT8]

Originally Posted By: NMBurb02
I could try putting in a 180F thermostat if you think that will help. It would be cheap and easy enough! Maybe get a tune to activate the fans sooner?


You are correct that the Tstat will do little if the fans don't come on at the correct temp.

IMO the radiator looks horrible, it needs to breathe freely without restriction. The factory setup runs the fluids through the radiator which is a great idea IF the radiator and cooling system are ok.

And times 10 on the OEM cooler. GM's standard truck part is a small flat plate design that comes with a huge bracket for under a hundred dollars. Easy to mount and plumb it in.

 

[NMBurb02]

Originally Posted By: Trav
The tranny temps seem to be mirroring the coolant temp which is to be expected.
Being an 06 they may have it running a little hotter than older cars.

I think i misunderstood. I was under the impression that it ran lower tranny temps then for some some reason started running hot.
The temps you have are a lot higher than my two but they are older and have coolers.
Still i don't like tranny temps that high OEM or not. 06 IIRC was the introduction of Dex VI a synthetic or semi synthetic fluid able to handle higher temps.

Lowering the thermostat 180f wont help much as in traffic it will just climb anyway to the fan on point.
I would probably do a cooler after the radiator, one from a car that had it OEM like the 9C1 Police package W body.

These are not like the cheesy aftermarket stuff, they use proper lines and mounting brackets.
Let me see if i can dig up some info.

I believe the tranny fluid did run cooler previously. I did not keep as close of an eye on the temps as I have since becoming concerned and having BITOG confirm that I should be concerned, but the only time it ever reached 221F, IIRC, was when I was climbing a few successive hills in 3rd gear and fairly warm weather. Also, the owners manual says to check the tranny fluid level when it is at normal operating temperature, which it says is 180-200F.