PontiacBonnevilleClub.com

Long time, no see guys!

I installed a Hayden 679 transmission cooler on my car. It is mounted on the passenger side, in front of the condenser. I went from the top port of the radiator (using Hayden 397 adapter) to the bottom of the cooler, then from the top of the cooler back to the stock top hose. The barbs on the cooler point to the passenger side (for reference). I ended up going with this cooler because it was the only one that I could find in town and I wanted it for a road trip.

Yesterday, I took a trip down to Chicago (~5hrs one-way). The car ran at a solid 186/188 on the flats and the trans was at 176/179 with the AC on doing 70mph. (I'm running a 185 t-stat.) Ambient temp indicated by the car topped out at 90 with a low of 82 late in the evening. In stop & go traffic (with the car already plenty hot), the trans would got up to 195 (this was with the A/C on) and the engine was right around the same temp. The engine cooled back down quickly, but the trans didn't.

My concern/question is that the transmission still seems to take quite a bit of time (compared to the engine) to cool back down after going up a hill or stopping/starting. Is this normal?
Others seem to report that after installing a cooler, the trans rarely ever gets above 185 and cruising around 165 - 170.

The engine will warm up to 196 or so going up a hill, but it cools back off pretty quick. The transmission on the other hand will warm up to 186 (or slightly more) and take forever to cool back down, if it cools down at all.

This may just be me being paranoid after installing a cooler rated at 30,000lbs.... So far, I haven't driven it completely hot (the trans) in stop & go traffic to see what it does. I was also having an issue with it bang shifting, but I think that may have been due to being over filled. I've sucked out some fluid to bring the level down, but haven't tested for bang shifting again yet. For all I know, being over filled may also have been hurting my temps, but we'll see.

Sorry for rambling on, but I just don't want to ruin a transmission that is only 1yr old after rebuild.

Any input/ideas/advice/comments/questions are greatly appreciated!

I haven't done this in a while, so forgive me for my forgetfulness, but did you route the cooler before or after the stock radiator cooler?

Other than that I'd wonder if there is enough airflow. My car with the cooler has never gone above 180.

From every thread I ran into dealing with the 00-05 Bonneville, I ran it the correct way (stock cooler running bottom inlet, top outlet).

The cooler I'm running is 11 x 11 x 3/4" and it goes from the radiator brace bar in front of the condenser all the way over to the edge of the condenser (of course, if most is blocked, the size doesn't matter one bit).

I know the bumper blocks a good portion of it, but its still pulling plenty of air with the fan on, and 70mph of force should be sufficient. The only other thing I could try is building an air duct to force air across it better, or cut holes in my bumper like a 6.5L 95-98 diesel Chevy....



The only issue with this (other than not looking the greatest for a Bonneville) is that the license plate takes up quite a bit of room, so a whole lot wouldn't be gained.