PontiacBonnevilleClub.com

I recently put a 180 degree thermostat in and had the PCM's fan turn-on temp lowered to correspond. I did this because I want my tranny temps a bit lower without adding an external transmission cooler. Does anyone know if this type of setup actually keeps the transmission any cooler, via the tiny transmission cooler inside the radiator?

While this setup seems to be working just fine so far, I am concerned that I might have problems with this once the nasty cold Illinois winter hits.
I have noticed that a number of people here have switched to a 180 without changing fan turn-on temps. Is this still an effective mod mod without the corresponding fan settings? I am asking all of this because I may be sending my PCM in soon and I am just wondering if I should switch it back to stock fan turn-on temps.

I put my Intense PCM in on superbowl sunday this past winter and it was 0*F outside. I survived the winter just fine with my 180* T-stat and 180* fan turn on. You should be just fine down in Illinois.

you won't have a problem in the winter. we have members in northern parts of Canada running them year round with no problems. Yes, the thermostat is still effective without the fan settings being changed, especially at cruising speed. it obviously won't help as much if you aren't getting airflow through the radiator though. the fans basically are replacing your movement. They dont do much when you are moving anyways.

The 180F stat and fan turn on should be fine as the car will heat up to the 180. What I would suggest against is keeping a drilled stat in for the winter. In some cases it has been found to take 15+ minutes for the car to heat up with only one 1/16 hole drilled in the stat.

I currently do not have a drilled thermostat, so what are the advantages of a drilled thermostat in warm weather? Also, has anyone seen a decrease in gas mileage in cold weather from the cooler thermostat?

I drive in warm weather all the time with my 180 drilled tstat. The advantage is that the car now typically runs at 180 degrees instead of 195. One member at WCBF said they lost about 1 mpg when using a 180 stat. I keep track of my gas mileage, and mine does not appear to be affected at all.

The lower temp may improve longevity of the intake manifold gaskets, and may reduce the incidence of UIM burn-through at the EGR on NA Bonnevilles. The failures of those components is at the very least partially related to heat, possibly to a very great extent.

You mentioned wanting to use a 180 to help keep the tranny cool. While it certainly shouldn't HURT, I think your benefit for the tranny might be marginal, and I think a tranny cooler would be a very good idea. I don't think the addition of a tranny cooler should be too bad for cold climates, I don't think I've ever heard of an owner's car having a transmission problem because it had a tranny cooler in cold weather. Even with the 180 stat, I do see evidence of tranny heatsoak affecting the engine temps when climbing over mountains. Other members have seen the same effect.

I have also noticed a drop in milage after changing to a 180 t-stat and autolite 104 plugs.

probably mostly the plugs^^^those are too cold if your almost stock...swap to the 605's instead

All that is done is what is listed in my sig.