This problem became apparent this last summer and I need to repair it before it starts warming back up around here. My Bonneville (96) has a new water pump, new t-stat, freshly flushed radiator, and it still gets way too hot in even moderately slow traffic. I would expect some extra heat if I'm sitting stopped in traffic on a hot day, but this happens even when I'm moving. The cooling system just can't seem to keep the car cool under any conditions over 80 degrees. It routinely heats up well above the 195 t-stat temp although it has not yet started reaching into the red yet. It has gotten close on a few occasions. I don't recall this being a problem before this last summer and I am suspecting the radiator may be either clogged somewhere or enough of the fins have been damaged over time that it just can't get rid of heat. Anyone feel my pain?

When it gets hot like that is there any differnce if you turn the heat on hot and fans on full speed?

That would lead you to think radiator.

Yes there is. It is one of the methods I used to cool it down when I was sitting in traffic and it was getting warmer than I was comfortable with. The heater in 110 degree weather isn't fun, but neither is replacing a melted down motor.

By running the heater you are essentially adding a smaller radiator onto the system.

Seems like you are not getting the max cooling from your radiator. check the condensor (the other item in front of the radiator) and see if it is full and blocking the airflow from the radiator. Otherwise I would assume the radiator is no longer performing up to spec. Also hang in and others will chime in with good possiblilites

I had about 4" of leaves and old dried bugs built up between the condensor and the Rad. Probably not your whole problem, but check and clean as necessary.

Are you sure that your e-fans are coming on?

I checked the fans and they are working. The problem exists even when the car is moving when the fans don't do much anyway, so I don't think they are the culprit. I will check for debris buildups.

Heck...I'm checking for debris tonight.... That'* a typical problem.

Did the overheating start before or after your replaced the water pump, T-stat, and flush? Wondering of the above work might have dislodged a chunk of something to partially plug your rad.

Also, did you make sure to bleed all the air out of the T-stat housing after that replacement?

I'm not trying to treat this too simply, just want to make sure you've eliminated the simple stuff before you go at repair/replacement of your rad.

The overheating started about a year after I replaced the water pump (the old one was marking its territory on my driveway ), t-stat was replaced along with the water pump and the system was bled fully and the flush was done after the problem was noticed in an effort to alleviate the problem by possibly dislodging any clogs in the radiator. The coolant did not look particularly filthy before the flush (it was just drained and replaced when I did the pump), but I went ahead and did it anyway hoping it would help.

Well, I'm sorta out of ideas, as it'* begginning to look to me like you might, indeed, have a partially clogged radiator. At this point it gets a little out of my experience range, as I've not worked on the bonne rad.

If your skills are up to it, you might try removing the rad hoses and backflushing it (outlet to inlet) to try and remove any softer, non-lodged obstacles. Of course, you have to be the judge as to how bad any fin damage is on it (since you mentioned that). Worst case, remove the core and have it repaired/replaced at a good radiator shop, if you have one around you. They can save you hundreds $, if they're good AND honest.

Anyone else have anything?