What else could be causing my car to overheat?

sashaa35

2003 Buick Rendezvous CXL. Just replaced the thermostat, cooling fans are working, I have no heat/ac air inside car and it still seems to be overheating. from the C to the H their are 3 lines mine tends to hit that 3rd line in just a matter of minutes. So is their a fix? and why do you think my ac/heat does not come on? Are the problems related?

ray80

When the T-stat was replaced was the air in system propely bled? If not that can cause no heat condition and possibly overheating
(potential for blown headgasket also if it had been driven when overheated)

Mr_Shiftright

No heat suggests low coolant level or air trapped in the cooling system. I would bleed the cooling system and double check the cooling fans for proper operation. Also, such a quick overheat might suggest a complete blockage or a head gasket problem.

sashaa35

Ok thanks guys, can you give me some step by step instructions on how to bleed the air system?

Woodwardc65

I have a 2003 Buick rendezvous I’ve got a overheating problem I’ve replaced everything i have already put 2000 thousand dollars into it
I’m at a loss please can someone please explain why my car keeps overheating

thecardoc3

Unfortunately, it doesn't work that way. Someone has to spend the time to prove what is going on. If I was going to start testing this, I would start by trying to get some details about when this is occurring. For example; Does it happen every time you try to use the car? How far, or how long do you have to drive it to get it to occur? Does it happen on the highway, at stops, or both? Can you tell if the cooling fan(s) is/are running at high speed when it happens? Are you judging the overheating by the dash gage or are you seeing steam, and hearing the coolant "thumping" (steam flashing) in the engine? Is this losing coolant and needing to be added? Is there a milky foam on the oil fill cap and the oil level at the correct height or higher? Is there visible steam from the exhaust and does it have a sweet odor?

With the above information A technician would be able to recreate the overheating event and start measuring for coolant flow and heat transfer. Using the scan tool and infrared camera or gun he/she could confirm just how hot the engine really is getting and if the engine data agrees or not.

Bamaboy9922

I know 10 years to late but who knows maybe help somebody out one day. I have an 2006 rendezvous CXL the 3.5. I didn't have an over heating issue til i tried doing a flush. Than it would over heat less than a min. But even when i purchased the vehicle the temp. Gage stayed at halfway mark. Which i figured was normal. But i just felt the engine was hotter than it should be. I eventually just assumed after i figured out where the bleeder valves was. New coolant, radiator cap, it went back like it did when i purchased it. So it wasn't ever over heating originally always just seemed hot to me. I accidentally fix the issue i haven't seen a solution to anywhere. Could be wrong but this worked for me. My car is almost staying to cool now lol I noticed most people say the AC at idle or slow traffic helps. Found that very odd should need to turn the heat wide open to cool it down not air. But some reason the AC helped i never in my life heard of that. So i decided to back it up a hill and park it a couple days let that pressure flow that way. Bc during my flush i had the front jacked up to help bleed the air out. So i just decided to do the other end by backing up a fairly steep hill and parking it a couple days. A couple days later i got in it turned the key on put it in neutral rolled down the hill a little bit more flat. Than cranked it up and instantly turned the ac on full blast. It blew air and some freon out the upper AC valve stem thing. I thought i done messed [non-permissible content removed] up lol But it did something i didn't expect. It stopped even feeling like a hot engine anymore. My temp guage doesn't get above a 1/4 now. You can touch the top of the engine 10 mins later hardly even warm. Usually about burn the hell out of you in 10 mins. Now i wish i kept the original thermostat in their but its all good. Sorry about the life story i just don't get on here often to respond. Try to make it clear as i could. Hope this helps somebody one day. Im already around 250.000 miles. Only other hard issue for me to figure out was a fuse box needed replaced once. Regular maintenance besides that. Let me know if this helps anybody.