2003 Chevy Venture Overheating issues

I have been chasing this overheating problem for a couple of months now, and I am thoroughly frustrated.

The first issue was a hole in a short, S-shaped hose that goes from the the air bleed valve on the top of the water pump, to a metal line that goes back to the heater coil…I think. After this fix lasted for a month, I decided to change the thermostat…what a pain in the arse! After changing the thermostat didn’t fix the problem, I decided to flush the radiator. After starting the engine to run the flush through the engine, a broken three prong elbow connector cleat in the upper back of the engine compartment was spewing coolant all over the engine. Must have broken off during the thermostat replacement ordeal. So I replaced THAT part, and tore up my hands in the process due to the limited space and numerous opportunities for scraping one’s knuckles, only to find that now there was a leak in the radiator. Replaced the radiator. Thought this was a done deal. Overheating began again after the hot weather spell a few days after replacing the radiator. Noticing that the radiator fans are not turning on, even when the engine coolant in bubbling over in the coolant reservoir, I figured this must be the issue…but I kept Googling for answers, and found someone that said replacing the hose clamps on that short S-shaped hose I replaced at the outset, with worm screw type hose clamps fixed the problem for him, so that’s what I did next…and it seemed to work. I took a 20 minute trip on the freeway to the other side of town, on a hot day, and with the air conditioner blasting…the temp gauge did not even get to middle. I was ecstatic…until, after the car had sat for 10 minutes, I started it up, AND THEN it began to overheat…UGH!! I ran the heater full blast in order to get it back home.

So now we get to today…I decided to try to replace the hose clamps on the three prong connector I had replace, with the screw type hose clamps, but it was impossible to remove two of the hoses from this connector, and I only only replaced one of them. Car still overheating. I then read that the radiator fans may not turn on if the AC needs to be charged, so I bought some refrigerant, but found that the system pressure is very high…so no charge needed.

I have not replaced any relays, fuses or fusible links to the fan, but I imagine the overheating is likely due to the fan not enganging when the coolant temp gets too high.

Can someone please tell me how to attack this? I can’t find my multimeter to see if power is getting to the fan motors, but that’s MY problem. Is this the next logical thing to do? I am tired of chasing this grrrr…Any advice at this point would be appreciated!


I know you thought you gave us a full description of your problem, but you did not. I know you are frusterated, but can you please tell us WHEN under what circumstances the van is over heating. Is it while at idle or slow speeds? Does it do it on the highway? maybe all of the time? Does you AC work? have you allowed the van to fully over heat or have you shut it down before then? These are all very important questions.

Thanks for the quick reply gsragtop! The overheating issue is compounded by the fact that it has been hot and humid lately, I live in Southern California and at least the humidity is abnormal here. The overheating occurs when the car is driven for extended durations…except for just after I replaced the hose clamps on the S-shaped hose on the front of the engine…I drove it for 20 minutes on the freeway, and it was doing just fine with the air conditioner blasting. I parked it for about 10 minutes while I ran inside a store, and when I restarted the engine, the air conditioner was not blowing cold, and the engine started to run warm then overheat…that is when I switched on the heater so I could limp back home. Since then, I only ran it one other time before today to take a short trip to the store in the evening. It ran warm but did not overheat…but the trip was like only 5 minutes in each direction. Today I drove it until it overheated…staying close to home, so no freeway. It took about 20 minutes to overheat…half the time it was idling in our driveway with no overheating, but then I took it on the streets, and it slowly started to run warm and then eventually overheat. I hope this helps…I’m really sure that if I can get the radiator fan working, the overheating should stop now…but that’s because, at heart, I am an optimist…lol!

Was the AC on today?? When you turn your AC on, if it is working it will FORCE the rad fans on. This is something you can check easy in your drive way. If the AC is on but no fans you most likley have a bad fan, or possibly a relay. If the Fan are running with the AC on, but when running warm the fans are not on with the AC off… Then you have a bed temp sensor…

I don’t know about the cooling fans. My daughers had 2 ejectri ones, one for regular driving, one behind the radiator. The fan was supposed to kick in when ac was on, it did not, replaced the fan, and now no intermittent overheating problem. Have you pressure tested the system?

Thanks again gsragtop. Fans are NOT working at all…AC or no AC. Barkydog… I haven’t taken to a shop yet…no dinero. Hoping to figure this out on my own vs. paying to have done. Maybe it is a simple thing to pressure test??

I’d try to find your multimeter.
Seriously, why mess around? Trace it back from the fans. Maybe force the fans on by shorting the thermo switch and go from there.

Think you’re right Remco…I can buy a cheap multimeter at Harbor Freight

It sure sounds like a bad fan motor, or relay.

Yup, that’s what I’m thinking as well.

Check the fuses also. Squeeze the upper radiator hose when cool, if it is significantly firmer when the engine is warmed up pressure is probably fine.

I have been having the same problems with my 03 Venture.
I had the thermostat replaced and the radiator flushed and it did nothing.
My van would overheat on any trip longer than 20 minutes and would overheat faster if I used the AC. It would really jump in heat at stoplights.
The fans were working and coming on at the right intervals.
I was at a loss for where to go with it and was dreading the summer heat.
I may have stumbled on a fix and it may apply to your van as well.
This last weekend the alternator died and the battery with it.
It was an expensive fix.(about $700)
An unexpected fix that came with the new alternator was the overheating stopped.
I drove all over town today with the AC blasting and zero overheating. (80degrees out)
It seems that my alternator had been going out for awhile without my knowledge.
It was probably not putting out enough juice to run the cooling fans at speed, especially when the AC was on and drawing more power.
I noticed there was also more pick-up in the engine. It seemed to drag between shifts sometimes and now shifts smoother.
I have the AWD Van so it needed the 120v Alternator.

Maybe have your mechanic check the output of your alternator. It may be the fix you are looking for.


You’re talking to a wall

This thread is 9 months old

OP is almost certainly not following this