Overheating

Hey guys,
During my holiday in the mountains I experienced some serious overheating problems with my Chevy Caprice. I've heard that you can solve this by adding external fans in front of the radiator. Which set up works best? Of what type of fans did some of you add to your car? And what's better; with a switch of automatic?

I would look toward a stuck thermostat, or a collapsed hose. You might even look at the viscous fan coupling.

I put the fans from a FW on my OCC. They work fine. I use a temp sender unit with a switch to turn the fans on at a given temp. I believe Spectre makes a thermostat housing that has a boss for a temp sender. You can use it to ground a relay to turn a fan on. There are different value switched temp senders so you can determine what temp you want the fan to come on, and shut off. You must have it come on after the thermostat opens, and disconnect below a predetermined point that is lower than the turn on temp. I had one that turned on at 210, and off at 198. You could even have the fan come on with the AC, and turn off when the AC is off with the car running. That setup will also turn off when the car is turned off. Just tap into the AC demand line (at the accumulator), and use it to close a relay. If it is automatic, you do not have to remember to turn it off.

My AC guy suggested that I have a fan running on the passenger's side whenever the AC is turned on. He demonstrated the difference with gauges on the AC and ran water over the passenger's side. It made the pressure go down on the "high side" by a substantial amount.

Any good fan will work. They are easy to install. You need a pusher fan for the front. The space that can be used is somewhat limited, because of the cross bracing in front of the condenser. Get a fan that fits the space there.

If I remember right your Caprice is a 91, does it have the original radiator? If it does it may be time for a new one.

Tom

A stock cooling system is up to the task. So, the issue is that something is not working. Rad cap not holding pressure. Bad hose. Bad rad. Clog. Stuck thermostat. Start with a pressure test and go from there. If history is unknown, change rad cap, rad hoses, thermostat. Flush and fresh coolant/distilled water mix. You don't need extra fans in these cars.

Thanks for the info guys. @Fred, do you have one or two extra fans? I think an automatic switch works best, but I'm not sure if I would connect it with the AC. Because, running the AC makes the car more warm, especially when doing some hill climbing. Do you have a link for a good fan?
@Tom, I have indeed a '91 Chevrolet Caprice. The radiator has been replaced 8 years ago, but a good flush wouldn't hurt. I believe there a special cleaning sets for a flush.
@Jay, I never have any overheating issues when I drive in normal conditions. but this holiday when it was 95 degrees and I had a hillclimb of 13% and was towing a 1500 LBS trailer, my car got seriously warm. But still, a good flush and new thermostat wouldn't hurt.

And would replacing my thermostat with a 195 degress thermostat help? Or should I stick to a 180 stat?

You shouldn't have a 180 stat. That is for LT1 cars.

I tend to agree with Jay. The stock system should be more than adequate for the job. Had a 91 Roadmaster with the 305, pulling a 3,000 lb. camper. Hardest it ever worked was a 10%-14% grade over a 10 mile stretch coming out of North Carolina into Virginia on a 95 degree day.

The temps went up a few needle widths but no more.

Time to go over the entire cooling system.

Bill

Ok uys, thanks. I guess it's time to go over the cooling system like Bill says. I cann't remember the last time I changed the coolant and the thermostat. What's the best stuff to put in the colling system and to get rid off all the junk that's piled up in there?

Flush it with water. If you use "radiator flush", you will probably be buying a water pump. The radiator flush usually removes the gunk that makes the seal work at the front of the water pump shaft. Or, put a new water pump on it, and use the "radiator flush". You may need a new pump anyway.

I believe that the wagons had a special tow option package? I think this includes an oil cooler and different gear ratio. I don't think my wagon has these options so maybe that's why it has trouble with a trailer in the mountains

The tow option for the early wagons had an oil cooler, and a wiring harness for the trailer electrical hookup. Other than that probably nothing. The oil cooler was hooked up to the radiator, and was not a stand alone cooler.

I do not have "extra" fans. I have the fans from a 93 Fleetwood in place of the original mechanical fan. Check your viscous drive for proper function. When they get older, they can fail, causing overheating.

What gear ratio do you have? G code of GU2 (2.73)or GU5 (3.23)? Unless you are pulling a heavy trailer, it should not matter which one you have, the trans will downshift to give you enough power to pull it. You might also try driving in D instead of OD.

Ok, I did not know that. I can imagine that the seprate oil cooler did a lot to prevent the wagons from overheating. But before installing extra fans, I'm going to flush my cooling system with a good radiator flush and after that with lots of water, install a new waterpump, and a new thermostat. I believe that since I own my wagon, I haven't changed the thermostat in 17 years. So, I think it's time to do that (lol). Than, fresh new coolant from a premium brand. I think all of that will do a lot for my car, and then I can decide if the extra fan is needed.

I would think about replacing the water pump, with a new one if possible not a remanufactured one, and see of there is a heavy duty version available. I would also replace the fan clutch with a heavy duty one. Along with the thermostat and coolant.

On the wife's old '89 Suburban, TBI 350, I did that and it made a difference, it did run slightly cooler and the gauge didn't fluctuate near as much. It never had an overheating problem but the pump was going bad...

This my set up when I go on holiday. We are with 6 persons (me, my wife, three sons and the girlfriend of my oldest son)
Behind the car is a tent trailer that unvolds at the campsite.

You need a turbocharger.

So, today I've replaced the waterpump, the thermostat 195 degree this time instead of the 180, fresh new coolant, new PCV hoses and valves and both the radiator hoses.

Is it normal that my temperature indicator in the dash reads a higher temperature now that I have a 195 thermos instead of the 180?

It will read higher with the 195 thermostat.

Ok Fred, thanks. So, would the 180 stat be better for my car to avoid overheating issues in mountaindriving? Or should I stick to the 195?

The computer will only go into closed loop if the temp is in the right range. The original thermostat is required for proper operation. Stick to the original spec 195. The temp gauge is controlled by a different sensor than the one for the computer.

Ok thanks Fred, I'll stick to the 195

Hey guys, so this is what my temperature meter now reads while driving on the highway with a speed of 80 miles per hour at 68 degrees with my new 195 degrees thermostat.
With my old 180 thermostat the needle was always near the first line (See the red arrow).

So, what do you all think? Normal reading now?

I'd be much more concerned with what the PCM thinks the temperature is rather than the dash gauge.

Dash reading is fine (and likely varies that much or more between cars with the same thermostat).

One more important thing that has occurred to me: do you still have the under bumper air dam? You need to. It helps draw air through the rad by negative pressure. Especially at the speeds and loads you drive with.

Thanks Jay, I now have one. I bought a nice one from Fred Kiehl. I never knew how important these things are.

I'm glad we are getting this figured out!

BTW, I'll be in your area in early May. I'll bring students there to commemorate the 75th anniversary of Liberation. I've been over a few times previously on personal and school trips. I proudly teach about the special relationship between the Dutch and Canada.

That's nice to hear Jay, many people here in Holland still have a warm heart towards the ones that liberated Europe from the Nazi's.