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240 Car overheating, new water pump, radiator and thermostat

VolvoPunch

Active member
Joined
Sep 11, 2006
Location
Bend, Or
I finally got my car running after about 2 years of it sitting around. I installed a new radiator, water pump and thermostat. I'm sure the cooling system has been dry for awhile since the car has been sitting for a few years without a motor.

Anyways I topped off the system, left coolant reservoir cap off and opened up and started the engine. Then I opened up the coolant bleeder port at the back of the block on the passenger side. A flow of coolant started to come out so I shut the drain valve thinking the block was getting filled with coolant now. I went back into the cabin and turned on the heat and allowing the fan to run on max. The air become warm but not scalding hot like I remember it used to be.

The top radiator house is hot and the bottom radiator house is cold as ice making be believe coolant is not flowing through. So I began to squeeze the top rubber housing hopping to get some coolant flowing though the system. The top is suppose to be hot and the bottom cool right? Coolant flows from the top of the radiator to the bottom?

At this point the engine had clearly warmed up and maybe come a bit to warm because you could not touch the cylinder head on the intake side it had gotten that warm from running for 4 or 5 minutes. At this point I realized the engine had started to over heat and MS was reporting temps in the 190f range so I shut it off. The E-Fan had been running constantly for several minutes but I was not seeing any changes in the temperatures.

What's wrong with my cooling system? :-(
 
...The top is suppose to be hot and the bottom cool right?

Bottom should not be cool. It should be warm. Both hoses should be too warm for you to comfortably touch for more than a few seconds. Sounds like the radiator is plugged. I'd take it out and reverse flush it with a garden hose. See if water comes out the other end, and make sure it does the same from either end. More importantly, see if a bunch of gunk comes out when you lightly pressurize it with water.
 
Sounds like you have an air lock.

+1. Helped a buddy with an air lock due to the same (complete coolant system overhual) in an old nissan pickup. We found it to be in the heater core. Fixed it by pulling the heater core hoses and raising the bottom hose above the top and filling it until we got no air no air at all. Hooked them back up carefully to keep them as full as possible and problem solved....
 
I removed the radiator and sprayed it out with a garden house; it was clean and clear with a good flow.

I then removed the intake manifold in order to get access to the heater core hoses. I pulled the heater core house off that attaches directly to the cylinder head and sprayed water through it. The water started to come gushing out of the bottom radiator house that attaches to the water pump and the drain valve on the block. So the flow was good and the water was clean and clear. I then reattached everything and started the car.

MS reported temps of 160f, the cylinder head was hot. The houses were all cold and the radiator was also cold.

I cannot get this car to cool itself.
 
190F isn't overheating. It sounds like your engine just isn't warm enough to open the t-stat. if you are wondering about functionality of the stat, just plunk it in a pan of water on the stove. Use an instant read thermometer to track the temp and see when it opens. Often you will have to go several degrees above the 'setpoint' before it will open fully. Also there is a little air bleed in the thermostat disc. that should be oriented at the top when the stat is installed. This air bleed will do just that, bleed the air out of the block as you are filling it. I used to do the same thing with my old pontiacs by drilling a small hole, but Volvo did it for us. The radiator will not warm up until the stat opens. Often if you watch the gauge the temp will overshoot past the stat setpoint and then drop back down. When its cold enough out, the thermostat may shut again (doubtful in Georgia though).
BTW, I cant comfortably touch the cyl head after my car is warmed up either and it never overheats. I have the stock stat in my B23 - 92C (197F). I'm frankly not sure what the 'red' range is on the temp gauge, but my guess is in the neighborhood of 240F+
 
Also never start the car and fill the system up. Fill the system up all the way with the engine off. Then pump the coolant back and forth by squeezing the upper and lower hoses a bunch of times. That will burp out a lot of air through the overflow tank. It will also let the little air bleed in the thermostat do it's job with getting air out of the cylinder head. Once that seems to subside a bit. Then you can start the engine and you should be fine. Also as mentioned 190F is just starting to open the stock 88C thermostat.

Make sure you use a phosphate and silicate free antifreeze.
 
I see 195-205F on the megatune gauge under normal running. I use a stock volvo temp sensor that would have been original to my '87 240 w/LH2.2 and I don't do any compensation in MS to try to make it match the GM sensor. Somewhere around 220ish it would probably start to boil over. I'm usually not looking at the gauge when it's gotten that hot.
 
The thermostat is what's causing my overheating issues. I removed the thermostat and the car cooled down just fine. I have three thermostats all different brands, two new one used. I dropped them into a pot of boiling water and they all opened up just fine. I decided to use try out the used Volvo thermostat since it opened up and I just replaced the gasket and installed it. The car is still overheating the the thermostat will not open up. This is extremely frustrating. I'm meeting resistance on almost every aspect of this car. If I ever get it running daily it will be a miracle.
 
You either have an air lock or some other problem. Did you use my method for making sure that you get coolant on both sides of the thermostat? Did you make sure to put the bleed hole at the top of the thermostat?
 
I don't know what's going on. But I'd want to try a new off the shelf Vernet thermostat and see how it is. I don't trust used thermostats even if they opened in a pot of boiling water. Especially if they are Wahler brand.
 
Did you happen to notice if it took exactly the same amount of coolant with the thermostat in place as it did with it out? If so it is not air locked.

Are you sure it is overheating? What year is the car? Does it have a temperature compensation board in place? Not sure what the first year for those were... 1985 or 86? If you are basing your overheating on a gauge with a comp board in there it could well be a bogus reading. Pull the board, throw it away and jumper the pins as shown in the image. Good luck.

Randy

<a href="http://s50.photobucket.com/albums/f325/rstarkie/volvo/?action=view&current=COMPBD.jpg" target="_blank"><img src="http://i50.photobucket.com/albums/f325/rstarkie/volvo/COMPBD.jpg" border="0" alt="Photobucket"></a>
 
The car is a 91 Volvo 240 with a 91 940 Turbo B230FT block and head. It's using MegaSquirt 2 and I'm able to use both the dash gauge and the MS coolant gauge to judge the temps. Yes the car is over heating, I have tried three different thermostats two new, one used. I install them with the air bleeder valve facing up. You cannot install these thermostats backwards. I burped the system several times and I made sure the squeeze the top house many times before starting the engine. I'm going to try one more thermostat and see if I get any results.
 
I know I'm bumping an old thread and I know that I don't even own a Volvo.
But no one have been able to figure out my issue that sounds EXACTLY the same as OP.
I would hope OP found out what was wrong by now.

Replaced radiator, waterpump, thermostat.
Tested old and new thermostats and they both open up like they suppose to.
Clutch fan is good. Electrical fan is good. It's properly burped.
Hoses don't collapse.
Upper hose is hot, lower hose is cold (not good).

Overheats with thermostat (installed correctly).
Doesn't without.

Checked temp with another gauge just to make sure and it's right on.

I drive S13 240SX with KA24DE if anyone is wondering.
 
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