Overheating issue

I am not the best mechanic in here, but for the sake of thought, lets pick it apart. Going well past 220 (if the gauge is correct) on a test drive suggests to me that the coolant flow through the radiator is restricted and the heat exchange is poor. The water pump seems good as per hose collapse issue. Thermostat has been replaced with no result. Radiator has been replaced with no result. If in fact the radiator is not blocked, and your thermostat is opening properly, and installed correct side up, I think then I would suspect something like a chunk of cast lodging itself in a key passage in the block....but I am not familiar with how the water passages are laid out to know if this is a remote possibility or not. If you take out the thermostat and suspend it in a pot of water on the stove, check the water temp if you have a thermometer to see what temp it is opening at, and at what temp it is fully opened. It should be fully opened before the water boils. Stick a garden hose in your upper radiator hose, aimed at the radiator with the bottom hose disconnected. Turn the hose on full blast and the water should run out as fast as it goes in. If all this checks out, I would try to backflush your block with the hose......but I cant tell you how exactly because I have never tried. You might have to remove the water pump to do that, but I would shop around for some expertise. If I were you, I would be pulling my hair out, but hang in there....a good result will come.

 

Also, if you have one of those infrared temperature guns get a 2nd opinion on what the temperature really is on the intake manifold and radiator.

MD

 

Went back through our discussions and noticed we never talked about checking if there is something in the upper rad hose. Maybe push a coat hanger through it.

MD

 

Get yourself one of those temp guns and double check the temp of the engine, hoses and radiator. Could be a bad gauge or sensor. I run a molded hose without a spring on my 306 along with a aluminum radiator with a 13lb cap, no issues.

 

Is the electric fan blowing in the correct direction?

 

I'll have to grab an inferred temp guns, although I'm sure it's correct. The car is usually puking some coolant/water as I get it home. The fan is indeed pulling.

 

If it's holding the coolant 220* isn't a issue... If it's overflowing, I'd suspect a leaking head gasket that's allowing compression into cooling system... I had that problem with old 5.0 in my Bird, fire ring burned, main body of gasket still OK... While running the coolant looked like I'd dumped Fizzies or Alka-Seltzer in it... Problem was on #3, pulling plug wire stopped the bubbles...

 

It's not holding at 220. It climbs and climbs. I compression tested the car about a week ago because I figured that was the issue as I previously blew a headgasket in the car. I'm going to compression test the car one more time and I'll see if maybe I was getting a false reading. The car runs fine and there's no sign of oil and cooling mixing, although there wasn't two years ago when my car blew the last one. Maybe it's too early if a leak for compression to be dropping any?

 

VC, when you went to the electric fan, I assume you got rid of the stock fan. The stock fan is attached to the water pump pulley. Stupid question but did you change anything with the routing of the fan belt to the water pump pulley?

MD

 

My Bird also ran fine with no mixing of coolant/oil, overfilled recovery reservoir after 10-15 min of running... Didn't show signs of overheating as long as coolant was full... The bubbles in mine were obvious after a couple minutes of running...

Any compression leak into cooling system that actually shows a drop would be making a geyser...

A compression leak tester will check for presence of combustion in the coolant...

 

Yes I got rid of the flex fan. The guy who had the car before me rigged up the power steering set up so I deleted that. I put a new smaller pully on the water pump to make use of one belt to run alt, water pump and the crank. That's all I did.

 

Ok, the smaller pulley will speed up the water pump and may contribute to increased suction at the hose so that's one observation.

 

Well I guess I didn't mean smaller. It's the same size just not pushed as far out as my last one. It just sits further in to allow for all pullys to line up on one belt.

 

Checked my setup and I see the crank, alternator and water pump pulley all spin in the same direction. Yours too? (Dumb question).

 

Yep. All in the same direction.