M44 overheating
 

Replaced the thermostat, new radiator, water pump, fan comes on when
temp at 12, then shuts off, temp rises toward red. I had heater on high,
bled air, but the overheat conditon continues. Top hose is hot and hard,
so shut off and let cool, then refill a little, bleed, start again. 6 times.
no leaks, no water at exhaust, don't know where it goes. When is the fan supposed to come on? When at low, when at high?
cyl 1 206 psi
2 201 psi
3 207 psi
4 207 psi
What is cause of this ? HELP!!!

Thermostat installed backwards. Sounds like you're not bleeding it properly.

CJ, Impossible! the thermostat is built into the houseing,
It is not separate, you buy & install the "assembly". When
and how does the fan operate? High & low?

Woke up this am, had to refill about 16 oz. Idled and reved
to 2500 rpm, went to 12 and stayed 5 min. I shut it off.
Will start in 2 hr to see. Also, this time the fan did not come
on at all so I shut it off. Now what?

Low speed fan is triggered by temp sensor, high speed triggered by A/C. How did you go about bleeding the system?

I have a manual and followed the directions section 170. A
bleed screw is next to cap. Filled to half, put heat on, turn
ignition on. then fill. Today is 8th refill i think.

I have a new temp switch, I just went and started engine,
then hit A/C and fan came on. Turned off A/C, no fan. So
How do I low speed on. Thanks, in advance.

Could maybe the wires in plug made in wrong position?

You might be able to trigger the low speed by unplugging the sensor and jumping the pins in the connector.

The fan shouldn't really cause the car to overheat though if everything else is working properly. When you turn the car on and it warms up, does the needle just keep rising? Are you getting warm air from the heater? I think you might have an air bubble trapped in your radiator.

I unplugged the switch, hooked my test pencil light to ground
on engine, in the plug are three wire posts, when I tried all 3
one of them turned on the high fan. Plastic Plug is heat deteriating. All three posts fell out.

You might have a bad relay. couldn't hurt to check all of the fuses and relays, but the fact that the connectors are deteriorating sounds like a likely culprit.

Also FWIW, I had a hairline crack in my radiator right next to the expansion tank. I couldn't see coolant leaking because it would evaporate on the hot radiator leaving no visible steam or moisture. You might try pressure testing your radiator.

Could a head gasket be the overheat prob? I just went out
and checked the coolant. is for first time at top. Brown wire
with white is the one that is starting fan. Will the manual tell
me if that is high or low?

Absolutely, but lets not go there yet. Unless you see signs of a blown head gasket, try to stay optimistic. Any smoke? coolant in the oil, oil in the coolant, sweet smell coming from exhaust?

You never answered if you were getting warm air from the heater. Also, expansion level rises when the coolant heats up, hence expansion.

As for wires, I'm not sure.

1. Black w/grey jumper wire to brown, high fan runs
2. Black w/green jumper to brown, nothing or to engine grd.
nada
Low fan must be bad?