Overheating? OM617 Replaced pump and thermostat, lower hose and coolant still cold.

[Zeitmas]

Bought a lovely pile of scrap with no documents and it's been a struggle finding and repairing problems. Still love the car

So, it gets hot and I don't know how hot because the temp gauge might not work (most electronics on it don't). With a hand in the vent while driving, I can feel big fluctuations with it being hot at idle.

I realized there was a problem when I heard light pinging when it was hot... Uh-oh. Just did a valve adjustment, so that's not it. Felt the lower hose and it was room temp.

Replaced the water pump, thermostat, and of course temp sender because the parts are cheap and I wanted to have fun. Thermostat and all that was orange... Rust? Flushed a half dozen times. Still rusty. I drained the radiator immediately after a good drive with the needle showing 80c and it was cold.

Is it going to be a head gasket next? Probably a waste of time in this old engine but it would be fun.

[hercules]

Sounds like a plugged radiator. Be sure to back flush block with thermostat
out or new radiator will also become plugged.

[Gasbeard]

Sounds like you have hot spots (air pockets in the coolant that need to work their way out). When you refill at the radiator after a thermostat replacement, the coolant doesn't work it's way through the block right away. Here is the procedure I used that worked for me.

Jack up the car as high as you can.
Loosen radiator cap.
Pull the hose at the firewall that runs into the back of the block.
With a funnel, pour coolant in until it overflows. Re attach hose to firewall.
While still jacked up, turn on car and turn heat on high. Keep revs sort of high for 5 min.
Without getting your hand chopped by the fan, squeeze the lower radiator hose 10 or 15 times.
Top off coolant, tighten cap.
Take a drive, repeat process as necessary until temp stabilizes.

[Father Of Giants]

Take the radiator to a radiator repair shop to be rodded out, it will be good as new.

[Mikebear79]

Is this the engine where the thermostat gets installed upside down? Just a thought.

[Clemson88]

The coolant won't circulate unless you fill the top radiator hose. The hose runs from the radiator to the thermostat housing. Remove the end attached to the radiator and fill it. Put your hand over the end after it's filled and get it back down and on the radiator outlet as quick as you can to avoid spilling all the coolant.

Fire it up, turn the heater on high and watch the thermostat to see if it's still overheating. If the thermostat doesn't open so the gauge drops when it gets to about 100C then shut the engine down and remove the thermostat for testing.

[okyoureabeast]

Yeah x2 on jacking up the front of the car and filling it from the engine hose. Let idle from cold to hot with the system on full heat defrost. That will burp the system.

Also, your electrical problems are probably just bad grounds. Add a new ground wire from your cluster to the chasis . The electronics are stupid simple but the grounds go bad.

Will most likely fix your I accirate gauges.

[tangofox007]

Originally Posted by okyoureabeast

Will most likely fix your I accirate gauges.

Accuracy is rapidly becoming an uncommon virtue.