Coolant system issue

[RoulerCo]

I recently replaced my entire cooling system for my 1600-2 because the car was overheating really quickly. After flushing the engine block, removing and replacing the radiator the water pump and the thermostat and all of the hoses the car is still over heating with fresh coolant.

 

when I touch the hoses, the one from the lower part of the radiator is cool to the touch and the one leading from the thermostat to the engine block is hot to the touch.

 

I feel like the water pump isn’t pushing water around of some reason because when I leave the radiator cap off and start the engine the fluid level doesn’t change. (Unsure if it should?) 

 

I can’t spot any liquid leaks but I did have some air leaks from some clamps that needed tightening some more.
 

Any help on what could be causing the problem? 🙂

[Stevenc22]

Hopefully you didn't make my mistake and leave a rag in the block like i did

 

Until the thermostat opens, there wont be flow through the radiator.

[visionaut]

Bad radiator cap?

Pinhole leak somewhere?

(both would cause system to not hold pressure when hot and cause overheating)

 

Motor running hot due to bad ignition timing? Pinging/detonating?

 

Replacement thermostat or pump is DOA?

 

[Son of Marty]

When you filled the system did you have the heater valve open and the front elevated a bit? If not there's a good chance you have a air lock in the system.

[RoulerCo]

1 minute ago, Son of Marty said:

When you filled the system did you have the heater valve open and the front elevated a bit? If not there's a good chance you have an air lock in the system.

Ah ok!

 

No, I didn’t do either of those. 
 

The heater in my car doesn’t work. The valve is stuck about half way. I can’t move either left or right. Can I drain the fluid and then still elevate the car on some axle stands and try it?

[Son of Marty]

Just now, RoulerCo said:

The heater in my car doesn’t work. The valve is stuck about half way. I can’t move either left or right. Can I drain the fluid and then still elevate the car on some axle stands and try it?

Yeah, I'd raise the nose and remove the drivers side heater hose, slowly add water until you get a steady stream out of the heater then replace the hose and slowly fill with anti freeze. Start the car with the rad cap off and let it warm up then cool down top off if needed put the cap on keep checking the level over the next few drives and the water level should level off about a inch or so down.

[Hans]

Just elevate car. Air leaks? System should be full of water.

[Son of Marty]

I'm not sure that with the valve 1/2 way open that you'll get enough flow through the heater core to purge all the air, but then I've never tried it.

[Mike Self]

1 hour ago, Son of Marty said:

I'd raise the nose and remove the drivers side heater hose, slowly add water until you get a steady stream out of the heater then replace the hose and slowly fill with anti freeze.

Before you do that, I'd lower the coolant level a little so you don't lose any, then remove the heater valve (leave the lever attached to its cable and note the position of the valve lever in relation to the position of the temperature control lever on the dash--it's easy to reinstall the valve lever so the control works backwards).

 

Presuming your valve is original (and smaller than the valves used from mid/late 71 on), it's all brass except for the two screws that hold the cover  to the valve body.  First try loosening the stuck valve; if you can't, then dismantle carefully, clean it up, replace the internal O ring, and if you're successful in removing those steel screws, replace 'em with stainless steel.  Once functioning properly, not only will you be able to bleed your cooling system properly, you'll have heat.

 

mike

[Dudeland]

Maybe some pics may help.  I would have said replace the thermostat, but I agree, sounds like an airlock. 

 

Is the thermostat itself hot?  Were you able to get the car up to temperature?

 

 

 

 

[Mikesmalaga72]

A pressure test of the cap and cooling system could get you closer to causes. A bad radiator cap releasing pressure too low lowers the boiling point of the coolant apx 3 degrees per pound of cap pressure rating. A good 50/50 mix of silicate free coolant and distilled water should be the baseline mix. A friend of mine had a radiator hose that kept blowing off without any other leaks. I gave him a known tested cap and it took care of the problem. Good luck. 

 

BMW 2002 cap rating is 1 Bar or 14.5 PSI 

[TobyB]

Quote

I feel like the water pump isn’t pushing water around of some reason

...because the thermostat's not opening?

 

I feel like there are a lot of questions still unanswered-

 

1- how do you know it's overheating?

 

2- does the thermostat housing get hot enough to burn the back of your fingers?

 

3- what does an IR thermometer aimed at the little stub hose between the thermostat and the water pump say?

 

4- have you boiled your thermostat yet?

 

t

 

[gwb72tii]

On 10/4/2023 at 8:16 PM, TobyB said:

...because the thermostat's not opening?