Coolant problem need help

[BILLDEUCE]

I keep losing coolant out of my explanation tank on top the engine it's coming out of the over flow tube to the point of almost emptying the tank trucks temp doesn't go above 185/190 during all types of operating conditions highway , around town and idealing tranny is good to. No white smoke either any help is greatly appreciate of what it maybe ?

 

[BILLDEUCE]

Truck is a 1990 m923a2 forgot that put that oops

 

[juanprado]

maybe a stuck thermostat?

Worse case Sounds like a possible head gasket failure/crack. Combustion seems to be getting in the cooling system. One was to check is to use dye and a lamp to check for leaks

 

[rrrr]

Check your oil to make sure there's no coolant in it. Sounds like what juanprado said.

 

[BILLDEUCE]

Oil looks good I don't get it that was the first thing I checked if burning coolant want you see it in the exhaust causing a whitish exhaust smoke ?

 

[Cruceno]

So coolant is coming out of the overflow tube at the expansion tank? In that case, it would seem that the system may be clogged somewhere downstream. If coolant is flowing into the expansion tank, and cannot make its way back into the radiator/engine, it will eventually fill the expansion tank and cause an overflow.

 

[BILLDEUCE]

Never thought of that now where to check should be fun

 

[Carlo]

I had a similar problem on my A1. I thought the water was coming from the expansion tank, the level was going down but the leak was just below the tank on the heat exchange cooler / transmission. A hose clamp on a tube had weakened. All the signs were saying the coolant on the floor was coming from the tank but it was not.
BUT on another note I had one of my A2's loose water regularly from the expansion tank till I changed the pressure cap.
Dont rule out what Juan said though. He knows the 900 series top to bottom.

 

[Cruceno]

Bill, you might want to try draining the entire system and see if the correct amount of coolant comes out. If the correct amount flows out, I think it would be safe to assume that it has a clear path from the expansion tank to the lower draincock. If only some drains out, and some remains in the expansion tank, that should indicate your problem is an internal blockage.

You guys feel free to correct my logic here, but that seems like a sound test.

I'd take that opportunity to give the system a good flush too. Maybe a coolant filter system as well? BTW How does your coolant look? Clear and bright? Or brown and gross?

 

[Nationwide 63s]

FWIW, might as well check the pump if the coolant is drained.

 

[mcmullag]

the tank sits above the whole engine and radiator so even if the tank only has a small amount of coolant in it, the important parts of the system are completely full. I don't know if this matters in your case, have you bled air out of the system with that doo hickey at the front of the intercooler thing on top of the engine?

 

[BILLDEUCE]

Yes I have done that just not sure why the system is building so much pressure I'm going to replace the cap and start there

 

[juanprado]

epay seller checkerboardfarms sells the 5 ton rad cap reasonable.

 

[Vintage iron]

I agree billdeuce I would have started with the radiator cap. I just had my own fail for no reason and it looked ok too.

 

[zout]

IF your filling the tank to full the system need to have at least and expansion point of 8 to 13 lbs of built air pressure in it to circulate which is done by the radiator cap - the cap tells you what pressure the system runs on.

If you fill to the top of the expansion tank - it will always PUKE out any coolant till there is a cushion of air pressure of that what equals the radiator cap -

 

[juanprado]

Most coolant systems do not want air at all as it creates air pocket and the coolant does not flow. Most repair manuals call for burping and bleeding out the air. Many modern vehicles have a bleeder screw for the purpose especially in transverse engines that sit at a slight angle.

Coolant flows because the impeller in the water pump that is belt driven pushes or pulls the water depending upon rotation.

A radiator cap pressurizes the system to raise the boiling point of the coolant. Water boils at 212f at normal pressure but in a closed system by adding pressure it raises the boiling point to 220-240 depending on the pressure. It has been a while but I am sure there is a chart of pressure to boiling point. It allows vehicles to run cooler with a pressurized system.

 

[djhenley]

It does t allow engines to run cooler per say. But raising the pressure increases the boiling point decreasing the possibility of boiling fluid around cylinder walls creating air bubbles or cavitation

 

[Vintage iron]

Cavitation will erode pin hikes in the cylinder walls if the coolant system is not maintained properly.

 

[1 Patriot-of-many]

Start simple. Coolant cap. Replace if there is any sign of weakness in the spring/gasket ect. Then move on to is there oil in the coolant? I have a bad oil cooler on my NHC250, once it warms up it's forcing oil into the coolant and both out the overflow tube.

 

[Carlo]

Cavitation will erode pin hikes in the cylinder walls if the coolant system is not maintained properly.

I had this happen on my JD 644c loader. I had water blowing out of the radiator cap and HD blow by. I had to rebuid the motor and changed the cylinders out.