DB 990 getting hot, but radiator is cold?

[JacobJ]

Tiny little baby steps Jacob

With engine running, and thermostat out, have you taken off the radiator cap and looked to see if water is gushing from top hose into rad.
If it isn't, water pump isn't pumping water.
Is fan belt tight enough to spin pump? (fan going round when engine's running indicates)
If it spins but don't pump, sounds like a bollixed pump.

'resistance' in rad would be several steps along the line yet.

I will try that tomorrow. I have had the radiator filled up too much lately, but will take some fluid out so I can see it better before I try.

Fan is turning and also the water pump pulley.

But sure, easy thing to test, so will do that tomorrow, but I am almost sure that the pump is working.

 

[JacobJ]

sure you need a new water pump
the fluid leakage is probably as OP said injector washer. May even be that you have 2 in there which will always cause issues

Is that easy to fix with the washer and how would I do that?

 

[nails]

Hello all

Having some overheating problems with my db 990. After about 15mins of work it overheats and it vents hot coolant out of the top of the radiator. But if I then touch the radiator it is all cold.

I have had the thermostat out and there was some nasty black fatty stuff on it, so I took it out and cleaned it. I also took the radiator off and put boiling water through it, took some radiator flush and look it sook in it for 2 hours. Water through again, remounted it. Put radiator flush in it and ran the tractor in idle for 45min. Drained and repeated. Put some need coolant in and it still gets too hot when put to work.

Before mounting the thermostat, I put it into some boiling water to test it. It opened fine. In the bottom of the thermostat it said 78, wich I guess is degress celsius. I can see, that original it should be a 82 degress thermostat. Could that be the problem? I. Also noticed, that the radiator cap didnt seel 100% when I had the radiator out and layed down to put the flush fluid in it. Could that be the problem?

I would really like to know if the water pump is working. Could I try to start the cold tractor with the tophose from the thermostat to the radiator off and without the thermostat installed? Would the pump, if it is working, push the coolant out? Or is there a better way to test it?

Hope there is one out there who has some ideas..

/Jacob

A water pump is only£38 so if in doubt replace it and the cap and the thermostat. Sometimes radiators appear to be clear but they are the problem but do that last as they are a lot more pricey.

 

[Exfarmer]

Is that easy to fix with the washer and how would I do that?

Take the injector out and hook out the washers place new washer in and screw injector back in

 

[JacobJ]

Take the injector out and hook out the washers place new washer in and screw injector back in

That sound easy, thanks for the info.

 

[Wisconsonian]

Tiny little baby steps Jacob

With engine running, and thermostat out, have you taken off the radiator cap and looked to see if water is gushing from top hose into rad.
If it isn't, water pump isn't pumping water.
Is fan belt tight enough to spin pump? (fan going round when engine's running indicates)
If it spins but don't pump, sounds like a bollixed pump.

'resistance' in rad would be several steps along the line yet.

The water won't be swirling in the radiator if the radiator is blocked. If the water is not flowing down through the radiator, then it won't be pumping up to the top for more than a second or two after start up.

The radiator plugged on the water side seems the most likely cause. We know there was gunk in it. My usual radiator flushing method is to remove both hoses and the cap, stick a running garden hose in the top, plug the bottom with a rag around an air gun nozzle. When the water overflows the top, give it a small shot of air, repeat until you don't get anymore gunk when you drain it from the bottom. That works well with mineral deposits, but might not be the best with oily, gunky deposits, that's why I suggested automatic dishwashing powder (cascade here).

 

[5020man]

The water won't be swirling in the radiator if the radiator is blocked. If the water is not flowing down through the radiator, then it won't be pumping up to the top for more than a second or two after start up.

The radiator plugged on the water side seems the most likely cause. We know there was gunk in it. My usual radiator flushing method is to remove both hoses and the cap, stick a running garden hose in the top, plug the bottom with a rag around an air gun nozzle. When the water overflows the top, give it a small shot of air, repeat until you don't get anymore gunk when you drain it from the bottom. That works well with mineral deposits, but might not be the best with oily, gunky deposits, that's why I suggested automatic dishwashing powder (cascade here).

Remove lower radiator hose, put hose pipe into filler neck ,turn on hose and see if water exits top or bottom of
the radiator.

 

[egbert]

The water won't be swirling in the radiator if the radiator is blocked. If the water is not flowing down through the radiator, then it won't be pumping up to the top for more than a second or two after start up.

The radiator plugged on the water side seems the most likely cause. We know there was gunk in it. My usual radiator flushing method is to remove both hoses and the cap, stick a running garden hose in the top, plug the bottom with a rag around an air gun nozzle. When the water overflows the top, give it a small shot of air, repeat until you don't get anymore gunk when you drain it from the bottom. That works well with mineral deposits, but might not be the best with oily, gunky deposits, that's why I suggested automatic dishwashing powder (cascade here).

If rad is blocked and pump working, taking cap off will result in water coming out of top...until vacuum beyond pump, ...wouldn't that obviously collapse bottom pipe?

 

[5020man]

If rad is blocked and pump working, taking cap off will result in water coming out of top...until vacuum beyond pump, ...wouldn't that obviously collapse bottom pipe?

Some lower hoses contain a coil spring to stop the hose collapsing.

 

[Wisconsonian]

I'm not sure how much suction a DB water pump will develop at idle. It's not that many years since water pumps were seen as optional. I'd think it would collapse a soft warm radiator hose without steel reinforcement, but I don't know that, and he didn't say that the lower hose didn't collapse, or I missed it.

If the water pump is not leaking, and turns smooth, then the impeller would have to have stripped out completely or worn the fins off to not work. Easy enough to pop it off, check, and put it right back on with some gasket sealer.

 

[egbert]

Some lower hoses contain a coil spring to stop the hose collapsing.

DBs...I think bottom hose was easy to spot as it shrank in

 

[Alchad]

Another possibility - OP mentioned in his first post that there was black gunge on the thermostat when he inspected. Could same gunge be fouling the water pump impellor?

 

[Pistonbroke]

Another possibility - OP mentioned in his first post that there was black gunge on the thermostat when he inspected. Could same gunge be fouling the water pump impellor?

Slightly different I know,but in laws central heating wasn't working,I took the pump out and all the vanes were choked up with greasy sludge. Cleaned it away it went

 

[Wisconsonian]

Any sludge would be far more likely to plug up the radiator tubes than the water pump, but we all know where my bet is on this one by now. A central heating pump is a little different as the sludge could stop the pump turning, and/or it could clog a closed impeller. Any tractor water pump of that era that I've seen has been a crude open impeller that wouldn't plug with small animals.

Even without taking the water pump off, sounds like the radiator has already been off, so popping off the hoses should be easy, then run a hose into the opening for the cap, the water should all run out the bottom hose without filling the top enough to run out the top hose nipple.