DB 990 getting hot, but radiator is cold?

[JacobJ]

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

 

[Longpod]

The radiator cap could well be the problem. Been having a similar problem with a JCB mini digger recently. A replacement cap sorted it.

 

[Boohoo]

Start with the simple things.
Try a new radiator cap first, you need a new one whether it's causing the problem or not.
If you take the thermostat out and replace the top hose you'll see the water circulating with the engine running and the radiator cap off. Usually the waterpumps leak before they stop circulating but anything is possible.

 

[Dry Rot]

Similar problem here but had the main dealer's mechanic call to listen to engine noise when he was passing. Amongst other things, he diagnosed a failed water pump. Just done a search and one of the symptom is a squealing water pump bearing, which it has. Also some water spillage on the shed floor. So I took the loader off today in readiness for more surgery tomorrow.

Is this a straight forward job? Anything I should look out for? The side panels are off already and I'm guessing the pump comes out after removing the fan but leaving the radiator in place?

 

[agrimax]

This would be on a 390 wouldn't it,or maybe you've a DB as well?
I think you'll have to remove the bonnet first and then unbolt the fan cowling and then remove the radiator before you can remove the fan...

 

[Dry Rot]

This would be on a 390 wouldn't it,or maybe you've a DB as well?
I think you'll have to remove the bonnet first and then unbolt the fan cowling and then remove the radiator before you can remove the fan...

Yes, a 390. The other is a 135. Thanks for that. I think I've had both off before so not a problem. Thanks!

 

[JacobJ]

Cool, thanks for all the inputs. I will replace the cap and try to check for circulation. Ill report back.

 

[Bald n Grumpy]

You've flushed the radiator internally so I'm assuming You've cleaned the outside? Can you see through it ,are the fins flattened and blocking air flow? Try running it for a few days without the thermostat fitted , won't do any harm. Water pump could be knackered without showing any external signs ( no wobbly fan or leaks )

 

[Alchad]

Immediate question is whether the water pump is working. Personally I’d remove it and check if the impeller is free and if the blades look OK. Alternatively slacken the fan belt and see if you can turn the pump pulley without resistance.

if it helps

 

[davidroberts30]

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

Test for headgasket issue's

 

[JacobJ]

Test for headgasket issue's

How can I do that? Had the impression that if that was the problem it would overheat very fast and because of the compression in the cylinders force the water out very fast, but I am new to this kind of stuff, so I have no experiance at all with head gasket problems.

 

[Pistonbroke]

How can I do that? Had the impression that if that was the problem it would overheat very fast and because of the compression in the cylinders force the water out very fast, but I am new to this kind of stuff, so I have no experiance at all with head gasket problems.
[/QUOTE
When the engine is running,are there bubbles coming up to the radiator cap,any sign of water on the engine oil dipstick or creamy sludge inside the filler cap

 

[JacobJ]

You've flushed the radiator internally so I'm assuming You've cleaned the outside? Can you see through it ,are the fins flattened and blocking air flow? Try running it for a few days without the thermostat fitted , won't do any harm. Water pump could be knackered without showing any external signs ( no wobbly fan or leaks )

No it is in quiet good and clean condition on the outside. I was thinking of trying without the thermostat, but got adviced against it because the thermostat is restricting flow, so the time the coolant is at running through the block needs to be low enough for the coolant to absorb the heat. If the thermostat is not present, the coolant will flow to fast and result in the engine running too hot. But what is right and wrong is beyond my knowledge, but thats why I have not done it yet.

 

[Y Fan Wen]

No it is in quiet good and clean condition on the outside. I was thinking of trying without the thermostat, but got adviced against it because the thermostat is restricting flow, so the time the coolant is at running through the block needs to be low enough for the coolant to absorb the heat. If the thermostat is not present, the coolant will flow to fast and result in the engine running too hot. But what is right and wrong is beyond my knowledge, but thats why I have not done it yet.

Who on earth told you that??!!!

 

[JacobJ]

An old fellow I talked to at the local parts shop, as we were waiting for the dealer. I can hear from your comment, that that is rubbish.

 

[Wisconsonian]

It's mostly rubbish. The faster the coolant moves, the more heat it moves. But there can be other factors that make a little restriction good for the system, like back pressure on the pump preventing cavitation and maintaining even flow. Removing the thermostat is not a great step. You know the thermostat is opening at a temp below boiling, if the top of the radiator is not hot when the engine is over the thermostat opening temp, then the water pump is not working, or the radiator is plugged completely inside. Does it have a cab heater? if that works, or the hoses get hot, then the water pump is working.

I would want to find out what the black stuff was, and how to dissolve it. Radiator flush is usually designed to dissolve hard water mineral deposits, and rust. Might try automatic dishwasher detergent in rainwater, run it till hot, drain while hot, repeat until it comes clean. Or test a sample to see what cleans it up.

 

[davidroberts30]

How can I do that? Had the impression that if that was the problem it would overheat very fast and because of the compression in the cylinders force the water out very fast, but I am new to this kind of stuff, so I have no experiance at all with head gasket problems.

Tie a latex glove over where the rad cap sits and start engine

 

[JacobJ]

Tie a latex glove over where the rad cap sits and start engine

So I take the overflow hose off and tie a glove over and start the engine? If it inflates, then I have a problem with the head gasket? Is that because it shows that there is comming air into the system?

 

[davidroberts30]

So I take the overflow hose off and tie a glove over and start the engine? If it inflates, then I have a problem with the head gasket? Is that because it shows that there is comming air into the system?

Yes something like that

 

[davidroberts30]

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?



/Jacob

Black stuff is residue from combustion gasses