721DH2 running hot need help!

Wife and I purchased this mower from the local dealer used with 520 hrs on it this spring. It has ran hot every since we purchased it. At first it would climb right shy of the red and hold steady. We took it back and they said they did some things to it. It continued to run hot. After 30 minutes it would reach the red. We took it back again. They said they tightened some belts.

Well, the mower still runs hot. It will run for about 30 minutes before reaching red then I have to disengauge the blades to let it cool off. I am about to the point of dropping it off and hiring an attorney. I got out the manual to check everything myself yesterday. I had to increase the tension on both belts (motor and manual 61" deck). But, I couldnt get the belt on the deck to specs. It states that the spring needs to be 5.75" but I cant get it that tight. There is still some slack in the belt when I have the spring tensioned as far as possible (5.5"). I'm assuming I need a new belt? Could this be causing the mower to overheat?

I also have noticed that the trimmings fill up the radiator gaurd within a few minutes of mowing. It cant help the problem but there is no way to keep it clean for a period long enough to mow a few acres. Maybe an eighth of an acre and its full of trimmings.

Any help would be greatly appreciated. I've searched and searched the net with no luck.

Alex

Have you check the radiator ?The fins will clog with dirt and chaff,take your compressor and blow behind the radiator to see if any material blows out.Sometimes overheating is symptomatic of a bad head gasket.Have you checked your oil and coolent .My 928d gets plenty of chaff in the rad screen but the temp never gets to the green.I always blow the rad and always blow chaff and dirt out of the fins so even though the screen keeps a lot of that from clogging the rad fins it does'nt protect it 100%...russ

Thanks. Yeah coolant and oil is good. I haven't tried using compressor from the rear but have cleaned from front often. Will try that and see if anything is in there. From what I can see it's pretty clean.

Regarding head gasket. I don't see any signs of seepage around the motor. That's what I should be looking for, correct? It only has 570 hrs on it. So I shouldn't have any real problems should I? The previous owner gave the shop all maintenance records with the trade. Seems like it was maintained properly even though the overheating problems.

Oil in the Coolant or coolant in the oil also blowing white smoke indictive of blown HG.Do you have coolant in the overflow bottle?Try cleaning the rad.also does that little door hood pop open when it's running?...russ

No white smoke for sure. If it bogs way down it's black for about one second which seems like any other diesel I've operated.

I'm not familar with the door you speak of though?

I'll check the overflow. I just checked trans, oil, and radiator. I didn't check the overflow.

Remove the radiator cap and look in... you should see coolant flowing rather quickly... if not the thermostat could be faulty OR the water pump may have some internal problems... also while you are at the coolant check it's temperature, I have also seen temp sending units & gauges be in error... also check the Lower Radiator hose to see if it is collapsed while the engine is running...

You have something wrong because diesel engines run cool....:smile:KennyV

KennyV said:

Remove the radiator cap and look in... you should see coolant flowing rather quickly... if not the thermostat could be faulty OR the water pump may have some internal problems... also while you are at the coolant check it's temperature, I have also seen temp sending units & gauges be in error... also check the Lower Radiator hose to see if it is collapsed while the engine is running...

You have something wrong because diesel engines run cool....:smile:KennyV

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ok, I'll check to see if its flowing good. I've never opened a radiator while the engine was on before. I assume I need to have it closed when first crank it though, correct?

I also assume the line on the bottom will be sucked in on itself is what you are saying?

What about the door that was mentioned prior, what and where is that?

Thanks all

alford35 said:

ok, I'll check to see if its flowing good. I've never opened a radiator while the engine was on before. I assume I need to have it closed when first crank it though, correct?

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I would open it while it is cool... then start it... you will see NO movement until the thermostat opens... then you will see a lot of movement...
While your warming up you should see NO exhaust gasses bubbling up in the radiator, (If you do that likely will be a head gasket failure...

The lower radiator is the suction side of the water pump, and should not collapse....

I'm not sure what door is refereed to... :smile:KennyV

Alex,Kenny gave good advice ,I was looking at my manuel for indication of a thermostat but it does'nt go into detail.Like he said though take the rad cap off and look for circulation with engine running,this could indicate bad water pump.I've got a 928d and on top the cowl just behind the rad cap is a small higned door that pops open to aid in air circulation,maybe your model does'nt have this feature.I do'nt see how a belt could lead to overheating,I put a new belt on my deck this spring and it was super tight installed new and did'nt overheat the engine.Just curious you say the mechanic tightened some bolts,did he tell you what bolts?...russ

173abn said:

Alex,Kenny gave good advice ,I was looking at my manuel for indication of a thermostat but it does'nt go into detail.Like he said though take the rad cap off and look for circulation with engine running,this could indicate bad water pump.I've got a 928d and on top the cowl just behind the rad cap is a small higned door that pops open to aid in air circulation,maybe your model does'nt have this feature.I do'nt see how a belt could lead to overheating,I put a new belt on my deck this spring and it was super tight installed new and did'nt overheat the engine.Just curious you say the mechanic tightened some bolts,did he tell you what bolts?...russ

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Yeah I dont think I have that door. Did I say bolts oops. I meant belts. I'll check the flow tonight and see what it looks like.