B2910 Weird Overheating Symptoms

[HThomure]

Hello all. I searched around for a thread that dealt with a similar situation as mine, but didn't turn anything up. If it's been covered before, I apologize.

As stated in the title of the thread, I have a B2910. I noticed recently while brush hogging, my temp gauge all the way up to the edge of the red. I immediately throttled back and headed for the shed. By the time I got there, the needle had dropped back to about halfway, more where I'd expect it to be.

I've been watching it for several days, and it always does the same thing: When under a load of any kind, it heats up very, very fast - on the order of about 30 minutes. Within a minute or two of taking it's load off it (disengaging the mower or brush hog) the needle drops. Even if I don't throttle it back, it still appears to cool down with in a couple of minutes. That seems like an awfully short amount of time for it to cool down that much.

Attached are photos of what I'm typically seeing. The hotter of the two temps (in case they don't upload in order) is after roughly 30 minutes of cutting grass under a fair load (I'm pulling a 72" farm king finish mower through some pretty thick grass). The cooler picture is what I saw within one minute of disengaging the mower, but NOT throttling back at all.

I did a good, thorough flush of the coolant, to no avail.

Water pump? Thermostat? Both? Any insight would be appreciated.

Thanks, everyone.

 

[ctmike]

With a 6 ft. mower in thick grass, I think you're asking a lot of the 22 hp at the PTO. The gauge is still below the red zone so I would just make sure the radiator fins are not clogged up with anything and go with it. Maybe mow more often so you're not taking as much of a cut. Just my opinion.

 

[HThomure]

Yeah. It's a new construction, so I'm working at getting the grass under control. It's not all thick, just in places. Even in the not-so-thick places, it tends to get warm, though not quite as warm.

 

[dmanlyr]

Looking at the pictures, I see absolutely no problem, both readings are in the normal operating range, and well below the "overheated" red range.

It is normal for some temp rise to occur under heavy load, nature of any cooling system.

David

 

[HThomure]

You're right, based on these photos. I forgot to mention that if I'd run it longer, it most certainly would have run up into the red. But as you can see, I was almost out of fuel, so I snapped the photo at that point. Sorry for the omission before.

 

[dmanlyr]

You're right, based on these photos. I forgot to mention that if I'd run it longer, it most certainly would have run up into the red. But as you can see, I was almost out of fuel, so I snapped the photo at that point. Sorry for the omission before.

Has it gone up to the red zone then? Or are you estimating that it would get up beyond the normal range?

If it is getting higher than the top of the normal operating range then I would say you have a issue. As mentioned, first make sure that the coolant level is correct, check the radiator fins and screen if equipped for plugging, they love to collect grass and other crud. Clean the fins opposite normal air flow. And then go from there.... Please post what you find.

One last thought, are you lugging the engine at all? IE running at the proper RPM for the PTO? Not taking it easy by operating below the recommended rpm range? If so, then it would be possible to induce a high speed lugging condition with a resultant overheating issue.

David

 

[85Hokie]

Has it gone up to the red zone then? Or are you estimating that it would get up beyond the normal range?

If it is getting higher than the top of the normal operating range then I would say you have a issue. As mentioned, first make sure that the coolant level is correct, check the radiator fins and screen if equipped for plugging, they love to collect grass and other crud. Clean the fins opposite normal air flow. And then go from there.... Please post what you find.

One last thought, are you lugging the engine at all? IE running at the proper RPM for the PTO? Not taking it easy by operating below the recommended rpm range? If so, then it would be possible to induce a high speed lugging condition with a resultant overheating issue.

David

I agree with the group - under heavy load, and you are not in red yet.
Do as everyone says - and report back.

 

[HThomure]

The only reason I can't say it's been in the red is because I haven't allowed it to get that hot. It has gotten up TO the red twice in recent days, but I've caught it both times and throttled back before it got INTO the red.

I flushed the coolant earlier today and put a 50-50 mix in, and have blown everything out twice to no avail.

I run it dead on the hash mark when using the PTO.

 

[kuboman]

Check the thermostat and make sure your radiator core is not plugged.

 

[HThomure]

Now I'm starting to get outside my comfort zone. I know where the thermostat is, and how to get to it, but I don't know how to check it. And I am completely clueless as to the core.

 

[meanjean]

For the $10 I would install a brand new thermostat.
Not sure if that's the actual price but replace anyways.

 

[HThomure]

I have no issues replacing the thermostat. I'm just really hoping to not have to replace the water pump.

 

[85Hokie]

I have no issues replacing the thermostat. I'm just really hoping to not have to replace the water pump.

Before you install new stat, take it out of the box and place it into boiling water with a pair of tongs or pliers......watch it open!

many a NEW thermostat have been bad out of the box!!!!

is the water pump weeping at all ?

 

[Billdog350]

Very unlikely its your water pump. With a steel impeller (I believe on your model), the only "failure" for the water pump would be seals/bearings and it leaking...which it sounds like is not the issue.

Make sure your fan belt is tight, a loose belt will slip at high rpm and cause reduced cooling. Your issue sounds exactly like a sluggish thermostat. Replace your $10 thermostat and put in some "water wetter" in your coolant to increase the thermal transfer. As long as your radiator isnt plugged (as everyone has said, make sure fins and screens aren't clogged), and you should be good to go.

My old B9200 doesn't have a temp gauge, just a idiot light...and its never come on...but who knows what's normal? Maybe under a heavy load mine is toward the top of the normal zone too? Sometimes gauges make people more worried than they should be.

Change the thermostat and check your belt, and get back to us. (85Hokie is right to check your old and new thermo). If you have a handheld infrared thermometer, you can check your REAL coolant temp and see exactly when the thermo opens and closes. Keep in mind thermostat technology hasn't changed in like 100 years and they're still pretty cheap and fail pretty easily. Start with the logical and cheap parts first!

 

[ShaunRH]

It shouldn't be the thermostat unless it's not opening 'fully' which might cause the issue and still need replacement. You can test the T-stat you have with a simple stovetop hot water test.

However, more likely the radiator is just not getting enough air through it or the paths are clogged. You said you flushed it, you should do that again just in case someone ran straight water through it in the past and it is calcified (which kills more than just flow, it also kills thermal transmission of the fins).

Double check that all the fins are clean and straight. So many people use a pressure washer to clean the grille and it goes through to the radiator and this bends fins like crazy. Also, all that mowing can plug up a radiator that doesn't have a pre-filter screen like nobody's business.

Very last thing would be to check your engine fuel use. If it seems especially 'thrifty' on fuel, it could be running really lean and this overheats the engine. Some tractor owners intentionally set their machines like this if they usually underwork the tractor. However it costs them if they forget about that then start working them hard. It's more common in gas engines than diesels but I have heard of it in diesels as well.

 

[HThomure]

Hello again, everyone. I apologize for having been away for so long. I hadn't gotten any reply notifications, so I didn't even realize anyone had replied since my last post.

Here's what I've had going since my last visit. I removed the thermostat and threw it into a pan of water, as the water heated up, the thermostat opened as I would have expected it to, so I assumed that wasn't the problem.

While the thermostat was out, I went ahead and ran the tractor just to see how it would behave. It still got warm, but never reached a point where I was nervous it was going to overheat like it had before.

But I tested the thermostat and it was good, right?

Well, today I finally got around to putting the thermostat back on, and brought the coolant level back up to where it should have been. (incidentally, the radiator sucked that water right down as I poured it, which to me, indicated the pump is ok.....that's right, isn't it?)

Within 30 minutes of running with the thermostat put back on, I was up in the red, spewing water out the overflow reservoir. I didn't keep running it like that, but wanted to see if it would actually go to the red, or just tease me. It wasn't teasing. I parked it for a few hours and let it cool off, and tried again. Same result, only this time it only took about 10 minutes.

So what I saw was it not overheating with no thermostat and overheating with a thermostat that I had already verified was working. Is there such a thing as it only partly working? I'm starting to think I should go ahead and replace it for $26 and see what happens. If I do, do I need to replace the gasket? It seems ok in there. No tears or degradation that I can see.

So that's the latest..........

 

[HThomure]

It shouldn't be the thermostat unless it's not opening 'fully' which might cause the issue and still need replacement. You can test the T-stat you have with a simple stovetop hot water test.

However, more likely the radiator is just not getting enough air through it or the paths are clogged. You said you flushed it, you should do that again just in case someone ran straight water through it in the past and it is calcified (which kills more than just flow, it also kills thermal transmission of the fins).

Double check that all the fins are clean and straight. So many people use a pressure washer to clean the grille and it goes through to the radiator and this bends fins like crazy. Also, all that mowing can plug up a radiator that doesn't have a pre-filter screen like nobody's business.

Very last thing would be to check your engine fuel use. If it seems especially 'thrifty' on fuel, it could be running really lean and this overheats the engine. Some tractor owners intentionally set their machines like this if they usually underwork the tractor. However it costs them if they forget about that then start working them hard. It's more common in gas engines than diesels but I have heard of it in diesels as well.

Just to reply to some things that have been suggested.

I don't have any issue with flushing again. However, there was coolant in the radiator when I flushed it, not straight water. And I'd be willing to bet it was the coolant that was in it when it was new. Just a feeling I have.

 

[HThomure]

Very unlikely its your water pump. With a steel impeller (I believe on your model), the only "failure" for the water pump would be seals/bearings and it leaking...which it sounds like is not the issue.

Make sure your fan belt is tight, a loose belt will slip at high rpm and cause reduced cooling. Your issue sounds exactly like a sluggish thermostat. Replace your $10 thermostat and put in some "water wetter" in your coolant to increase the thermal transfer. As long as your radiator isnt plugged (as everyone has said, make sure fins and screens aren't clogged), and you should be good to go.

My old B9200 doesn't have a temp gauge, just a idiot light...and its never come on...but who knows what's normal? Maybe under a heavy load mine is toward the top of the normal zone too? Sometimes gauges make people more worried than they should be.

Change the thermostat and check your belt, and get back to us. (85Hokie is right to check your old and new thermo). If you have a handheld infrared thermometer, you can check your REAL coolant temp and see exactly when the thermo opens and closes. Keep in mind thermostat technology hasn't changed in like 100 years and they're still pretty cheap and fail pretty easily. Start with the logical and cheap parts first!

I believe the fan belt to be good and tight, and the fins and screens appear to be pretty clean, unless they get dirty somewhere that can't be easily seen. I am pretty diligent about my maintenance.

 

[kuboman]

I am betting your radiator is plugged on the inside. When it is running hot and is revved up is the fan blowing lots of air? Is the air hot? is the bottom radiator hose hot, warm, or cool? If your rad is plugged on the inside your bottom hose will be luke warm or even cool. If you are getting good flow through the rad then it should be very warm.

 

[HThomure]

I am betting your radiator is plugged on the inside. When it is running hot and is revved up is the fan blowing lots of air? Is the air hot? is the bottom radiator hose hot, warm, or cool? If your rad is plugged on the inside your bottom hose will be luke warm or even cool. If you are getting good flow through the rad then it should be very warm.

Sounds easy enough to check. I'll check it tomorrow. Thanks.