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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

Click to expand...

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?

Click to expand...

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

Click to expand...

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.

OK, turned mower on, waited a while. Looked to be flow inside the radiator. The radiator hose seemed fine, it wasnt collapsed on itself. The coolant overflow on the other hand has nothing in it.

Ok, found one problem so now what?

Thanks guys

I've looked at the manual and dont understand how to fill the overflow. And, it also says two different things. One, mix 50-50 antifreeze water and two top off with only water.

It may be that I have to take off the engine housing to get to it?

alex,unfortunally I believe thats the only way to put fluid in there,there should be a mark on the tank to fill it to.I would go with the 50-50 mix.let us know what happens ..russ

Ok. That's what I was affraid of. Oh well, only about 10 bolts I would guess. Will fill tomorrow. Need to see what color antifreeze is and match it.

Not much help but fwiw,...I've mowed with my 721D now for a little less than 2 months with no fluid in the overflow tank at all. I noticed it after my first mow, but didn't think to much about it cause the gauge was ~ 3/4's the way up in the white, so I didn't bother with it yet. Then one day I was bush hogging a hillside with it, working the trany's more than usual with the hill side & tall weeds. The wind was blowing the chaff back on me & the mower. The temp was about 1/4 the way up into the green when I finished. I thought it was going to be the "less fluid" but it appears to me, that it ended up being more chaff than usual in the screen & radiator than my normal mowing. So I've yet to fill the overflow tank.

I've had my grasshopper for 1 summer now and I'll say that this mower is the most sensitive to overheating I have ever seen. I have to constantly stop and clean the vent over the radiator every 30 minutes or when the needle hits the red mark. It seems like poor engineering to me having the intake vent into the radiator being where it is. Also have to be sure to keep high levels of water/coolant in the radiator.

OK, update

I did everything that was suggested. I topped off coolant, blew radiator out from both front and back, and checked for any pump problems.

Well after blowing the radiator out really good it helped a lot but didnt stop the mower from reaching the hot limit. It now takes atleast 3-4 times as long for it to get hot.

I agree about the clippings piling up on both the radiator and the screen very quickly. There is no way the motor will ever run at its optimal temp with the clipping covering its airway within a few short minutes.

I have searched through my two manuals and cant find the thermostat location. I looked over each manual like 4 different times thinking I was over looking it but I believe that it isnt in the exploded diagram and nowhere in the other manual either. Could someone link me to its location or just take a picture of it for me please? It shouldnt be hard to change should it? I will be the first to tell you that I'm not very mechanically inclined although I have the tools and manage to get the job done if it is rather straight forward.

I was thinking that changing the thrmostat and the radiator cap should be my next steps? Does that sound right?

Thanks everyone. Its not as bad as it was but there is still a problem unless it is truly the design flaw of where the radiator is located. This last time I mowed for about an hour before the light came on and had to desengage the blades for it to cool down.

If you have a thermostat it should be located at the upper rad hose where it goes to the water pump.That said I'm going out on a limb and will say it proably does'nt have one.My 928d and my Yanmar tractor don't have one.If you can't find it in the manuel then it does not have one...russ

OK, if it doesnt have a thermostat then what should my next move be? I'm gonna pick up a radiator cap for sure but then what?

Maybe have the radiator proffesionally cleaned out?

I really have no idea. If it ends up being that I need to do something serious then I will just go and drop it off at the Grasshopper dealer where we bought it and tell him to either keep it or bring it to my house when it is working correctly.

I may sound kind of like a jack ***** but the wife and I had been talking to the owner about buying the shop from him since he is ready to retire before we bought this mower from him. When I took it back the first time he acted really nice and said yeah no problem I'll get it figured out for you. Then the second time it was like he wasnt happy to see me back in there. Thats when I told him that if there is something wrong I'll just pay the cash difference for a brand new one. He was persistant that it was just something small and needed to be found that there is nothing wrong with the unit.

Its now starting to really get to me being that he and his family are patients of my wife and now itseems as if my service has been less than adequate. I've now done more trouble shooting than he has for this mower that he claims has nothing wrong with it, that its just a matter of finding it. He claims that he doesnt have the grass to mow and test it out after the changes he makes. Once someone spends over $9000 on a mower from you and excuses like that are your reasoning for not knowing if its fixed or not, things have to change.

Sorry for the rant guys but this type of stuff is what I deal with in my line of work so when its done to me personally on a somewhat mutual deal then it really gets to me. I turn laborers and subcontractors away on a daily basis just because I dont deal with people that take what they can get if they can get away with it, if you know what I mean.

alford35,if it were my mower I'd take it back and tell him to fix it or get your money back.It sounds to me he knew it had a problem before he sold it to you.My Yanmar tractor would overheat so I replaced the head gasket but I figured that while I had it tore down I would get the injectors tested,I took them to a diesel shop along with the head.They found one bad injector was dumping too much fuel causing it to overheat and also had bent the intake valve.I had them test the head for warpage and rebuid the head and all 3 injectors.That was three yrs. ago and haven'nt had no problems since.I 'm sorry I can't be any more help and wish someone here could give you better info.When I mow w/my 928d the screen gets really covered w/chaff but rarely gets even to the green mark.Please keep us updated on what you decide to do .I for one would really like to know what your problem turns out to be...russ

I just wanted to reply in this thread because I did once and I have the same exact problem. I am so frustrated with my mower......because on one hand I LOVE the way it cuts....the thing is an outright beast.

On the other hand, it is the most sensitve machine I have ever operated in terms of over-heating and clogging the radiator vent.

I have a 3 acre field I cut once every 2-3 weeks. The grass gets to be about 12-14" high.....it's not thick grass either. It would be very light duty work for a bushhog and SHOULD be just right for a mower like this grasshopper I have.

That said, today I had to stop every 200 yards to clean off the radiator cover today. I was getting so mad. Literally 15-20 seconds after I cleaned it off, it would be covered again with grass clippings. How the heck can someone engineer a machine like this? I even got so perturbed I stopped, went back to the house, and got my cell phone to take pictures of it.

Here is a picture of the area where the air-intake is, behind the seat. Seems stupid to me that this is almost directly behind the side-chute of the mower deck



Now here is what my cover would look like within 20-30 seconds after cleaning it off




I am almost to the point of trying to build some type of side plates that restrict the ability of grass to get in to the sides, leaving only the top open to the air......this would obviously restrict air movement but damn it can't be worse than the way this thing is sucking in grass constantly.

That is exactly how mine looks after just a minute of cutting as well. I still don't have the mower running correctly but once the season is over it's going back to the dealer.

...ekim22, my 04 721D screen has yet to get that clogged, close,...but not quite that bad. Mine has only gotten close to that when the wind was blowing at me from the right side, ...blowing the clippings all over me & the mower.
...I noticed something in your pic that may or may not help. My 04 hopper has a flat rubber seal attached to the bottom of the screen so that when the screen is seated the seal makes contact with the black sheet metal in front of it, sealing off the area underneath. Is it possible that some clippings are coming up thru there. I don't have the mower handy at the moment for a pic so I'll use yours. The dotted line represents the rubber that's down (over the brown edge) & out of sight.

thehemikid said:

...ekim22, my 04 721D screen has yet to get that clogged, close,...but not quite that bad. Mine has only gotten close to that when the wind was blowing at me from the right side, ...blowing the clippings all over me & the mower.
...I noticed something in your pic that may or may not help. My 04 hopper has a flat rubber seal attached to the bottom of the screen so that when the screen is seated the seal makes contact with the black sheet metal in front of it, sealing off the area underneath. Is it possible that some clippings are coming up thru there. I don't have the mower handy at the moment for a pic so I'll use yours. The dotted line represents the rubber that's down (over the brown edge) & out of sight.

Click to expand...

Yea, you know that does make some sense. I may try making something like that out of old window screen or something.

...I got a better look at mine the other day, & it didn't have the black piece of metal I thought it had. It just seals against the back side of the "brown" metal seen in your pic.

...If I can remember tomorrow I'll take you some pics. The flat rubber seal is riveted to the bottom of the screen.

...Again I'm not sure how much (if any at all ) this will help, but it can't hurt.

...Fwiw, here are some pics of the seal on my 03 ( I think I said 04 before, my bad ).

...I don't know how to link several pics in one post, so I have to do a few posts for the different views.

...Lower screen seal 2

...Last one, Lower screen seal 3

Was just wondering if yours has the "Deck Flap" at the rear of the deck ?

Does the mower have a lot of blowout ?
Deck set up correctly so as to minimize blow out ?
Using the recommended blades for the deck ?

The above would help by putting less grass clippings in the air for the rad to suck in.

Hope you figure it out'

my screen also has that rubber on the bottom,it still clogs but for some reason never gets out of the white zone.I wonder ,I have a 928D and on the engine cowl it has this small door on top that pops open when the engine is running.Prehaps this helps in cooling.I don't believe the 721D has this feature.It just might be a design flaw with this model...russ

...Fwiw, my screen today, after a mow, but it never got out of the white on the gage.