Couple of B7100 operation questions

[bobm39]

My tractor is a 1992 B7100 with about 1600 hours. I mow approx 4+ acres of mostly sloping land. I find mowing in 4 wheel drive works best due to the sloping. I have tried 2 wheel drive mowing but then the rear wheels are not enough in many spots and end up back in 4 wheel drive. For that reason I just leave it in 4 wheel drive. I also mow in low. Does 4 wheel drive mowing add much to engine operation temperature? The B7100, at least mine, will over heat and the whistle blows during most mowing. I keep the grill and radiator clean before or after each mowing and often times will stop mowing and clean during a mowing.

I believe the overheating is quite common on the B7100. Has anyone come up with a cure for this?

Coolant level is checked and topped off before each mowing and when overheated allowed to cool and topped off again.

I am in the process of working with a couple of dealers regarding a replacement for this tractor. The overheating is one of the reason I have for replacing but I don't want to be to quick to empty the wallet if I don't have to.

 

[Tig]

Hi Bob,
I have a B7100 but I do not mow. I grade and dig. The rad was plugged with dirt and grass when I got my tractor a year ago so I carefully blew it out with compressed air. I have never had it overheat. What come to my mind is;
-Are the RPMs high enough to prevent the engine from "lugging".
-A defect somewhere in the cooling system. Plugged passage? I found a soapy blob blocking a passage when I had the engine apart last spring. Doesn't take much when there is no water pump.
-Are you using a proper coolant mix?
-How big is your mower? Is it too big for the machine?
I appologize if some of these intems are obvious and you have checked them. I just didn't want to overlook the basics. Perhaps a more experienced owner will be able to give you more insight.

 

[Egon]

Mine will also overheat on heavy mowing on hills. It has a 60 inch mower. On flat land there is no problem.

Maybe taking smaller slices and speed down on the uphill portion would help?

 

[Bird]

My B7100 was a 1995 model and I only had it 4 years, so it never overheated. However, you mention topping off the radiator. And Tig has already asked if you're using the proper coolant mix. One of the things I did not like about the B7100 was the lack of a coolant recovery jug. So I guess you know that if you top off the radiator, the first time it gets warm it's going to push some out the overflow, so then when it cools, the level will be at least an inch or more below the top. If you keep topping it off with plain water (or straight antifreeze), the proper mix will no longer exist.

 

[bobm39]

Thanks for the comments.

I'm mowing with a 54" deck. Would like to have moved to a 60" deck but knew that would put more stress on the tractor.

Water / coolant mix. It does not matter whether it be 50/50 or 100 % water.

I generally run at full or near full throttle, slower seems to lug.

When I have filled the radiator I will fill to just below the opening. It has been my understanding that a radiator will find it's own level, meaning that it will push out on it's own what it cannot hold. Other than filling on that basis I have had times that when refilling I have had to add more than 1/2 gal at a time. Whenever I have checked the level if I can feel water at about 1" level I do not top off.

I'm just concerned that at some point when I overheat it will be the last time.

 

[lp333]

... Water / coolant mix. It does not matter whether it be 50/50 or 100 % water...

Yes it does matter. Have you tried using 100% coolant without dilutung it with any water?

 

[Tig]

I think what Bob meant is that it seems to act the same with mixed coolant as it does with straight water. Antifreeze with it's higher boiling point and better heat transfer properties should work better, but if it still boils over it's not good enough.
I was thinking about how the glycol raises the boiling point and that got me to wondering if you have the correct pressure rad cap. It could even be defective. As the system heats up and pressure increases the cap is supposed to keep pressure on the system up to a safe point before it releases. The increased pressure raises the boiling point of the coolant. That's why you never take the cap off a hot radiator. The drop in pressure can cause what can be described as as an explosion of very very hot coolant.

 

[Mith]

If I remember correctly, its a thermosyphon system (no water pump) and should therefore be run on 30/70 mix antifreeze to water.

 

[bobm39]

I'm not sure what the proper pressure cap is but want to think I have either a 12 or 13 lb cap. Somewhere I saw that may be to high, if so then my boil over would be sooner not later. Tig is correct, it doesn't matter what ratio I mix I get overheating/ boilover.

I have drained the radiator and flushed it out with just plain water. Nothing unusual came out, actually I had hoped something would.

I'm going to try sometype of flush tonight and see if that does anything.

 

[robbieo11]

u have never mention if u are running it wide open or not
i have found backing throttle about 2 inche from wide open is best for mowing however it may seem like it is a liitle under powered on slops that is why i use 4 low to mow my areas. 99%of the time i use 4 high though