Troubleshooting quick heating :

[Harry in Ky]

Okay, so what have you used this tractor for in the past? Your current problem is something that just now showed up? Is this 10 ft mower something you just brought into the game? The over heating didn't take place before this mower came on the scene? We're still missing a lot of details here and making guesses based on assumptions.

More than likely the engine has no dedicated breather tube you could use to evaluate crankcase pressure or vapor flow, it's probably tied into the intake somewhere. This in itself adds to the possibility that compression pulses in the crankcase COULD be making noises in the intake that sound like they may be related to a head gasket leaking. My experience is that when a head gasket has leaks that bad, you notice it while running, not just hard starting. It will miss, at least run rough, it will smoke more than it did before, and it will most likely be low on power.

 

[FMFProperties]

It was the clogged radiator fins, all good now.

 

[ning]

it gets very hot after 15 minutes while cutting with the 10' mower

Ok this is interesting
1. "it gets very hot after 15 minutes while cutting with the 10' mower"
2. "if I use a lower gear it doesn't overheat"
3. 2018 Branson Tractor 4520C = 42hp PTO claimed
4. Has A/C

So aside from the likely (according to the above - I personally don't have a clue and came here to learn) head gasket.... that's a big mower for the tractor, and even in light stuff you're probably pushing it too hard when not in a low gear. If you have the A/C running, you could be down 1-4HP further, and if you're not cutting really light stuff, you're going to bog down really quickly. Given the likelihood of head gasket issues, you're almost certainly not at rated power, so running an already too-big mower makes it even more too-big.

What are you mowing?
How tall is it when you're mowing?
Is the ground level or sloped?
Which gear are you running in?
Is this a rotary or flail?

 

[Harry in Ky]

Well we know a bit more now than we did at the beginning of all this. I came in thinking the tractor (probably) handled this load without much problem at some point back when, but then things had changed. I agree that a 10 ft mower is probably pushing the tractor's limits to begin with. I see others pulling mowers that size with 50 HP tractors complaining of over heating. With everything optimal it doesn't take long for build up in the radiator and coolers to start taking affect. The added load of climbing hills in anything other than lower gears and you reach that "too hot" point pretty quickly. In this area everybody has hills so I'm just guessing you do as well.

Your description indicates you do have a problem, and if you're lucky it will only go as deep as a head gasket. I'll wait and see how that goes.

 

[FMFProperties]

It was the clogged radiator fins, all good now.

 

[Harry in Ky]

Good luck with the head gasket.

 

[FMFProperties]

It was the clogged radiator fins, all good now.

 

[oldnslo]

When you are trying to mow with the 10 ft mower at your desired travel speed what is the RPM of engine vs not moving?

What color is the exhaust when trying to mow?

What happens if you take a partial cut like 7 or 8 ft vs full 10 ft?

 

[K5lwq]

Had the tractor not overheated and started having trouble then it would not be unreasonable for it to handle that type of mowing with the 10 ft. But you would have to keep an eye on it for sure. Also it wouldn’t be to terrible hard to add the turbo to that engine and pick up 7 or so more HP. But at this point we hope it is just the gasket but likely will be more than that as Harry explained. But fingers crossed.

 

[FMFProperties]

It was the clogged radiator fins, all good now.