S470D Overheating

Steve777 · Aug 18, 2016

I was mowing tall grass with a 4' brush hog yesterday and the Temp light came on, first I had ever seen it. No clouds of steam or dripping coolant, and the engine did not smell really hot. But stopped the tractor in place and went back to take a look this evening, it was near dark when I got home today, so I did not have a lot of time to do much.

First I checked the coolant level in the radiator, and it was down, missing about 1 qt. This was full about 6 weeks ago when I last checked. No obvious leaks at the hoses. Could not see the water pump well enough to say but nothing that stood out there as being wet. I refilled and ran for a bit with the radiator cap off. The top of the radiator got hot as the engine heated up, but I did not feel the whole of the fin area getting hot. But I only had time to run for a few minutes, so other than being able to say the thermostat opened some not sure I really learned much.

So I was thinking of going thru the basics on cooling before anything else. Flush the radiator inside and out (and back flush it too) with cleaner. Replace the radiator cap and coolant. Then try it again with some load and see how it does.

I had a few questions on the cooling system which I hope people here know:

1. What pressure cap? I've read everything from 9# up to 15# in various posts here. What's the right value? And does Napa or some other generic auto parts brand make one (I'd like to get this tomorrow)?

2. What's the total coolant capacity of the S470D?

3. I assume just regular green anti-freeze in a 50/50 mix. Or does this take some special coolant or additives?

Also curious, are the various radiator hoses still available? Anyone know the part numbers? It's probably time to replace them too.

And same questions on the thermostat and water pump. Are those standard parts or special for these Satohs? Hopefully won't need those but just in case.

TIA

oliver28472 · Aug 18, 2016

1. Cap pressure is 10 psi, from my Buck manual
2. Coolant capacity is 5 liters
3. I use 50/50 mix. I use a laundry soap container (rinsed) that will hold over 2 gallons. I pour in a gallon of distilled water and a gallon of antifreeze.
Get an overflow hose long enough to be able to see the end of it while operating. Mine used to overheat too, mainly because my radiator was damaged from 3 separate rollovers. Several tubes were soldered shut which caused a loss of cooling ability. It was ran that way for years until I sprung for a used radiator form West Kentucky Tractor parts. The new/used radiator had a nipple on the bottom instead of a plug. I put some hose on that with a quarter turn ball valve with fittings bought from Lowes. I also made a screen to go in front of the radiator using 1/4" plywood for the frame & stapled some screen on. You will need to remove the radiator to clean all the bugs and chaff out of the fins. Use a garden hose for that, not a pressure washer. If that doesn't help you will need to take the radiator to a shop and have it rodded out. Mine has not overheated since I swapped in the new radiator. Mine has a thermostat but I don't know what temp.

Steve777 · Aug 18, 2016

Well I brushed the weed and seeds off the front of the radiator and things ran well for an hour, until I noticed the fan belt starting to come apart. No doubt a good part of the overheating I was seeing.

Managed to take it off before it totally self destructed, but I am having a heck of a time finding a matching belt at the auto parts places. It looks like a 3/8" wide x 37" OD belt, which could be a 3V370 or 3L370 depending upon whether its a 3L or 3V belt. But my existing belt is pretty worn out and the measurements could well be wrong.

Does anyone know what the right belt number is for a S470D?

oliver28472 · Aug 19, 2016

I searched the Mitsubishi/Satoh forum and found that I had answered this question a while back. Gates 7320 or NAPA NBH 257375.

Steve777 · Aug 20, 2016

Thanks Oliver. I took a look at those belt numbers, and while I'm sure they would fit, I don't think those belts really are the right fit. Here's why:

The belt I removed was just under 3/8" wide at the top, about 1/4" tall and flat on the inside/bottom. The belts you mention are both much bigger in both dimensions and are wavey on the bottom. Basically those belts are the standard for modern auto use, designed for bigger diameter and width pulleys. After doing some research it seems the belt I took off matches a 3L370 belt perfectly. The 3L series has the smaller dimensions and is designed for lower HP applications and smaller diameter pulleys. It also sits fully inside the pulley grooves on my Buck. I did try the Napa belt and it does not sit in the pulley but rides up higher on the pulley walls, only maybe 1/2 of the walls making contact. It would still work no doubt, but it is not going to be as efficient a power transfer and likely will heat up more and I would suspect wear out sooner.

Anyway, I pass along what I found out in case it might help anyone else. One other thing, the 3L370 belt was 1/3 the price of the Napa one.