My friend went riding with us and borrowed a 400 foreman. Looks like it is in great shape, stock tires, no mods. It sounds like it runs great and does 46mph.

But, the fan ran constantly. It rans earlier and stayed on longer than any of the big bore, water pumping, belt slinging quads that were with him on the trail. He had to stop a bunch of times to cool off, telling us it overheated. He checked the oil and it was right on the mark.

Why would an air cooled foreman 400 overheat on a relatively flat trail, driving from 10mph to 30 mph most of the time?

The engine fins were clean and the radiator was clean. Anyway, the owner of the 400 bought it from a dealer who rebuilt the engine, since the original died from too much mud riding (at least that was the story). Not sure I believe it. Maybe it died from this overheating problem, on the previous owner who happened to drive in the mud. I have ridden around other foremans and they never did this, especially not on an easy trail. There was no trailer, no packs, and carrying one guy that is average sized.

Any ideas?

 

<< and the radiator was clean >>

that's an oil cooler you're talking about. i have an idea, check the oil filter, if it's in backwards it won't let oil serculate the top end, or the oil cooler. when it's in backwards the oil can't pass through because the filter has a hole at one end, and i believe it has to face out. this will quickly ruin a motor. check the oil cooler itself, make sure it's REAL clean, and that all of the cores are still there. (i'm not sure a oil cooler goes bad like a rad tough)

 

Tanks for the info, I am gonna tell my friend to check those two things and change the oil himself. He doesn't own it, but nobody rides it but him.

Do you wash those internal oil filters or just replace themeach change?

 

The 400 and 450 Foreman's fan will come on even after moderate use on the trail. Perfectly normal.

The oil filters are the paper element type and must be replaced.

K&amp;P offers a stainless steel screen oil filter that will last the lifetime of the quad. Just clean it at each oil change. They run about $65.00 depending on the dealer. Your dealer can get you one or try Scotts.

 

they're like 7 bucks cdn. (what's that like 4 buck U.S??) don't try cleaning this type. but if the red overheat light comes on the damage is all ready done. my mechanic says so anywho.

 

The red light often has come on. He stops overy time it does.

You don't think the engine could run for 300 mile with the filter backwards?

 

Maybe they are using auto oil in it too. I already know why not to do that. I will talk to him today and ask him a few things.

 

17000 miles on a 450-s and nothing like this. Sometimes take a can of carb cleaner and clean the oil radiator. One of my kids has a 500 HO that had a heating problem. His radiator was gummed up with mud from mud bogging, and it wasn't easly seen. After he wised up and cleaned everything out no more problem. I'd think it would be something like that, or a collapsed oil hose.

 

my 450 runs really cool. On a 3 hour hard trail ride the fan is usaually on about 45 min.

 

someone put dads 300 honda filter in backwards and it ran for about 700 miles, and was still working fine, just squelling. the little oil that was trapped in the top end was grey sludge. it ruined the head (where the cam runs on) the cam, rocker arms,piston, rings............................................. .............................................. over 1000 dollars (incl. labour)