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Have a Canadian customer and friend in Arizona on his new to him 2001 Sb coupe trike and is having issues overheating.

Is fine on the highway but in town / stop and go traffic it boils over.

Rad is full...fluid looks ok.

Water Pump seems to be running fine.

Fan is running as it should.

Tried a new rad cap with no difference.

Has no thermostat which lots and lots of SB and BB have done without issue.

Makes no sense as everything seems to be working like it should.

Any thoughts???

Have him find a Merc Cruiser Boat engine dealer.
Then buy a 152 degree Merc Cruiser thermostat.
It's for a SB Chevy engine.

Paul H

That is a strange one!

Just some ideas:

Is it truly running hot, or is it just venting fluid via the radiator cap overflow? What is the temperature gauge showing?

Does it have a overflow/recovery tank?

A couple of times, I have had the switch that turns the fan on and off get flakey.

May not be getting proper airflow. Are the fins behind the radiator fan dirty?

I’d bet that it’s fan or radiator related. Highway speeds are enough to keep air flowing over the radiator.

It’s new to him, has it been that way since he got it? Did someone wire the fan backwards? He should verify air flow over the radiator.

Jack wrote:I’d bet that it’s fan or radiator related. Highway speeds are enough to keep air flowing over the radiator.

It’s new to him, has it been that way since he got it? Did someone wire the fan backwards? He should verify air flow over the radiator.

After our conversation today I mentioned to him about him possibly having installed/wired the new fan I supplied backwards...have not heard back from him yet...possibility

He never rode it here in Canada after purchase in December due to you know..Ol' Man Winter in Saskatchewan...trailered it to Arizona and now the problem.

mmaupin wrote:That is a strange one!

Just some ideas:

Is it truly running hot, or is it just venting fluid via the radiator cap overflow? What is the temperature gauge showing?

Does it have a overflow/recovery tank?

A couple of times, I have had the switch that turns the fan on and off get flakey.

May not be getting proper airflow. Are the fins behind the radiator fan dirty?

No overflow tank...gauge is working properly he assumes. FAn is running when it should.

I asked him to do a test in the morning when air is cooler. Start trike let it warm to fan coming on and make sure the fan cools it just sitting there idling and fan shuts off.

Did you pull a line off to check the water pump flow? A backwards fan may do it, but whether its pushing or pulling air shouldn't matter much.

When i reassembled my BB after the refresh, i noticed my temps were much higher than before. So after some looking around i noticed my hose from the pump to the manifold was kinked. Straightened it out, and now normal temps. Worth a look.

Foose1986 wrote:Did you pull a line off to check the water pump flow? A backwards fan may do it, but whether its pushing or pulling air shouldn't matter much.

Sorry, have to disagree with that. Pulling hot air through the radiator will be a lot less effective than pulling cold air through. Although Arizona is a bit warm I believe !! So maybe it the same there ?
He really needs an expansion tank as the coolant will expand and come out the cap. That leaves you short of coolant for the next ride. That’s how I see it anyway. Had the same issue in the Uk until I fitted an expansion tank

Foose1986 wrote:Did you pull a line off to check the water pump flow? A backwards fan may do it, but whether its pushing or pulling air shouldn't matter much.

Actually it does matter as I found out quite a few years ago.

On the other Forum someone shared the wiring to make the fan run in reverse when you were in really slow traffic to have it pull air away from you rather than push. It did not cool anywhere near what it did when it was running in the right direction / pushing air..so I never used it much at all.

CanuckHoss wrote:

Foose1986 wrote:Did you pull a line off to check the water pump flow? A backwards fan may do it, but whether its pushing or pulling air shouldn't matter much.

Actually it does matter as I found out quite a few years ago.

On the other Forum someone shared the wiring to make the fan run in reverse when you were in really slow traffic to have it pull air away from you rather than push. It did not cool anywhere near what it did when it was running in the right direction / pushing air..so I never used it much at all.

Interesting. In my past experiences it didn't matter, and you had the option of push/suck. But these were larger diesel motors. Must come down to CFM of the fan itself.

WELL WELL WELL!!!

My initial question to him was about the new fan he put on as the chrome on the old was peeling....question was "is the fan running the right direction?" He thought for sure it was.

He called a bit ago to say when he fired it up this morning and waited for the fan to cut in it was indeed running in the WRONG direction and pulling air. He changed the wiring and went riding and no issues...

All is WELL and thank you everyone for your suggestions.

Glad it was something simple, and free. Typical symptoms for that, would have been surprised if it was anything else.

Jack wrote:Glad it was something simple, and free. Typical symptoms for that, would have been surprised if it was anything else.

Agreed Jack.

As always...look first at the things you just changed..hmmmm..the fan!!