Honda 3.5 thermostat or no thermostat

[Farmer fab]

Trying to make my buddy's buggy run cooler. Hears what we have, it's a manx that I built with a 3.5 in it with the radiator in the front. We started with a stock thermostat in it and around town it would get to 230 then back down to 200. On the freeway never get above 215 but in the dez at superstition last weekend it got to 260 then back down to 220. Oh and the radiator is a 31 by 16 CBR double pass and the lines are 1 1/2 aluminum. Any help would be appreciated thanks

[takotruckin]

A thermostat change isn't likely going to help it. Post pics of the system and maybe we can help. It sounds like it is lacking flow, either water or air.

[baja5]

A thermostat change isn't likely going to help it. Post pics of the system and maybe we can help. It sounds like it is lacking flow, either water or air.

Good info right there. There are a couple schools of thought on thermostats. Some like the coolant to be free flowing to run cooler however if the coolant isn't in the radiator long enough to transfer the heat the car will get hot I've time. I run a thermostat in mine. I was having cooling problems initially, on longer runs the temp would creep up even with the fans on. I went to 1350cfm Spal fans and have been good since. Even when we do the night run in the summer, and last year we ran a good 45 miles in 110 degree heat, the car never gets over 210. I don't have the best radiator location either, it's behind the rear bench seat. Hope that helps.

[jt1967]

I run a thermostat in mine I too don't get the best air flow and my fans cycle a lot but I still wouldn't remove the thermostat. I would look to improve air flow to heip just my 2 cents

[jt1967]

But then again I would listen to Baja5 he's the Honda Mechanic I value his opinion

[Marc]

No experience with Hondas, but I used to build small-block Chev V8s for a late-model car and we found it better to run a flow restrictor at the t'stat location rather than leaving it wide-open (nobody runs t'stats because of the potential liability of having one stick shut) - like baja5 said, it IS possible to push the water through the radiator too fast for it to transfer heat...also, having some restriction keeps the pressure higher in the heads which reduces localized boiling. On the Chebbys a 5/8" I.D. washer worked well for us.

Steam entrapment can cause all sorts of mysterious temp-control issues, and with a remotely-mounted radiator it's more likely. I once owned a `54 Vette with a `55 Olds V8; the coolant outlet on the engine was the high point of the system and steam could form there, resisting coolant flow to the radiator. Didn't have any problems on the road, but it only took a few minutes at idle on a hot day to start overheating. My "fix" was a high-mounted overflow bottle and an ⅛" pipe nipple tapped into the t'stat housing to relieve the steam bubble. The bottle drain was plumbed into the low-pressure side of the heater hose, so there was always a small flow bypassing the radiator, but if a steam bubble formed it could vent & condense in the bottle. If your radiator's lower than the outlet neck on the engine, something like this may help.

[Farmer fab]

Thanks for all the info guys. I am pretty sure it lack of water flow. Cause at speed its fine it's when u are stop or slow speed crawling it starts to heat up. Baja5 your car runs at 110?

[Getrdone]

He meant 210.

[baja5]

He meant 210.

Yes, 210, sorry. I edited it in my post.

[takotruckin]

Thanks for all the info guys. I am pretty sure it lack of water flow. Cause at speed its fine it's when u are stop or slow speed crawling it starts to heat up. Baja5 your car runs at 110?

That could still be a water flow or airflow problem.

[Marc]

Another concern with a remote-mounted radiator is air entrapment at the top. Fiat X-1/9s (midengine/front radiator) for example, had a bleeder valve on the radiator to enable venting air from the system at the front.

[883]

With good temps on the freeway (high air flow, but also high load), I'd lean towards not enough fan for the stop and go or crawling situations.

Just my $.02

[Getrdone]

The "expensive" spals kick ass! The affordable ones, not so much. I bought the "affordable" ones first and upgraded to the heavy duty ones. Issue fixed. They weigh much more, and move a butt load more air.

And amps!

[takotruckin]

Ford Taurus fan. Lots of air, lots of amps, not a lot of money

[Farmer fab]

Thanks for all the info guys. The other question I have for the Honda guys is what temp does your fans come on at? Cause we put a new fan switch on it to and it doesn't turn the fans on tell 230.