Engine Bay Temperature & Self-resetting circuit breakers? (1 Viewer)

[Bud_Dude]

So yesterday (June 3) doing some simple wheeling up the forest road to Santa Rosa & Toro Peaks, outside temp mid-80's... I get almost to the peak and one the 30 amp self resetting circuit breakers mounted to my battery box trips and takes out my ham radio and other accessories. We were stopped for lunch and walking and radio play, so no big deal. But I popped open the hood and damn it's hot in there, like burned my arm on the hood gas lift. After it cooled down for half an hour it was all good the breaker reset itself and no more problem rest of the day.
But now I have a nagging question in my head as to whether these self-resetting circuit breakers are such a good idea. I mean they're great in that you don't need to worry about a fuse blowing that you probably don't have a spare for, but if they're going to trip due to excessive engine bay temperature maybe sticking with good ol' fuses is the better plan.

Anyone else seen this happen in the past?

Any ideas on cooling the engine compartment during slow drives in the hills?

 

[RET2]

As a fan of circuit breakers, at least the manual reset type, I would suggest moving it to a location that has better air flow? Negative cable looks like it may need attention also.

 

[elripster]

I use those too. Are you able to locate them to the other side of the battery tray? That's the cool side.

 

[BreckenridgeCruiser]

How long since you checked your fan clutch? They wear out and can be slow to lock up... or not lock at all... You can also get ones that lock up earlier to help keep airflow across the radiator...

 

[BMinSD]

I finally solved my running hot issue with one of the Witts End modified fan clutches. I was sceptical as I had a fresh Toyota clutch installed that did not solve it. Really helped pulling the grades with my trailer behind.

 

[Justsendit]

So your saying Santa Rosa Mt is open
I'm big on resettable breakers, beats blowing a fuse and realizing you left your spares on your garage bench

 

[Bud_Dude]

So your saying Santa Rosa Mt is open
I'm big on resettable breakers, beats blowing a fuse and realizing you left your spares on your garage bench

Yes - Ted and I drove up there yesterday and Santa Rosa and Toro Pk roads are open and largely freshly graded, for better or worse, meaning we 2wd cars can really make it to many of the yellow post camp sites. We even had a visit at the summit of Santa Rosa from a Subaru Crosstrek that made it and saw other 2wd vehicles camping pretty far up on Toro. We'd didn't explore the harder 4wd trails and saved them for another day.

 

[Bud_Dude]

How long since you checked your fan clutch? They wear out and can be slow to lock up... or not lock at all... You can also get ones that lock up earlier to help keep airflow across the radiator...

The radiator and 'allegedly' the fan clutch were replaced by the PO not long before I got the truck... no receipts or dates though.

 

[Bud_Dude]

I use those too. Are you able to locate them to the other side of the battery tray? That's the cool side.

Hard to put them inside the battery tray without interfering with battery removal/installation.

 

[Bud_Dude]

I finally solved my running hot issue with one of the Witts End modified fan clutches. I was sceptical as I had a fresh Toyota clutch installed that did not solve it. Really helped pulling the grades with my trailer behind.

At $250 Wits End is sure proud of those modified fan clutches! I think all they do is replace the fluid in them with the heavier silicone oil. New ASIN blue clutches are about $80 on Amazon with free shipping. I do think I'll get some 20K silicone oil though and rebuild the one I have. Doesn't seem like that hard of a project.

 

[flyingmonkey]

The radiator and 'allegedly' the fan clutch were replaced by the PO not long before I got the truck... no receipts or dates though.

Do you know what your engine temp was? Does it normally run hot? I have an auxiliary fan, but even when wheeling I hardly run it.

 

[Bud_Dude]

Do you know what your engine temp was? Does it normally run hot? I have an auxiliary fan, but even when wheeling I hardly run it.

The engine itself doesn't even get close to overheating and the radiator is new. I've not measured the engine compartment temps as yet but intend to do so to quantify any changes I might make. The hard part is replicating the environmental and operational conditions that triggered the problem in the first place. That'll mean another trip up that hill on a warm day.

 

[RET2]

Hard to put them inside the battery tray without interfering with battery removal/installation.

Just a thought, how often do you install or remove the battery? Once every 3-5 yrs? Perhaps the small task of dealing with the circuit breaker location may not be an issue then?

 

[flyingmonkey]

The engine itself doesn't even get close to overheating and the radiator is new. I've not measured the engine compartment temps as yet but intend to do so to quantify any changes I might make. The hard part is replicating the environmental and operational conditions that triggered the problem in the first place. That'll mean another trip up that hill on a warm day.

Roger that. I've seen people install louvers on the hood to allow hot air to escape.

 

[619TOY]

Those self-resetting breakers are definitely affected by heat, but the bigger problem I have with them is that if a wire happens to get shorted, they can just start cycling. Arc, reset, arc, reset, arc, you get the picture. I’d recommend replacing them with fuses. MIDI fuses are nearly identical in footprint, so the process should be pretty simple. The breakers may seem convenient, but a properly fused circuit should never really blow a fuse.
Self-resetting breaker graph:

 

[Bud_Dude]

Roger that. I've seen people install louvers on the hood to allow hot air to escape.

Yep - I've seen some photos and write ups on the louvers... that's a whole lotta work, body work, paint, etc... $$$ to do it right. Also, I reckon, likely subjecting parts of the engine compartment to water that normally never see it. Given our normal rain fall here, probably not a huge problem in SD but a consideration.

 

[Bud_Dude]

Those self-resetting breakers are definitely affected by heat, but the bigger problem I have with them is that if a wire happens to get shorted, they can just start cycling. Arc, reset, arc, reset, arc, you get the picture. I’d recommend replacing them with fuses. MIDI fuses are nearly identical in footprint, so the process should be pretty simple. The breakers may seem convenient, but a properly fused circuit should never really blow a fuse.
Self-resetting breaker graph:

View attachment 2330299

Thanks for the charts! Great to see the effect of temperature on these. I knew they were calibrated for some nominal temperature (thought I'd seen 100F somewhere), but I reckon the temp under the hood was over 150F... which would explain why a 5 amp load on a 30A breaker tripped it...

 

[landcruising]

Could also just be a bad breaker. I would also suggest modifying the fan clutch new or not. There is a very long write up on modifying them and the effects. I personally opened a nearly new blue clutch to modify myself and tested it. It was way out of spec. I tried to modify it but snapped a bolt and gouged the plate surface, so ended up buying a pre modified one from wits end, with good results.

 

[badsamaritan]

I'm not super up to speed on the 80 series but I thought Landcruiser Phil had come up with a kit that was just a pusher electric fan to help with airflow at low speeds. Might be worth looking into.

Edit,

found it, here's the link

LCP

Battery Bracket Upgrade Jack Adapters Mud Flap Eliminators Rear Heater Delete Hose Severe Duty Rear Sway Bar Links Severe Duty Front Sway Bar Mounts Shifter Extension Sway Bar Disconnects T-Shirts Window Mods

sites.google.com

 

[Overlandeffex]

Bud, I re did my fan clutch on my own. Super easy to change the engagement spot with some fluid and adjustment of the spring. Can help you re do it with some help for my speedo...