Cooling question/problem

[SR2dude]

Hello everyone!

I hope everyone is having a good weekend and enjoying life.

I recently took a trip to the desert for the maiden offroad voyage of my Scout. Everything went great and, like usual, it did everything asked.

However, one problem is with my engine temp. Do scouts usually run hot? I have an aftermarket temp gauge and according to the gauge it was running at around 250 degrees the whole time. Of course its going to be running hot because I'm in the desert but it was unusually hotter. So when I got back to camp I opened up the hood to help it cool down and I started checking everything just to do a shake down. I felt the upper radiator hose and it felt like it was under a massive amount of pressure. Usually I can squeeze the hose and it compresses but this time I squeezed it and it felt like a solid pipe. It had no give to it at all like usual. Is there any reason for this? I have 2 e-fans blowing air in and I'm thinking there not enough thats why it was running hot? It usually runs at around 200 or so. Is that a good temp? New radiator?

Sorry, I know its a lot of questions but any help would be greatly appreciated. Thanks!

D

 

[Scoutboy74]

What year of Scout and which engine/trans package? 250 degrees if actual is dangerously hot for any IH sv8 or 4-banger to be running for any length of time. What's the status of your thermostat? The normal operating temperature for your engine should match the t-stat set point if functional. The outside ambient temperature should have little to do with your coolant temp provided the vehicle is moving at a constant speed above 25 mph. I recommend getting an el cheapo harbur fayk tulz ir thermometer that you can use to shoot some temps at various points along the cooling path. If you're seeing readings much over what your t-stat set point is, you've got some major cooling system issues.

 

[scoutaddict]

Hey man. I recently took my Scout on its maiden voyage also and had the same problems u are describing. I got a 345/727/300 combo in my Scout II. I have new hoses, new thermostat, and the big ass custom aluminum radiator sold here at IHOnly. My radiator hoses were rock solid also. I have the stock fan and dont know if it does anything when I am rockcrawling seeing I am near idle most of the time. I am thinking of adding an electric fan into the mix. What gives??

 

[Michael Mayben]

As always, my standard admonishment here is "these vehicles weren't broke from the factory".

They get broke when we screw with 'em.

Ambient temperature has virtually nothing to do with engine operating temperature, it's no hotter in "the desert" than in the mountains. Engine load does have everything to do with engine temp. Engine load varies tremendously regarding a motor vehicles, these are not stationary engines running at fixed load at a constant speed, 24/7.

Have the vehicles in discussion here had a complete engine cooling diagnostic performed?? That includes checking for combustion gases in the coolant indicating head gasket, cylinder head issues), pulling the soft plugs out of the blocks and cleaning all the accumulated shit out of the water jackets, had the radiator flow tested, and had the entire cooling system pressure tested at operating temperature???

Has the cooling system been completely purged of all air and incorporate a proper coolant recovery system?

Is the thermostat the proper design for the ihc bypass system and is the thermostat housing clean with an unrestricted air bleed? Has the thermostat been bench tested? It's not enough to say "it's a new one".

Has the water pump been recently changed and was the volute clearance tested at that time?

If a thermo-control viscous cooling fan clutch is present, is it completely functional and tested??

I have no use for electric fans on these vehicles, those lead to all kinds of setup issues and they certainly are not needed on a trail rig unless extreme water depth is routinely encountered. The oem fan with a shroud used without a clutch is way more than capable of handling the heat exchange potential of any oem ihc-size radiator package if the system is properly serviced.

Whether the radiator is oem brass/copper or aluminum makes no difference in this regard as long as it is of sufficient heat exchange capacity, the fin pitch is no finer than oem, and it has a flow rating equal to the oem system.

And...the oem design calls for a 13psi pressure cap that must operate correctly and be used in conjunction with a coolant recovery system. So if the system is holding proper pressure, you would certainly expect to feel a "hard hose"!! A crossflow (parallel flow) radiator should have no air inside if it's been properly burped during a service operation. Any air not purged during service is burped into the recovery bottle when the cap activates, then only 100% liquid coolant is drawn back into the system when cooling down.

When the vehicle has been operated under heavy load and is immediately shut down, I'd certainly expect to see a coolant temp rise of over 40*>50*f since there is now no air flow across the heat exchanger and the coolant is absorbing heat from non-circulating coolant! The pressure rise inside the sealed system is going to exceed the pop-off point of the cap and coolant is going to burp into the bottle,...it will be pulled back into the radiator system once the engine coolant temp drops again.