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Rear rad hill climb woes

skipnrocks

skipnrocks

Well-Known Member
Joined
Oct 1, 2011
Messages
1,355
Location
Billings Montana
So I'm not totally sure where to start. But my rig has the rad in back coolant inning through the Chassis. It stays cool while riding. But when I do repeated full throttle climbs in a row it will try and overheat. At first it was because my cap was a 12-14 psi once I bumped it to 18 it has gotten a lot better. But there are so many rigs with the same setup. What's my issue? I am running a built 383 if that makes any difference?
 
I guess I should add it doesn't ever just get got it starts to blow by the overflow and then heats up fast. I don't know that I can get a higher psi cap
 
Sounds like a flow issue or maybe exhaust gas getting into the system somewhere

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Have there ever been any occasions that you load the engine real heavy on level ground and noticed a spike in temperature? Would be interested to know if angle (incline) could be eliminated from the possibilities.
 
Fin I hot rod it around the trails underload tge thermostat stays cool. I can only figure it has to do with the pressure of flowing it all the way down to the radiator and back up. The only other thing I can figure is that somehow it's sucking air in when its trying to draw the coolant back up to the motor. I don't have any leaks so unless the vacuum under the steep incline is drawing air in somewhere? Does that seem like it could be even with no leaks? If so how the crap do I find such a vacuum leak?
 
Try doing several hard pulls on flat ground with the brakes dragging you down and see if it does the same thing...

I would also test for combustion gasses..... you could be pressurizing the cooling system and venting pressure all the time but when going up hill you blow coolant out because the gasses stay on top ie in the engine.
 
How do you of test for combustion gas? And how do you get that? Leak in the head? I get my shocks back this week. I'll have to get them on to test a hard pull.
 
Someone brought up maybe the rear hose when warm and under the pressure of high rpm and a lot of vacumm maybe flattening?! I have a normal flex rad hose back there??
 
I have a dusal flex 12s I believe. Sealed around then shroud pulling air. I have hot riffed the desert on 100+ degree days but when I hot rod a steep hill about third attempt it's pissed.
 
SBJeepn said:
Someone brought up maybe the rear hose when warm and under the pressure of high rpm and a lot of vacumm maybe flattening?! I have a normal flex rad hose back there??
Click to expand...
I have had that happen before,find you a hose that is reinforced,or put the wire spring insert in it.
 
It sounds like you might have a pump issue. Not in the sense that you have a bad pump or one that doesn't work but one that is operating at max capacity under normal conditions and not able to handle additional strain. I am assuming in your discussion that the hills you speak of are gradient of 30 degrees or so and that on slight hills you don't have this issue. You would be adding a lot of head pressure to your system when on a steep incline. Not sure if I can describe this in the proper manner. When trying to move water with a pump uphill it will only move water up a certain distance before the weight of the water overcomes the pump and it no longer can move the water. Provided you stay under that pumps maximum lift height you never have a problem. In your case at level or minor incline you don't have an issue. Too much angle though and the weight is just too much for the pump to move. Try putting the rig on a stationary incline and see if it gives you a temperature spike. If it does you may need to add a small 12v boost pump in your system or check and see if you need to eliminate something that is choking down your system. Tight bends that kind of thing.
 
The weight of the water flowing downhill in a closed system cancels the weight of the water flowing uphill
It could be 10,000 feet and it would still pump

Another thought just occured to me.... what about adding a degas bottle over the front of the engine (higher than the radiator if possible).... if you have any air in your system it seems that it might find the pump on a steep climb and cause it to air lock.... just a theory ymmv
 
gottagofast said:
The weight of the water flowing downhill in a closed system cancels the weight of the water flowing uphill
It could be 10,000 feet and it would still pump

Another thought just occured to me.... what about adding a degas bottle over the front of the engine (higher than the radiator if possible).... if you have any air in your system it seems that it might find the pump on a steep climb and cause it to air lock.... just a theory ymmv
Click to expand...
. I never heard of that. I'll have to google it
 
Ok so I did some reading. But now I need help connecting it to your thoughts. Basically best I can tell it's an active resivoir fluid goes in and out and the gas separates and is left in the tank. But from there why put it in the front. And which side of the system do you put it on. And how will that change flow since the pump will be either pushing it all the way through then sucking it from this tank?
 
I think because air goes to the highest point and when hitting a big hill, the highest point is likely the front of your rig.
 
My question would be does it change the dynamic of flow to where the output has to push all the way down and back up to the degas tank? Or will it still suck back up to help withflow? I thought of putting an electric water pump at the radiator but maybe that won't eork
 

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