Rear rad hill climb woes

gottagofast · Dec 17, 2017

Water is pumped by pushing it..... yes the degas bote would be to remove air from the coolant flow at the high point.... since coolant flows in the top and out the bottom of the bottle, the air never circulates as long as you don't flip....

The radiator should perform the same function but maybe it isn't working at extreme angles.....
Do you have the top leaning forward or backwards or straight up?

skipnrocks · Dec 17, 2017

The rad is leaning forward so on a steep climb it would be nearly vertical.

skipnrocks · Dec 17, 2017

Lil ugly said:
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.

I just rearead this. I can crawl any incline all day and the temp stays the same But if I do a multiple full trottle assault that is when it spikes. It seems to be contingent on incline being steep and high throttle. Any other combo and it's not an issue

Beerj · Dec 17, 2017

Have you tried just ripping around at high throttle on flat ground for a while? The cooling system may just be inadequate overall but has only been pushed too far on those climbs.

skipnrocks · Dec 17, 2017

I have I raced it for an hour through the hills in Moab in 100 degree weather without it raising any concerning amount.

Moto85 · Dec 17, 2017

I'm a bike mechanic, but an engine is an engine.
I've seen several bikes with similar overheating issues with a blown head gasket. Same symptoms as what you have. Can ride it all day no problems but when the hammer is REALLY laid down it is making enough pressure to blow by the gasket. I've had 2 this year like that and my work neighbors had 3... A couple of heads needed decked.

skipnrocks · Dec 17, 2017

Good crap I hope that's not it. Newer engine and all. Wouldn't I have fluid loss or burning coolant or coolant in the oil

gottagofast · Dec 17, 2017

Not necessarily... Hence the reason I suggested a combustion gas test early on in the thread...

Maybe you just need more air flow over the radiator...

I'm assuming that you're hose going into the radiator is at the top and coming out is at the bottom... That's how it should be and would help prevent air from returning to the water pump

skipnrocks · Dec 18, 2017

Yep that is how it's set up. I guess I'll have to get one of those testers and see what's going on. Start rulingsome stuff out

Beerj · Dec 18, 2017

What temp thermostat are you running? I had the opposite problem before I went with a 160° stat. Would try to overheat at idle but cooled once I got the rpm's up.

Moto85 · Dec 18, 2017

SBJeepn said:
Good crap I hope that's not it. Newer engine and all. Wouldn't I have fluid loss or burning coolant or coolant in the oil

These have all been on newer bikes. Less than 10k miles I wanna say. It was pretty hard to diagnose because it would only leak when you really gave it the business (150+mph). The head gasket was blown, but only bad enough to leak under extreme load and throttle. Leak down or compression tests didn't help diagnose because it could hold that pressure on the lift...
They'd actually push the coolant into the overflow tank and have a big air pocket in the engine. So it was hard to tell you'd lost coolant in the rad because the overflow was still full.
I'm not saying that's what's wrong with yours, but it's very possible from what you described. These people really rode their **** too. We've probably got 20 more customers that would have the same issue if they didn't put around like grandma all day. It gave me new appreciation for ARP studs and similar products to get more clamping force on the gaskets.
I'm with the other guy, if you can test for combustion gas in the coolant it would rule all this out pretty quickly.

skipnrocks · Dec 18, 2017

Moto85 said:
These have all been on newer bikes. Less than 10k miles I wanna say. It was pretty hard to diagnose because it would only leak when you really gave it the business (150+mph). The head gasket was blown, but only bad enough to leak under extreme load and throttle. Leak down or compression tests didn't help diagnose because it could hold that pressure on the lift...
They'd actually push the coolant into the overflow tank and have a big air pocket in the engine. So it was hard to tell you'd lost coolant in the rad because the overflow was still full.
I'm not saying that's what's wrong with yours, but it's very possible from what you described. These people really rode their **** too. We've probably got 20 more customers that would have the same issue if they didn't put around like grandma all day. It gave me new appreciation for ARP studs and similar products to get more clamping force on the gaskets.
I'm with the other guy, if you can test for combustion gas in the coolant it would rule all this out pretty quickly.

Makes sense. I'll have to get a tester. Will it test posative for a while after the offense or do you have to do it asap

skipnrocks · Dec 18, 2017

Beerj said:
What temp thermostat are you running? I had the opposite problem before I went with a 160° stat. Would try to overheat at idle but cooled once I got the rpm's up.

I have a 160 also. Some race brand. It was a pricey bigger but helped compared to stock junk

gottagofast · Dec 18, 2017

SBJeepn said:
Makes sense. I'll have to get a tester. Will it test posative for a while after the offense or do you have to do it asap

Now that I'm not certain of... I'd say test it and if you get a negative go rape it a little while and test it again

Moto85 · Dec 19, 2017

SBJeepn said:
Makes sense. I'll have to get a tester. Will it test posative for a while after the offense or do you have to do it asap

I have no idea. I've not used said tester. All my diagnosis was covered under manufacturer warranty, so I wasn't trying to speed it up if ya know what I mean. I'll test everything they tell me to test, and charge warranty for it. :smoke:

Hudson1 · Dec 20, 2017

I had about a year of frustrating out of a rig with a rear mounted radiator. Jeep 4.0 with a blown head gasket. Replacing the head gasket fixed the issue. It did not always show up. Some rides it was great on others it would spew water out all day.

skipnrocks · Dec 21, 2017

Hudson1 said:
I had about a year of frustrating out of a rig with a rear mounted radiator. Jeep 4.0 with a blown head gasket. Replacing the head gasket fixed the issue. It did not always show up. Some rides it was great on others it would spew water out all day.

That must be what it is. Wonder how long it would take on my 383 to swap gaskets. Can you tell where the blow by is when you pull the head?