Rear Mount Radiator - Cooling Problems

krang00

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Yes, I know, the title is basically an oxymoron but I'm stumped and have no idea what else to try.

I drift so I was looking to move the radiator to the rear to help with weight bias plus I had major overheating problems with it squashed up front between my intercooler and big hot turbo.

I have a Meizer electric pump and recently replaced the thermostat with a 180 degree unit.

The car will idle and sit around 190 ect but as soon as I add any load it overheats and dumps water out of the back. I've tried vacuum bleeding, tilting the car a thousand different ways and burping it that way, but still it just pours out the overflow.

Do I have the hot and cold on the radiator hooked up wrong?

Now that I'm thinking of it, I forgot to include that the turbo is water cooled so perhaps that's not plumbed correctly and causing problems? Is there a flow direction or could the turbo heat be causing it to bubble or get not move water properly?

See attachments for pics and the layout. Thanks for any ideas!
 

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krang00

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Could it be that the turbo is somehow sucking all the cold water into it and not letting it get into the block at the bottom and then feeding it all into the upper hot tube and right back out.. essentially a bypass? Not sure how all these thermodynamics work exactly :)
 

TexasBlownV8

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The cooling on my turbos run out from the block on the lower-driver side (from the side plug), through the turbos, then back to the exist of the coolant crossover on the way to the radiator on the passenger side of the engine. No overheating issues.
 

krang00

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So, should the top of the radiator be connected to the top of the engine where the thermostat is and the bottom of the radiator should go to the bottom of the engine block? Because I think I have mine reversed.
 

groundpounder

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Yes, on the stock setup the bottom radiator to bottom of block and top to top. You get a boost in that cold water sinks to the bottom of the radiator. Are you running a Degas bottle/tank?
 

krang00

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I'm not running a degas tank, I have an aftermarket reservoir that has the actual pressurized cap on it which vents to an overflow bottle. I'm going to try switching the lines, I definitely have it backwards as far as top of engine to top of radiator.
 

groundpounder

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Ok, I missed that in the drawing of your system. Where is your air flow coming from prior to the radiator? Is the fan pulling air from under the car? Seems like the air would be very hot after going around the engine/turbo/exhaust before entering the radiator. Is the radiator hot air ducted out of the "trunk"? Seems like the hot air could rise/be sucked back into radiator in a closed loop.
 

krang00

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Air flow to the radiator is coming from naca ducts in the quarter windows and behind the doors in the fender. The tubing is aluminum.... I was hoping with that much extra it will add more cooling surface instead of doing it all in flex tube.

I think switching the lines so top of block goes to top of radiator may have fixed it. It cycled up to 200 f then i saw ect's drop to around 178, then back up to 200 and down again. This was all on the lift though so I'm going to drive it tonight and see if it holds up.
 

Wes06

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May want to do what dob did and box the radiator in the trunk. So all the air being fed into the trunk will be forced through the radiator rather than given the option to simply go around it
 

86GT351

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Air flow to the radiator is coming from naca ducts in the quarter windows and behind the doors in the fender. The tubing is aluminum.... I was hoping with that much extra it will add more cooling surface instead of doing it all in flex tube.

I think switching the lines so top of block goes to top of radiator may have fixed it. It cycled up to 200 f then i saw ect's drop to around 178, then back up to 200 and down again. This was all on the lift though so I'm going to drive it tonight and see if it holds up.

That's good. I only asked because I have a friend with a Fox body Mustang and he got the Hard Metal Chrome Upper and Lower radiator Hoses. Base engine temp went up almost 10 degrees.
 

tjm73

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Sounds like you need to get more airflow across the radiator. I like the idea of sealing it off from the undercar heat. Would also look at getting more air into the trunk before the radiator. Wall it off from each side so your volume of air can only go through it.
 

krang00

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I agree, definitely can't hurt to wall off the radiator sides. I'd like to convert the rear window to lexan or something and add a few more ducts that vent ahead of the radiator there too.

Although, now that I think of it. At the last race when the car overheated I thought the thermostat had froze so I pulled out the guts so it was basically open all the time. The car actually ran too cold... such that it was stuck in "cold start" mode of tuning. So, that would tell me it wasn't a radiator cooling problem but maybe just air in the block or pump not keeping up?
 

tjm73

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You may have an air purging issue like you say. If air gets stuck in a high spot cooling definitely suffers.
 

krang00

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Looks like things are working ok, at least around town and some spirited driving. Any reason not to run a higher pressure radiator cap?
 

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