Hoping for some help from some members who may have this same problem. I have a YJ with 5.0 EFI roller motor conversion. Pulled from a late model non MAS. I am running an aluminium Griffin radiator custom Aluminium shroud, (ran it with and without and over heated with and without shroud) very good high efficient electric fan. This is wired with thermo controller and a bypass on off switch. I was running a 180 Thermostat. HAve lowered to 160 and still over heats on highway. Has a Mile Marker winch up front (only thing blocking the grill area) Truck runs fantastic around town with no problems even in the heat of summer and traffic. Motor runs flawless idle all the way up . PROBLEM: When I run at highway speeds it overheats. Fan on, fan off I've tried everything..Get it off the highway and it will cool back down. It is only tacking out at 2400 or 2500 rpm in 4th (has a T18 and 4:10 running 38 SSR'S) It's not running lean, plugs all look good.
I'm going nuts on this one guys...Any other 5.0 swaps have this problem? Or anyone had similar issue. Any help on this one would be VERY appreciated.
i thought i was the only guy with a 5.0 swap in a YJ....mine is the same setup as you almost...except i run a stock rad with a clutch fan...i bought it with the swap done like this..never overheated unless i was beating it hard on the trails...then the rad got clogged with mud and the fins were beat up pretty badly that you could see right thru the rad....i got a stock replacement and plan to do a efan on it also....maybe try bleeding the air out of the system somehow...post up some pics of your setup
I'll post some pics tomorrow. it really is strange. I do not believe it is air pocket at this point. The winch shouldn't effect it. (I had same winch on my CJ and no overheating issues) This one is running the 5.0 but I'm at a loss on the highway problem.
I run the same radiator, different motor but same rad. It sounds like you have air in there. At high speeds it will overhead with air trapped inside. It gets trapped in the block. This sounds stupid but I had to put my jeep on a ramp to rid the air enough. I had no way to force the water through.
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Your electric fan may be impeding air flow at highway speeds. I know this sounds weird, but in some cases the air coming in is at a higher speed than the fan will allow, thus the fan ends up being a restriction. You might want to runs a different fan configuration to see if that is a problem.
I ran the set-up with different fan and no shroud and same problem, 180 160 thermostats and it does have additive now added to try and lower the temp even more. Same situation hot day highway she overheats. Pull off and run at around town speeds she cools back down. replaced the fan with the biggest you can run and a custom made aluminium low profile shroud and same results. Tried running at highway speeds and turned the fan off so it is free spinning ...same results. This thing is killing me guys.
What rpm are you running at on the highway? Might want to try a Edelbrock Victor Water Pump it should lower your temp by 15 Deg. I think it is water flow not air flow. When you run around town your keeping the rpms up and going down the highway therenot as high.
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Have you run it without the winch in place (with that motor)? Depending on the size and profile of the winch and fairlead it could start to buffet the air at higher speeds and direct it up over the hood and reduce what's pasting through the grill.
Did the high flow when I dropped the 302 rollere EFI in. With the overflow tank I would have to assume if it had an air pocket it would dissapate? Don't really know on that. I know others run this same set-up and say no overheat issues so I'm thinking something is strange. You would think around town it would overheat..not running down the highway
I got a 302-t18 setup with a winch up front and an electric pusher fan in front of a 3 core stock style radiator and no problems. Do you hear any pinging or faint knocking? I'd sure check that timing. Mine is at 6 degrees btdc base timing with a carb. Also can't remember but do some smallblock fords depending on year have reversed water pumps like some chevy small blocks? Any Ford guys out there? Chime in if that may be the case.
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