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Old 11-30-2011, 05:20 PM
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Horizontal Radiator behind SBC with twin fans, but still overheats

I am finally getting my shopping cart rod on the road, but I am having some overheating problems. The radiator is mounted horizontally behing the engine and right above the TH350 trans. There are two 14" fans pulling air down through a full shroud. The plumbing comes up from the bottom and I am thinking that the radiator is trapping air and does not have enough liquid-to-aluminum-fin contact. I can only run it about a mile before it overheats.

The way the radiator hoses are placed around the frame does not allow me to tilt the radiator up to use the stock drain or cap to bleed off air. The system is filled and air bled from a cap above the 165 degree thermostat. I am thinking about drilling and taping a small hole in one of the end caps to bleed off any air stuck in the radiator. Anybody ever tried that? Is the plastic on the end cap of a 1988 chevy truck radiator thick enough to hold a screw and rubber washer in a 13 psi system?
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Old 11-30-2011, 06:49 PM
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I would think the petcock would work as an air bleed. Attach a hose to the petcock and run it to a level higher than the engine leaving it open while you fill the system. I think the air would escape. SOmebody think that through for me.
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Old 11-30-2011, 07:08 PM
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Quote:
Originally Posted by patentguy
I am finally getting my shopping cart rod on the road, but I am having some overheating problems. The radiator is mounted horizontally behing the engine and right above the TH350 trans. There are two 14" fans pulling air down through a full shroud. The plumbing comes up from the bottom and I am thinking that the radiator is trapping air and does not have enough liquid-to-aluminum-fin contact. I can only run it about a mile before it overheats.

The way the radiator hoses are placed around the frame does not allow me to tilt the radiator up to use the stock drain or cap to bleed off air. The system is filled and air bled from a cap above the 165 degree thermostat. I am thinking about drilling and taping a small hole in one of the end caps to bleed off any air stuck in the radiator. Anybody ever tried that? Is the plastic on the end cap of a 1988 chevy truck radiator thick enough to hold a screw and rubber washer in a 13 psi system?
With the eng. higher than rad. air trapment in the eng will be an ongoing prob.
Looks like you could easily tilt the rad. up so that rad. cap/filler is higher than the eng. (same angle as existing frame tubes) ; then figure a way to route your hoses. This will also allow a direct flow of air on the face of the rad.

Last edited by 406 bug; 11-30-2011 at 07:22 PM.
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Old 11-30-2011, 07:32 PM
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Try this. Remove the thermostat housing and thermostat. This is where your going to fill your system. If your radiator petcock isn't located at the high point of your radiator attach a piece of hosing to it and raise it above your radiator. Open the petcock and until coolent flows nicely. Close the petcock and fill your system while holding the radiator hose end level with the thermostat opening in the block until the system is filled and the coolent runs from both the block and hose. Re-install the thermostat and housing and quickly re-attach the radiator hose. Run it until it get up to operating temp and the thermostat is open. Blip the throttle a few times to get any trapped air to move to the top of the engine. Let it completely cool down ( the next day) pull the thermo housing and check the level for any trapped air. re-fill as necessary. You might also want to install a thermostat housing that has a tapped hole for a temp sensor. Chevy used them. You can install a short piece pf pipe in it that becomes the high point of the system and with some pipe fittings attach a petcock on top of the engine which will become your bleed point.
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Old 11-30-2011, 07:33 PM
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Buggy project heat

1st like your hotrod. Where you have the radiator now will never work. Air will always be a problem and your fan what little air its pulling is hot air. Why don;t you just mount the thing where it belongs ,make a nice cart oriented grill and headlight piece and solve the heating problem. Looks like you have plenty of room. All the eyes are going to be looking at the cart gorng down the road,not the drivetrain.Take a look at the Baha ottroad trucks,their radiators are in the back but still mounted higher than the engine. One thing that might help would be to find an older V-8 Mustang radiator. Smaller ,taking up less space but will cool your engine fine.
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Old 12-05-2011, 09:11 AM
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Keeping air out of the horizontal radiator

Thanks everyone, always great advice here. I kept the radiator hooked up to the cooling system, but tilted one corner up until it was at the same level as the system cap mounted above the thermostat (see pic). I added fluid until it was flowing out of the bleeder valve on the radiator, closed it all up and ran the engine for a bit, let it cool and checked the coolant level again. It looks like I have all the air out of the system now and on several test runs the engine stayed at normal temp the entire time. The large truck radiator and twin 14" fans seem to be doing the job of cooling, but I guess my question now is will air accumulate in the radiator over time, creating the same situation I just fixed. The filler cap is the highest point in the system and I added a bleeder port to the top of the radiator end cap to bleed any accumulated air. If air is going to be problem, I will have to look at mounting the radiator upright somewhere else. I like the low profile look of where it's at but I need max cooling capacity. This is going to be a parade vehicle, so it is going to be idling on summer days. My other thought was to add a small vertical radiator with an electric fan at the front of the engine and run the heater hose ports to that secondary radiator.

It was great getting this silly thing running. It rides a little stiff, but it is very stable for something that looks top-heavy:

http://www.flickr.com/photos/kathyca...in/photostream
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Old 12-05-2011, 10:02 AM
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if you already tilted up the rad so the cap is even with the top (highest point)
if you put an overflow bottle on it like the truck rad had stock
it should alow air out, but will suck fluid in if it wants some

wait, did you leave it mounted up or out it back down?
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Old 12-05-2011, 10:13 AM
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Quote:
Originally Posted by matts37chev
if you already tilted up the rad so the cap is even with the top (highest point)
if you put an overflow bottle on it like the truck rad had stock
it should alow air out, but will suck fluid in if it wants some

wait, did you leave it mounted up or out it back down?
Sorry, I was not clear on that, I tilted it up to fill the system and bleed out any air and then mounted it back down in the horizontal position. The system is running with an expansion tank and so far it appears to be venting and drawing coolant back in as needed.
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Old 12-05-2011, 10:15 AM
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Pic of the filler cap and temporary expansion tank.
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Old 12-05-2011, 10:18 AM
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Quote:
Originally Posted by patentguy
Thanks everyone, always great advice here. I kept the radiator hooked up to the cooling system, but tilted one corner up until it was at the same level as the system cap mounted above the thermostat (see pic). I added fluid until it was flowing out of the bleeder valve on the radiator, closed it all up and ran the engine for a bit, let it cool and checked the coolant level again. It looks like I have all the air out of the system now and on several test runs the engine stayed at normal temp the entire time. The large truck radiator and twin 14" fans seem to be doing the job of cooling, but I guess my question now is will air accumulate in the radiator over time, creating the same situation I just fixed. The filler cap is the highest point in the system and I added a bleeder port to the top of the radiator end cap to bleed any accumulated air. If air is going to be problem, I will have to look at mounting the radiator upright somewhere else. I like the low profile look of where it's at but I need max cooling capacity. This is going to be a parade vehicle, so it is going to be idling on summer days. My other thought was to add a small vertical radiator with an electric fan at the front of the engine and run the heater hose ports to that secondary radiator.

It was great getting this silly thing running. It rides a little stiff, but it is very stable for something that looks top-heavy:

http://www.flickr.com/photos/kathyca...in/photostream

Great job on the Cart. Here is something you might want to consider. If you think about grocery carts and how shoppers load them up, you usually see the big bulky items on the bottom of the cart; this presents an ideal opportunity for you to screen the motor/drivetrain/radiator. Replicate a giant box of Tide or other large item for the bottom, along with a few items in the basket.
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Old 12-05-2011, 10:48 AM
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Some ideas just do not work..I would get that radiator up as vertical as I could and get some shrouding on it to direct air into the radiator which will help the fans. Then lets get a fill on it above the highest level of coolant. Ford used a remote fill on some thunderbirds which had the radiator mounted very low in order to get a good fill..

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Old 12-07-2011, 04:40 PM
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70s Corvettes have the radiator at a steep angle in front, and there have been mid engine cars with the radiator installed flat in the back. I've seen a couple truck rods with the radiator flat in the back. The flat mounting won't affect cooling as long as there is adequate air flow. The mounting just effects filling, and that problem has been solved. There should be no more problems with it as is. You might want to let it idle for 3-4 hours while you watch the temp gauge just to make sure -- wouldn't want to find out there is a problem in the middle of a parade!
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Old 12-07-2011, 05:09 PM
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Quote:
Originally Posted by farna
70s Corvettes have the radiator at a steep angle in front, and there have been mid engine cars with the radiator installed flat in the back. I've seen a couple truck rods with the radiator flat in the back. The flat mounting won't affect cooling as long as there is adequate air flow. The mounting just effects filling, and that problem has been solved. There should be no more problems with it as is. You might want to let it idle for 3-4 hours while you watch the temp gauge just to make sure -- wouldn't want to find out there is a problem in the middle of a parade!
Thanks Farna, my plan this weekend is to let it sit idling and see if the cooling system can keep up. If the system can't handle the heat I will look at alternative locations for the radiator. I need to commit to the position before the cart gets taken apart to get ready for paint.

BTW One of my first cars was a Rambler wagon, a '63 is on my list of cars I want to own again.
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Old 12-08-2011, 09:02 AM
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I agree, that is a very cool project

with the filler cap on the thermostat housing and a spit can it should be fine
if you were to tilt the rad a very small amount, (maybe add a 1" spacer to the mount) and add a spit can to it, you should have no problems at all
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Old 12-08-2011, 04:23 PM
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That is one crazy ride, nice job.

I think you would have better luck moving the air up from the bottom rather than pulling it down with the fans. Can you mount your fans and shroud up top? or reverse polarity? hot air rises. Maybe you could fab some air deflectors to direct cool air from under the chassis up towards the bottom of the rad and that would help the air flow move up through the rad along with the fans. The rad will cool better with up flow IMHO
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