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Topic Review (Newest First)
09-04-2012 02:07 PM
Dmgarage All very good ideas. My first choice would be to install a larger radiator. However I may be limited with the frontal area of the truck and the surrounding components. I will look closely at this first. Of course I would then need to install a new arrangement with the fan(s) and shroud also. The looping length of tubing may work too. Thanks a lot for the reply!
09-04-2012 01:44 PM
oldbogie
Quote:
Originally Posted by Dmgarage View Post
I should re-phrase that. I installed it as it is now, but the rad came with the truck.
The surface difference between what you've got and what is needed is 36 percent. That's a lot; there are no tricks to overcome this it's just too big a number for fans and water wetter to overcome. I see the paint is probably custom and the opening in the truck's radiator support frame is probably too small so cutting that frame and touching up the paint is sure to be difficult, but I really don't see much in viable options.

However, over the years I done some tricky things where space in hot rods of the 1920's and 30's just didn't offer sufficient radiator space behind the grill without ruining the lines and or finishes. Some of these include:

- Installing a large as practical oil cooler with a thermostat. A lot of load can be taken off the radiator by cooling the oil. But the oil cooler installation needs to include a by-passing thermostat because you need to get the oil temp up but then maintain it. If it's too low the oil can't eliminate trapped water (a component of blow by) which reduces its and the engine's components life span. This can take 10-15 degrees off the coolant temp.

- Using hidden secondary cooling. Capture the coolant from the radiator before it goes back to the pump and run it through a looping length of 1-1/2 inch copper pipe clamped to the frame. You can have a well equipped plumbing or radiator shop roll a bead on the ends where the hoses will attach. Rubber hose adapters see WYSCO from your browser can adapt the 1-3/4 Chevy pump feed side hose to the 1-5/8ths of the tube/pipe. This adds volume capacity to the coolant and uses the contact point to the frame as a heat sink. This method keeps the thermostat and bypass intact and functional. You can tap a secondary radiator into the bypass but this leads into a remote thermostat housing which gets complicated and not very visually pleasing.
09-04-2012 01:00 PM
Dmgarage I should re-phrase that. I installed it as it is now, but the rad came with the truck.
09-04-2012 11:19 AM
Dmgarage It is a 56 Chevy Truck with a new aluminum cross flow rad (I did not put it in) pic attached (I hope)
09-04-2012 11:12 AM
oldbogie
Quote:
Originally Posted by Dmgarage View Post
Thats what I was afraid of. Do you think if I put on a clutch fan with a shroud it would be sufficient? Although I only have 4 3/4" from the water pump pulley surface to the radiator. I am not sure I can get a fan short enough with the clutch.
I doubt that would work, the problem is one of areas (tube to fin contact and fin to air) If it won't cool with 60-70 mph air flow through the core from the vehicle's motion, it is not likely that any fan that fits the available space can do as well let alone better.

What is the vehicle? I get the feeling we're talking a older design with a vertical flow radiator. These can be a problem where space for the cooling system is concerned. These older machines had trouble keeping the 100 horse power engines of their day cool. Admittedly we have a lot more Rocket Science available, but it still is not easy to provide adaquate cooling within the available space.

Bogie
09-04-2012 11:02 AM
Dmgarage Thats what I was afraid of. Do you think if I put on a clutch fan with a shroud it would be sufficient? Although I only have 4 3/4" from the water pump pulley surface to the radiator. I am not sure I can get a fan short enough with the clutch.
09-04-2012 10:09 AM
oldbogie
Quote:
Originally Posted by Dmgarage View Post
Well, I did all of the things I had previously listed plus put a new Edelbrock water pump and 180* high flow thermostat. I also added Redline water wetter to the coolant mix. It does run cooler, but simply not as cool as it should. Cruises around town at about 205. I took it on the highway for a few miles and it got up to 215 and I believe it would of kept climbing. The rad is aluminum and and measures 22" wide (with the tanks) and 19" high. Is this too small? Engine is a 355 that made just over 400 hp.
The radiator is too small for this engine. A crossflow of 30x19 inches with 2 rows of 1 inch tubes would be the minimum. With a 180 thermostat (opening temp) this combination should show 190-195 all the time. The 30x19 is a production size radiator for the 350s for machines such as the Monte-Carlo, Malibu, etc. These cars came originally with with a copper-brass radiator of these same external dimensions but they used 3 and sometimes 4 tubes of about .5 inch wide.

A vertical flow radiator would need to be the same area dimensions as the crossflow with the same tube count and size just stood on end.

Bogie
09-03-2012 08:35 AM
Dmgarage
update

Well, I did all of the things I had previously listed plus put a new Edelbrock water pump and 180* high flow thermostat. I also added Redline water wetter to the coolant mix. It does run cooler, but simply not as cool as it should. Cruises around town at about 205. I took it on the highway for a few miles and it got up to 215 and I believe it would of kept climbing. The rad is aluminum and and measures 22" wide (with the tanks) and 19" high. Is this too small? Engine is a 355 that made just over 400 hp.
08-12-2012 07:30 AM
Dmgarage I decided I am doing this right. As I already said, I will do the bypass. Im also going to move the radiator forward 3/4 of an inch. that will allow me to use a flex a lite "black magic" fan I already have that is fully shrouded covering almost the whole radiator core and pulls 2800 cfm. It has a thermostat to control it which I will set at 185-190*. I will also go back to using an engine thermostat of 180* with a couple bypass holes drilled in it. This should do it and do it the right way. What do you think. Thanks again for the advice.
08-11-2012 04:02 PM
Dmgarage I agree with you, the lower temp thermostat is only delaying the inevitable. It will get the temp up just idling in the shop with the fan running. The core is not dirty or clogged at all. The fan is a typical 16" that is attached right to the core with the nylon mounts. the only shroud is the one the fan provides for that 16" diameter. Im fairly certain this is probably the problem. I really would like to get a shroud to mount the electric fan in. Jegs does sell an aluminum one that accomodates the fan, I just am not sure I have the clearance between the rad and pump. I am trying to avoid remounting the rad. I can only move it forward about 3/4 of an inch anyway.The core size of the the rad is roughly 16x19 and it is a thick aluminum one so that should be sufficient. The air conditioning condenser is mounted a couple inches in front of the radiator too. Im not sure how much that affects things.
OK on the bypass purpose, I completly understand.
08-11-2012 03:05 PM
oldbogie
Quote:
Originally Posted by Dmgarage View Post
This is an old school hot rod. 56 Chevy truck with a carb in front of a turbo 350. It has a large aluminum radiator & only a 16" electric fan. If there is any problem it is that the fan is not doing a good enough job. I was hoping doing the bypass might help. I would put a stronger, better shrouded fan on, but I am limited by the space between the rad & the water pump (about 3 1/2"). I may end up putting a mechanical fan on with a custom made shroud.
So does it get hot when standing/idling or when cruising?

Typically when idling it's an air flow issue through the core.

When it happens at cruise either the radiator is too small or the flow through the tubes is restricted because of dirt and corrosion becoming lodged in the tubes.

Usually lowering the thermostat opening temp only delays the overheat situation but doesn't change the end result if the engine is operated long enough. If you get a sustained difference it probably tells you the original thermostat is defective.

The bypass has little effect on temperatures whether it's there or not, all it does is recycle coolant when the thermostat is closed so hot spots can't form in otherwise cold castings. When a local area is hot enough to boil coolant to steam then local cooling of that place stops and the area super heats very quickly unless there is enough coolant circulation to keep these hot spots around exhaust valve seats and spark plugs wet. Keep in mind that when the engine is cold, pressure has not built up in the cooling system, therefore local boiling will happen at a much lower temperature than when the system is hot and pressurized.

A fan whether electric or pump driven off the engine needs a shroud that fits around the perimeter of the core, usually the tanks and radiator's frame, at one end and over the fan blades (about half deep of blade width). This lets the fan lower the air pressure inside the shroud so that air flows in over all the surface area of the core. This has a massive improvement in cooling capability compared to any other configuration of fan or fans. Certainly a larger more streamlined enclosure is more efficient, but even a couple, three inches deep is a significant improvement in fan/cooling performance.

Bogie
08-11-2012 01:51 PM
Dmgarage Also, the one time it did reach 215, I had a 180* stat with no bypass holes in it. It was also the first drive w the new engine
08-11-2012 01:49 PM
Dmgarage This is an old school hot rod. 56 Chevy truck with a carb in front of a turbo 350. It has a large aluminum radiator & only a 16" electric fan. If there is any problem it is that the fan is not doing a good enough job. I was hoping doing the bypass might help. I would put a stronger, better shrouded fan on, but I am limited by the space between the rad & the water pump (about 3 1/2"). I may end up putting a mechanical fan on with a custom made shroud.
08-11-2012 11:47 AM
oldbogie
Quote:
Originally Posted by Dmgarage View Post
Thanks for the response. I looked into this because the car does run on the hot side. (seeing 215 occasionally) I just dropped down to a 160* thermostat that I drilled 4 3/16 holes in. I was originally thinking that would be sufficient for the bypass function. However, after thinking some more and reading more posts, I think I will also do the external bypass. I think I will bring a 5/8 line from the driver side rear coolant port of the intake to the 5/8 nipple on the suction side of the water pump. I also need to hook up the return side heater hose here. Would it be acceptable to use a 5/8 tee just off the nipple on the top of the pump with one line obviously going to the pump, one line going to the heater core, and one line going to the coolant port at the rear drivers side of the intake? This car does not have any ports on the radiator.
This sounds acceptable, what about the 160 thermostat and the 215 temperatures, is this together or some other situation/combination of things?

Unless you did modifications to the EFI computer, a 160 degree thermostat and running at that temp will keep the fuel injection in cold start mode (choke function on a carburetor if you will) which will keep the mixture too rich. This is hard on the catalytic converter running 'em hot and, also, hard on the pistons, rings, and cylinder walls as the excess unburnt fuel in the blow by washes the top end lube off the cylinder walls. Anytime the engine is under about 175 degrees the cold start function kicks in, so you don't want to use a thermostat lower than 180. All this of course depends on the real running temp of the engine, if it runs 215 with a 160 thermostat the fueling is correct but you've got problems elsewhere perhaps with flow rate through the radiator which may need replacement because the core tubes are plugging up, or something like that.

Bogie
08-11-2012 05:26 AM
Dmgarage
Thanks

Thanks for the response. I looked into this because the car does run on the hot side. (seeing 215 occasionally) I just dropped down to a 160* thermostat that I drilled 4 3/16 holes in. I was originally thinking that would be sufficient for the bypass function. However, after thinking some more and reading more posts, I think I will also do the external bypass. I think I will bring a 5/8 line from the driver side rear coolant port of the intake to the 5/8 nipple on the suction side of the water pump. I also need to hook up the return side heater hose here. Would it be acceptable to use a 5/8 tee just off the nipple on the top of the pump with one line obviously going to the pump, one line going to the heater core, and one line going to the coolant port at the rear drivers side of the intake? This car does not have any ports on the radiator.
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