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Topic Review (Newest First)
10-15-2012 07:28 PM
oldbogie
Quote:
Originally Posted by movinon View Post
Hello to all!! need some help,looking at an Elcamino 350 crate motor not sure of hp has 650 carb 373 posi.When air is on engine overheats,new alum. radiator 2 12 inch electric fans he told me it needs a 3rd 12 inch fan? the 2 now run constantly[no thermostat] keep air off he said it doesnt overheat.Do you think it just needs that 3rd fan?...thanks for the help...Don
ps 4speed stick tranny
How large is the radiator's core and are the tanks plastic or aluminum? Following that how many rows of tubes are in the radiator 1 or 2 or more and how large are they 1 inch wide or 1.25 inch wide or something else?

The problem you describe is typical of insufficient heat transfer area for the temperature gradient of the entering air. You can put as many fans on it as a DC7 has propellers and the thing will be more likely to fly than cool the engine.

Obviously when the cabin is being cooled there are two problems that result in the engine overheat:
1) Air conditioning pulls a lot of power off the engine, more power always equals more heat so the radiaitor needs to work harder.
2)The condenser being in front of the radiator is surrendering heat to the incoming air flow as well as restricting in an aerodynamic sense how much air gets to the radiator.

So the Delta T (temperature differencce) across the radiator is suffering from the flow restriction from the condenser, while it also increases the incoming air temperature to the radiator so less heat transfer can happen while more heat is being put into the coolant. Frankly I'm with your friend in calling the quits at 210, that's just to damn edgy, the down side is the engine needs to be cooled and shutting it off only lets it heat soak to a higher coolant temp. This risks cracking castings because it will get localized boiling without the movement and pump pressure present when the engine is running, sitting still engine off you're 100% dependant that the pressure cap may provide enough system wide pressure to prevent that from happening.

Somewhere in here were the words under-drive pulleys, this is a gamble for a few horsepower on the top end where the thing probably spends little time. These things are dangerous devices in the hands of people who don't appriciate what they are for. In a high RPM engine there is a point where the typical water pump develops much more flow than the engine requires, this is typically a race engine that isn't running air conditioning and is mounted in a relativily open engine room with a lot of airflow around the engine. This is nothing like the typical street driven car with all the gadgets and space restrictions one can put into the engine room. The power extraction from the water pump is an inverse parabolic curve, in that it comes up a little bit but sags against RPMs using damn little power till the RPMs start climbing above 3500 then it gets to a moderate 5 to 7 horses which grows to 20 or 30 horses at 6000. Slowing the pump if it's a production pump starves the engine for coolant flow at low to moderate speeds while reducing the high end impact. A high volume pump can restore the flow while turning slower but this begs the question how much volume is the high volume pump delivering compared to the stock pump? Unless you doing the measuring you'll find this isn't easy data to find other than a percentage aginst some unknown OEM number. So on the street just buy an OEM pump and run it with OEM pulleys and forget the games advertisers suck you into. Racers have turned them faster or slower, shaved off impellor fins and all sorts of bass-akwards tricks to walk the line between enough cooling and reducing power extration when what is needed is a variable speed or variable output pump that sees some slowing or flow reduction from variable vanes as the RPMs go up. But the complexity of such a drive or vane control causes people to shy away. The reason for the need is that pump output goes up geometrically with RPM but the engine's cooling needs go up more linearly. So the pump could use a form of regulation to put it's output into agreement with the engine's coolant flow needs besides spinning the pump and regulating the output through the enigne with a thermostat or restrictor as that doesn't address the power extraction problem of the pump.

If you're really jammed for space and can't get a larger radiator in there or some space between the condenser and radiator, maybe with scoop between them to pull up some air that hasn't been through the condenser will help. After returning to the good sense GM engineers had on pulley ratios, you may find an oil cooler mounted somewhere besides in front or behind the radiator will be helpful. Getting 50 degrees off the oil temp will typically take about 15off the coolant.

Bogie
10-15-2012 09:45 AM
bigdog7373
Quote:
Originally Posted by GMCTRUCKS View Post
I have those pulleys and what I did is I installed a high flow water pump and it does just fine even in this stop and go Texas heat im telling you the pump does really put out more water I seen the flow before and after.
I have no problem with underdrive pullies when they are used correctly, which in your case they are. My buddy has them on his gti and he gained like 5hp just from the crank pulley. If they work use them, but if you start having cooling, charging, or a/c problems then you know that you need to change something.
10-15-2012 06:45 AM
GMCTRUCKS
Quote:
Originally Posted by bigdog7373 View Post
210 isnt overheating. You didnt say whether there is a shroud on it or not.
What do the pullies look like on the water pump/ crank. Sounds like he might have those "underdrive" pullies and its getting just enough flow at idle to keep it cool but as soon as the a/c is on there's too much heat for it to keep up.
I have those pulleys and what I did is I installed a high flow water pump and it does just fine even in this stop and go Texas heat im telling you the pump does really put out more water I seen the flow before and after.
10-14-2012 04:41 PM
bigdog7373 The oil leak could be the seal on the back of the manifold. A lot of people use those little rubber pieces with no rtv on them which will cause a leak on the front, rear or both on the manifold.

Can you post some pictures of the fan/ rad setup so we can see what you're working with.
10-14-2012 04:00 PM
Jim Rockford try and get a clutch fan with a thermal clutch , whatever you do don't use a junk *** flex fan, those thing eat HP and the blades can break off and do some damage to the car or someone, Maybe you guys can take some factory stuff and make a good electric fan setups..


10-14-2012 03:31 PM
T-bucket23 You are most likely not moving enough air. If there is room, loose the electric fans and get a good engine drive fan with a shroud and most likely your issue will go away. When the air is on the condenser gets hot and pre heats the air that is supposed to be cooling the radiator. If it is good at idle and on the highway without the air on then the cooling system is most likely up to snuff. I would not put 3 fans on anything. The cases of the fans will be blocking a good portion of the radiator surface area and will probably hurt more than they help.
210 is not to hot but the engine should run at +- 10 degrees of the thermostat rating. If not somethin is wrong.
10-14-2012 03:07 PM
movinon the car has aluminum cone where fan should be the electric fans have plastic shrouds on each of them. I cant believe the owner never reseached the temp of his engine ? He shuts off air at 210 i wonder if it gets alot hotter or will it cap out at 210? I will have to buy to find out.I dont think it could be a tough fix.I may not buy it also has oil leak behind engine[rear main?] He just had new clutch install and didnt fix the main??i am suspitious on that one![i would go back to a fan and full shroud that car originaly had]. seeya..Don
10-14-2012 02:20 PM
bigdog7373 210 isnt overheating. You didnt say whether there is a shroud on it or not.
What do the pullies look like on the water pump/ crank. Sounds like he might have those "underdrive" pullies and its getting just enough flow at idle to keep it cool but as soon as the a/c is on there's too much heat for it to keep up.
10-14-2012 02:02 PM
movinon okay i saw the car today and took a 15 minut ride it ran just under 180 turned on air but didnt see much movement on guage.He gets nervios when it climbes to 210 and he shuts off air.it has a bigger cam[some lope]it also doesnt have an engine run fan just electric fans on engine side of radiator[pull] 180 thermostat on engine adjustable thermostat on elec.fans How hot should the 350 run? maybe 215/220?..thanks for all the help...Don
10-14-2012 09:29 AM
bigdog7373 I believe what he was saying is that the fans don't have a thermostat, not that the engine doesn't have one.

Op you can use puller fans mounted inside the engine bay or pusher fans mounted on the front of the rab/a/c condenser, although the first method mentioned is better.
Does it have a shroud?
10-14-2012 07:35 AM
delawarebill
over heat

i agree with CD.. u do need a stat.. if its just a summer driver then go with a 165. drill one or 2 small (1/8") holes in the stat just inside the gasket area. this will let the air to escape when filling and will prevent air bound. then take a harder look at the fans.. including a shroud.
10-14-2012 12:08 AM
cdminter59
Overheating

First thing you should do is install a 180* thermostat. Then you will need a shroud to cover most of the radiator. Do you know the cfm of the fans? I looked up a BE COOL Radiator Module, it has a 19x33 radiator, dual 13" puller fans, 2000 cfm fans with a shroud. In a single fan it takes a 16" diameter, 1610 cfm puller fan, with a shroud that covers most of the radiator. Without a thermostat and a shroud it will always run hot.
10-13-2012 08:39 PM
movinon i will go to see car tomorrow picture of motor not to clear i believe they are pushing fans,no shroud and i cant see the fan blade used on engine drive. He said it gets hot in traffic. thanks...Don
10-13-2012 08:16 PM
bigdog7373 Are they pusher or puller fans? Two 12's should keep it cool just fine if they are pullers. Does it overheat while moving too?
10-13-2012 04:16 PM
movinon
overheating

Hello to all!! need some help,looking at an Elcamino 350 crate motor not sure of hp has 650 carb 373 posi.When air is on engine overheats,new alum. radiator 2 12 inch electric fans he told me it needs a 3rd 12 inch fan? the 2 now run constantly[no thermostat] keep air off he said it doesnt overheat.Do you think it just needs that 3rd fan?...thanks for the help...Don
ps 4speed stick tranny

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