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overheating

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dwnuk

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1958 MGA. tuned, carbs rebuilt, timing fine, correct cap, installed shroud, added electric fan (when switched on doesn't seem to decrease temp) wetter water. took out therm. At 40-45 mph runs at 185-190. At 60 runs at 205 to 210. City stop and go runs 205-215 when stopped in traffic. The car is driven in a moderate climate usually between 75 and 85. When car is shut off after a run temp goes to 225 plus. Replaced radiator 3 years ago. Looking for any suggestions.

thanks
 
When was last time engine itself was back flushed?
 
Dwnuk, Sounds like the added electric fan may actually be blocking the incoming cooling air.You did not say whether it is a puller or a pusher fan installation.---Keoke
 
\
HI, Mounting the fan in front of the radiator constitutes a pusher configuration.If the fan has insufficient power to force a high volume of air through the radiator it will cause heating at speed by blocking the incoming cooling air.---Fwiw---Keoke
 
Hello Dwnuk,

thermostat if you haven't already checked it, water pump effectiveness, which can be affected by old hoses but unlikely if you renewed the radiator. Correct specification radiator?
An electric fan, indeed any fan is not generally required when driving on the open road, forward motion gives more air than any fan.

Certainly circulation around the engine block is another valid area to check.

Alec
 
How's your ignition curve? Retarded timing will cause excess heat, and if your springs are worn (i.e. timing advance comes in too early) and you set the timing at idle, you timing will be retarded at speed.

Never run without a thermostat. You might consider fitting a thermostat in conjunction with a blanking sleeve:
https://mgaguru.com/mgtech/cooling/cool_103.htm

There are other interesting pages on that site -- poke around a little! ;-)

BTW -- I don't like to see my engine run less than about 200ÂşF.....

HTH!
 
have you checked the actual coolant temp with a known good thermometer? Gauges have been known to be incorrect.
 
The added fan - was that an aftermarket in addition to the MG fans or are you talking about them? If an addition, it'll do nothing except cause problems....the cooling system, when set up properly, doesn't need additional fans....problem now is getting everything set up.
 
I second the comment about adding a thermostat with a blanking sleeve! That alone could cure your overheating! You need to slow the water own as it goes though the radiator or the radiator can't absorb heat fast enough for it to be removed!
Jeff
 
[ QUOTE ]

BTW -- I don't like to see my engine run less than about 200ÂşF.....


[/ QUOTE ]
Really???......Mine doesn't like to idle well at that temp.
(And it makes me nervous) /ubbthreads/images/graemlins/eek.gif

A perhaps interesting footnote.....
I can almost tell what the ambient temperature is by looking at my gage and subtracting 100.
(for temps 65F and above) /ubbthreads/images/graemlins/yesnod.gif
 
Think the good book says like 180-190 and that's hot enough thanks.
 
Depends on which book you're referring to. You want to run the engine as hot as is practicable. Running it too cool makes it wear quicker, make less power, and burn more fuel. Peter Burgess (MGB tuning guru) in his book "How to Power Tune the MGB 4-Cylinder Engine" says "The ideal 'stat is 88 degrees Celcius (190F) ." The late, great Smokey Yunick says:
[ QUOTE ]
" It is easy to see how overheating can be a problem, but I think some racers overlook the fact that it is possible to 'overcool' the engine. Some guys go to great lengths to keep the engine temperature down to 180 degrees. And, though the engine doesn't overheat, they don't realize that they're putting energy (heat) into the cooling system that could be used to produce power at the crankshaft.
Running the engine at 180 degrees will drop the overall horsepower by 2%-3%. For max power the cooling temp should be at least 200 degrees...."

[/ QUOTE ]


With a 50/50 mix of coolant and water and a 16 psi radiator cap, you won't overheat until the other side of 265ÂşF....
 
[ QUOTE ]

Running the engine at 180 degrees will drop the overall horsepower by 2%-3%. For max power the cooling temp should be at least 200 degrees...."

[/ QUOTE ]
Coincidently.....You can increase hp 2-3% by taking the fan off. /ubbthreads/images/graemlins/grin.gif
 
/ubbthreads/images/graemlins/iagree.gif However Jeff, the blanking sleeve really does not slow the flow of water down in the cooling system.What it does is block off the bypass port so that all the water in the system is routed through the radiator for cooling.Lacking this sleeve, a portion of the coolant will be passed thru the pypass port and never gets processed correctly leading to higher runing temperatures.---Keoke
 
Off the wall comment. These electrical fans are usually set up as pullers, that is to mount it between the radiator and the engine. To use the fan as a pusher, you reverse the fan and reverse the pos/neg wires. Are you sure both were done when you fan was mounted?
 
Surely one 'pushes' from in front of the radiator and 'pulls' from behind it ... no?
 
[ QUOTE ]
Surely one 'pushes' from in front of the radiator and 'pulls' from behind it ... no?

[/ QUOTE ]

-----Wakatai yo!---Keoke- /ubbthreads/images/graemlins/grin.gif
 
/ubbthreads/images/graemlins/grin.gif
 
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