toofer

I`ve been having a overheating problem on my 1980 S. I have flushed the entire system twice, installed a radiator electric cooling fan kit, am running 50/50 coolant with water wetter. It will not overheat at an idle or while driving and keeping the RPMs below 3000. However, if I run it hard or keep RPMs up over the 3000 it will raise engine temp to last bar before going into red. I have never let it go into red, I always drop my RPMs and it cools back down. Sometimes, after driving it like I love driving it, high RPMs, and shutting off the engine for a couple of hours or less, when I restart there is a distinct dead miss for about 10 sec then smooths out. I`m wondering if I could have a very small leak in a head gasket between water jacket and exhaust valve. Or even worse a small crack in the head in same area blowing hot exhaust into coolant. Anybody ever had problems like these. If so I could use some help . Thanks, Toofer

toofer

Sorry I meant 50 coolant and 50 water + water wetter

mark kibort

if you have a headgasket leak into the water jacket, under high load, the water level will rise and push out the water and thats how it usually over heats.
sounds like you might have a water pump issue, could be the impeller is slipping on the shaft. (doesnt spin as fast as it needs to at the high rpms)

its a tricky one to diagnos. scots, which was a major headgasket leak, would only show itself on race day. However, the head gasket leak detection kit found the issue. (measures exhaust gases present in the over flow bottle)

mk

Jim bailey - 928 International

What happens if you turn the heater on HIGH HEATwhen the car is hot .? What turns on the aftermarket fans ? which thermostat are you using? , do you have an oil cooler ? , How is the oil pressure at idle when "hot" ? what oil do you run? How old is the radiator ?

mark kibort

all that jim says , and also check the lower radiator hose when its overheating to see if its real hot as well as feel the radiator top to bottom is it hot in all places or are there cool spots. probably a radiator issue.

ZEUS+

Follow Jim and Marks suggestions. A combustion gas tester is a great tool.
http://www.napaonline.com/MasterPage...F+Engine+Block
You could also pull the spark plugs after cooldown and check for coolant fouling. As engine cools and contracts coolant could leak in from the pressure. That could explain the miss on start up. Hope it's something else.

toofer

Wow, lets see, turning on the heater doesn`t change temp but does cool it alittle, AC fan controlled by Temp sensor at bottom of radiator on drivers side, kit came with temp sensor which is mounted on upper radiator hose and set to 160 degrees, I believe the themostat is 175 degree, oil pressure at idle when warm is about 3rd bar, when cold it is at 5 bars, radiator is new and yes it has an oil cooler. I think thats about everything, oh there feels like a very slight difference from top to bottom radiator hoses. I have been very deliberate in toubleshooting this cooling system over several weeks it took to test and replace parts. What or where can I find this "head gasket leak detection kit"? Hopfully with this info I`m providing you`ll get a better picture of my concerns that it may be a head or head gasket. Thanks for the help. Toofer

Jim bailey - 928 International

do you still have an A/C condenser in front of the radiator ?

toofer

Jim, yep still there.

mark kibort

If the hoses are different temps, there could be a circulation issue.
they both should be hot. Hot means the engine is gettting rid of the heat.

the kit is at any auto parts store.

Is the water level going up when you over heat? are you loosing water? is the oil getting milky looking?

those are the signs of a head gasket issue.


mk