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Triumph TR6 - Engine Overheating

The engine in question went back together last August. It's been moderately modified, and I opted for an electric fan for cooling. I had no problems late last summer and all through the winter.

I've just converted to a triple Stromberg set-up and ironed out the bugs with carb needle valves so mixtures are good and all is syncronized.

Now the engine is running hot, and all of a sudden. The funny thing is that even though the gauge shows hot, if I burp the radiator cap, only a small amount of coolant flows out to the bottle - maybe 1/3 cup.

I changed out the thermostat (160 F), but that didn't make much difference. I'm now thinking of replacing the 4 month old temp sending unit as it may have gone bad.

Beyond that, the next plan is to pull the thermostat again, put the housing back together, and run the car to see if there is good circulation from the pump. Anyone know if the impeller can come off if the engine backfires and spins backwards when shutting down?
Brent B

Arrgh - I had an awful thought. Blown head gasket. But wouldn't that give out lots of gas/ steam while running?
Brent B

Hi Brent

Take the car to a rad shop or garage and have them test the actual coolant temp. It just takes a minute with the proper meter.

Pick a small one and buy them a coffee even if they charge you. They paid for the trick tools. Mine was $165.00 Canadian almost never use it. Always good to make friends with trick tools when you are on a quest?

Then you know where to start.
If the sender is shorted it will go high.

Bill

Bill Brayford

Brent
I presume u have a 50/50 ratio of water/antfreeze. I can not see the temp sender going south that quick and think your pump will not spin off...open the cap at cold start car ..is coolant circulating (after it warms up to open the t-stat)? I run with a bottle of water wetter in the rad...this will make engine run cooler. Do you have a new or old rad?
Rick C
Rick Crawford

Thanks, Rick. I run a 50/50 mixture, and even have about half a bottle of Water Wetter in there. I'm going to retorque the the head, then do the test you describe. One thing I did stumble across, the goof that reworked my radiator last year painted it AND the fins. That paint may be a problem for 2 reasons - poor thermal conductivity and the extra thickness of the fins, while not much, would restrict air flow a bit.

The head gasket is going to be the last resort, so might as well try a new sending unit. Then pull the radiator, get some paint stripper, and go after the radiator.
Brent B

Brent, the paint is not your problem. The paint is
there only to seal the copper from the elements so
that it does not corode. The colour black radiates
heat faster than any other colour so is the perfect colour for a radiator. As Bill says, get an accurate
reading on the coolant temp while running.
190F - 200F is where you want it. If it is hotter than
this then consider putting the mechanical fan back on
as well.
Chris
Christopher Trace

Ok. Retorqued head. Cap off start & warm-up shows coolant circulates fine. No unusual bubbles were noted.

Changed the 7 psig radiator cap to a 13. Took a drive. All was well for 10 minutes, then it started to overheat. I pulled off the road at a convenient point, depressured the cap, and saw bubbles. Probably not air.... looks like a head gasket change is in order. Better not be a cracked head, dammit!
Brent B

This thread was discussed between 15/04/2003 and 16/04/2003

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