Supercharged coolant system woes

[graham]

Is it possible that the solid gasket is preventing you from bleeding the system properly? There could be trapped pockets of air (hotspots) immediately under the top face of the block.

[David.H]

I have a Rover 12 tourer and when I got it it overheated at the drop of a hat (never mind a flag!) Investigation showed no thermostat! This caused exactlly the situation of water going through too fast. New stat fitted - problem solved (until the radiator clogged up near solid with crud when I really started using the car! Then a new core fixed it permanently (I hope!) It has a water pump....and flushed waterways.

[Colin Reed]

HI SAM,
Where does the copper pipe from the top of the radiator go to

[Cliff Ringrose]

Davids experience with the Rover is exactly what led to my solution. Talking to one of the 750F drivers about my overheating he mentioned that with the OHV Reliant engine they used to remove the thermostat, but always replaced it with a disk with a smaller hole to restrict the flow, otherwise the coolant did not have time to do its job, leading to a sudden hot spot and rapid and drastic overheating.
Cliff.

[NBS]

Hope you get it sorted Sam Good luck.

[Charles P]

Please do report back on how you fix it

Charles

[Dirk73]

Hi all, many thanks for the replies

After scrutineering on Friday I had some time to test the flow of the system and add bleed screws to the pipes around the pump. Unless it was bled properly the pump often had an airlock and so I thought that might have been the problem as Ian suggested. 

With the radiator removed and the pipes setup to draw water from one large bucket and return it to another, the flow was around 60gph at 1500rpm, rising with more revs. 
I did test runs up and down a hilly road on Sat morning to see if it had improved, the air temp was cool (5 degrees) and i couldn't get the rad temp to go over 50 degrees. 
We did 5 qualifying laps on Sunday morning before it boiled and the same in the race. 
My conclusion is that it needs a deeper rad core & I'll get one made up that sits lower and has an integral header tank. 

I don't know if Circuit de remparts invite A7s every year but I would certainly  come back again if they did. 

The logistics of getting all the race cars and fuel/spares etc into the city centre is a bit fraught but the circuit itself is fantastic and I feel privileged to have been on it (albeit briefly!) 
Sam 
(aka Dirk73)

[Cliff Ringrose]

Sorry to hear that your woes continue.
At the risk of harping on, did you try my suggestion of restricting the flow out of the engine? A theory that seems to be bourn out by Davids' experience.
The symptons you have, and the remedies you are trying, are exactly the same as I had twenty odd years ago.
I had an alloy header tank made that almost doubled the water capacity. No effect whatsoever. More in hope than expectancy I fitted a very short length of smaller dia. hose into the return hose. No cost at all, and instantly reversible if it didn't work.
It did work and finaly ended over a seasons worth of frustrating dissapointment.
Cliff.

[Steve Jones]

Discussion at Harewood on Saturday about a similar problem on a similar car in the past came to the same conclusion as has Cliff, above. In that case, the coolant was moving around the system too fast and failing to remove heat from the engine. A restrictor in the system solved the problem.

Steve

[Mark Dymond]

60gph sounds marginal, I make that 0.3W/degree of cooling capacity, I may have made a calculation error but if not, this means a 100% effective radiator can only remove just over 20KW of heat. Can someone check if this is correct?