Msa Pulsar overheating

[adebaker1]

Hi everyone was at Blyton Rally day this weekend when my MSA pulsar started getting hot after 4/5 laps so had to keep letting her cool down before going out again!
I have just changed the original rad cap for one off one of my spare car's, it said 1.1 Bar on it. I took it out on the back roads flat out for an hour and half a tank of fuel later and temp never went above half way? Is she cured the old cap rubber looked iffy?

 

[fubar andy]

From what you've mentioned it sounds like you've sorted it. However for track work I would change the following:

Rad cap (new would be best)
Thermostat - new (not the housing, just the internals)
Check rad, see how corroded it is.

That should iliminate any real overheating issues.

 

[Jon Olds]

I posted a thread years ago discussing the pulsar cooling design. Not sure it was ever properly discussed. (Or I didn't understand the answer!) My application is MSA tarmac also, where you are basically at full throttle everywhere, except when you are on full brakes. The average speeds on rallies is quite low. At full chat, the intercooler does a good job of pre heating the air into the rad, unlike anything you would see on the road. The radiator sits at roughly the same level as the top of the water level in the head. The rad is not full of water (most VW's are and bleed continuously back to the heater tank, so keeping the rad full). The stat is near the top of the head and needs water level to open it.
Should the water level drop a small amount, for any reason;
The stat is starved of water, tends to close
The top of the head (the hottest part of the engine!) tends to be starved of water
The system has no expansion tank.
Any over pressurisation tends to lift the relief in the cap
I'm hoping someone is going to put me right on the system design and enlighten me on how good it is
Jon