K Series Radiator, Expansion tank venting?

[7 Sevens]

Hi All,

 

I thought I would ask for some opinions on my K series following an excellent trip to Spa on Monday

 

Engine is a 1600 with Piper Cams, Throttle Bodies and Emerald running at a verified 160bhp. Prior to the trip I replaced all the water hoses and topped it back up with 5.1litres of coolant as I also have a heater. So should have avoided any trapped air by getting the correct amount back in.

 

I was running the car for about 7-9 lap sessions with water temp at a consistent 80c increasing to 90c by the last lap. Oil was also up around 80-90c at the end so no indications of running to hot.

 

However at the end of the Kemmel straight when I was pulling near top revs I had a splash of coolant come out of the bonnet vents and onto the Brooklands screen. It’s also out of the front side skin and all over the inside of the engine bay. I thought it was coming from the expansion bottle cap that may have vented under extreme load but tricky to say. I certainly didn’t have any hose leaks and over the course of the afternoon I had a few more runs as I was barely losing any coolant in the tank. In fact it only appeared to be doing this on the Kemmel and under extreme load.

 

So has anyone had a similar experience/symptom? Could it purely be the cap venting under extreme v max load? Should the cap do this or should I replace that and the tank? Would it be worthwhile upgrading the radiator to an Ali one to minimise heat build up? Is it the start of something else and I should be doing some preventive maintenance? Thoughts?

 

[grumpy the 7th]

Mark, hi

 

Coolant tastes sweet doesn't it

 

I hope it's not the dreaded K series HG failure symptoms 😔

 

Mine used to 'blow' coolant from the expansion tank out of the bonnet vents BUT only after giving my car the fullest stick I could muster. ie a long session of constant 6k+ revs. I renewed the header cap, then thermostat and even the water rail ball bearing valve thingy (pipe from top of header tank to rail under fuel rail) All to no avail.

 

A new HG was the only way I cured it

[7 Sevens]

Hi Roger,

 

Thanks for the reply, I was being to wonder if mine was the only one doing that. It sounds very similar as the two points were at the end of Kemmel and entering the Bus Stop so under full loads. Perhaps and fingers crossed it wouldn't happen during less vigorous driving conditions.

 

I had a full face helmet on but could still taste the lovely mix of coolant and brake fluid

 

I think I'll probably replace the cap and gasket and see if that resolves it. Time to draw up the winter to do list.

 

[TomB]

I bloody hope for your sake you wern't leaking brake fluid at Spa

[grumpy the 7th]

Quoting 7 Sevens: 

I had a full face helmet on but could still taste the lovely mix of coolant and brake fluid

 

I hope you meant the taste of hot brake AROMA 😬not fluid

[7 Sevens]

Not leaking/pouring fluid as now that would be scary. Pedal remained good throughout as I've got a high grade AP fluid in it.

 

However it was sweating fluid out of the fluid reservoir/cap during heavy braking. I've been told that's not unusual on a number of the race cars. Going to replace the reservoir as well in case its starting to fail.

 

Besides, isn't the trick to a fast time is keeping off the brakes