K Series Overheating. CC Stumped. POBC Help!

[charlie_pank]

@Klonko - now that new information has come to light about water blowing past the expansion tank lid, I would suggest the following:

 

1. Check the operation of the thermostat in a pan of water on the stove

2. Check the operation of the fan thermistor in a pan of water on the stove

3. Check the fan works by shorting the thermistor terminals

4. Check the operation of the water pump - perhaps turn it by hand while the thermostat is removed and check for water flow through the radiator?

 

My guess it will be one or more of options 1,2, and 3. If it's not then perhaps a massive airlock was caused by blowing coolant past the expansion cap (I'm assuming you topped it up again once it had cooled down, NOT while it was hot?). I think once those caps have blown, they have to be replaced - otherwise they don't pressurise the system properly.

[Mr Locust]

Engine coolant flows from the head through the top hose to the radiator and returns from the radiator to the engine through the bottom hose. The thermostat is at the engine end of the bottom hose.

 

Coolant from the head also flows from the head to the bypass circuit via the heater (where fitted) and returns to the engine at the thermostat housing (under the inlet manifold/tb's).

 

If everything is working and the temperature is up to 'normal' the top hose and the bypass hose (before heater) should be at the same temperature.

[Bumble]

Hi Ken,

 

Yhm

 

Bumble

[Piers Rendell]

I too have an R300K with CC Throttle Bodies. Two weeks after getting the car on a run down to Goodwood, I got into a traffic jam on the M25 in summer time. The temperature climbed right up and the engine stated to miss fire and loose power.

 

Once I got going after the jam caused by an accident, the temperature whent down to 70 ish and the engine them ran smoothly. CC found that the water Temp sender was faulty and the fuse to the cooling fan had blown. I had thought that the engine ran very cool, but it was a duff sender.

 

The point I want to make is the poor running when very hot and the normal running when cool, but I am no expert on this engine.

[Bio]

Try changing the temp gauge sensor and fit a new stat (Caterham 74 degree R500) or Halfords 82 Degree.

Ensure that the stat has a 3.00mm hole drilled in the flange.

The fan should cut in and out, if not test the fan by shorting out the wires at the rad switch and ensure the rad is completely full by removing the top rad bleed bolt and filling from there.

 

John

[Kevsta]

I'm no expert - but if collant is blowing past the cap then the pressure in the system is getting bl00dy high! It must therefore be because something is being added to the coolant system to cause such an increase in pressure (I appreciate heat will cause expansion of the water but as it is a pressurised system it cannot boil up and add air?). So could it not be that you have HG problems and as temp rises and you use the engine with more guts the blow by the cyclinder is passing air into the coolant and expanding it (thus pushing the water out of the cap as the combustion pressure is say 130psi)?

 

Have you/CC tried a compression test? Is there a way of turning the engine over on the starter and taking a pressure reading of the collant system to see if the coolant system is going up in pressure (which would therefore be coming from the combustion chamber).

 

Not sure if the above helps or not but thought I'd add to the ideas...

 

Kev

[Kenno]

I think it's the fact it's so intermittent which is proving difficult to troubleshoot.

 

They've put a new tank cap on, bled the system and removed some coolant pipework which I'm told is unnecessary.

 

Hoping it may have been an airlock and I pick the car up next Saturday. Time will tell I guess.