32 replies to this topic

[AGRO_RB]

Drove from Christchurch Airport to Dunedin last weekend, 356km, and from the minute we got up to motorway speeds my motor started running hot. Most of the time it would sit at about 3/4 on the factory clubman gauge but would creep towards the red sitting in traffic and climbing hills. Towards the end, which was all uphill, the car had boiled almost ALL of its coolant out of the overflow. I had fitted a 74 degree thermostat, rad cap and auxiliary electric fan the night before the trip and topped everything up with 50/50 coolant and let it run up to temperature with the cap off, no air bubbles. On the last 300m before we got home the gauge shot into the red again and the motor cut out on us, it isn't seized but there was a strong smell of burning oil and smoking around the tappet cover. We let it cool, started it first flick of the key as usual and drove it to the house where it's been sitting since. What could be causing my problems? I've got no tools anymore so can't do a compression test or get the head off for a look. With the motor getting so hot will this have done lasting damage? I really can't afford a rebuild or another engine at the moment due to redundancy and have just sold my 1275 to pay the bills. I bought the car with a fairly neglected cooling system (full of rusty tap water) and being my daily driver I never got round to inspecting anything else I.e. Waterpump. Heater tap is permanently open and the car is fitted with an aftermarket heater. Motor is a standard 998 with bypass hose in a '73 Clubman.

[AGRO_RB]

Forgot to add we had to top the radiator up every 20 mins or so of driving.

[grumpy dad]

Hi

is the rad cap the right presser ?

[Ethel]

I'd add an oil change to your plans, getting that hot won't have done it any favours permanent damage will depend on whether the oil broke down and allowed metal on metal contact, oil pressure will give you a hint. Two options spring to mind: a faulty pressure cap, or other leak, that led to it boiling over and losing the coolant; a blown head gasket sucking the coolant in and blowing it out the exhaust. I suppose a general lack of cooling capacity (sludge) or a stuck closed thermostat are also worth looking at.

[AGRO_RB]

Brand new 74 degree thermostat, brand new 7lb cap, the old one.was 7lb as.well.

[AGRO_RB]

Also no steam from the exhaust but the coolant does smell of hydrocarbons...

[jedduh01]

Rusted out water pump impeller, or stuck bum New thermostat.  Top hose getting hot while overheating?

[AGRO_RB]

Top hose was ROASTING, couldnt touch the radiator, cooling system WAS pressurising but no pressure at the cap after coolant had boiled.

[Carlos W]

I'd flush the cooling system!

Perhaps its full of sludge from being neglected!

Also worth getting the timing and mixture checked!

For an extra bit of cooling in these situations you can always chuck the heater on!

[Vipernoir]

First thing I'd look at is the brand new rad cap.

 

There has been a dodgy batch circulating that are not deep enough to seal - the rubber seal on the end of the spring doesn't reach the inner seal face of the radiator.

[jime17]

Should the rad cap not be 15lb?

[Ethel]

They may all look the same but there are a lot of old style metal pressure caps. It sounds like it'd have to be pretty bad to be the head gasket so you might see bubbles/ fumes in the top of the radiator, or the pressure rising prematurely with a (working) cap fitted, squeeze the top hose to test.

 

The heater is also a good indicator for nursing an overheating engine, if it goes cold it's time to stop & add water!

[AGRO_RB]

Coolant flush and waterpump will be the first port of call I think. How do you know if the.caps dud? Tested the thermostat in boiling water and it opened fully, no issues there.

Any recommendations for coolant flush? Remembering we mostly get US and Aussie brands over here. There doesn't seem to be any excessive bubbling in the filler neck to suggest a blown headgasket, I'm hoping a good flush, new radiator (I'd rather just use a performance 2 core than the 40 year old original), water pump, hoses, a functional heater tap and some more quality coolant will see me right. Is 50/50 premix ok or should I look at something else? It's Prestone coolant, which certainly isn't cheap stuff.

[firstforward]

Why did you fit a 74 Degree stat, did you already have some overheating problems?

[Dan]

Yes the cap should be 15lb, and are you are the new aux fan is blowing the right way? Is the mechanical fan still in place?