Overheating!!

 my 1989 eunos 1.6 had problems last year which Geoff Walton correctly diagnosed as thermostat, housing and water pump. They got replaced last March and car was fine since then…till last week

 

same thing again rising temp off scale, no heat or air coming through heater , water going all over engine etc etc

 

after a couple of days of messing cleaning tubes/pipes etc and making sure water flowing through system when engine running a mate said run engine for 20 mins with rad cap off and rad topped up to top. I did and water looked like pan of water coming to boil, this also revealed nothing was leaking

 

today car is fine, I’ve done 4 10 mile journeys with no prob on temp gauge, no water coming from header tank and full heat and air out of heater blowers

 

does this sound like I had an air lock or something?

Yup.

 In one word, Yes. Those are the symptoms of an air lock.  I remain puzzled as to how it happened out of the blue though?!?

My last sporty car - a GTM K3 had a radiator at the front and was mid-engined.  I had some overheating on that and replaced some parts and was reminded (although I had previous experience with previous cars) that its important to ensure there is no air trapped in the system. Some owners even fit a bleed valve to the cooling system on GTM’s

 this should be best case scenario for me the cos I didn’t fancy a big bill as I’m selling up soon

 

it shouldn’t have caused lasting damage

 

would it be a good idea t get a full coolant change done and oil change perhaps as oil pressure reduces wit hhigher engine heat?

Hi Simon

I think the air lock is most likely, if you want to be sure it’s all out, put the front of the car onto a set of ramps, or something to get the front of the car in the air, so that the rad filler is higher than the heater matrix. Run the car with the rad cap off, as you have done, when the water starts to really swirl in the header tank, squeeze the top hose, be careful not to scald yourself with the water. The squeezing causes the water to pulse in the system thus dislodging any air locks that are stuck in the water passages etc.

All engines run a little lower oil pressure when the engine is hot, caued by the oil thining slightly when hot, nothing to worry about