Mk1 Interceptor Engine Temperatures

[Joseph]

Yep, tried that one....Thermostat in or out gives the same temperature readings on the gauge.

I can't remember what's in it at the moment but for the sake of a few quid I'll order a new high flow 160

Cheers

Joe

[Kevin Birch]

It sounds like timing, if it was ok until it was tuned. I set my timing as per the book, and got it spot on, 5 degrees advance at tickover, with 38 degrees maximum advance above 2500 revs, with both vacuum and mechanical advance working as they should. The car lost power, and the temperature just kept going up and up. Increased the advance by a couple of degrees at a time and the power came back in and the cooling went back to normal.
If you mark the distributor position before you start, then slacken the clamp and turn it abou 3 or 4 degrees clockwise as you look at the top of the distributor, you will advance it. take it for a spin, and see what happens, and if it improves just keep advancing a couple of degrees at a time until the engine starts pinking. Easy to do and easy to put back. Its a free fix if it is the problem and saves all that messing around with flushing etc.

Kev

[Basil McKinley]

Having a free flowing system can actually cause a bigger problem, because the water flows so quickly it spends less time in the radiator getting rid of heat. It also picks up less heat in the engine so you can run hotter. A long time ago you could buy a large washer to go in place of the thermostat on a Mini in auto parts shops for this very reason.

My understanding is that the thermostat or restrictor maintains a higher coolant pressure in the engine (between pump discharge and thermostat) which increases the boiling point of the coolant. This helps minimise the formation of steam which is an insulator that inhibits heat transfer from the engine to the coolant. So a thermostat should always be used.

With regard to coolant flow rate through the radiator it is true that the higher the coolant flow rate the lower will be its temperature change through the radiator. This however does not mean that less heat is rejected. The overall rate of heat transfer from coolant to air is directly proportional to temperature difference between the coolant and the air passing through the radiator and this will increase with higher flow rates. The heat given up by the coolant as it passes through the radiator is proportional to the coolant temperature change between inlet and outlet, the mass flow rate of coolant and its specific heat capacity. With higher flow rates the coolant temperature change is less, but this is more than made up for by the increased mass flow rate of coolant. The same principles govern the heat transfer between the engine and coolant within the engine cooling passages,

Regards,
Basil

[Joseph]

Sorry it's been a bit slow but work's been getting in the way of tinkering, but I have a slight update on this one...

Replaced with a new high flow 160 thermostat - let it idle whilst watching the temp gauge - went up to just above N and then dropped back and stayed in the happy zone - thermostat working fine then. Took it for a 30 minute drive through town so only speeds of around 0-20mph and the gauge kept creeping up until it was approaching the hot zone again. So it looks as if the problem was not with the thermostat. Yesterday however I advanced the distributor by around 5mm (difficult to tell degrees) after marking the original position. Just twisting it you could hear the engine sound sweeter, tickover was a bit higher but it just sounded 'happier', I pushed it a bit further and it sounded even better (although the tickover raised again slightly), so not wanting to push it too much with the first test I took it back to the first 5mm advance and took her out for a drive.

What a difference! It's really hard to tell with Interceptors as there is never a shortage of power, but the car just seemed more responsive and eager at low revs - I wouldn't say it felt any faster, but just different. Anyway, went to pick the mrs and kid up so a 20 minute drive with the gauge just siting above the N as it used to do, but then a further drive of 20 minutes back it just didn't keep on going up and sat just above the N! I think we might have cracked it!

I'm not getting my hopes up just yet as it was a colder day and I have still to take it on a longer run where I can get up to speeds above 30mph but advancing the timing certainly seems to have made a difference.

I'll keep you posted....

Cheers

Joe

[Steve Payne]

Joe

I would suggest you get the ignition timing checked properly with a timing gun, adjusting it by ear is OK to get you going but you could still be running with not enough advance.

I have found some of these engines will take mid teens advance with no negative effect.

Steve