Overheating - Help!!

[Pointshape]

Ok, so I have just had my 72 Spyder conversion plus 2 returned after a 300 hour full body fix and respiratory.
Before it went in, it would run really hot so I had a new Coolex rad, new thermostat and fan put in whilst it was at the garage.
But it is still running really hot??
Even going along a straight road on a coldish day, it will constantly creep to over 100. The fan cuts in and pulls it back down to 90 degrees - sometimes 85.
But it will then go right back up to over 100 again and then be cooked by the fan and come back down.
The good thing is the fan is obviously doing the job but it must be putting a lot of stress on it and it will only be a matter of time before it gives up and I?m pullednup in the side of the road.
Is this constant up and down normal? Is there anything I am missing to keep it running cooler. I expect it to heat up in slow or static traffic but just running along why is it always doing this????

[mbell]

When you say Spyder do you mean zetec conversion or just chassis etc?

Have you tested your thermostat for operation?

Your symptoms could be just not enough coolant flow. Most likely cause would be thermostat that doesn't fully open.

Does your car have the foam strip on the underside of the bonnet? Is the "card" piece under the radiator in place?

With out these a lot of air flow could bypass the radiator and therefore limit the heat removed by the radiator.

[alan.barker]

Check temp with IR Thermometre to be sure what your seeing indicated at the dash Temp Gauge is correct.
Has the correct Temp Sensor been fitted in the Cylinder Head
Alan

[Concrete-crusher]

Something I missed a few years ago was the effect of timing on the amount of heat the engine generates, this might be worth checking.

My car still creeps up to around 100 in stationary traffic, but driving it drops to a steady 70-80

Steve

[Pointshape]

Yes, it the Zetec conversion, sorry!!
There is nothing directly underneath the bonnet. Do you have any pictures or know where I can get the foam?
Same with the card underneath the radiator - would you be able to expand on this?

[miked]

Zetec from original Ford installation have a two position dual port thermostat with bypass circuit to give a nice warm up graph line without a cold shock. Also fastest warm up for emmisions limitation and quicker heater operation. Being at the rear of the engine means that it usually gets omitted in a Lotus as it fouls the bulk head.
The units that replace this from some of the after market suppliers are usually not dual port. They are a simple rail unit with a standard stat. There is much discussion witin the Seven community about these kits. People having to drill holes in the stats with some happy with them and others not. Lots of arguement.
Check with who did the engine and what was done with the stat arrangement. Also what temp is the stat.
Paul Dunnell does a proper dual port kit for the Zetec which replicates what the Ford one did but in a nice tight space. Lovely kit but expensive. I have one that i fitted to a 2 litre silvertop. Runs at 90.
Not saying it is this but some more information for you about Zetec cooling. Lots of other things to check with the rad air flow and any items interfering with air flow.
Mike

[gus]

If the fan pulls it down to a normal temperature then it is not running hot

You fan thermostat is goofy

[miked]

Shouldn't be gathering temperature when car is travelling with adequate airflow through the nose.

[gus]

If the fan pulls it down it is not getting adequate airflow

Mine can get warm on the highway because I never put the foam around the radiator

[prezoom]

Miked is spot on with the cooling rail when utilizing a Zetec engine. I think the water rail from Dunnell is the only one that provides for the dual path thermostat. I personally did not like what was available from the vendors, and built my own, including the provision for a dual path thermostat. One of the reasons for doing this was the location of the rail itself, being directly above the exhaust manifold. Nice and tidy, but essentially a secondary heat source that had to dealt with. I also used a much larger radiator, desert living/driving, from wizard cooling.com. They offer a do-it-yourself kit, including all the needed parts, that allows you to place the inlet and outlet anywhere you want. I have a tig welder so the placement of the inlet/outlet/temperature sensor was no problem. Being of crossflow design, I also cut into the left side tank and installed a diversion plate in the center that turns the radiator into a dual path flow, with the water from the engine crossing over the top half of the radiator to the right side, then down and back to the left side to enter the engine. Sort of like having two (2) small radiators. Also, all air entering the nose of the car is either directed into the air intake box of the engine or through the radiator. No air bypasses the radiator into the engine compartment. The bonnet provides the seal at the top. Even the bracket that holds the Miata/MX5 electric headlight motor is part of the inward air diversion. The radiator being as large as it is, has the bottom set down in the nose in front of the steering, then tilting back towards the engine. The radiator cap is located on an expansion tank I constructed from aluminum. A single 12 inch electric cooling fan is located behind the radiator, pulling the air through. I also installed a plate below the steering rack mounts, utilizing the long rack securing U bolts, that reaches from the front crossmember/vacuum tank to the underside of the nose/body. This also blocks air from underneath, that can pass around the steering rack. It also helps to provide a low pressure area behind the radiator assisting more airflow through the radiator. I run a 192 degree thermostat and the engine temperature rarely exceeds 85c, and never above 95c, and does not fluctuate as the thermostat opens and closes as it does on my S2. The dual path of the thermostat seems to even out the changes in engine temperature.

[Pointshape]

Thanks for all these.
I do wonder how adding foam or an insulation level under the bonnet can help with overheating though.
Won?t it just make the engine bay hotter and worsen the heat retention around the radiator?
Would like to know more about the plate that should be under the radiator...

[mbell]

Items 24 and 26 on;
http://rdent.com/manuals/plus2/cooling_system/ka.htm

I made the lower one out of a sheet of abs plastic. Haven't done the foam yet (not having any issues) but is just plain foam probably 2" * 2" glued to the bonnet.

[Mick6186]

Hi,
The foam is a square section strip that is glued to the bonnet to close the gap between bonnet and top of radiator to ensure the air coming through the front of the car goes through the rad and not over it. The card flap at the bottom does the same thing,
Mick

[Pointshape]

Awesome - thanks for the info.
Does anyone have any pictures of where this foam goes and where I can get it?

[69S4]

Here's a link to the top foam -

https://paulmattysportscars.co.uk/product/foam-radiator-top-bonnet/