2 litre Zetec, plumber as per Paul Toyne, except I have T'd the two small outlets together and run them forward as one. No thermostat, just a thermostat plate so effectively an open thermostat all the time. 1.8 Escort water pump so I hope it turns the right way.

Mostly runs fine at 75-90 degrees C. But lately has started to quite rapidly get very hot, 120 degrees or so, especially when idling stationary just after a run. This temperature does fluctuate a little, and fairly rapidly.

Today it did it again, with a bit of tappet noise, possibly thogh cos I'd just come round a corner fast and surged the oil. Fan did not cut in, but it did run when on a rolling road Saturday, with o overheating problems.

Took the header cap off - a bit of pressure but no fountain. Dunked finger in - warm but not very hot. Top pipes and radiator pretty warm but not boiling. Loosened the thermostat housing - fairly hot water out but didn't feel boiling.

Ran a few seconds with the cap off - plenty of flow coming through the small top hose, pretty warm but not bad to put a finger in, few bubbles coming through.

Bled everything thorougly yesterday so if there's any air in there it isn't locking. There's a temperature telltale on the end of a water gallery which hasn't gone over 100.

So I'm a bit confused. The sender is new, but could it be the guage? Could the water pump be pumping the wrong way - which way should water flow and how can I tell? Could there be a strange intermittent blockage somewhere?

Thanks all,
Bewildered.

i dont think the heater matrix pipes should be linked in with radiator. they should be joined to each other and thats it.

Have you got a good earth on the gauge and sender?

Just checked the earth and they're fine, 0 resistance.

It may be I suppose that now Ihave effectively two pointless bypass pipes, since there's no thermostat, I'm just pumping water round the pipes rather than through the rad - ie out of the 2 bypass pipes, down to the bottom of the rad and straight in to the pump again. Does anybody blank these off completely?

My heater outlet and bypass both go to the bottom hose. Why no thermostat? Use the thermo housing as designed by Ford and you get quick warm up and constant temp. I run a 93 deg thermostat and my fan cuts in at 99 deg after a few mins of idle. My rad sits slightly higher than the engine so air can get trapped in the top, but just bleed it with the small pipe outlet in the Polo rad.

Overheated once before with a thermostat and Tiger told me they don't reccomend fittting a stat, and they don't find thermostats to their cars.

Running without a thermostat kills engines.

Stick a Landrover remote thermostat in the top hose and connect the 3rd connection back to either the by-pass or "T"it into the bottom hose.


This thermostat opens on flow pressure as well as temperature so you get fast warm up and coolant flow when you gun the engine.

I must say that after talking to Jim on Tigers stand at a show I'm not surprised.... Modern engines need to run at the correct temp, not sure how they do this without a thermostat.

Interestingly the resistance to earth of the gauge is much higher with the lights on. Which is interesting.

Here's how it's plumbed now. I suspect a lot of flow is just going round the bypass, ie following the blue arrows, and thus is missing the rad completely. Should I block one or both of the bypass pipes? What's the best way to do this?


Plumbing

That's the same as mine, heater and bypass connected to bottom hose "T" piece, big pipe to rad top connection. The only difference is the header tank connects to the small outlet on the thermo housing and the big one connects to the bottom hose. this means the system fills from the bottom up and pushes the air out. Also I seem to remember the thermostat blanks off one of the smaller pipes as it opens, but i cant remember 100%.

Thanks. Have you got equal diameter pipes running from the small outlets, or have you reduced the size of the hose hat normally supplies the heater?

I have mine conected in a similiar way, the small hose on the exhaust side goes to the bottom hose Tee piece and the one on the inlet side which normally feeds the heater is blanked off the header tank is teed into this bypass hose.The thermostat shuts the bypass hose from the head when it opens routing all the water through the top hose and rad.With no thermostat it will be flowing though top hose and bypass at the same time which could cause it to bypass the rad when hot.
Paul.

Thanks. Thermostat going back in then!
Ed

PS what have you yoused to blank the inlet side hose hole off with?
ta

[Edited on 2/3/09 by edspurrier]

My small heater hoses are the same size, one is quite tight!

Thanks. Ironic that I've tried to fix an imaginary overheating problem, and created a real one.

I fitted a short length of hose and then turned an ally plug to fit it and secured it with a pipe clip.
Paul.

quote:

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Originally posted by edspurrier
Thanks. Thermostat going back in then!
Ed

PS what have you yoused to blank the inlet side hose hole off with?
ta

[Edited on 2/3/09 by edspurrier]

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Thanks, I'll do same. Though I wonder - if the heater side bypass is always open, why not run a small diameter hose from that to a T in to the radiator top hose? That way there would always be a little flow through the rad, even if the thermostat failed. Though would take longer to warm up.

brother in laws 2 litre zetec kept showing it was running hot he had an airlock in the thermostat/ sender housing housing got rid of the aurlock all fine now.

Sorted, hopefully. Abandonded the heater side bypass hose which is now blocked off. Ran it to warm with the cap off to get the air out - makes a good bubbling noise when the stat opens and air comes out of that side of the system! and all seems oK. Bit of tappet rattle from No1 initially, which was drawing a bit less air than the others, but balanced and running sweetly so don;t think I've mangled it by overheating.
Flush air out of rad tomorrow.
Thanks all
Ed