Raceline water rail, Zetec engine and overheating.

[chris_cussen]

My experiment to determine if the fan was coming on when the engine was getting hot was documented in another thread Got-puzzled continued with the engine getting hotter.
I have a Zetec engine with a Raceline water rail to move the location of the thermostat from the rear of the engine block to near the front of the engine.

Experimentally I ran the engine without a thermostat and the overheating didn’t happen. So I tried to contact Raceline to find out exactly which thermostat they used, but failed by both telephone and email to get any response. However my local motor factors measured the old one an then next day the replacement turned up.

Thermostat fitted and off for a test drive. This time dramatic overheating! Strangely the top hose was cold and so was the radiator. When it cooled down I removed to top hose and it was full of water, so I dismissed the idea of it being an airlock. I removed the thermostat and returned home, engine staying cool.

Expecting the new thermostat to be defective I dropped it in hot water, and it opened fully. Weird!

I compared the two thermostats and noticed the old one had a small hole drilled in one side. So I drilled a 5mm hole in the new thermostat on hey presto! –engine runs at the right temperature.

Without the hole there is no water flow past the thermostat so it is sitting in cool water and never opens. With the hole there is sufficient flow for it to warm up and open.

So, Zetec enging + Raceline water rail + new thermostat requires a 5mm hole in the edge to work.

[greyV8pete]

Re: Raceline water rail, Zetec engine and overheating.

The 5mm hole will be an air bleed, they sometimes have a jiggle pin in them to act as a sort of shut off valve once the coolant is flowing. Without the hole in the new thermostat I am guessing you had a major air lock in the water rail. The thermostat should be fitted with the hole at the top to ensure max air can escape.Peter.

[b_caswell]

Re: Raceline water rail, Zetec engine and overheating.

If you read the blurb on the Raceline site this is what it says
During the warm-up phase a small by-pass hole in the thermostat allows some water flow, so preventing local overheating.

[Ye Ol Ripper]

Re: Raceline water rail, Zetec engine and overheating.

A useful tip with the Zetec engine.
Because it is notoriously difficult to bleed airlocks in fiestas and the 1.7 Puma is to carefully release the screw thread pressure cap on the water bottle to let the pressure escape 3 or 4 times.
This forces the water around the system. This is done at normal idling speed and there is no need to rev the engine up whilst bleeding. Then once hot water is circulating through all the pipes, allow to cool for 2 hours and then top up the water reservoir level , it may then take another 3/4 litre. Ensure you are using a 50% mix of red concentrated antifreeze with distilled water or the dearer way of using ready mixed .

[Dane_Rescueman]

Re: Raceline water rail, Zetec engine and overheating.

Hi, it's a red herring from me....
With my Pinto it is easy, when in a hurry, to fit the thermostat the wrong way round. I've done it once and others may have done.
The capsule has to be towards the block. Just maybe your theromostat is inserted so that it's capsule is towards the radiator and not the cylinder head (via the water rail).
If the Pinto thermostat is inserted the wrong way round, hot coolant can't reach the capsule with an overheat situation as the result.
Just trying to help. The Pinto thermostat has a microscopic brass pin valve in that little hole you report. It must be there to prevent airlocks too.
I hope you sort it out soon.

[chris_cussen]

Re: Raceline water rail, Zetec engine and overheating.

Yes its all sorted, the hole did the trick.
The raceline water rail is machined so that is is nearly impossible to put the stat in the wrong way round.

[milliemarlin]

Re: Raceline water rail, Zetec engine and overheating.

With the pinto and zetec thermostats mounted in the block circulation of the water will ensure that the thermostat is at a similar temperature to the engine. With a remote mounting the hot water needs to circulate thought the rail to warm up the thermostat. The hole allows that circulation without significantly reducing the engine warm up.
Paul