Nearly Boiled Over

[Al Milton]

Coming home from work yesterday (8 mile journey), the new Zetec nearly boiled over.

Fan was running (comes on at 90, but temp guage was just under 120 and climbing.

 

Got home, and a nice jet of steam was venting from the overflow, the water rail was dry (once it had cooled down).

Spoke to Richard at GBS and the outcome is:

Fit a larger rad fan (only got a 10" at present)

Remove thermostat and check it's working correctly, then drill additional holes around the circumference (there is a hole approx 5mm diameter there already) to aid better circulation.

Richard is also going to send down a new rad cap (20lb) to replace the existing 13lb cap.

 

Hopefully these will cure the issue, if not, then i'll probably remove the thermostat altogether.

 

Ah well, stops me burning my head in the sun

[Guest Deathbystan]

Is it a 2 stage thermostat? If it is, I wouldn't run it permanently without that in the system....it can cause hot spots in the water jacket.

[Al Milton]

Thermostat is off and appears to be working.

It is opening in a pot of boiling water.

According to the stamp on the bottom of the stat, it opens at 91 degrees.

It doesn't appear to be a 2 stage stat

 

Now need a new housing gasket as destroyed the one there to get the stat out - think it had been baked on!!

[Snapperpaul]

An earlier opening thermostat also gives a bit more leeway.

The 90 degree starts to open at 91 but takes a few more degrees to fully open

Try a 85 degree stat that should be fully open at 90 giving the rad and fan more of a chance

[Guest robinj66]

Al

I think I have a spare rad from a 1.8 Ford diesel van . I use this type on my S7 (2. and my Cobra. Let me know if you need it

[Al Milton]

Snapperpaul, the 85 degree thermostat makes sense, i'll hunt one down.

 

Robin, thanks for the rad offer, i'll bear it in mind if all else fails!

You never know, we may make it down to ponce a coffee

[steve in stockport]

I wouldn't want to be fitting a 20lb cap, all you're doing with that is hiding the problem by raising the boiling point with a higher pressure cap.

Have a look at other areas, make ducting to channel the air through the rad, air locks etc. You don't need a huge radiator if your system is well designed, I ran a very small Seat radiator, mounted at the front of the chassis in the full air flow and it cooled an EFI pinto and a 175 bhp red top in all traffic and weather conditions, even sitting in jams at over 35 degrees in France

[Guest robinj66]

Sorry Al - was possibly a bit too "relaxed" when i typed that

 

I meant a rad fan - blows a nice gale . You've got my number so give me a bell.

 

 

In fact i have a number of spare rads as well if you want one.

[fry61]

How many miles has your new engine done Al? Could be it's still a little too tight for welly; take some lead out your shoe.

[Andy Spencer]

Drilling a lot more holes in the stat will also mean your warm up cycle extends considerably, especially in winter. I have two 3mm holes and works fine.

I'd go for the lower stat first and see what happens, mine is an 85 degree.

[Guest mower man]

As above get a lower stat ,ensure air is going through rad core and also getting out from engine bay!,should cure your probs --mowerman

[Al Milton]

Lower stat collected (82 degrees), will fit this afternoon when I get home.

 

Bob, the engine has done about 400 miles now, but on the way home when the kettle happend was only poodling around 50 all the way then hit traffic in the town.

 

Mick, there is air coming through the rad, but a larger fan should improve things.

 

Steve, the 20lb cap was recommended by Richard at GBS. The cooling set up is currently identical to the GBS demo car

[Longboarder]

Before the raceline water-rail came along the common problem with zetecs was overcooling. The main problem with the raceline rail is the stat is remote from the block and not in direct water flow. There are tricks that reduce the effect of this but it remains essentially a bad thing.

 

Nigel

[Andy Spencer]

Before the raceline water-rail came along the common problem with zetecs was overcooling. The main problem with the raceline rail is the stat is remote from the block and not in direct water flow. There are tricks that reduce the effect of this but it remains essentially a bad thing.

 

Nigel

Agree with Nigel as always, but don't lose faith. I've been running a raceline rail since 2006, many thousands of miles with no problems at all. 85ish degree stat, two 3mm holes drilled. Enough to get flow for water to open stat, but also warms up to stat opening within 3 or 4 miles, even in winter. Runs at just around 90 degrees on the move, will sit in a traffic jam with fan cycling on / off and sit at about 100 in the hottest weather conditions, less when cooler or in winter. Doesn't use or lose coolant. It can be done, but as Nigel says a bit of trickery required to overcome the design and principle shortfalls.

[Al Milton]

Nigel / Andy, the cooling system was fine until Wednesday just gone, guess it was just one of those things, but I was glad it happened close to home.

 

82 degree thermostat fitted this evening (with a couple of 4mm holes for good measure).

Engine warmed up on tickover nice and steady, reached 90 degrees and the fan cut in.

 

A few drips from the overflow but was not overly concerned, however......

Blipped the throttle, then a few spits then a couple of small pours.

The small pours co-incided with blipping the throttle, so I am leaning towards the rad cap failing (or failed), or the cooling system over pressurising (but I really don't want to be going there yet).

The rad cap is a 13lb cap, which equates to around 0.9bar, so will try a 15lb cap (about 1.02bar) to see if this alleviates.

This sort of ties in with Richard sending down a 20lb cap as in my first post

 

Off to Halfords in the morning (trade card in hand of course)