David Jenkins
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| posted on 8/9/03 at 08:39 PM |
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Hot coolant!
OK - now that my engine's running, it's getting too hot. After running for 5 minutes or so, the temperature gets up to 100C and water
starts venting out of the pressure cap overflow like there's no tomorrow. The engine block is hot (obviously), but the radiator is cold - the
top hose is cold, and the bottom one is starting to get hot from the pump end. The water being vented isn't particularly hot.
My guess is that water expansion in the block is pushing water back up the rad and out of the vent.
For those that don't know, it's a 1660 X-flow. The plumbing is very simple - hose from bottom of rad to the pump, and top of the rad to
the thermostat housing/pressure cap. One other smaller pipe from the secondary pump connection to the inlet manifold connector. No auto choke
connection or heater.
My first thought was that the thermostat was knackered, but I've just tested that with a pan of water and a thermometer, and everything is up to
spec (starts to open at 88C, fully open at 100C, opens about 10mm).
Any suggestions? Air lock somewhere? Simply got too much water in, and it's venting the excess?
Where should the water level be when cold?
and finally,
What temperature should I see when it's ticking over on my drive?
cheers,
David
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Stu16v
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| posted on 8/9/03 at 08:53 PM |
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Symptoms indicate either a) knackered thermostat, or b) air lock.
As you have effectively eliminated the thermstat then it sounds like you have had an airlock around the thermostat area, so it hasnt been emersed in
water, and subsequently hasnt opened.
When refilling, try loosening the top hose at the thermostat, to allow trapped air to escape. I guess that this is probably the highest point in the
system now, except for your expansion tank......
Dont just build it.....make it!
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stephen_gusterson
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| posted on 8/9/03 at 10:02 PM |
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when I had a 2 year old ford fiesta in 1978, whenever it was drained and refilled with water it always threw a wobbler and boiled over. Once it had
done that and was topped back up, it was fine.
I put it down to an air lock.
Sometimes just squeezing the hozes with the cap off can help....
the expansion tank being the highest point is important I think - you dont have an issue with a 'high' section of piping trapping air?
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David Jenkins
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| posted on 9/9/03 at 08:06 AM |
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The highest point is the Fiesta-style thermostat cover, which is ideal.
I think I'll try filling the block, then putting in the thermostat, fixing the cover and topping up the rest.
How high should the water level be?
cheers,
David
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Deckman001
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| posted on 9/9/03 at 08:14 AM |
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David, if the highest point is the thermostat, you'll need to make sure it is imersed in water to work properly, fill it up slowly making sure
you squeeze the hoses to try to force out the airalso try (carefully) to run the engine without the stat cover on to make sure the stat lets water
past it
Hope it helps
Jason
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Rob Lane
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| posted on 9/9/03 at 08:21 AM |
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Forget testing the thermostat that way, it simply doesn't work properly. Gives duff results.
Could be an airlock, can you bleed at highest point of system? Cap on rad should be at highest point or a secondary filling point on an expansion
bottle fed from top of rad is needed to vent air and get water level above engine.
Could be pump, they can snap impeller shaft and leave rest still turning. Rarish though.
Overfilling would spill out when hot but only after rad etc is up to temp.
Check cap poundage, I used a 15lb cap and an overflow bottle with bleedback.
I also had bleed screw in stat cap top.
I still believe it's the stat, with airlock maybe as well. Common on Xfows.
Testing 1 :-
Stats are cheap items, just cut off the bridge and remove the gubbins leaving just the plate. Fit the plate and refill. Test engine, it should now
circulate and actually run cool.
Testing 2 :-
Go out and buy another stat and fit it.
I've had these things duff straight from box though.
Testing 3 :-
Check with cap off rad or whatever and check for circulation when revved slightly. This only works if stat is open.
Car should run at around 90 as a steady temp.
Rob Lane
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David Jenkins
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| posted on 9/9/03 at 10:56 AM |
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Rob,
That gives me a few options to play with!!
A few answers to your comments/suggestions...
The thermostat, cap and pump are all new. As you say, that doesn't mean they're right, but lessens the chance of them being wrong.
When I tested the 'stat I used a thermometer from the laboratory where my son works... supposedly 0.5 degree accuracy... well, I got 103 degrees
in a boiling saucepan! (and I did have the correct amount of thermometer in the liquid). This does put a question mark over my tests, but the error
would be the 'stat opening early rather than late.
Test 1 is probably the next move - will probably do test 3 at the same time. Obviously, this will lead to test 2!
Many thanks,
David
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David Jenkins
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| posted on 9/9/03 at 01:47 PM |
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Matter of interest - do I have to hack to pieces what may be a perfectly good thermostat?
Can I just leave it out - or does it form part of the water-tight seal around the cover?
cheers,
David
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jollygreengiant
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| posted on 9/9/03 at 02:10 PM |
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David, Just a quick cheat that is some simes used in the garage trade where vehicles are known to suffer air-lock problems around the thermostat. Take
a small drill bit (1.0mm max) and drill a hole in the the thermostat plate to allow air to pass through. Some thermostat manufacturers build a small
air bleed into the thermostat anyway.
Enjoy.
And thermostats control the flow of water around the cylinder block, no thermostat = hot spots in the cooling system
[Edited on 9/9/03 by jollygreengiant]
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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David Jenkins
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| posted on 9/9/03 at 02:23 PM |
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Thanks, JGG.
Another course of action to try...
David
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Rob Lane
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| posted on 9/9/03 at 03:48 PM |
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I'm not suggesting leaving stat out but just for the test purposes. Cover will seal with a gasket without stat in.
I can't remember where I got my stat cover from but I had one with a small water pipe outlet which I drilled and plugged and used as a bleed. Can
just be seen in pic below.
I'm sure it's air related and just needs bleeding out.
 
Rescued attachment CamCover.jpg
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Rob Lane
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| posted on 9/9/03 at 03:52 PM |
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Wow, forgot how nice that Xflow looked with Webers on.
I've remembered now, it's a Fiesta stat housing with electric fan switch on top. The small pipe was removed and a thread cut in for a
plug. You could also loosen the fan switch to let out air as a last resort.
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stephen_gusterson
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| posted on 9/9/03 at 06:48 PM |
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I thought all thermostats had (or used to have) approx 2mm hole for air bleed with a 'jiggle pin' in it.
a jiggle pin was a small split pin to keep the hole from furring up.
atb
steve
ps - I recon 1mm hole might be too small and the water meniscus might not break through it.....
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jollygreengiant
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| posted on 10/9/03 at 09:25 PM |
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quote:
Originally posted by stephen_gusterson
I thought all thermostats had (or used to have) approx 2mm hole for air bleed with a 'jiggle pin' in it.
a jiggle pin was a small split pin to keep the hole from furring up.
atb
steve
ps - I recon 1mm hole might be too small and the water meniscus might not break through it.....
Most thermostat used to come with jiggle pins but now due to manufacturing cost and the relentless cost savings by accountants most come without.
As for the hole size you are not wanting water to flow through it but you do want the air to flow through thus reducing the risk of air locks before
the thermostat opens.
Enjoy.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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David Jenkins
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| posted on 10/9/03 at 09:31 PM |
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I've now drilled the hole (just over 1mm) and re-fitted everything, and it seems to have done the trick (although I haven't run the engine
yet  )
I got a remarkable amount of air through the hole when I topped up the system, and a whole lot more when I squeezed the hoses...
At the end, all I got were ripples in the water, so now I know that there's no air under the 'stat.
cheers to all,
David
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Mark H
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| posted on 12/9/03 at 12:39 PM |
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David,
As you are aware, I've got a 1660 xf. On tickover (to answer your quenstion earlier on) the temp with fan on sits at 85 degrees. On a run it
doesn't get any hotter (unless I forget to turn the fan on in traffic, or at the SVA centre).
Hope this helps.
Mark Harrison and
Q986 KCP back from the dead...
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David Jenkins
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| posted on 12/9/03 at 12:53 PM |
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Thanks to Rob and Mark
I now have a good idea what's normal - btween 85 & 90 degrees.
cheers,
David
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Peteff
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| posted on 12/9/03 at 02:01 PM |
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Just had the same problem.
Bottom hose went the other week and I replaced it. Got home and stopped the engine, it was like Mt Etna. I ran it while I filled it up after it had
cooled and it's been alright since. If you run it with the rad cap off you can see when the stat opens and the level drops as the block fills to
the top.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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David Jenkins
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| posted on 12/9/03 at 02:11 PM |
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Pete,
In my case the stat probably wouldn't have opened - I think I probably had an inch or so of air under it. The temp gauge was in the water, but
not the stat's wax capsule.
As I said earlier, I shifted a lot of air when filling after re-fitting the drilled stat! 
cheers,
David
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