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Author: Subject: zetec silvertop heat soak ingf after trning off hot?
baz-R

posted on 19/5/16 at 05:53 PM Reply With Quote
zetec silvertop heat soak ingf after trning off hot?

i have an od issue with my 1800 zetec silvertop install

i have no running cooling (80-88c driving 95 traffic and fan running) issues and am piped up the same as this without the rad bleed pipe as i dont require it with my type of rad
the heater matrix port is blanked on the std zetec stat housing




if i drive the car exessively hard (track session) and slow down and turn off the engine will boil without the engine running and temp rises also the engine stays quite hot when i turn off after traffic driving and reluctent to turn over on restart

i think i have some kind of thermo syphon issue?
anyone else had same kind of issue?

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britishtrident

posted on 19/5/16 at 08:05 PM Reply With Quote
There is no obvious reason why that setup shouldn't work. Not an unkown problem although this is the first time I have heard of it on a Zetec Heat continues to get rejected to the coolant after the engines is stopped however with normal coolant the system shouldn't boil untill about 120+c
One thing I would do is check the ignition timing through the full RPM range if the timing hasn't got sufficent advance more heat will get rejected. The other thing I would do is a cold pressure test on the full system including the pressure cap, the pressure cap should lift between 1.4 and 1.8 bar and reseat quickly when the pressure falls back withing the working range.

Next on the list comes the simple modification of drilling the thermostat
Acid cleaning the system with citric might help.

If none of the above work you can consider fitting a timer on the fan and a small auxilary electric water pump.





[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]

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big_wasa

posted on 19/5/16 at 08:09 PM Reply With Quote
It's how I plumbed mine.
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baz-R

posted on 19/5/16 at 08:29 PM Reply With Quote
is putting out about 175bhp at the crank N/A and is happy and cool whith the engine running. its done abot 4k including a track session and a few hillclimbs so cant be anything too serious.

mabe its a bleed pipe blocked or somthing i will have blow it all through.

i didnt know if blocking off the heater matrix would effect anything?

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baz-R

posted on 19/5/16 at 08:34 PM Reply With Quote
quote:
Originally posted by britishtrident
There is no obvious reason why that setup shouldn't work. Not an unkown problem although this is the first time I have heard of it on a Zetec Heat continues to get rejected to the coolant after the engines is stopped however with normal coolant the system shouldn't boil untill about 120+c
One thing I would do is check the ignition timing through the full RPM range if the timing hasn't got sufficent advance more heat will get rejected. The other thing I would do is a cold pressure test on the full system including the pressure cap, the pressure cap should lift between 1.4 and 1.8 bar and reseat quickly when the pressure falls back withing the working range.

Next on the list comes the simple modification of drilling the thermostat
Acid cleaning the system with citric might help.

If none of the above work you can consider fitting a timer on the fan and a small auxilary electric water pump.



its all been set up on a dyno so has the optimum advance at all loads and rpms i also have a rover header tank and no problems with any coolent loss

fan is set to run with ign off so keeps it on until fan swith cools down

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Kdempsie

posted on 19/5/16 at 09:32 PM Reply With Quote
Could the header tank cap be leaking and unable to hold the pressure with the post stop heat soak?
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02GF74

posted on 19/5/16 at 09:56 PM Reply With Quote
Draw arrows on yer picture to show flow.

Hot water should enter top of radiator if you have headers top and bottom.





Visit China. Meet the child that made your trainers.


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baz-R

posted on 19/5/16 at 10:37 PM Reply With Quote
quote:
Originally posted by Kdempsie
Could the header tank cap be leaking and unable to hold the pressure with the post stop heat soak?


thats a good point i hadnt thort of that i might even have one that opens too early and venting to alow boiling!

im using a rover expansion tank form a rover 45 diesel i think and i undrstand you can get a few diffrent pressure caps

i have PCD100160 as a part no for one of the caps but cant find out what pressure rating it is?

anyone know what pressure caps are avalble for rover tanks?

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britishtrident

posted on 20/5/16 at 06:56 AM Reply With Quote
Cold pressure test to cap blow off pressure then see if the pressure valve cap in the cap reseats when the pressure falls to 0.1 bar below the blow off pressure. Also the vacuum breaker in the cap it cools relieves the vacuum as it cools.

OEM MG-Rover X-Part caps have a reputation for sticking once they lifted and only reseating once the system returns to ambient, caps sold by Halfords have a good reputation in MGF and MG TF circles.





[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]

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baz-R

posted on 20/5/16 at 02:40 PM Reply With Quote
i can hear hissing as it sucks the air back in on cool down somtimes and used the old cap i got on the tank so i will just get a new one
there only abot 5-10 quid so will just bung one on and flush it out

there are a few diffrent pressures apperntly 1bar upto 1.4bar 1bar is quite common but i need to find out what the 1.4 bar is from to get a new one

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baz-R

posted on 24/5/16 at 09:47 PM Reply With Quote
i got a new cap for 2.98 inc vat (Blue print make) identical to the orignal inc part no. cast in, the sealing washer looks like its made from a different rubber?

pressure relief should be 1 bar and i cant find any higher ones?

ford ones are 1.2bar for this engine so i hope it isn't too low!

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