froggy
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| posted on 2/10/11 at 09:36 AM |
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mid engined coolant layout
now that the car is up and running i may have an issue with the cooling system . i need to vaccum fill it and have another bleeding session but it
seems to be struggling to flow properly as the pressure builds in the header tank at the back and once the front fans kick in the rad goes pretty cool
as if the coolant isnt flowing properly .
here is my plumbing which i used on the twin bike engine set up although the top hose at the front was above the top of the water level in the engines
at the back
looking at the elise and vx220 it doesnt look much different but i may have missed something , the only issue i can see is the bleed to header tank is
at the same level as the stat housing rather than coming from the top of the rad as it did in the donor car
the cap on the rad at the front is 1.1 bar and hasnt vented and it certainly seems like an air lock as the water temp is around 90c at the header tank
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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Adey1984
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| posted on 2/10/11 at 09:46 AM |
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I'd have a bleed at the top of the rad, looks like an air trap
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Fred W B
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| posted on 2/10/11 at 09:54 AM |
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Absolutely, you need a bleed from the top of the rad back to the header tank, no way at the moment for air to get out the rad. You can take it from
the neck just under the cap.
Cheers
Fred W B
[Edited on 2/10/11 by Fred W B]
[Edited on 2/10/11 by Fred W B]
[Edited on 2/10/11 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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froggy
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| posted on 2/10/11 at 09:59 AM |
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can the bleed follow the front to back pipes and still work properly ?
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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indykid
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| posted on 2/10/11 at 10:17 AM |
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quote:
Originally posted by froggy
can the bleed follow the front to back pipes and still work properly ?
I would have thought the first time it got any water in it, the air wouldn't be able to clear it unless you actively promoted flow through
it.
I'm not sure how effective your heater will be, but I guess it depends on the restriction of the downstream rad piping governing the pressure
differential between the rad pipes
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rachaeljf
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| posted on 2/10/11 at 11:31 AM |
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From that diagram you appear to be pumping coolant straight into the header tank. The coolant has nowhere to go except back to the head via the top
bleed pipe. If you have replaced the engine's belt driven pump with an electric one, the new one should pump into the original's inlet,
i.e. into the block.
The header tank bottom pipe should tee into the return pipe from the radiator, before the inlet to the pump.
You need a bleed nipple on the top of the rad somewhere. There is no need to provide a bleed pipe back to the header tank. You will need to open it to
fill the system, and maybe periodically open it to remove any trapped air.
The heater should take its feed direct from the head, i.e. not controlled by the thermostat. The heater return is ok as you have it.
Cheers R
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britishtrident
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| posted on 2/10/11 at 11:54 AM |
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Two header tanks is a no-no -- one header tank and one presure cap .
I you want the heater to work you need to plumb the heater in on the engine side of thermostat, to do this it must either fed directly from the head
or you can do what some MGTF and Lotus Elise owners have done, remove the existing thermostat and fit an external Rover/LandRover PRT thermostat
(sometimes called a PRRT) in the front compartment. If you search on PRT conversion you should find the info you require, the parts required are
a Landrover TD5 thermostat and a 32mm tee (as sold for fish ponds plumbing) both are available very cheaply off ebay
[Edited on 2/10/11 by britishtrident]
[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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froggy
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| posted on 2/10/11 at 12:22 PM |
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i used the filler on the rad to bleed the front end and the pipe from the water pump to the header tank is the same as the factory set up . the only
difference is the bleed to the header is coming from the head before the thermostat rather than from the top of the rad .
to copy the saab system i would need to run a bleed hose from the front of the car to the header tank and use the current bleed hose to get any air
out of the head with the stat shut .
one thing niggling me is the diameter of the hose from the top of the water pump to the header which may be fine in the saab with the short coolant
lines but it might be too long and the flow is going straight up to the header tank and may need a restrictor to force the coolant through the block
instead
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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owelly
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| posted on 2/10/11 at 01:25 PM |
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And another thought: Would the coolant take the easiest route through the heater matrix rather than the main rad? Have you tried fitting a restriction
into the heater hose (or clamp it with moleys).
http://www.ppcmag.co.uk
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froggy
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| posted on 2/10/11 at 02:31 PM |
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I put a cable operated valve in the inlet hose so I can block the line into the heater . Il try clamping the line from the top of the water pump to
the header and add a bleed from the Rad to the header tank . If I copy the saab layout and it still struggles to keep cool idling it must be flow as
the system
Is definitely big enough to do it
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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Trev Borg
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| posted on 2/10/11 at 05:27 PM |
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The mgf has a bleed on the rad, a bleed on on the heater matrix and a bleed on the engine coolant pipes.
When the system is filled, all three of these need to be bled to ensure there are no water traps.
Before you judge a man, walk a mile in his shoes.
By that time, who cares.
You're a mile away, and you've got his shoes
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britishtrident
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| posted on 2/10/11 at 06:47 PM |
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quote:
Originally posted by froggy
i used the filler on the rad to bleed the front end and the pipe from the water pump to the header tank is the same as the factory set up . the only
difference is the bleed to the header is coming from the head before the thermostat rather than from the top of the rad .
to copy the saab system i would need to run a bleed hose from the front of the car to the header tank and use the current bleed hose to get any air
out of the head with the stat shut .
one thing niggling me is the diameter of the hose from the top of the water pump to the header which may be fine in the saab with the short coolant
lines but it might be too long and the flow is going straight up to the header tank and may need a restrictor to force the coolant through the block
instead
You must have only one pressure cap or the system will airlock after a few cold starts. A cooling system pressure cap actually contains two
valves, the obvious one is the pressure relief valve but it also contains a vacuum relief valve to let air into the system when it cools and
prevent the radiator imitating classic crushed can high school physics experiment.
As to the bleed pipe from top of the rad it won't have any effect the same points are already connected by a bigger bore hose, as has been
already sugested all you need is a simple bleed screw at the top of the rad.
However the real problem is the thermostat is not getting flow around it when it is closed either connect the connection at the bottom of the header
tank to the bottom hose near the water pump or ditch the standard thermostat and fit a Landrover TD5 thermostat close to the rad --- as I already
posted loads of info on this in the Elise and MG owners websites.
As for vacuum filling it is not required all you need is to open the bleed points when filling run for a couple of minutes with them open, close
them let the engine cool top up and repeat the process a few times.
[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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froggy
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| posted on 2/10/11 at 09:12 PM |
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The pipe from the bottom of the header goes to the water pump and the vac point on the rad filler neck is blanked off so it's not drawing as it
cools down . I will alter the heater circuit to copy the Saab layout but the valve is closed at the moment so as long as it's bled it should
work , il do some more bleeding tomorrow
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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froggy
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| posted on 3/10/11 at 04:51 PM |
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clamped the bleed line from the heater outlet on the head which is before the thermostat and all is well now . hopefully i can live with the system as
it is with the header tank a good eight inches above the head it shouldnt give any issues.
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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