header tank

289, FIA & Daytona topics
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agnoraan
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Re: header tank

Post by agnoraan »

Whilst driving in free air. Mine has always run around the 70 deg mark, its only when I get into slow moving or stationary traffic that the temp rises to 90 deg and then the fan cuts in and holds that temperature. Once running back in free air again the temp drops back down to 70 deg within a mile or so. It's been like this since I've owned it (just over a year now). I've had quite a few V8 SD1's and they've always run at 90 deg regardless of traffic conditions. I've never been able to understand why this engine normally runs so cool, any thoughts?
Nige
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agnoraan
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Re: header tank

Post by agnoraan »

Forgot to say that mine runs a standard SD1radiator, Edelbrock intake with a 390 Holley carb. I dont notice any surge in temperature whilst driving it.
Nige
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David Large
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Re: header tank

Post by David Large »

peterc wrote:David,
Do you get a surge in temperature a mile or so after demanding extra power to overtake or race up a hill. I believe this is caused by the thermostat being a long way away from the temp sensor on the Eldebroxk Rover manifold. I didn't think that having a straight thermostat outlet would change that.
On a level cruise at 65 mph my temp can drop below the 82C of the stat so I'm definitely getting enough cooling.
Peter C
Peter,

I don't recognise the symptoms you describe; my car behaves exactly as Nige describes. So if we are in very slow moving or stop start traffic on a particularly warm day then it struggles to cope.
If I accelerate to go faster for any reason then the engine runs cooler.

I did struggle on the Stelvio pass last year when it dumped a fair amount of water. It doesn't like altitude

I run an MGB GT V8 radiator

David
David Large
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peterc
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Re: header tank

Post by peterc »

I didn't have an over heat during the 30 mins queuing to get into the Cranleigh show. Although I do confess that I switched on the manual override to the fan when the temp rose to 90C as a precaution and on this particular occasion when half way into the grounds we put on the heater fan to keep the temp below 94C. The temp actually went down at that point so we switched the heater off after 5 mins. The carb did get a bit fluffy towards the end.
I have been less concerned over the slow moving issues than the temp fluctuation during normal driving involving changes in power demand.
Maybe having 270bhp from a 4.6 has something to do with it. I don't think the routing of the top hose has any part to play.
Peter C
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Post by catsx11 »

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David Large
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Re: header tank

Post by David Large »

peterc wrote:I didn't have an over heat during the 30 mins queuing to get into the Cranleigh show. Although I do confess that I switched on the manual override to the fan when the temp rose to 90C as a precaution and on this particular occasion when half way into the grounds we put on the heater fan to keep the temp below 94C. The temp actually went down at that point so we switched the heater off after 5 mins. The carb did get a bit fluffy towards the end.
I have been less concerned over the slow moving issues than the temp fluctuation during normal driving involving changes in power demand.
Maybe having 270bhp from a 4.6 has something to do with it. I don't think the routing of the top hose has any part to play.
Peter C
Peter,

I don't think that having 270bhp from a 4.6 has anything to do with it. My car has always behaved the same with the original 3.5 litre engine and with my current 240bhp 4 litre engine. I suspect that there is alway air in my system because of the routing of the top hose and this is not good.

David
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Paul Blore
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Re: header tank

Post by Paul Blore »

If you lift the front of the car as high as possible on axle stands, does that help to expel any air from the system?

Paul
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Roger King
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Re: header tank

Post by Roger King »

My system, to original spec, is particularly difficult to fill. Best technique is to fill the header tank, then top up using the highest point you can achieve - which in my case is the input hose to the heater, disconnected and held up above the scuttle. There is an air bleed screw in the rad top hose, so I fill via the heater until water comes out of the top hose air bleed.
I always make sure any thermostat has two 1/8" holes drilled in the base plate, one at the top and one at the bottom. But this is AC's production system, obviously - not modified.
An interesting note from the 'Ford Cobra Guide' of 1964 which Peter Adams kindly introduced me to is contained in the list of things SAC did to cars on their arrival at the Shelby works for engine installation. One thing they did routinely was to remove the 195° thermostat and substitute a 160° (a modification confirmed by Dan Case in the US, 'original' owner for over 40 years). I've done this with mine and it seems to have made a difference to running temperature, although this has not yet been tested in heavy traffic on a hot day.

Roger
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Re: header tank

Post by peterc »

I have checked the position of my top hose with a spirit level hence the mod to fill the header tank to the brim by having the overflow. I also have a blead point in the heater top hose to ensure air doesn't get trapped in that circuit. I'm now pretty happy that there is no air in the system with the higher level of water and the blead point.
I also run with a 5mm hole in the thermostat to ensure air can get past and out from the manifold and will also provide some degree of flow to help the temperature sender register earlier.
Converting Rogers quoted temps that's 195F to 90C and 160F to 71C seems quite a low temp for the thermostat setting. I have not seen anything lower than 82C which I have fitted.
As already related the temp can get below 80C when the engine is in a steady cruise and I don't demand loads of power.
It's surprising we all have slightly different views on the higher temperature subject even with just considering the Rover engine set up.
Peter C
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Roger King
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Re: header tank

Post by Roger King »

peterc wrote:I have checked the position of my top hose with a spirit level hence the mod to fill the header tank to the brim by having the overflow. I also have a blead point in the heater top hose to ensure air doesn't get trapped in that circuit. I'm now pretty happy that there is no air in the system with the higher level of water and the blead point.
I also run with a 5mm hole in the thermostat to ensure air can get past and out from the manifold and will also provide some degree of flow to help the temperature sender register earlier.
Converting Rogers quoted temps that's 195F to 90C and 160F to 71C seems quite a low temp for the thermostat setting. I have not seen anything lower than 82C which I have fitted.
As already related the temp can get below 80C when the engine is in a steady cruise and I don't demand loads of power.
It's surprising we all have slightly different views on the higher temperature subject even with just considering the Rover engine set up.
Peter C
I'm talking Ford, or more accurately AC as manufactured using Ford components. And it's worth remembering that because the thermostat opens at 71°C, that doesn't mean the engine is running at that temp. It means simply that the whole cooling system is now in play as things get hotter (which they do).
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