E Type Cooling

[fareaster]

I have had a series 3 V12 E Type for the last 20 years. It has always had a tendency to blow water out of the header tank overflow after a run even though coolant temp never exceeds middle position on the gauge when the fans kick in. I keep the coolant level at the weld seam half way down the header tank to allow for expansion. For the record the engine has been rebuilt (about 10,000 miles ago) and the radiator replaced.
I have done a sniff test (negative) on the coolant, there is no oil in the water or vica versa so I assume the head gaskets are OK. I have also replaced the radiator cap (with standard 13 psi)
Next on the agenda is to flush out the cooling system and replace the thermostats and hoses.
I am also considering replacing the radiator cap with one with a higher blow off pressure (15/18 psi).
What is the PH experience here, would I be masking a problem by fitting a higher pressure radiator cap?

[a8hex]

What happens to the temperature after you switch off? It sounds like your boiling the coolant after turning the engine off, at that point the water pump stops running, even if you've got your fans wired to keep running even with the ignition turned off. My XK150 does this, although I've not seen it pouring water out at this point, but the gauge certainly goes off the top if I'm not careful.
I usually turn the engine off for a while and then wait for the temp to get high and then start her again for a few seconds to pump some fresh water into the block and then turn her off again and all is OK.
I tempted to fit a small auxiliary water pump so that the water can be circulated while the engine is not running but the temp is still above the level where the fans kick in. I've been considering the Davies Craig unit for this.

[fareaster]

There is some heat soak after I switch off, the temp gauge rises slightly and the fans kick in for a few minutes (I leave the ignition switch in the aux position so they can)

[lowdrag]

When the engine was rebuilt was the block properly flushed through? My early 3.8 always dumps water, no matter what, after the engine is turned off in summer, so I think nothing of it. I wouldn't go higher than 13 lb for the cap unless you take advice on the hoses because you are risking blowing a hose otherwise. Mine originally had a 4lb cap but with modern hoses I use a 13 lb one now, but it still blows out water.

[fareaster]

The engine was rebuilt by Ron Beaty, sadly I can no longer call him up and ask him whether he flushed the block, given his experience I’m sure he did. The replacement hoses I intend to fit are 3 ply silicon rated to 70 psi, so shouldn’t be a problem. Don’t know what the current standard hoses are but given the fact that these are about 8 years old now I wouldn’t use the uprated cap with them.
I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

[lowdrag]

Personally, I'd just live with it and avoid risking the pressure causing damage elsewhere. I've never known an E-type not to dump water, (and I've had mine and been a club member 28 years) and when she over heats - yes - people always point out I've got a radiator leak. Every now and agin I top up with neat antifreeze to compensate.

[a8hex]

fareaster said:

I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car…….

Because everyone knows you're supposed to have an oil puddle under a old Jaguar

Edited by a8hex on Wednesday 17th November 17:34

[jagracer]

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

[Toma500]

Try some Water Wetter availiable on Ebay and Frosts makes a noticeable difference lowers temps by as much as 10 deg and faster warm up alot of us TVR lot use it.

[Bozwell]

there are a couple of small pipes that run next to the top hoses on the V12 that are quite often blocked up where they join the head. because they are small bore it doesn't take much. the hoses are usualy ok , it's the metal pipe in where it joins the head that blocks up from a build up of gunge/ corrosion. i think these hoses are air bleeds so only flow a small amount of coolant but obviously when blocked the system will have air trapped constantly. also you are not overfilling the expansion tank are you?

[RW774]

Check the header tank cap ring isn`t worn out, which would give the symptoms of a weak cap.It doesn`t take much. I`ve had the problem on many Jaguars.Imagine how many times the cap is removed over the years and its` only a ramped brass securing ring.Rad specialists normally don`t bother to change the neck unless you stipulate it.Remote header tanks made from brass , most people don`t give them a second look. Don`t increase the cap pressure for goodness sake .If the ring is worn it won`t make any difference.

[fareaster]

a8hex said:

fareaster said:

I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car…….

Because everyone knows you're supposed to have an oil puddle under a old Jaguar

Edited by a8hex on Wednesday 17th November 17:34

Got one of those too.....

[fareaster]

Bozwell said:

there are a couple of small pipes that run next to the top hoses on the V12 that are quite often blocked up where they join the head. because they are small bore it doesn't take much. the hoses are usualy ok , it's the metal pipe in where it joins the head that blocks up from a build up of gunge/ corrosion. i think these hoses are air bleeds so only flow a small amount of coolant but obviously when blocked the system will have air trapped constantly. also you are not overfilling the expansion tank are you?

You mean the the pipes that run from the header tank to the water jacket under the inlet manifold, I'll check those, thanks.
Interestingly the manual says fill the tank to the top, I don't, I only top it up if it drops below the weld seam halfway down.

[fareaster]

jagracer said:

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

Not too much - 100/200 cc's.
Don't think that would work, the cap plunger only lifts to allow coolant to blow off when the system pressure exceeds 13 psi. When the engine cools the the pressure is below that and the plunger closed. If I used a cap without a plunger then it would work but the system would be running at atmospheric pressure and have a lower boiling point.

[jagracer]

fareaster said:

jagracer said:

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

Not too much - 100/200 cc's.
Don't think that would work, the cap plunger only lifts to allow coolant to blow off when the system pressure exceeds 13 psi. When the engine cools the the pressure is below that and the plunger closed. If I used a cap without a plunger then it would work but the system would be running at atmospheric pressure and have a lower boiling point.

Pressure rad caps have a two way valve so they will draw water back. When my engine was regularly getting very hot I used a 5 litre bottle with a bit of water in the bottom as an expansion tank, it would always draw the excess water back when it cooled.

Edited by jagracer on Thursday 18th November 09:32

[fareaster]

RW774 said:

Check the header tank cap ring isn`t worn out, which would give the symptoms of a weak cap.It doesn`t take much. I`ve had the problem on many Jaguars.Imagine how many times the cap is removed over the years and its` only a ramped brass securing ring.Rad specialists normally don`t bother to change the neck unless you stipulate it.Remote header tanks made from brass , most people don`t give them a second look. Don`t increase the cap pressure for goodness sake .If the ring is worn it won`t make any difference.

Initially that was an issue insomuch as one of the two closing tangs was bent and not hooking up when I closed the cap (hope you understand what I mean). Net result was, as you suggest, a weak cap. On the old cap the sealing ring was missing effectively increasing the blow off pressure – kind of two wrongs making a right…. Both now corrected.
On the subject of wear I measured the plunger height and the neck depth and there is some compression there but not having access to specs I don’t know whether it’s correct.
Given the excellent feedback I’ve been getting, don’t think I’ll be increasing the cap pressure. If I use silicon hoses I’m sure they would be capable but just for the sake of discussion what other component in the cooling system could be compromised by doing so?

[fareaster]

jagracer said:

fareaster said:

jagracer said:

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

Not too much - 100/200 cc's.
Don't think that would work, the cap plunger only lifts to allow coolant to blow off when the system pressure exceeds 13 psi. When the engine cools the the pressure is below that and the plunger closed. If I used a cap without a plunger then it would work but the system would be running at atmospheric pressure and have a lower boiling point.

Pressure rad caps have a two way valve so they will draw water back. When my engine was regularly getting very hot I used a 5 litre bottle with a bit of water in the bottom as an expansion tank, it would always draw the excess water back when it cooled.

Edited by jagracer on Thursday 18th November 09:32

I' m looking at my rad cap as I type this, can't see any evidence of a two way valve, it's a simple plunger and spring. I'll have a look around and try and find the cap you mentioned

[lowdrag]

Perhaps he's thinking of modern cars that have expansion tanks. I know many people put a Renault 5 expansion tank on the picture frame with a modern two way radiator cap. That way it's a sealed system and expands and contracts as necessary.

[jagracer]

fareaster said:

jagracer said:

fareaster said:

jagracer said:

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

Not too much - 100/200 cc's.
Don't think that would work, the cap plunger only lifts to allow coolant to blow off when the system pressure exceeds 13 psi. When the engine cools the the pressure is below that and the plunger closed. If I used a cap without a plunger then it would work but the system would be running at atmospheric pressure and have a lower boiling point.

Pressure rad caps have a two way valve so they will draw water back. When my engine was regularly getting very hot I used a 5 litre bottle with a bit of water in the bottom as an expansion tank, it would always draw the excess water back when it cooled.

Edited by jagracer on Thursday 18th November 09:32

I' m looking at my rad cap as I type this, can't see any evidence of a two way valve, it's a simple plunger and spring. I'll have a look around and try and find the cap you mentioned

On the rubber sealing ring is there a round metal plate that looks like it is holding the rubber ring in place, if there is, while holding the cap can you lift this metal ring away from the rubber seal? I've arrowed the bit I mean in the picture

Edited by jagracer on Thursday 18th November 12:36

[fareaster]

jagracer said:

fareaster said:

jagracer said:

fareaster said:

jagracer said:

fareaster said:

I’ve actually tie wrapped a plastic bottle to the lower fan support stay and routed the overflow pipe into it to collect what is blown out.. I did this so I could monitor just how much it blows out and because I got fed up with having the p#ss taken out of me by fellow classic car club members about the puddle of coolant under my car……. Every so often I empty it back into the header tank.

You could put a small amount of water in this bottle and run the pipe into the water, when the engine cools it will suck the water back into the header tank so you need never worry about pouring it back. How much does it blow out?

Not too much - 100/200 cc's.
Don't think that would work, the cap plunger only lifts to allow coolant to blow off when the system pressure exceeds 13 psi. When the engine cools the the pressure is below that and the plunger closed. If I used a cap without a plunger then it would work but the system would be running at atmospheric pressure and have a lower boiling point.

Pressure rad caps have a two way valve so they will draw water back. When my engine was regularly getting very hot I used a 5 litre bottle with a bit of water in the bottom as an expansion tank, it would always draw the excess water back when it cooled.

Edited by jagracer on Thursday 18th November 09:32

I' m looking at my rad cap as I type this, can't see any evidence of a two way valve, it's a simple plunger and spring. I'll have a look around and try and find the cap you mentioned

On the rubber sealing ring is there a round metal plate that looks like it is holding the rubber ring in place, if there is, while holding the cap can you lift this metal ring away from the rubber seal? I've arrowed the bit I mean in the picture

Edited by jagracer on Thursday 18th November 12:36

You are absolutely right it does lift, my apologies. If I'd thought about it properly I would have realised it has to be there to allow air back into the system to prevent the hoses collapsing when the engine cools.
It is not, however, drawing back coolant into the header tank even though the drain hose is immersed in the expelled coolant in the bottle. Reason could be that the bottle is some 45cms below the header tank and the vacuum generated is not suffcient to raise the coolant that amount. It might then work if I can relocate the bottle to just under the header tank cap, how far below was your bottle?