Cooling system caps
#1
Join Date: Feb 2017
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Hi everyone,
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
#2
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Hi everyone,
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
Spring pressure cap on overflow tank
Walter
#4
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#5
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#7
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On the Jaguar, the blanking cap is at the highest point on the coolant circuit and is used for filling the engine with coolant. Whne cold this should be completely full with about 1/2" gap from the top of the blanking cap so you can see the two pipe apertures. One of these pipes goes to the expansion tank that has the pressure cap on it. When the coolant warms up it expands and passes into the expansion tank. On cooling down, the liquid is drawn back into the engine. When filling afresh, a small amount of coolant is added to the expansion tank, the Jaguar instructions tell you how much. Later expansion tanks were plastic.
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#8
#9
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Yes, you are correct. I also have an '87 and we have only the plastic expansion tank equipped with a pressure relieving cap. No other cooling system pressure caps. The expansion tank relieves to the overflow tank, located under the driver's side wing, which then returns coolant back to the expansion tank upon cooling.
#11
Join Date: Mar 2014
Location: Tehama County, California, USA
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Hi everyone,
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
I've started working on the cooling system, I removed the metal overflow reservoir tank because it's got a little leak that needs welding up (gosh there was some rusty metal that I shook out of the bottom of the tank!) my question is to do with the caps, I think someone has put the wrong one on the reservoir, it has the spring loaded one on the tank and on the engine filler (the main one) it has a flat cap, no thermostat, spring loaded. Which one should be on which? My gut tells me they are on the wrong way!
cheers
Scotty.
Your post reminded me of the 1969 Datsun roadster I used to have (part of me wishes I still had it), and the BRASS expansion tank, which needed soldered up once, but Never (of course) corroded!
![](https://cimg7.ibsrv.net/gimg/www.jaguarforums.com-vbulletin/640x480/p6010068_04c16c527b8ba54b986de201d8d7832f3a67c401.jpg)
Pressure cap on the tank, No cap on the rad (no room under that hood!)
Filling it was a rather tedious operation.
(';')
#13
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Yes, you are correct. I also have an '87 and we have only the plastic expansion tank equipped with a pressure relieving cap. No other cooling system pressure caps. The expansion tank relieves to the overflow tank, located under the driver's side wing, which then returns coolant back to the expansion tank upon cooling.
All rather a long time ago, like the late 80s. Funny, but i seemed to have a lot more energy then and would work in an unheated, freezing cold garage on the Jaguar. I must have been nuts !!