S2 4.2l expansion tank cap
#2
the higher the cap pressure calibration, the more pressure buildup before it opens. That is what I have been told.
For example, my '65 3.8 engine came from the factory with a 4lb. radiator cap, then it was "factory updated" through a Service Bulletin to 7lbs., to avoid blowing up the radiators of the 1960s I suppose.
12lb. seems to me like a better radiator cap calibration, not 15lbs. not 13lbs.
For example, my '65 3.8 engine came from the factory with a 4lb. radiator cap, then it was "factory updated" through a Service Bulletin to 7lbs., to avoid blowing up the radiators of the 1960s I suppose.
12lb. seems to me like a better radiator cap calibration, not 15lbs. not 13lbs.
#3
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,929
Received 10,989 Likes
on
7,216 Posts
Higher pressure = higher boiling point.
From memory, at 15 psi a 50/50 water/coolant mix will boil at 258ºF at sea level. A 13 psi cap would lower that to about 250ºF. It's all a bit academic since our engines typically run in the 180º-210ºF range and we pull over to the side of the road (well, most of us) long before reaching boil-over point.
15-16 pounds is almost an industry standard; very common since the 70s on most cars.
Cheers
DD
From memory, at 15 psi a 50/50 water/coolant mix will boil at 258ºF at sea level. A 13 psi cap would lower that to about 250ºF. It's all a bit academic since our engines typically run in the 180º-210ºF range and we pull over to the side of the road (well, most of us) long before reaching boil-over point.
15-16 pounds is almost an industry standard; very common since the 70s on most cars.
Cheers
DD
#4
Join Date: Jul 2012
Location: Walnut Creek, California
Posts: 6,796
Received 2,399 Likes
on
1,880 Posts
#5
#6
13lb Cap
Now I'm confused. Just received my new 13lb overflow cap and thought the cap was supposed to have TWO rubber seals - a smaller one at the bottom under pressure by the spring (which the one pictured has) and a second one just under the top of the cap to seal the top (which this one does NOT have). What is correct?
Thanks, Bill
Thanks, Bill
#7
Trending Topics
#9
Well your memory may be correct ! It's just that I don't remember having anything like you describe on my Series 3, but it was a long time ago that I had it, from 1988-2002
#10
That cap is correct for the Series 2 cars as made by Jaguar.
There was NO atmospheric overflow tank, so no need for the upper cap seal. The excess coolant simply spurted on the ground, and the system found its own level.When an owner fitted an aftermarket "catch container" AKA an atmospheric tank, then YES, the upper seal is then needed, to allow the return of coolant to the radiator from the atmospheric tank as the system cools.
There was NO atmospheric overflow tank, so no need for the upper cap seal. The excess coolant simply spurted on the ground, and the system found its own level.When an owner fitted an aftermarket "catch container" AKA an atmospheric tank, then YES, the upper seal is then needed, to allow the return of coolant to the radiator from the atmospheric tank as the system cools.
The following 3 users liked this post by Grant Francis:
The following users liked this post:
Grant Francis (03-17-2018)
#12
#14
#15
So does my 1984 XJ-6 by the way..
#17
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,929
Received 10,989 Likes
on
7,216 Posts
According to the parts catalog......
https://www.jaguarclassicparts.com/u...r-vehicle-info
The correct cap for a Series II is a JLM9652...which does not have the upper seal...for the reason Grant mentioned
https://www.ebay.com/itm/JAGUAR-DAIM...-/201477981249
Cheers
DD
https://www.jaguarclassicparts.com/u...r-vehicle-info
The correct cap for a Series II is a JLM9652...which does not have the upper seal...for the reason Grant mentioned
https://www.ebay.com/itm/JAGUAR-DAIM...-/201477981249
Cheers
DD
The following users liked this post:
Grant Francis (03-18-2018)
#18
no, you just published your email to the russian spies. Erase it by editing your post. Not a good idea to post your e-mail address.
if you want to send someone a private message (PM), you click on the forum member's name, a menu pops up, and you select "SEND PRIVATE MESSAGE",
this takes you to your private mailbox in this forum, where a window will open with a text box where you type your message, the recipient's name is already in the box.
if you want to send someone a private message (PM), you click on the forum member's name, a menu pops up, and you select "SEND PRIVATE MESSAGE",
this takes you to your private mailbox in this forum, where a window will open with a text box where you type your message, the recipient's name is already in the box.
#19
According to the parts catalog......
https://www.jaguarclassicparts.com/u...r-vehicle-info
The correct cap for a Series II is a JLM9652...which does not have the upper seal...for the reason Grant mentioned
https://www.ebay.com/itm/JAGUAR-DAIM...-/201477981249 Cheers DD
https://www.jaguarclassicparts.com/u...r-vehicle-info
The correct cap for a Series II is a JLM9652...which does not have the upper seal...for the reason Grant mentioned
https://www.ebay.com/itm/JAGUAR-DAIM...-/201477981249 Cheers DD
#20
Oh boy.
You can use a double seal cap on a car without an atmospheric catch tank, the car has no idea. The air being allowed back in when cooled will still do the same.
The other way round, WITH an atmospheric catch tank, you NEED a double seal cap NO exceptions. The coolant flows TO the catch tank, as the system heats up, BUT, as it cools down, the lack of top seal will allow air to be sucked into the system, in lieu of coolant, and the catch can will stay at its HOT level.
Single seal caps down here were very hard to find a few years ago, as the manufacturers went with double seal cap only, as it will work on either spec car, as I stated. Single seal caps are now reappearing for some bizzare reason. We have both is stock at work, which I find DUMB, as stock is duplicated, and most classic cars requiring a single seal cap, do have an owner fitted catch can, so a double seal cap is mandatory.
All my old stuff have catch cans and a double seal cap.
You can use a double seal cap on a car without an atmospheric catch tank, the car has no idea. The air being allowed back in when cooled will still do the same.
The other way round, WITH an atmospheric catch tank, you NEED a double seal cap NO exceptions. The coolant flows TO the catch tank, as the system heats up, BUT, as it cools down, the lack of top seal will allow air to be sucked into the system, in lieu of coolant, and the catch can will stay at its HOT level.
Single seal caps down here were very hard to find a few years ago, as the manufacturers went with double seal cap only, as it will work on either spec car, as I stated. Single seal caps are now reappearing for some bizzare reason. We have both is stock at work, which I find DUMB, as stock is duplicated, and most classic cars requiring a single seal cap, do have an owner fitted catch can, so a double seal cap is mandatory.
All my old stuff have catch cans and a double seal cap.
The following users liked this post:
Doug (03-18-2018)