Can't find a low pressure radiator cap. Does anybody(Dan maybe?) have a source and part number for a 7 lb cap that will fit the standard Dart radiator? When you go into parts stores today the first thing they ask is car and year. If you say anything else they look at you like you came from Mars.

Sam

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Stant 11228 is the one you want.
(It is not the "lever-lock" variety though.)

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. . . there was good sport at his making.

As far as I'm aware there's no low-pressure cap configured for use with a coolant reserve tank -- I seem to recall your car having a reserve tank, though maybe I'm wrong.

Are you seeking such a cap because of Evans waterless coolant? I run regular-pressure caps with Evans coolant; once all the water vapour is bled from the system no substantial pressure develops so it doesn't matter what the cap's pressure rating is.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It does have an overflow tank. Could you run a low pressure cap with an overflow, or would it puke it all out?
Sam

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You need a double-seal cap for a reserve tank to work correctly. The single-seal type caps have a rubber gasket only on the spring-loaded plunger, not on the larger ring that surrounds it. I am not aware of any low-pressure double-seal caps; by the time coolant reserve tanks came along, factory-specified 7-pound caps were a distant memory.

See my previous post in this thread for why you don't need a low-pressure cap.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I wonder if I have the right cap on now. What years would have the expansion tank on them?

Thanks, Sam

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Take off the cap and look at the radiator neck. There are two round surfaces facing the sky: the upper/larger/outer one at the very top, and then the lower/smaller/inner one that forms the hole you actually pour coolant into.

Now look at the radiator cap. The spring-loaded plunger with the rubber washer and the central metal disc seals the lower/smaller/inner hole. Outboard of that, just below the underside of the radiator cap body, is a metal ring. On a cap for use without a reserve tank, this metal ring has no rubber washer. On a cap for use with a reserve tank, this metal ring has a rubber washer.

You can use a double-seal cap with or without a reserve tank. A reserve tank will be useless if you use a single-seal cap.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan, That was good info as usual. The problem is if I go in and try to buy such a cap from a local parts place they WILL look at me like I have two heads. I need to give them a model and year car. So when did Mother Mopar start putting the double seal, expansion tank style cap on? I will check what I have of course and see if it is good. Now keep in mind, I have a separate filler neck up top, and the radiator filler is down lower, which is where the expansion tank comes off. Seems like maybe I need a single seal up top and double seal down low. Thanks for any further info.

Sam

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Use a double-seal cap such as Stant 10231 or Chrysler 5207 9880AA. If you gotta have make-model-year, tell them you're working on a 1991 Dodge Spirit with 3.0 V6.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Good, Thanks.
Sam

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Dan I went and checked the radiator caps, and you will not believe what I found. Both upper and lower caps are 7 pounds, and both have the two rings of rubber, one on the wide, upper part of the cap, and another ring of rubber on the lower part that sticks down into the neck. Both have an S on them, which I assume identifies them as Stant. Both are made in Mexico. I could not find a part number on either one. One of them came with the cast metal fitting that is the upper filler. I bought it at a speed shop. I do not know where the other came from. I am feeling a little silly, and somewhat puzzled, but pleased that I already had what I was looking for. Kind of like Dorothy in the Wizard of Oz, huh.

Sam

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Interesting! (And easy and inexpensive).

My guess is the single-seal caps are being discontinued (or have been discontinued) because no harm or problem comes of using a double-seal cap in a single-seal application, but the obverse is not true, and the cost of the upper seal would be small compared to the cost savings of making, packaging, warehousing, and distributing a smaller product line.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sam,

I know my 74 Swinger came with and expansion coolant tank stock. SL6 Dan could tell you when they started on the "A" bodies. I have seen them from 73/74 cars on up......

I have always used double seal caps from 7 lbs up to 20 lbs. Currently using the stock double sealed 16 lb cap.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG