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BJ8 radiator cap

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LGB

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I have a recently restored 1966 BJ8. The radiator has an overflow, but neither the "new" nor a recent replacement 7psi radiator cap (see below) seems to prevent light leaking across the top of the radiator and inevitable blowback spots on the carbs, etc. Could this be a quality/sealing issue, or perhaps the wrong length? I know it should be a 1" and not a 0.75".

The car runs normally, getting into the overheat zone only on very hot days in extremely heavy traffic.

Any advice would be welcome. In particular, if it is likely to be the cap then where I could get the best quality with a good seal.

Thanks.

IMG_5061.jpg
 
I have noticed that a cap bought from a local parts store is always too short to seal well. Give a call to Healey Surgeons in Tacoma Park, Md. They always have the right stuff.
 
LGB said:
I have a recently restored 1966 BJ8. The radiator has an overflow, but neither the "new" nor a recent replacement 7psi radiator cap (see below) seems to prevent light leaking across the top of the radiator and inevitable blowback spots on the carbs, etc. Could this be a quality/sealing issue, or perhaps the wrong length? I know it should be a 1" and not a 0.75".

The car runs normally, getting into the overheat zone only on very hot days in extremely heavy traffic.

Any advice would be welcome. In particular, if it is likely to be the cap then where I could get the best quality with a good seal.

Thanks.

View attachment 46373
Click to expand...

The depth of the cap should match that of the sealing portion of the filler neck - the stock setup is 1"

A radiator shop can pressure test your cap and cooling system to determine where it's leaking. I bought a pressure tester years ago and it's been probably the most useful specialty too I ever bought:
https://www.pbase.com/stevegerow/image/81903194

PS - I don't think it's the cap, as you've gotten the same results with two different caps.

PPS - this looks good:
screenshot.779.jpg
 
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If you are using the proper cap with the longer seal (Moss or BCS), then a certain amount of fluid will overflow until it reaches the proper level in the radiator. Then you should not have any overflow. The level is usually about 1 inch below the rim any more and it leaks out.
 
  1. Is there a rubber seal between the cap and the top of the radiator neck? Required for coolant recovery systems; not clear if you have one.
  2. Is the tube from the radiator neck to the overflow free flowing?
  3. Is there leakage between the overflow tubing and the little rolled tube in the side of the radiator neck where the tubing attaches?

Those are possible sources of leakage.
 
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Welcome LGB and Happy Holidays,

For most of my Healey ownership, I had kept my BJ8 Phase 1 consistent with how it was when I bought it new. However, since the 1990, I started to install a number of non-obvious changes that either made driving my Healey more reliable or comfortable. One of these changes was as a result of acquiring the wrong radiator cap and experiencing the loss of coolant you described. After some research and conversations, I realized that the installation of a non-pressurized coolant recovery system was an easy addition that would eliminated coolant loss during July 4th parades. This change, and some others that are also DIY have been described in an article "I Always Wanted a COOL Car" (https://drive.google.com/file/d/0Bwqddve6a2OTN2tlUHk2SWZPT1k/view?usp=sharing) that may be of interest to you.

Enjoy your Healey in the New Year,
Ray(64BJ8P1)
 
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