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Radiator Cap pressure rating  Rating:  Rating
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 Posted: 06-06-2008 03:54 am
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dwalls1
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Hi All!

      I have searched the archives and my J-H service manual, but can not come up with a definitive answer as to what pressure the radiator cap should be rated at. The service manual says the system is rated at 7 lbs. Does this mean I should use a 7# cap? I have been running a 13# cap since I installed the newly recored radiator and it seems to be doing fine. I have a 7# cap ready to go on if anyone here says that's the way to go. (oops! I checked the book again and it says the system is  a 10 # system. Guess I got confused by the metric equivalent. Still leaves me wondering, though) Thank You everyone for your help and encouragement. Dale

Last edited on 06-07-2008 01:45 am by dwalls1

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 Posted: 06-11-2008 03:55 pm
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Greg Fletcher
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If the cooling system is in good condition, it's probably not a big deal.

Theoretically, an over-pressurized system could result in internal leaks. If you have an old engine and an iffy head gasket from years of abuse and neglect, I'd prefer to have the correctly rated cap and some metallic block sealer inside. FYI, Lotus recommend metallic block sealer (Bar's Leaks) for engines with marginal liner nip.

I still have the original, low pressure cap on my radiator and it seems to work just fine.

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 Posted: 06-12-2008 12:01 am
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dwalls1
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Thanks Greg!

    What is the rating on your low pressure cap? Should I switch to the 7# cap I have? I have had no overheat problems since I got the recored super leggerra radiator installed, even after a long period of idling while parked the gauge needle was 1/4" away from the red zone. Thanks again, Dale

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 Posted: 06-13-2008 10:39 pm
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Greg Fletcher
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I'd use the 7# cap.

Your Superleggerra radiator might need more capacity?

The JH temp gauge should always be at or near the center on a correctly set up JH, no matter how hot it is outside or how long you've been idling. 3/4 into the gauge is way too high, I would not find that acceptable. You might want to test the coolant to see if the gauge is accurate. High temperature is your foe!

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 Posted: 06-14-2008 01:35 am
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dwalls1
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Hi Guy!

    Me thinks the radiator is OK, but I will need to install an electric fan if I'm going to leave it idling for long periods. I don't expect to idle all that much and the single instance when I did was inadvertant if not mildly stupid. As soon as the car was moving even at 20 mph the temp dropped off. The gauge doesn't get to the half way mark during normal operation. Thanks for the tip on the cap pressure, I will change it to the 7# right away. I am really loving this car and it is an added plus that my wife enjoys it too. Hope to find time when we're not driving it to clean up the wheels and other things. Now if I can just find all the visor mount screws before the visors get back from Delta. Two of them grew teeth and chewed their way out of the Zip Lock bag I had them in. I think a std thread screw will replace them, but it's a detail that will bug me anyway. Thanks again, Dale
 Reread your last and I will double check the gauge against the temp probe on my multi meter. Seems I should have gotten some coolant into the reserve tank when the gauge got over the half way mark, but I didn't.

Last edited on 06-14-2008 01:42 am by dwalls1

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 Posted: 06-14-2008 03:45 am
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Jensen Healey
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Superleggerra? Is that Italian? Italian radiators never worked! ;-)

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 Posted: 06-14-2008 04:53 am
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dwalls1
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I'm pretty sure it's Italian, related perhaps to their reputation for being hot blooded. Actually I think it just means extra fast. But then again it could reference leggy Italian ladies. When I first heard it it was used to refer to anything that was first rate. Speaking of which, my wife and I just got in from a topless drive in the cool of the evening in our J-H. Stopped off for a Fuddrucker's hamburger at the mall and drove home the long way. Everything working pretty well, though I need to get serious about a new exhaust system. Put 2 new speakers in, but can't hear the radio for the noise. Take care all,  Dale

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 Posted: 06-16-2008 01:02 pm
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Lash Russell
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Hi Dale,

     I just finished the project you are getting into, replacing the visors.  The screws you are missing are (button cap screw #10 - 32 x 1" long).  I purchased new ones from Home Depot in stainless for 99 cents a pair.  My originals were a bit rusty so I undid the two screws holding the rear view mirror on and the entire valence peice came off.  This allowed me to replace the square nuts (#10 - 32) that those screws thread into.  I washed the valence with warm soapy then a couple of good cleanings with TSP followod by a couple of coats of black vinyl pain and it looks better than new.  Replacement screws for the rear view mirror are #8 x 1" oval head phillips (also stainless from Home Depot).

     If you are putting in new visors from Delta you might want to replace the fasteners and clean up the valence, I'm glad I did it as I has most of the stuff undone anyway.

Lash

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 Posted: 06-16-2008 04:08 pm
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Greg Fletcher
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Superleggerra = Superlight.

Ok, the system pressure is rated at 10 pounds, so any cap near, at or around that rating will be fine.

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 Posted: 06-17-2008 12:12 am
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dwalls1
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Hey Lash,

   Thanks for the good word on the visors. I found the two missing screws, they were under the ramps in a place they couldn't possibly have been. Talked to Delta today and they are returning my visors. I think he said around $ 45.00 plus shipping, should have them up tomorrow as service is pretty good from there to here. I got the hockey sticks cleaned up and painted so I'm ready to install as soon as they get here. Thanks again,  Dale

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 Posted: 06-17-2008 12:19 am
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dwalls1
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Superleggerra Greg, I put the 7# cap on last night, but only drove a short distance, my round trip to work is just 4 miles so I don't stress anything on that jaunt. I guess the higher pressure would run cooler as the boiling point of the coolant is higher in relation to the pressure. But, the 7# cap will not strain things as much maybe. Thank you so much for your patience in clarifying this. Dale

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 Posted: 06-15-2009 03:26 am
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dwalls1
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I seem to be losing coolant somewhere. I suspect it is going away as vapor when the engine's good and warm. If I pressure test the system where should I look for leaks? I can't recall where the water pump seal weep hole is. Of course it could be leaking into a cylinder, but I'm not getting a clear indication of coolant in the oil. Any thoughts and recommendations welcome.

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