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Coolant Leaks

Posted by DWinne

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Coolant Leaks #1
DWinne Dave Winne Liverpool, NY, USA	Posted: August 02, 2012 04:41AM Registered: 1 year ago Posts: 32

After parking the Cee in the garage after the trip back from Watkins Glen, I noticed a puddle of antifreeze on the garage floor. At first I thought it was coming out of the overflow tube.After pressurizing the system to about ten pounds, I noticed that it was leaking around the top hose connections and around the filler cap on the t-stat housing. I cured the hose leaks by replacing the new wire clamps with stainless band clamps. However, I still have a slight leak around the cap. It is a new replacement cap. Doe a certain brand of cap seal better than another? Does anyone have a solution to this problem? I don't believe that a new neck assembly is readily available.
Thanks for your help,
Dave Winne
Liverpool, NY

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Re: Coolant Leaks #2
mgcgt2912 Richard Bailey Cully, East Devon England, United Kingdom 1969 MG MGC GT	Posted: August 02, 2012 07:34AM Registered: 2 years ago Posts: 683

Forgive me if this is an insulting question ?
When I bought my C , I found that the PO had fitted a pressure cap to the filler. Result was a weep whenever it got hot.
Your filler cap is "plain" I assume ?
R

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Re: Coolant Leaks #3
DWinne Dave Winne Liverpool, NY, USA	Posted: August 02, 2012 07:56AM Registered: 1 year ago Posts: 32

Yes, it is a plain filler cap.
Dave

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Re: Coolant Leaks #4
mhirsch13 Mike Hirschman Maple Grove, Minnesota, USA 1969 MG MGC GT	Posted: August 02, 2012 09:15AM Registered: 5 years ago Posts: 85

Dave,
Two reasons that I have run into for leaks on the thermostat housing are a poor or hard rubber gasket in the cap, and there is a soft metal flange where the cap mates to the housing. Because it is a soft metal, that sealing surface can be banged and the surface can become uneven, resulting in a poor sealing surface with the rubber/cap. If that is the case, some small hand tools can reshape that flange until it has an even surface again. Be gentle with that flange, they are hard to find. Good luck, Mike

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Re: Coolant Leaks #5
emadak Ed 123Ignitionusa Ohio, USA 1969 MG MGC	Posted: August 02, 2012 09:34AM Registered: 6 years ago Posts: 705

You should check the surface for imperfections as Mike says. I have wire brushed and soldered the area and then using a flat file given it a resurface. In addition the tabs on the cap can be gently bent to give more pressure. Eventually as the rubber gets old the cap will need to be replaced. Hope this helps

Regards
Ed
Amgcr#1419
Http://www.mgccars.com/
Http://123ignitionusa.com/

Edited 1 time(s). Last edit at 08/02/2012 09:35AM by emadak.

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Re: Coolant Leaks #6
Swamperca Swamper CA Nor Cal, USA 1969 MG MGB GT "Rat" 1969 MG MGC GT "A 69 MGC" 1970 MG MGB GT "Widow" 1971 MG MGB "Ruby" 1974 MG MGB "Groovy B"	Posted: August 02, 2012 11:06AM Registered: 8 years ago Posts: 7,659

Maybe a thicker rubber seal and softer on the cap?????

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Re: Coolant Leaks #7
DWinne Dave Winne Liverpool, NY, USA	Posted: August 02, 2012 12:00PM Registered: 1 year ago Posts: 32

All - Thanks for the great suggestions.
Mike- have already massaged the neck with hand tools and smoothed gently with a file. It is better but not perfect. I wonder if maybe the repro cap could use a thicker rubber? (Bice to see you at the show on Saturday at Watkins Glen. I have been very busy since I got back, will try to get a few minutes to send you a list of bits from the Cee that are MIA).
Swamper - probably a good idea to build up with some solder and then smoothe out with a file. Might be worth a try.
As a last resort, I may have to have to get a new neck from a radiator shop and solder onto the flange...
Regards,
Dave

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Re: Coolant Leaks #8
PFT-000 Bruce Ibbotson Brisbane, Australia 1968 MG MGC GT "The Truck"	Posted: August 02, 2012 07:59PM Registered: 11 months ago Posts: 403

Hi Dave,

The original factory plain cap had a thick rubber disc and it sealed well until after many years it developed a grove so it would only seal if put on in the same position, if turned 180 degrees it would weep.
Replacement caps were then the same as the factory caps.

But over time the after market caps had thinner rubber seals which only worked for a short time before they leaked.

I found by cutting a piece of thick gasket material to put between the cap and the seal these caps then worked OK.

The problem seems to be that replacement caps have much thinner rubber seals. Try putting a piece of 20 thou or so gasket material in the cap then putting the rubber washer in.

Cheers,
Bruce.

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Re: Coolant Leaks #9
T.Gallagher Tim Gallagher Bow, New Hampshire, USA 1969 MG MGC	Posted: August 03, 2012 05:53AM Registered: 5 years ago Posts: 45

I had the same issue last year and tried to massage the flange back to normal with little success. I found a hairline crack where the metal comes up to make the first bend.

Anyway.....I took my entire filler neck off and brought it to my local radiator shop where they replaced that top flange piece your having trouble with. It's made up of two pieces. The only unique piece is the bottom triangle. The top flange is apparently a standard off the shelf item that's soldered to the bottom triangle! I think the guy charged me $8 total including his labor to put it together.

I also found a line on the correct Non-pressurized cap which I have pictured below and now have a couple of spares just in case...;-)

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Attachments:

Radiator_cap.JPG (27.8 KB) –

Re: Coolant Leaks #10
Larry92021 Larry Hallanger San Diego area, CA, USA 1949 MG YT 1958 MG MGA 1500 1969 MG MGC 1972 MG MGB GT	Posted: August 03, 2012 01:53PM Registered: 3 years ago Posts: 333

Tim

I believe that you mean a "non-pressure relief cap" rather than a "Non-pressurized cap". The pressure relief cap is on the overflow tank.

Larry
San Diego area, CA

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Re: Coolant Leaks #11
DWinne Dave Winne Liverpool, NY, USA	Posted: August 03, 2012 03:15PM Registered: 1 year ago Posts: 32

Tim,
Thanks for the info on the Stant caps. I ordered two from NAPA this afternoon.
I think I have a solution for the worn filler neck - I ordered a billet filler neck from Summit Racing.
I will fab an aluminum flange plate and have the billet neck welded to the plate. Now the next job is removing the three bolts securing the flange to the extension piece - waiting for the PB Blaster to work ...
Safety Fast (and hopefully without coolant drips),
Dave

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Re: Coolant Leaks #12
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: August 04, 2012 11:09AM Registered: 4 years ago Posts: 13,095

No dog in this fight but both Robert Shaw and Stant parts can be problematic...same company fwiw. For that matter, Rick Ingram got the last of my NOS Wax-Stat blanking caps and its rubber was defective.

Just a little trick I have learned over the years. Virtually any alloy part on an engine will warp slightly if hardware is used to secure it. If you can, get a piece of wet/dry sandpaper and secure it to a tile...I have a granite tile I use. When you first hit the alloy piece on the paper you will be amazed at how typically it is not level.

Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
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