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Discussion Starter · #1 ·
Can this be repaired or can the gasket be replaced? Anyone know who does these? It’s an orignal for a 68 gto.
144266
 

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Recommend you just buy a new cap, the rubber and spring are likely shot. Keep that one if you want to have original, but drive with one that won’t overheat…..$15 or so
 

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Discussion Starter · #3 ·
Recommend you just buy a new cap, the rubber and spring are likely shot. Keep that one if you want to have original, but drive with one that won’t overheat…..$15 or so
I do have another cap on it. I’m asking if and who repairs these.
 

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Never heard of anyone repairing radiator caps but I'm sure someone might do it. IMHO its more cost effective to buy an NOS or used original cap than paying someone to repair.
 

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There is a pretty nice looking 15lb big ear cap on ebay right now. Says early take off from 70 Chevelle. $115. obo from New Jersey.

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Discussion Starter · #6 ·
There is a pretty nice looking 15lb big ear cap on ebay right now. Says early take off from 70 Chevelle. $115. obo from New Jersey.

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yesh it might be best to find another one. The other one was ineBay too for 65. I was thinking about getting it if it could be fixed on the cheap. Thx for the heads up
 

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I've repaired radiator caps before. But it isn't easy or inexpensive. The ones I did were for a Pierce Arrow and had glass ornaments attached. After I figured out how to make actual working caps from the parts my client provided and I fabricated some missing bits, it took about 5-6 hours per cap plus materials to assemble them. And I had some time making a stamping die for the brass washer / machiningbit & etc.

In the case of your GTO cap it would be far cheaper to buy an NOS cap. But if you wanted to do yours I'd start by unrolling the crimp around the inner rubber washer diameter to remove the old rubber. Since the old rubber is shot you could dig it out to gain a purchase point to start un-crimping. Making a new rubber isn't hard. But rolling the crimp back down is.

Of possible interest: The pressure a cap develops is dependent on crushing the sealing spring a specific distance. Since most aftermarket radiator filler necks and caps don't meet assembly spec for distance from the seat to the rubber gasket (too big of a space) many new caps don't actually hold the pressure you'd expect. To really set that up properly you need a pressure gauge in the block or head and some rubber shims to put between the cap rubber seal and radiator filler neck seat. Run the car through various cycles to set the actual pressure tested when hot and when engine is off, but before the engine cools. Aluminum radiators are very subject to having this problem.

For your consideration: a few weeks ago I helped a very knowledgeable client in cars and engineering who's GT40's coolant loss problem was remedied after I advised him to inspect his cap and pressures. He'd been fighting random coolant loss for many years with subsequent overheating. When tested, his new 24 lb racing cap was only holding 7 lbs on it's overly deep seat. I'd offer up an opinion that more than half of the cars I work with have cap pressure issues that can be solved by testing actual cooling system pressures then changing the filler neck or shimming.

Perhaps you might enjoy these photos of some of the Pierce Arrow caps I fabricated. They won some awards at their National convention a bunch of years ago. I think they ended up being sold to an overseas collector. Best of luck fixing your GTO. Ladd

 

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yesh it might be best to find another one. The other one was ineBay too for 65. I was thinking about getting it if it could be fixed on the cheap. Thx for the heads up
No problem.. if you don't find one at a more reasonable price let me know if you want. I'm going to Norwalk at the end of July. I have a small list for my 66.

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Discussion Starter · #10 ·
No problem.. if you don't find one at a more reasonable price let me know if you want. I'm going to Norwalk at the end of July. I have a small list for my 66.

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Norwalk ct? I’m not too far from there. Whats in Norwalk?
 

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Norwalk ct? I’m not too far from there. Whats in Norwalk?
Norwalk, Ohio. Summit Motorsports Park. Pontiac Tri-Power Nationals at the end of this month.

I know where Norwalk, CT is. I was born in Stamford and moved "north" to Danielson when I was 5. Mom was born/grew up in Stamford.
 

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Discussion Starter · #12 ·
I've repaired radiator caps before. But it isn't easy or inexpensive. The ones I did were for a Pierce Arrow and had glass ornaments attached. After I figured out how to make actual working caps from the parts my client provided and I fabricated some missing bits, it took about 5-6 hours per cap plus materials to assemble them. And I had some time making a stamping die for the brass washer / machiningbit & etc.

In the case of your GTO cap it would be far cheaper to buy an NOS cap. But if you wanted to do yours I'd start by unrolling the crimp around the inner rubber washer diameter to remove the old rubber. Since the old rubber is shot you could dig it out to gain a purchase point to start un-crimping. Making a new rubber isn't hard. But rolling the crimp back down is.

Of possible interest: The pressure a cap develops is dependent on crushing the sealing spring a specific distance. Since most aftermarket radiator filler necks and caps don't meet assembly spec for distance from the seat to the rubber gasket (too big of a space) many new caps don't actually hold the pressure you'd expect. To really set that up properly you need a pressure gauge in the block or head and some rubber shims to put between the cap rubber seal and radiator filler neck seat. Run the car through various cycles to set the actual pressure tested when hot and when engine is off, but before the engine cools. Aluminum radiators are very subject to having this problem.

For your consideration: a few weeks ago I helped a very knowledgeable client in cars and engineering who's GT40's coolant loss problem was remedied after I advised him to inspect his cap and pressures. He'd been fighting random coolant loss for many years with subsequent overheating. When tested, his new 24 lb racing cap was only holding 7 lbs on it's overly deep seat. I'd offer up an opinion that more than half of the cars I work with have cap pressure issues that can be solved by testing actual cooling system pressures then changing the filler neck or shimming.

Perhaps you might enjoy these photos of some of the Pierce Arrow caps I fabricated. They won some awards at their National convention a bunch of years ago. I think they ended up being sold to an overseas collector. Best of luck fixing your GTO. Ladd

Wow you have a wicked talent. Those caps are very nice. Real works of art.

im gonna go the route of finding a good original cap. Thanks for great explanation and issues with after market caps.
 

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Discussion Starter · #13 ·
Norwalk, Ohio. Summit Motorsports Park. Pontiac Tri-Power Nationals at the end of this month.

I know where Norwalk, CT is. I was born in Stamford and moved "north" to Danielson when I was 5. Mom was born/grew up in Stamford.
Small world. I live in RI and I drive through Danielson sometimes on way to Putnam. Im looking for an original cap. Also looking for a gas cap too but it’s confusing to know what an original gas cap is for a 68. When r u going to Norwalk?
 

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Norwalk ct? I’m not too far from there. Whats in Norwalk?
Norwalk Ohio, near Sandusky. Summit Motorsports Park. Ames Pontiac nationals July 29-31. Huge all Pontiac show, Drag race, car corral, swap meet.

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I don't think restoring a cap is a big deal. I see in some corvette forums NCRS guys doing it. I believe they have an all new underside (guts) riveted onto their original cap.

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Small world. I live in RI and I drive through Danielson sometimes on way to Putnam. Im looking for an original cap. Also looking for a gas cap too but it’s confusing to know what an original gas cap is for a 68. When r u going to Norwalk?
My brother lives in Kingston, RI, right near Quonsett Industrial Park. My daughter is in Fall River, MA. Was just up there for a visit - posted my vacation pics "The Lounge" at the bottom of the page.

Made my reservations, got my vacation days off from work, and I'll be at Norwalk. Was there in 2018 and would have gone last year, but Covid messed that up. I don't go every year anymore than I go to the big shows here in my area every year - I give it a break and then there is usually a new group of cars to look at.
 

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Just and FYI. I had purchased a new radiator cap from one of the GTO vendors (but I don't recall which one off hand). Went to install it and noticed it has a very strong spring compared the original. I had to push down really hard to turn it to seat. Took car out for a ride and no issues.

After car sat for a few days I opened the hood and my brother notice the upper hose was collapsed. I am like well that's weird it never did that before. Only thing I did was changed the cap. I took the cap off and there was a like a vacuum on the system. Replaced new cap with the old cap on took it out for a drive. I let the car sit a day or two and this time hose was fine (no vacuum/pressure on system). Decided to put the new one back on one more time same thing as before upper hose collapsed again after car sat for a few day. I order one from Advance Auto put that one on no issues....
 
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