Lower-pressure radiator cap?

[Ike Clanton]

Anybody know a part number for, say, a 10-12 lb radiator cap that will fit a stock radiator rather than the 16 lb one?

[nfldfordltd]

I don't know the part number, but I put a 15 lb cap on my 88 Town Car and it helped enormously. I bought it at a Chevy dealer, all Ford caps that fit were 16 lb.
I don't think I've burst any heater cores, or assorted hoses since I went to the 15 lb cap.

[t65neon5]

Anybody know a part number for, say, a 10-12 lb radiator cap that will fit a stock radiator rather than the 16 lb one?

.....murray/motorrad part # 7009=9lb, 7013=13lb., couldn't find a 10 or 12 lb cap

[gadget73]

If your cooling system is in good shape, theres no reason not to use the stock cap.

[Ike Clanton]

I also found a Stant 7 lb cap, 10228.

[CheeseSteakJim]

Uh, yeah, putting a lower pressure cap on your car is decreasing the cooling capacity of your entire system. If you're blowing hoses and heater cores with a stock cap there's more problems there.

[johnunit]

I also would question whether 15 vs. 16lbs would make much of a difference. Definitely going about the problem from the wrong end. They worked with 16lb caps stock, why does the car not anymore?


Also, the trend in general is to more pressure. The newer Ford and Mazda engines are mostly 21lb caps.

[nfldfordltd]

I don't know why I had the problems I did. I tried everything (including no less than 4 16 lb caps) But with the 16 lb cap it used to pop hoses, heater cores and even block heaters/frost plugs for fun. It seems much better now with the 15 lb cap. Still lots of pressure in the top rad hose at normal operating temperature and it never gets hot so I call it a job well done.

[WagonMan]

I agree 100% with nfldfordltd. I just replaced all the hoses on my 89 Colony Park and put a new 16lb cap on and still had issues including coolant seeping from the timing cover. I replaced the timing cover gaskets and everything was fine for a day, then it started seeping again! The upper radiator hose was as hard as a wedding dick! I put an old 14lb cap on it and everything is fine now. WagonMan

[gadget73]

makes me wonder if those caps are lifting at the pressure they are marked to. Also, aftermarket radiators don't always have the cap area made right. Someone on here had an aftermarket rad that wouldn't make pressure at all, and I think it was finally determined that they made the neck too deep for the cap to seal in. Maybe some are made too shallow and cause the cap to run at higher pressure.

[Ike Clanton]

FWIW I had suspicions that the old (as in about 2 years old) 16 lb cap I was using was holding more than 16 lbs. Additionally, it never seemed to pull coolant back out of the reservoir once the engine cooled.

The new, lower-pressure cap I installed is working fine.

[sly]

all 16# here on the 88, 82, and 93... and the aftermarket rads seem good with it too.