Proper Radiator Cap for Manual Mishimoto Radiator?

[Chythar]

From a previous thread, the Manual radiators use a small "import" radiator cap, and the auto's use the standard-sized Mustang cap. I've tried guessing the right part number for the smaller cap on my Manual radiator, but it just won't hold pressure. Anyone have any ideas?

 

[vladasap]

stant 16 psi or the one that they gave you

as long as it fits n its a 16psi you are good to go

 

[Chythar]

Sadly, the one I got with the radiator won't hold 10PSI with the cap tester I have I bought a Stant cap that looks like a good fit but it only holds 13psi. Both caps are marked 16psi. Could just be two bad caps but I wanted to check. I was hoping I would get lucky and get a Stant part number.

The radiator pressure tester and cap adapters are paying off big time, they're well worth the cost.

I have the Stant cap number I used but it's at home, I'll post it later.

 

[juiced_94gt]

I put a stock motorcraft in and it worked great, it's the new plastic one from the dealer.

 

[Chythar]

The Stant I tried is #11233. It looks identical to the one I got with my Mishimoto, but the spring just doesn't seem long enough. I have to push the stocker down on my Cobra clone to get it to engage the lip on my Fluidyne. But neither the original or this Stant need any pressure to lock on. Does that make sense?

 

[Chythar]

Well, I have a resolution to this issue. I e-mailed Mishimoto asking for the right cap for my radiator, and they sent me TWO caps - the "standard" cap that is a stock fit and their "import" cap. The import cap is a perfect fit. Both caps are 1.3mBar (19lbs). The import 19lbs pressure tests at EXACTLY 16lbs, so I am set.     Bad thing is, this cap from Mishimoto is a painful $25!     And they sent me TWO caps for free. Must be one heck of a markup on that price.

One thing I found while researching this issue is that the pressure rating on the caps is really a range of values. A 16lb cap is allowed to be anywhere between 14-18 lbs, and every cap I've been testing lately has been testing at the low end of the spectrum. So your coolant system may not be holding 16lbs of pressure even with a new cap. Just something to be aware of.

 

[94GTCoupe]

hey Matt,
hows that 19lb cap been working for you?
just got my replacement radiator from Mishimoto,it came with a 19lb cap.
i've been using the 16lb Mishimoto cap that came with the 1st radiator i got from them.(2 radiators ago)

you think i should use the 19lb cap with this radiator?

 

[Chythar]

The only reason you may not want to use it is you may find a weak spot in your coolant system. and extra 3 psi isn't much but if you have a cracked hose or something close to giving way this might push it too far. My 19psi cap tested out to 16psi, so I'm still just holding 16psi. The cap still works well, I might add. I did use the larger 19psi cap on my Cobra clone, still holding just fine with no leaks at 19psi.

 

[94GTCoupe]

Posted via Mobile Device
thanks matt.
all my hoses are new,aswell as the thermostat.
i think i'll try the 19lb cap.