Mishimoto Radiator leak 1987 Foxbody 5.0

PHoffman

New Member
Dec 24, 2024
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Sacramento
I’m trying to find the leak on my mishimoto radiator or it could be a hose leak. Coolant is leaking but can’t tell where it’s coming from. I did notice a small leak from the overflow nipple so I just replaced the overflow nipple with a cap and clamp. This looks like it’s coming from the bottom. Any suggestions would be great. Thank you.

The pictures are from the left and the right side.
 

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Put this in with the coolant:


Hose down the engine bay and let it dry.

Start the car and let it get to operating temp.

Shine a UV light into the nooks and crannies. Should stand out like a creep show.
 
Put this in with the coolant:


Hose down the engine bay and let it dry.

Start the car and let it get to operating temp.

Shine a UV light into the nooks and crannies. Should stand out like a creep show.
Thanks for the recommendation. I have one coming today. Hopefully I find that creep.
 
I had a Mishimoto radiator in my old fox that developed a pinhole leak on the passenger side middle of the radiator end. Ended up replacing it with a Griffin radiator. Mine was obvious, i started 'steaming' while driving in traffic one day, pulled over and saw the steam shooting out of the pinhole. The above suggestion is good to identify the leak since you can't determine where its coming from.
 
Gotcha. I haven’t jacked the car up yet so I’m crawling under it and looking but can only see so much. I might just take the radiator out to see if I can find it. I did just check it and it’s leaking on both sides but can’t pinpoint where it’s coming from. I don’t think it’s coming from the top. I believe it’s coming from right underneath that black rubber piece? Please see pics on both sides. Is there a connecter or something loose under the rubber piece. Also coolant on the ground right under that rubber piece. Sorry no car expert but learning.
 

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Hook up a pressure tester to it.... If your taking it out, take it to a radiator shop and let them test it and give you an estimate for repair....