Radiator help. Kind of urgent

[Adam in CLE]

Hi all. Have alignment scheduled for Monday and state inspection mid next week for my second Goblin. The radiator plug threads aren't holding and is full of coolant. I'm looking to see if anybody knows the diameter and thread pitch of the radiator drain hole. If anybody has a line on a replacement that would be awesome as well.

Thanks in advance for the help, Adam

 

[Gtstorey]

Does your plug have an oring on it? If not Teflon tape will probably get you by temporarily,

 

[Adam in CLE]

It does. Good call but need a permanent fix.

 

[Ross]

epoxy in a new drain valve?
buy a thread measuring tool?
I have noticed that DF has changed the radiator supplier a few times. My radiator probably isn't the same as yours.

 

[Gtstorey]

A new o-ring might be a permanent fix.

 

[Adam in CLE]

Just need a replacement plug and looking for the size and pitch. The threads are bad but am full of coolant in the system and trying not to drain it since I just filled and bled it a few days ago. I have a thread measuring tool. I was hoping to take and replace and not loose too much coolant.

 

[Ross]

My red neck filling method can purge air from a goblin radiator in two short drives.
Drain the system, save the fluid, fix the plug, refill, go for a short drive. 4000 rpm for 10 seconds, top up the coolant. Repeat a few times, go ahead and tag red line, pretty soon it won't take any more coolant, and the air is out.

 

[Gtstorey]

Decent chance it’s pipe thread but that’s just a guess.

If it was mine, I would get a rubber plug about the right size and stick it in while I figure out the threads. Someone in the process of building might be able to get you an answer but being the July 4th weekend, traffic will be down. And I’m not sure there are a lot of builders on here right now that are in that stage of building. It’s mostly late stage builders and complete cars.

 

[Desert Sasqwatch]

As @Gtstorey stated, it's likely pipe thread - 1/8 NPT - since it's not a very large hole. Cheap $ at the local hardware store.

 

[ah.b.normal]

Maybe make an expansion plug out of a small bolt, washer, 1” segment of rubber hose and another washer and nut. Desperate times call for desperate measures. The big ones are factory made, just use smaller hardware. You won’t be able to torque the heck out of it but any seal is good! I once made one for an oil pan drain. Got me home.

 

[duthehustle93]

Parts stores usually have an aisle of a bunch of generic dorman stuff with a decent selection of rad drain plugs. There has been a couple times where I couldn't find a plug so I tapped the drain to the closest NPT size which is a permanent fix.

 

[ah.b.normal]

Parts stores usually have an aisle of a bunch of generic dorman stuff with a decent selection of rad drain plugs. There has been a couple times where I couldn't find a plug so I tapped the drain to the closest NPT size which is a permanent fix.

Yup, there's that option. Or tap it to the next largest NC or metric thread size and use a bolt and O ring.

 

[Adam]

I reached out to our radiator supplier and they say the drain plug threads are 1/4-18 NPT.