Radiator drain tube (1 Viewer)

[Travis Kinney]

I've rebuilt my engine and put it back into pig, about to put radiator back in but I hate the little plastic plug that it came with. Had to reach up to it with needle nose pliers to remove it.

I loved the long drain down tube on my old radiator but the threaded hole on new radiator base is much smaller (see photo).

I'd like to use my old drain tube, but need to size it down from M16x1.25 to M10x1.5

Any websites I should go to for that type of fitting?

I'm wondering about just buying a M10x1.5 pipe fitting and have it welded to end of my drain tube.

or I could just use a long M10x1.5 bolt.

Not sure what to do. Just don't want to use that plastic plug that came with newer radiator.

 

[Stumpalama]

I agree, it makes a frickin' mess. I'll be interested to see what comes up.
Could you find another valve fitting that would thread in, then attach a flex hose to that when needing to drain it? It may be easier to source something like that.

 

[Travis Kinney]

Yeah, I've been obsessively scouring the web for a M16x1.25 female x M10x1.5 male adapter with no luck.
I need to stop obsessing and get back to work!

But.....I did think I could weld on an M10x1.5 fitting to the old drain pipe!

 

[sggoat]

Did you try Parker Hydraulics? I got several JIS/BSPT fittings from them.

 

[Stumpalama]

Your positive it is a metric fitting? It would seem logic would dictate that a pipe fitting be used for a drain plug. I think it is worth the few bucks it costs to get a valve fitting that will fit the new hole. I will be taking your idea to use on mine when I pull the rad for my 2FE build later this summer.

 

[bikersmurf]

X2 re pipe fitting.
I removed my long tube in 1996, and replaced it with a plug from the local plumbing supply.

 

[byrd_hntr]

Could you just use a M10.1.5 male with a hose barb on it and then some heater hose and ball valve on the bottom of the hose? I did this with a genset a few times to make draining the oil easier.

 

[Travis Kinney]

Well, it might not be metric. A M10x1.5 screws into base of radiator easily. Not sure what the closest standard bolt size is to that.
Thread on drop-tube measures at 16mm but may not be and it's not the best match at 1.25 thread pitch on my gauge, so maybe that isn't either.
I was planning to buy some nuts at the hardware store today that are this size to see if it screws on.

Might look at a conversion chart online to see what the closest standard bolt sizes are and try those too. Will be much easier to find a an adapter that isn't metric.

 

[Travis Kinney]

Ok, so I stopped by ACE Hardware and the guy said to try the brass pipe fittings.
A 3/8NPT to 1/4NPT screwed onto down tube. Then I screwed on a 1/4NPT to 1/8NPT.

The 1/8NPT looks like the right diameter (about the width of a 10mm bolt).

However, a M10x1.5 screws into radiator hole easily (maybe just a little to easily, which got me thinking it might not be metric).

Anyway, the threads on an 1/8NPT are too fine. The threads on the 1/4NPT are really close to the 10Mx1.5 bolt.
I don't think they maybe an 1/8NPT with the more course threads of 1/4NPT.

One thing that the old radiator had going for it was the large drain size. It drained quick. The newer ones have a tiny hole.

So......I'm thinking of buying a 1/4NPT tap and will make the hole into the radiator a little large. There is a welded (or soldered) hex area on radiator base that is thicker than surrounding side wall for the thread connection. I think I can drill and tap it slightly larger. The advantage is one less fitting and a large drain hole and be able to use old style draincock.

 

[Steamer]

The drill bit size for 1/4 npt is 7/16. For 3/8 npt it's 37/64 so which ever works best for the hole you're starting with. I've done this on several radiators. It gives you plenty of options for fittings & drain cocks that can be easily found at local hardware stores. Just keep it short so it's protected. When it's time to drain you can screw a barbed fitting with a piece of hose into the valve/cock for easy non spill draining. It also makes it easy to drain just a little now and then to get rid of any sediment the might be collecting. I also have a 3/8" ball valve for the block drain and take a little out of there now & then. Good luck!

 

[Josie'sLandCruiser]

Hi all,

From my experience, Toyota used British Pipe Thread, not National Pipe Thread in the coolant system. These are very similar, but are not the same.

Travis, it is unfortunate that you are experiencing this issue with the aftermarket 55 Series radiator drain cock. I used an aftermarket FJ40 replacement radiator a few years ago and yes, it came with a short, plastic drain plug. But, I was able to retro-fit the original Toyota long drain cock without issue.

Good luck,

Alan

 

[Weber Sarge]

It must be the Champion radiator , ran into the same issue myself and just machined a new extension pipe from stainless to fit the hole . I think the best solution would be to take it to a radiator shop and have them install the proper bung into the radiator to install the stock drain extension . I hate that plastic piece of junk on an otherwise nice radiator as well .
Sarge

 

[Travis Kinney]

Well, instead of having the bung in the radiator based changed out, it has enough "meat" to it, that I drilled it larger and tapped it with NPT threads. Bought a fitting at Ace Hardware and was able to attach my old drain extension right to it.

 

[Racer65]

If it's any consolation, the plastic drain tube on my last aftermarket radiator lasted 15 years before it started leaking. By that time the entire radiator needed to be replaced anyways.

 

[cims1970fj40]

@Travis Kinney how did your setup work on yours? Any leaks are any other problems. I’m needing to do the same and trying to plan on how to address it. Thanks in advance.

 

[Travis Kinney]

It works perfect. I'd forgotten that I tapped the hole larger to add on a piece of black iron pipe. Hasn't leaked a drop and easy to drain down.

 

[cims1970fj40]

Thanks for the feedback!