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MG TD TF 1500 - radiator

I was taking my radiator partially apart to clean and have presure checked. I triedto remove the drain valve and it twisted of threads and all. Is it possible to find the threads to reattach to the lower radiator tank so that I might be able to srew the valve back in properly?

Rob
Rob Welborne

I think it is just a threaded plate or nut soldered to the lower tank. If you could find a nut that the drain tap screws into, just have that soldered on. Or have to find out the exact thread size of the tap and buy a threading tap and make a fitting.
George Butz

Hi Rob,

Sorry about your problems - we've all done similar things! The original threads were BSP (British Standard Pipe), and although I'm all for DIY on our cars,it might be better to take your rad. to a 'local rad. repairer'and have the job done. I think a 'very close to BSP,' American thread is used on your rads and they could solder a new female thread into the rad. which might take the original drain tap, or just use a new hex blanking bolt.

I believe BSP taps and dies are available in the States, and others will know of suppliers. Once to hand the rad repairer or you, could then tap out an undersize new soldered on female thread, to exactly suit your original drain tap.

At the end of the day it's your choice as to whether or not to use the original threads. Personally I wouldn't alter the treads on your drain tap.

Hope this helps,

John
J C Mitchell

Thanks guys,

I actually have it at the radiator shop at this time. He is going to see if he can remove the threaded pipe and replace it but I have a feeling I will need to find a new piece and get it to him so that it might be repaired. Whenever I look for a shop to do work such as machine and radiator I always try and find a shop that has been around a few decades with an owner/operator that looks to be about 100 years old. I always seem to get the highest quality work:)

Rob
Rob Welborne

I bet Hugh Pite (jenntoo@shaw.ca) can help you out.

Larry
Larry Shoer

Hi Rob, a PO had soldered a large nut onto my radiator, with a bolt to act as a plug. This was leaking, but when I tried to undo the bolt, the whole lot sheared off leaving a substantial hole in the lower tank. To repair this, I found a standard brass plumbing fitting which fitted the drain tap thread (I had purchased a tap already). A friend silver-soldered the fitting into a square of copper sheet and I then soft soldered the copper sheet to the tank. The overlap between the copper and the brass of the tank is about 1/2". Has been leak free for more than a year now as well as looking more original. Matt

Matt Davis

If needs be,I have a lower tank from a scrapped radiator that you could remove the fitting from or use the whole tank. Lemme know if I can help-will need to go to the barn and locate the proper box. Dan
Dan Craig

Matt,

I am only assuming that the tap threads are metric. I have no idea what type of threads are available on brass plumbing fixtures here but that is a good idea that I will look into first.

Dan,

I appreciate the offer. If I need to go that route would it be much of a problem for you to remove the lower tank to mail me? It must be getting pretty cold in Missouri. That barn might be a little chilly to look around in:)

Rob
Rob Welborne

Matt,

After a little research I am going to assume that the threads used on the drain tap are BSPT. British standard pipe thread. Assuming those standards have been in place since the 50's. My tap is with the Radiator shop so I can't check. Of course I have no BSPT refrence any way. It would be great if anyone with their radiator out at this time could check the threads and let me know.

Rob
Rob Welborne

Rob, I would think it almost certain that the threads are BSP as all UK threaded plumbing fittings are still BSP size. I have a spare radiator tap (bought from Moss, but not used as it has no means of fitting the copper discharge pipe) and the outer diameter of the threads measures just over 1/2", according to tables on the Internet, this would be 1/4" BSP (presumably the diameter relates to the internal diameter of the pipe). Matt
Matt Davis

There are two forms of British Pipe threads. There is a tapered thread (BSPT) similar to the American thread (NPT) and a straight or parallel thread (BSPP). I have in my hands a drain tap. It is an after market replica and I cannot measure nay taper on the threads. It also came to me with a fiber gasket. So I believe the MG-TD radiator has a BSPP thread. It appears to be a 1/4" pipe thread since the OD is around 1/2" The pitch of the NPT thread would be 18 TPI. The BSP(X) seems to be (19 tpi.
I measured the drain tap I have with a Whithwoth thread gauge and while 19 fits well, 18 tpi seems to fit also.
Now the BPT(X) thread has a vee angle of 55 degrees while the NPT has an angle of 60 degrees.
The wrong angle on the threads can cause grief.

With a straight thread anyone with a proper lathe could cut you a thread and make a replacement part. But most older lathe will not cut a 19 TPI thread. My Southbend 10L skips 19, as does my 9" normally. However I can get to 19.2 and perhaps 19.042 TPI, in a non-standard configuration on my 9" lathe by juggling some non-standard gears that I happen to have for cutting metric threads. The threads on the drain tap are short and I would think 19.2 would fit quite nicely.

If all else fails, feel free to contact me off line and we can set this up. There would be no machining charge. I do have a piece of 1-1/16 brass that I could hog the part out of. I don't have much brass, so you may luck out but If you felt the need you couls provide the material. I measure 0.775" on the OD of the flange.
I do have a 55 degree internal threading tool I just made when I fabbed up a new nut for the tachometer drive, so its just a matter of you measuring the part and my fabbing it. I can test the thread fit with the drain tap I have.


Jim B.
JA Benjamin

Oh yes eeengineer-at-verizon-dot-net


JA Benjamin

Thanks Jim,

That is a very generous offer of your time and skills. Let me see what the radiator guy tells me on Monday about the part i gave him.

Rob
Rob Welborne

I just wanted to say thanks to everyone who offered info, personal help, and parts. It was very considerate of the group as always. The radiator man was able to repair the dislodged threads to factory new. Well, they at least look great.

Thanks again,

Rob
Rob Welborne

Hi Rob,
in last weeks I improved my radiator with a little "Tunnel" around the fan blade and I installed aditional two little electric fans in the upper region of the radiator. I think, I can drive through a desert now. If you are interested, I send you pics.

Kind regards
Klaus
Klaus Harthof

Klaus would you please post the pictures of your "tunnel" on this BBS? Many of us could benefit from your project.
Jim Merz

Klaus,

Glad to hear from you again, Was going to send you a picture of my engine progress when I finished putting it together hopefully this month. Please send the pictures. It is always around 100 degrees in Texas in the middle of summer. I am surprised you needed better cooling where you live.

Rob
Rob Welborne

This thread was discussed between 03/12/2011 and 15/12/2011

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