Our engines had a strange mix of threads, that is most likely 3/8" NPT or possibly 3/8" BSP, not much difference between them over such a short length. Thread angle for BSP is 55 degrees and for NPT it is 60 degrees, BSP is 19TPI and NPT is 18 but as said over short distances are interchangeable.

 

3/8 is just under 10mm though. This measures 16.68mm.
My thread chart shows M17 as between 16.732 and 16.968.

 

It’s 1/4 BSPT. All Patrol tapered threads are BSPT

 

OK, first of all, its a straight thread not tapered. It also measures 16.68mm in diameter.
So its not 3/8 or 1/4. Other threads in the thermostat housing are metric. I'm tapping into one thats M12x1.5
Please, I'm after the answer from someone who knows.
Guessing's not helping.

 

There are straight threads in this as well, and you are confusing the measurement with ordinary bolts not pipe threads, 3/8NPT is 16.6mm. I didn't offer it as be all or end all but as a suggestion, not a guess as you put it. The OD is correct for what I suggested and i also gave you the TPI so you could check, I know there are NPT threads on my Japanese engine, so sorry mate I won't offer you anything at all in the future.

 

Sorry mate, didn't mean to offend. I do appreciate the input but as you can imagine when I get suggestions from 3/8NPT to 1/4BSP you can understand my frustration. The plug is back in and I was hoping to get the fitting to install when the turbo arrives, so I really need to know the actual size.
Here's one of my thread spec charts that says 3/8NPT has an OD of 17.055mm.
Totally confused!

 

My reply wasn’t a suggestion. A TD42 engine block coolant drain plug is 1/4 BSPT. I repeat that all Patrol tapered threads are BSPT.

If it were a straight thread it would screw right through because there’s no bolt head to stop it. Can’t you see that?

Geez, it’s hard to help some people..

 

As said in such short sections there is very little difference, BSP is marginally the closest. BSP is made up of two things BSPT (tapered) and BSPP (parallel)

https://www.valvesonline.com.au/references/threads/

According to my charts 1/4" BSPT is 13.1mm OD, so I'm not sure it is that,

 

So does 1/4 BSPT measure 16.68mm OD?

 

Have a look at the chart I put up...... I didn't put it up for my own info, I've worked in engineering all my friggin life.

Edit: BSPP and BSPT are the same except one is parallel and one is tapered.

 

The picture said it all, the vernier read 16.68mm so it's 3/8"..... I've put up the charts what more can be done? Damn this has been hard, I'm out of here before I have a coronary.....

 

If it’s a TD42Ti block it should have the factory M12 turbo coolant feed with a bung in it. M12 x 1.5 from memory.
It’s just slightly forward of the block drain plug.

 

From memory, the only 3/8 BSPT bung in the TD42 block was for the oil return from the vacuum pump when the vacuum pump was on the alternator.
That was just forward of the left side engine mount.

 

Yeah I didn't see any other plug around the block coolant drain. I have heard it was M12x1.5 but that obviously wasn't the one I located. The plug I pulled was the one mentioned in the workshop manual, just above the oil pressure relief valve on the LHS towards the rear of the block. Pretty much up behind the dump pipe.
I'll have another look for the M12 plug tomorrow.
Thanks

 

Lol interesting discussion here guys. Nissan use BSPT i don't know any BSPP or Yank NPT crap in a nissan TD42. 16mm is 5/8 inch in old school and for 5/8 inch in pipe talk is 3/8 BSP and for a Nissan thats 3/8 BSPT.

The TD42 drain square head plug is 3/8 BSPT.

Bob the plug or the water inlet plug for a turbo engine or a TD42T engine has a fitting in the block which is 12mm x 1.5mm pitch. Your engine isn't a factory turbo engine i assume so you will not have this fitting just in front of the oil relief assembly. You have the 3/8 BSPT fitting just behind the oil relief assembly. Which is fine to use for your turbo water cooling assembly.

Pic's of real taps 1/4 BSPF and 3/8 BSPF. OK thats even more confusion, Damn and more @@##$$ but the British Standard Pipe Parallel (BSPP) screw thread was changed to British Standard Pipe Fitting (BSPF) screw thread to remove the confusion between the like sounding BSPP/BSPT screw thread designations

 

Lol interesting discussion here guys. Nissan use BSPT i don't know any BSPP or Yank NPT crap in a nissan TD42. 16mm is 5/8 inch in old school and for 5/8 inch in pipe talk is 3/8 BSP and for a Nissan thats 3/8 BSPT.

The TD42 drain square head plug is 3/8 BSPT.

Bob the plug or the water inlet plug for a turbo engine or a TD42T engine has a fitting in the block which is 12mm x 1.5mm pitch. Your engine isn't a factory turbo engine i assume so you will not have this fitting just in front of the oil relief assembly. You have the 3/8 BSPT fitting just behind the oil relief assembly. Which is fine to use for your turbo water cooling assembly.

Pic's of real taps 1/4 BSP and 3/8 BSP.

Edzackery, it isn't so hard is it he asked to identify the thread, his vernier pics and my charts tell it all. My bloody fuel filter outlet is 1/4" BSPT and other bits on the engine are BSPT, but if you can't get BSPT then NPT can be used successfully, I've done it.

 

This is my TD42T coolant drain plug. It takes a 12mm socket..
..

 

All good John you have a T engine which is very different with its drain plug hence the square head is a dead giveaway for BSP

 

Which TD42 block has a square head 3/8 BSPT coolant drain plug?

The pic the OP posted of the 3/8 BSPT bung has a hex head and it just looks too big to be the coolant drain unless Nissan, for whatever reason, changed the bung size for the Ti block to a near 17mm hole.. or someone buggered the thread at some point and drilled/tapped to next size up.

 

Thanks Peter,
My engine does have the factory turbo. Its a 2005 TD42Ti so I'm assuming there's an M12x1.5 plug hiding in there too? The turbo never had the water cooling connected. It looks the same as John's motor.
I have M12x1.5 to 6AN fittings already, hence my desire to use that port.
Cheers,
Bob

 

You're right John, its a hex head but I think its factory. I'm the second owner and the original owner never did any work on the car himself.
So, after all this, I've deduced that it's a 3/8BSP with a hex head but that's not the plug I want anyway. It is a coolant drain though, confirmed in the workshop manual.
The M12x1.5 plug is the one I want.
Actually, I'd like to do exactly as you've done there John.
Thanks,
Bob

 

The M12x1.5 plug is the one I want.
Actually, I'd like to do exactly as you've done there John.
Thanks,
Bob

If you're going to use a 12mm banjo, get one that's slightly angled so it comes away from the block and that allows you to position it anywhere without touching.

 

I just had another look at the photo I posted, it does look square in the photo but its actually a 12mm hex. Exactly the same as John's motor.

 

Then I stand corrected on the plug size. It's never looked that big to me and I've had mine out several times

 

Yep, sounds good John.
Was yours a bit close was it?

 

It depends on the thickness of the nut on the ferrule. If you make your own braided hoses then you can place it where you like but if it's a bought fixed length you might not have the liberty of putting it as you want.
Same on the CHRA but I don't know how that works on the BW. It was an issue on my P4x4 18G so I modified the banjo to create the angle.

You'll see what I mean when you do it..

 

I'll have the hoses made to length and use these fittings for feed and return to the M12 plug in the thermostat housing. M14 banjos should work on the BW.

 

If you're not using a 12mm banjo then no problem.

In spite of what others insist on, I'm not a fan of running the coolant return to the thermostat housing.
That connection beside the temp sensors is the hottest exit from the front of the head (that's why it feeds the heater) and is at the same high side water pump pressure as the turbo block feed.

The factory turbo coolant return goes to the lower pressure water pump inlet (same as the heater flow return) where the lower rad hose connects.
This gives you a better high to low pressure flow and will have a better thermo syphoning effect when you shutdown.

 

Good point John.
Dare I ask, WHAT SIZE THREAD IS THAT?

 

Let's see if I can get it right.. the factory turbo coolant return banjo on the water pump inlet is M16 x 1.5.

See the pressure outlet to the heater just above the spare bung?
..

 

Yep, makes perfect sense but I have a heater hose there. Where's yours?
I could just tee off of it but it wouldn't be as tidy.

 

Are you sure it's for the heater? Doesn't just go to an expansion tank does it?