Thread sizes???? Ed. C or Sensei or anybody??

Submitted: Sunday, Apr 04, 2004 at 19:31
ThreadID: 11822 Views:2091 Replies:3 FollowUps:6
This Thread has been Archived
G'day all,

Back in POST # 11,482 I asked about fitting an oil pressure gauge to my 4.2 Patrol. Ed.C & Sensei both kindly gave me a lot of advice....thanks again for that.

I have now got a VDO 100psi gauge and sender unit; ordered through a local auto sparky. I asked them to get me an adapter too (1/8bsp male & 1/8ntp female). It got stuffed up somewhere along the way and they sent a 1/4bsp male+1/8ntp female. Anyway, I've fitted and wired as much as I could and have also slightly moved a pipe which was in the way of where I want to fit the sender.

As part of my preparations I decided to bench test the whole lot. I have a first generation ARB compressor which has numerous outlets. I removed one of the 1/8" plugs on the compressor, believing it to be a bsp arrangement. I tried to fit the sender unit and hey fitted. I then went on to test it and all went okay.

My question is therefore.....does anybody know what the ARB compressor's 1/8" thread type is? (bsp or npt). I have a few different brass fittings that fit the compressor as well as the new sender unit fits. I always believed these brass fittings to be BSP.

On friday afternoon after I picked up the unit from the auto sparky, I did a run around of every possible place that might stock a brass adaptor. A couple of them said the only difference between the 2 thread types is that one has 27tpi, the other 28tpi (threads per inch). One bloke at a large tractor place said he is aware there is a slight difference but he just uses a spanner to force a fitting in and never has any worries. Sounds a bit rough to me.

I also priced a bottle of Loctite hydraulic thread sealant and nearly fell over when I was quoted $30- for about 100ml. I only need a couple of drops!!!

Anyway, if anybody has anything worth letting me know about, I'd appreciate it. I will be getting on to the auto sparky tomorrow to let them know that I had no luck getting the conversion adaptor and seeing if they can get it for me. It just seems strange how well the unit fitted in to the ARB compressor (bsp thread????)


Back Expand Un-Read 0 Moderator

Reply By: sensei - Monday, Apr 05, 2004 at 00:05

Monday, Apr 05, 2004 at 00:05
Hi Roachie,
Im unsure as too what type of thread is on your ARb compressor but there is a way you can check the threads. Yep there is a 1 tpi difference between BSP and NPT and yes alot of people do just screw them in, me included. I have done that in the past on different things and had no problems but only when I've had no choice about it. To check the threads just hold the sender in one hand, the plug in the other hand and place the plug on the top of the thread of the sender. Check to see in any light comes throught the two threads, if there is none or very little ( a bit hard to discribe this) then the two threads must be the same..BSP.
If that is not enough try to get hold of some thread gauges and check the threads on the sender/plug with them.
If you beleive they are the same thread then try the sender into the block of the engine by hand, if it feels OK then great.
Just one more thing, if memory serves me correctly the the VDO electric sender units are all BSP and you may have nothing to worry about, but of course please check the thread size first.

Hope this helps Roachie.
AnswerID: 53200

Follow Up By: Roachie - Monday, Apr 05, 2004 at 09:29

Monday, Apr 05, 2004 at 09:29
Thanks for the suggestion mate. I may try that later. If the plug was a bit easier to get at, I reckon I'd just rip it out and try the sender unit in the hole. But if it doesn't fit properly, I'll have to put it all back together again and keep looking for a adaptor.
FollowupID: 314952

Reply By: Member - Ed. C.- Monday, Apr 05, 2004 at 02:20

Monday, Apr 05, 2004 at 02:20
G'day Roachie,
I presume the sender unit you got with your 100psi VDO gauge is Part # 360.086...
If so, then the thread is 1/8"-27NPTF... It is *NOT* BSP (28tpi)....
Shoot me a line with your postal address details at....


There's a Pirtek outlet just up the road from me, & I'm pretty sure they'll have the correct adaptor for your application... I'll go & get one & send it to ya, & you can buy me a beer when & if we should happen to cross paths....

Regards, Ed. C.

Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

My Profile  Send Message

AnswerID: 53202

Follow Up By: Roachie - Monday, Apr 05, 2004 at 09:34

Monday, Apr 05, 2004 at 09:34
G'day Ed.C
You're right about that part number.
Thanks very much for the offer of the Pirtek part, but I'll try to get the Auto Electric people to get one in for me. They have a pretty good service; I only ordered the gauge around 4-30pm last thursday and it was in their shop at 3-30pm friday. So hopefully tomorrow??
I would be reluctant to try the 27 tpi into the 28tpi idea. I know it's bloody close, but we're talking about the possibility of a major failure (maybe) if I get it wrong.
FollowupID: 314953

Follow Up By: Member - Ed. C.- Monday, Apr 05, 2004 at 19:33

Monday, Apr 05, 2004 at 19:33
G'day Roachie,
No problem!!
It is true that it is indeed possible to "mismatch" the 2 thread types, and I'm sure that there are many who would not even "feel" the difference when tightening them up, but I certainly would not recommend it if the correct fitting is available....
If you have any difficulty locating that adaptor, then my offer stands, OK?

Regards, Ed. C.
Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

My Profile  Send Message

FollowupID: 315005

Reply By: Member - Ruth D (QLD) - Monday, Apr 05, 2004 at 07:27

Monday, Apr 05, 2004 at 07:27
Hey Roachie, Pesty turned up yesterday - he beat Andrew & Jen - they should arrive today. They went into Kalamurina but the water has dropped 12 feet in four days there. Spent the whole afternoon yakking away - had a great time. Going yabbie hunting today and big roast dinner tonight. Should be fun. He told me all about you and Des Lexik.
AnswerID: 53205

Follow Up By: Roachie - Monday, Apr 05, 2004 at 09:27

Monday, Apr 05, 2004 at 09:27
G'day Ruth,

It's funny, but I thought y'all were a bit particular about who you let into your lovely town.....I must have been wrong if you've let Pesty in!!!LOLOL But then again he does have his best asset with him (I mean Glenda; not the Landcruiser!!!).

I hope he's going to see John over at the Museum. I've been telling him it' a great place (& he'll probably get some ideas on how to moderise his old bucket of bolts).

Somebody must have pulled the plug out if Kalamurina's gone down 12 feet in 4 days...WOW!!!

When you see them again later, please pass my regards on to them.


FollowupID: 314951

Follow Up By: Member - Ruth D (QLD) - Monday, Apr 05, 2004 at 17:50

Monday, Apr 05, 2004 at 17:50
They've been annoying me all day and now the McDonalds have arrived too. They are all coming for Roast Road Kill Dinner tonight - outside after the flies have gone to bed and by the beautiful moonlight looking over the Billabong and maybe with Willem's bottle of Muscat (no, that's a joke) - just some Merlot for Glenda and myself. Pesty can drink water. Andrew can look after the kids and Jenelle can have the night off.
FollowupID: 314995

Follow Up By: Baz (NSW) - Monday, Apr 05, 2004 at 18:54

Monday, Apr 05, 2004 at 18:54
Roachie there is a thing that measure's thread sizes, look's similar to a set of feeler gauges bit smaller, i think you can still get them from tool places or auto spare's shop's.

FollowupID: 315003

Sponsored Links