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Hi guys,

I'm restoring an 87 Impulse, 4ZC1-T, and I am down to one part:



This is a water nipple that drains coolant into the turbo. It threads into the (USA) driver's side of the block. You can see my original one there is totally stuffed. Years of bad coolant have basically rusted the thing out.

I've been everywhere over here and NO stores carry metric pipe fittings like this. I've got a replacement on order through Isuzu and it has been on back order for months, I am starting to think it ain't coming in.

Do you guys have sources down under for weird parts like this? I think it is a M.14 but both fine and course thread nuts do not fit it right, so I honestly have no clue what it is.

Thanks - Bart
http://www.isuzugeek.org

I think they are usually 14x1.5. Count 5 threads & measure, 10 x 1.5 = 15mm hence 5 = 7.5mm = .295 = .3" =~5/16". (Or .246 = .25" = ~1/4" for 1.25mm pitch)

In that range, there are no "course & fine" metric threads - they are typically 1.0, 1.25, 1.5, 1.75mm pitch (etc?).

IZU069 wrote:I think they are usually 14x1.5. Count 5 threads & measure, 10 x 1.5 = 15mm hence 5 = 7.5mm = .295 = .3" =~5/16". (Or .246 = .25" = ~1/4" for 1.25mm pitch)

That hurts my brain...

IZU069 wrote:In that range, there are no "course & fine" metric threads - they are typically 1.0, 1.25, 1.5, 1.75mm pitch (etc?).

Right, those are what we have over here, but nothing seems to fit right. I can spin a 1.5 nut on but it fits "loose". So maybe it is 1.25.

Bart

A 1.25 should lock up as should any incorrect pitch.

Just try any Japanese or almost any imported car. That size & pitch is quite common - unless its a Yank vehicle.

IZU069 wrote:A 1.25 should lock up as should any incorrect pitch.

Just try any Japanese or almost any imported car. That size & pitch is quite common - unless its a Yank vehicle.

Quite common for you guys in Oz, I'm sure. That's why I posted on here to see if it is a common part you can get anywhere. All my parts stores over here have SAE pipe fittings and no Metric. Its been very difficult so far. Its weird too because I have one of these:

http://cgi.ebay.com/ebaymotors/Metric-S ... 256261b4f6

And it doesn't match anything. Nearest I can figure is 14mm with some oddball pitch.

I have a few other places to check. Maybe I could find an adapter or something.

Thanks -Bart

Jap cars are metric.
So too most of your imported cars.


But you are right - it is an oddball thread.
It's called BSP Whitworth 1/4" Gas.
It's close to 13mm x 1.25 (19 per inch)

IZU069 wrote:Jap cars are metric.
So too most of your imported cars.


But you are right - it is an oddball thread.
It's called BSP Whitworth 1/4" Gas.
It's close to 13mm x 1.25 (19 per inch)

There it is!!! Honestly, I was thinking it was 13mm because it really doesn't fit right in a 14mm hole, nor does it even go into a 12mm hole!!

Thanks!!!!

Bart

Yeah... D'oh!
The others are 12x1.25mm (I think) - eg, oil etc into turbo.

Your pic above looked like the BIG water etc off other engines (my OHVs etc) which I thought were 14mm but are actually 16mm (x1.5?).


But that BSP 1/4G is the same as used for the oil galley on the RHS if the block (just above the sump) and are the same as the oil pressure switch and (gauge) sender. (I have a redundant oil pressure switch in the galley (the other is under the oil filter on the G-OHV engines - not the same a 4Z engines) plus a oil-pressure sender.

The BSP Gas is one of the few imperial threads used on the Isuzus - I guess being a common thread for oil switches etc, and a good tapered thread for fluids etc.


Sorry I didn't think of it before - d'oh!!

But those 1/4G barbs should be as common as L. The barb is ~9-10mm (3/8").
My 4ZC1-t barb looks to be brass and is as good as new. Brass & copper can be a bit sus with alloy heads (electrolysis), but that doesn't appear to be a problem provided coolant is used. (Plus maybe its remoteness from alloy heads & water pumps.)

Thanks, I printed out your info. Now I just need to find a place that carries these kind of fittings with this weird threading.

Bart

They are imperial. And very common for oil switches etc, though many use the smaller 1/8G (28 threads/inch & smaller diameter).

Should be easy to get from any place that supplies hydraulic & air fittings etc.

Yup, I'm headed to a specialty pipe fitting shop after work, they think they might have something or at least an adapter.

Bart

Righto you guys. BSP (or British Standard Pipe) thread comes in two forms, BSPP (parallel) and BSPT (taper) The main reason Isuzu had these on their engine blocks is a hang over from the day when isuzu used to market british cars like Wolseley's in the early days and later Hillmans. The same reason is why early Nissan (Datsun) push rod engines were in fact copies of the BMC "A" series donks, so much in fact that many gaskets were interchangeable between datsun and BMC.// Back to the subject. In the USA they don't use BSP in either form very much. They use NPT (national Pipe thread) and it isn't the same as BSP. It is NEARLY the same but just different enough to be a pain in the rectum. If you can't find a BSP fitting to braze a hose tail on to I can probably find you something here. You will still need to make the hose tail part as we didn't have water cooled turbos so don't have the fitting.

Thanks, gents. I'm almost there. Yesterday after work I went to a specialty pipe and hose shop. They had a BSP to SAE adapter that fits my block. Now I just need to go get a 1/2" SAE nipple and I am home free....UNLESS it ends up sticking out to far (the whole fitting with be about 1"-1.5"s longer) because of the adapter. I won't know until I get to assembling the motor on the stand. But, the adapter is a promising option. I just don't like it because it creates another area for potential leaks, but I can probably put some sort of sealant on the threads when I assemble the new nipple to the adapter.

Bart

use "loctite 567" brilliant stuff, will never leak

Wedgie is NEARLY right, the reason that a BSP thread was used in the block is so that its will accept a BSPT threaded spigot - yes, the spigot you are all talking about is actually tapered and designed so that it could be installed without the need for any sealant or copper gasket etc.

Many of the older, established gas and pipe specialists over here can unearth fittings which are similar, but I do have a few reasonable used ones knocking about if anyone is really stuck.

Along with a cellar full of about ten grands' worth of new and used JR Piazza spares