RTH! Messed up threads on block drain (1 Viewer)

[Ninjaracing13]

Does anyone know what the thread pitch is for the brass plug on the block drain? It looks awful close to 1/4 NPT but can't confirm.

Looks like whoever installed it last might have gotten a little strong with the plug. It was probably me, but I'm just going to go ahead and blame the PO.

Thanks in advance

 

[1973Guppie]

Is the plug or the block stripped threads? the plug is brass so that it will strip much easier than the block. Most likely you can get a new plug and just install it. I would not use a standard bolt or other here, get an oem brass threaded unit.

 

[Ninjaracing13]

Its the plug that has marred threads, might have had some crud in the threads on the block. Didn't kill the whole plug, just the first thread. It seems the thread is 12x1.5,

 

[1973Guppie]

find the right size by matching it up at a hardware store, get a new brass oem plug and grab a tap to clean out the block threads. Then it will be nice and clean install.

 

[Ninjaracing13]

That's pretty much how it worked out. I matched it up with my tap set, chased the threads, and used a bolt with a little Teflon on it so I could finish flushing the coolant. Hopefully the dealership can get me a plug soon.

Thank you for the help

 

[Rifleman]

Just as an FYI, some of the pipe plugs on our trucks are in fact not NTP pipe thread, or metric pipe thread, but are in fact British standard pipe thread, and these thread pitches are NOT interchangeable. Case in point, the fill plugs on top of the front axle steering knuckles are in fact British standard pipe thread.

 

[Ninjaracing13]

Just as an FYI, some of the pipe plugs on our trucks are in fact not NTP pipe thread, or metric pipe thread, but are in fact British standard pipe thread, and these thread pitches are NOT interchangeable. Case in point, the fill plugs on top of the front axle steering knuckles are in fact British standard pipe thread.

Isn't the oil pressure sender threads also british? I didn't know that about the knuckle plugs. Continued searching found 90910-09129, its the drain cock, haven't found a part number for just the plug yet. Anyone know if it will work?

 

[flintknapper]

Isn't the oil pressure sender threads also British? I didn't know that about the knuckle plugs. Continued searching found 90910-09129, its the drain cock, haven't found a part number for just the plug yet. Anyone know if it will work?

Yes. I found that out recently when relocating my OPS.

 

[Ninjaracing13]

In case anyone comes across this looking for the part number.

The plug is 96431-23814

Got one coming

 

[bloc]

On the earlier 1FZ (at least) the block drain isn't tapered pipe thread at all. It is straight thread with a tapered angle shoulder on the end that seals against a cone inside the block.

 

[Rifleman]

The best, and quickest source for British standard pipe plugs that I've found, other then going to the dealership is in the McMaster Carr catalog. BSPT plugs are on the left side of the McMaster Carr web page that i posted a link to.
McMaster-Carr

 

[Ninjaracing13]

On the earlier 1FZ (at least) the block drain isn't tapered pipe thread at all. It is straight thread with a tapered angle shoulder on the end that seals against a cone inside the block.

I think you are correct judging by the picture.

I'm guessing by the way mine came out, whoever removed it last cranked it in smashing the first few threads into the tapered seat.

 

[Malleus]

This was a common design choice in the past. For all non pressurized fittings, British Standard Parallel Pipe (BSPP) threads were used. For pressure applications, metric series which are not typically used to fasten machine components are used, along with a copper compression washer. The banjo bolts on the fuel and brake lines are an example.

Generally, if you find a copper washer under the bolt head, the thread's metric.

 

[bloc]

There is no crush washer but with it being on an import and not being tapered I'm assuming it's still metric thread.

 

[Kernal]

For comparison here's a photo of the block drain and plug from my early 1996 model 1FZFE for comparison:

 

[bloc]

Was there any kind of sealant on the threads?

 

[Kernal]

Not on mine: AFAIK one purpose of using tapered pipe threads in this type of application is that they will prevent leaks without using sealant.

 

[bloc]

You'll still find some kind of sealant an almost any tapered joint. just curious whether they change the machining of the block for the different drain setup.

Does the end of the plug seal against the insert or the block itself?

 

[Ninjaracing13]

Looking into the hole there doesn't seem to be a tapered seat. the protrusion ahead of threads must be to make it much harder to get in crooked and cross thread.

On another note.... new plug does not want to go in, doesn't even want to start. The threads look good aside from some corrosion at the face. The only thing that half way screws in (by hand) is a worn out old brass airline fitting I had laying around. I'm hoping the po didn't try to retap the hole with 1/4 NPT, but I wouldnt be surprised

 

[Ninjaracing13]

The threads are shiny because I was trying to clean them with a small wire brush. Not sure where I can find a bspt tap to chase threads with.