RTH-Engine Coolant Drain Plug

[southerncruiser62]

So I purchased a new short block from Toyota and the old coolant drain plug off my 95 block doesn't fit the new block....after doing some research and speaking with cruiserdan we found a superceded part number and ordered the new plug. Received it yesterday and it is the same as the old one. This has been brought up in another thread but no conclusion was made. I have an assembled motor and am planning to drop it in this weekend but want to resolve this drain plug issue before it becomes to difficult to reach and an issue later.

Has anyone found a solution to this issue or know the pitch on these new toyota short blocks? I was really hoping to get this cruiser going again this weekend.

TIA for any help.

 

[BlackLS1]

threads could be dirty, but i would start with a pitch gauge and measure the opening to try and source a correct bolt from toyota. i think toyota lists the thread size and pitch when selling them so you make certain you are buying the right one.

 

[southerncruiser62]

Threads are clean, this is a Brand New OEM Toyota Block. Quick look with a flashlight verifies they are clean. I spent an hour at local toyota dealer this afternoon working with them to try and figure it out. Unfortunately I can't just load the new engine in the back of the 100 and carry it up there. I am moving forward with install and hoping someone will have had the same issue. I will just have to install plug once verified through wheel well now.

The other question about this opening is whether the plug is tapered, by visual inspection of the new and old plug I doesn't appear. I have heard mention though that some believe it is a pipe thread.

 

[Rifleman]

The other question about this opening is whether the plug is tapered, by visual inspection of the new and old plug I doesn't appear. I have heard mention though that some believe it is a pipe thread.

I know this is an old thread, but I came across it and wanted to provide some information on the correct thread for our blocks drain plug. The plugs on our engines, and steering knuckles are NOT American NTP pipe, they are in fact British standard Whitworth. Whitworth pipe threads come in 2 different styles, and are NOT interchangeable with American pipe threads. Both the 1/4 and 3/8 inch Whitworth plugs have 19 threads per inch. Both the 1/4 and 3/8 inch NPT plugs have 18 threads pre inch, so you can see there both close in thread count. Even though an American pipe plug will start in the hole, and you may get a turn or two on it, don't do it, It'll damage the threads in the block or knuckle.

British Standard Pipe Parallel thread (BSPP) straight Parallel threads.
British Standard Pipe Taper thread (BSPT) whose diameter increases or decreases along the length of the thread.


If you can't find Withworth pipe plugs from your local vendor you can order them from McMaster-Carr
BSPT

BSPP

• For Use With: Air, Water
• Specifications Met: ISO 7.1, ISO 228

Pipe
Size Material Plug
Construction Hex
Size, mm Max. Pressure Gasket
Material Each
BSPT
1/8 Nickel-Plated Brass Solid 5 2,900 psi @ 72° F __ 4860K131 $1.89
1/4 Nickel-Plated Brass Solid 6 2,100 psi @ 72° F __ 4860K132 2.92
3/8 Nickel-Plated Brass Solid 8 1,450 psi @ 72° F __ 4860K133 3.26
1/2 Nickel-Plated Brass Solid 10 1,450 psi @ 72° F __ 4860K134 6.09
3/4 Brass Solid 12 1,750 psi @ 72° F __ 4860K135 16.91
BSPP
1/8 Nickel-Plated Brass Solid 5 2,900 psi @ 72° F Rubber 4860K125 3.74
1/4 Nickel-Plated Brass Solid 6 2,100 psi @ 72° F Rubber 4860K126 5.11
3/8 Nickel-Plated Brass Solid 8 1,450 psi @ 72° F Rubber 4860K127 5.76
1/2 Nickel-Plated Brass Solid 10 1,450 psi @ 72° F Rubber 4860K128 9.77


Plugs with External Square Drive Style

• For Use With: Air, Water
• Specifications Met: ISO 7.1, ISO 228

Pipe
Size Material Plug
Construction Max. Pressure Each
BSPT
1/8 Nickel-Plated Brass Hollow 1,000 psi @ 72° F 4860K315 $8.40
1/4 Nickel-Plated Brass Hollow 1,000 psi @ 72° F 4860K316 13.21
3/8 Nickel-Plated Brass Hollow 1,000 psi @ 72° F 4860K317 14.60
1/2 Nickel-Plated Brass Hollow 1,000 psi @ 72° F 4860K318 15.75
3/4 Nickel-Plated Brass Hollow 1,000 psi @ 72° F 4860K319 20.07

 

[musthave]

Threads are clean, this is a Brand New OEM Toyota Block. Quick look with a flashlight verifies they are clean. I spent an hour at local toyota dealer this afternoon working with them to try and figure it out. Unfortunately I can't just load the new engine in the back of the 100 and carry it up there. I am moving forward with install and hoping someone will have had the same issue. I will just have to install plug once verified through wheel well now.

The other question about this opening is whether the plug is tapered, by visual inspection of the new and old plug I doesn't appear. I have heard mention though that some believe it is a pipe thread.

Hey, what did you end up doing with this? I am in the exact same predicament. Did you go with a Whitworth plug? It's bizarre that the OEM one doesn't fit.

 

[Kernal]

This is an updated drain cock that should fit:

 

[Bambusiero]

Just throwing in my 0.02 worth, in case it helps - the threads on the normal brass plug do not provide the liquid/pressure seal, they are straight M14x1.5mm. I fitted that size standard bolt into the opening - finger tight. There is a non-threaded extended section with a cone on the end, that seals into a female cone seat.
- well... I dunno if Mr.T's tap said M14-1.5 or BSPP on it, but I do know that my brass plug measured out as close as I could tell to M14-1.5 and that size bolt from the hardware store turned right in without need of a wrench - and they matched up to each other. 19 threads per inch is 1.337mm for what it's worth.
Some photos.