Oil gallery plug-Anyone know the thread size?

[shinyribs]

Trying to get the cases squeaky clean before I pc them. I wasn't comfy not being able to run a brush thru this gallery. I decided to drill out what looked like a solid,pressed in plug. Turns out it was actually threaded. There is enough material there to drill and tap for a 1/4'' pipe plug,which was Plan A. But if I can find the proper plug for this hole that'll be even better. Anyone have a clue? I sure dont!

[Hellbilly429]

Take the old plug down to autozone or your local hardware shop and size it up boss, or were you looking for an answer tonight?

[shinyribs]

Ah, I left out that detail. I didn't know it was a threaded plug. All that's left of it is a lump of shavings. Totally gone. I hate to carry the case into the hardware store to size it up looking like a big ol goober

[TOOLS1]

It should be a Metric 1/4" NPT.
TOOLS
P.S. NPT=National Pipe Thread.

[shultz_1978]

If it is the 1/4 npt it should be a 1/4-18 npt. It maybe British.

If it is the 1/4-18 try to get the socket flush seal style.  

[shinyribs]

I tried a 1/4'' NPT and its way smaller. It's a shade bigger than a 1/8'' NPT. If you put an 1/8'' pipe plug in this hole the outer edges of the plug just barely rattle around inside the inner edges of the hole-if that makes any sense. Drilling it out to a 1/4'' plug would actually have to remove a fair amount of material.

Thanks though guys. I do appreciate it. I'll see if I can ID the actual thread for future reference before I caveman it

[robs750]

shinyribs wrote

I'll see if I can ID the actual thread for future reference before I caveman it

I was going to suggest measuring the the Id with some calipers or drill shanks and then you may be able to figure out the major dia for the plug/bolt.You can measure the pitch with a metric pitch gauge or take a guess.

Is it a straight or tapered thread?

[shinyribs]

Rob, it seems to be straight which is very odd. No taper, no o-rings, no nothing.  And since it had no head on it, no crush washer. Id love to know how they even installed it. I'm guessing they screw them in and then grind the heads off???  I dunno.  I'll take some measurements and see what I can come up with

[shinyribs]

Measures right around 10-10.2mm. Kinda tough to get at with the calipers. It just now occurred to me while typing to try a 10mm banjo bolt.If that doesn't pan out I'm just gonna take this thing into town with me.

[robs750]

Your going to have to add on to the ID measurement.Maybe a 12-13 MM bolt.

[shinyribs]

Didn't find any metric bolt that would fit. 10mm too small. 12mm too big. I took the case over to the section of taps. 7/16 NF seemed to be the right diameter, but none of the tpi 's were right. A 3/8" NF 24 tpi seemed to match the thread pitch just right, but there was no 7/16- 24 tpi. If I had to guess that would have been right, but I don't even know if that size exists.

Its fixing to be 1/4" NPT here in a bit :)

[Lucky 1]

Be very careful when installing a pipe plug into a aluminum engine case.
It is tapered do you can crack the case if you over do it.
Also uses a steel pipe plug on the case NOT brass. Less corrosion potential.

[Lucky 1]

Where is this engine going? What bike?

[robs750]

I would not use a NPT tap.

Being a machinist ,I would measure the pitch with my metric pitch gauge and find a bolt or set set screw.

If I could not find a metric bolt or set screw,I would find the closest SAE bolt/set set screw and chase the thread with the corresponding tap.Install the new bolt/set screw with thread sealer.

[shultz_1978]

A fine thread 7/16 is only 20tpi . How so are you wanting to get this plug or maybe a socket set screw. I can try to find some thing at work Monday.

[shultz_1978]

What about a 3/8-24 tpi Socket set screw with thread seal lock tight?  

[shinyribs]

Well poo. I shoulda checked in here earlier. I already tapped it for 1/4'' NPT. I never thought about the tapered thread cracking the housingThere is alot of beef there. I wonder if it would be OK as long as I used some really good selaer and didn't overdo it on the torque. And by really good sealer I mean epoxy. Only problem with that is it would be permanently glued in at that point.

You know,I could tap it out a little bigger and use a straight thread bolt and a crush washer! Not alot of room there for a bolt head of any type,though.

Lucky,this is supposed to be the engine for Hackjob...if I dont ruin it first!lol

Rob,(and Lucky)thanks for pointing out about the tapered thread issue.That's a very good point!

Shultz,that was a stab in the dark on the 7/16''-24 tpi.  lol     The 3/8'' -24tpi laid in the threads perfect,but the diameter was too small. I really have no clue what this thing is. Nothing fits it. And I still can figure out what was sealing it in the first place! You mentioned thread sealing lock tite. Does that stuff seal good enough that I could possibly use that with my 1/4'' pipe plug without needing alot of torque?

Oh,and on the brass plug thing. I had a hard time finding a brass plug with an allen head(3 stores to get one)which I really wanted. I was thinking the soft brass would seal up easier than a hard steel plug. Is brass really a no-no with AL?


Thanks for all the help and info guys! I'm not dead set on using this pipe plug. I'm still open to any suggestions.

[shultz_1978]

The thread sealer lock tight well help seal it, but well not harden like standerd lock tight. I believe it is blue not the red stuff.

I really do no about the brass and aluminum thing. They use brass ferrules compresion fittings in all kinds of mat'l.

The only time I have seen any issuse is when you get corrosion in the thread. Most of the time that is steel bolts in aluminum.

[robs750]

shultz_1978 wrote

The thread sealer lock tight well help seal it, but well not harden like standerd lock tight. I believe it is blue not the red stuff.

Loctite Thread Sealer is white ,IIRC.
The removable Loctite is blue and the high strength is red.

Theres also a cylindrical retaining Loctite which is green.

I really don't think there would be an issue with corrosion using a brass plug.

[shinyribs]

Thanks Rob.And I agree with you and Shultz,I dont really see any major issues with using the brass plug.

The green cylindrical loctite you mentioned. What is that stuff for? Cylinder sleeve or over sized bearing holes? Never heard of that before.