What to use to seal crankcase plugs..

Mike Juzenas · 02-07-2006, 07:35 AM

I pulled a few of the larger plugs on my 3.6 block to make sure the main oil galley was clean. I turned out to be a waste of time but that's ok at least I know that now.

Now I need to put the plugs back in. I have the replacement Aluminium plugs. The shop manual says to "Apply Optimoly HT (copper paste) to plug and press plug in flush". Is this the preferred method or is there any other methods, for instance using some of the case sealer?

Any help is appreciated, I would rather this did not leak. ;-)

Cheers,

Mike

goose2 · 02-07-2006, 08:28 AM

I just did this too. I put a thin coat of the loctite case sealant on the plug, tapped it in, ground off the external face clean, washed with MEK, and put a thick coat of JB weld over the plugs.

Mike Juzenas · 02-07-2006, 08:56 AM

I was thinking about the JB Weld as well...I guess it can't hurt!

Thanks,

Mike

AFJuvat · 02-07-2006, 05:14 PM

Third vote for JB weld.

AFJ

cnavarro · 02-07-2006, 06:07 PM

How about tapping the galleys and plugging them with aeroquip AN/NPT aluminum plugs? I did this on my 914 and just loctited them in. I don't quite trust using a factory plug once the original has been removed.

Henry Schmidt · Henry Schmidt's Garage

Charles has the right idea. Tap the holes and use pipe plugs. It's what we do and we have never experienced ant problems.
This allows for easy cleaning during future rebuilds [specially for race engines]

Mike Juzenas · 02-09-2006, 07:16 AM

I will see what kind of plugs I can get at that size. I know they can't go too deep, there seems to be a ridge machined into the hole to hold the backside of the plug.

Good ideal though. I am going to use plugs to clean the tubs in the cam towers so why not the big ones in the block?

Thanks!

Mike

Mike Juzenas · 02-12-2006, 11:20 PM

Quote:

Originally posted by Henry Schmidt
Charles has the right idea. Tap the holes and use pipe plugs. It's what we do and we have never experienced ant problems.
This allows for easy cleaning during future rebuilds [specially for race engines]

Any idea of the size that you use? And do you have a special tap or just use a normal tap? I mean you don't want to go too deep...

I am ready to do this so tomorrow I will look around for some plugs.

Cheers,

Mike

Porsche_monkey · 02-13-2006, 04:37 AM

Use only liquid teflon on the threads, do not use teflon tape.

Mike Juzenas · 10:39 AM

OK I was going to use either red locktite or case sealer on the threads.

What size plug did you use? The SAI plugs appear to be either too small (1/2") or too large (3/4"). If its a metric plug then it likely 24mm since the hold is 22mm and needs threads cut.

Cheers,

Mike

Determined · Determined's Garage

Another vote for JB weld on the outer surface, it is very close to factory specification. Not to mention it is recommended in Wayne's book as well. I just completed my case sealing as well.

Good luck,

Alex

bpu699 · 09-23-2017, 03:33 PM

Bringing back an old thread...

For the case plugs, do you guys just use a wire brush like Wayne suggests, or do you sand over the plug to give the jb weld something to bite into...?

If you use a wire wheel, it turns the metal shiny...not sure jb weld will stick...

Can't say I have seen ANY threads about these leaking. On my car, most of the original epoxy was long gone... Can't say it was leaking...

1990C4S · 09-24-2017, 03:35 PM

Wire brush and acetone will work.

bpu699 · 09-24-2017, 05:46 PM

Will do...

outsider347 · 12-23-2018, 01:23 PM

What size tap & plugs did you guys use?
Tks for your response.

outsider347 · 12-26-2018, 03:33 AM

Anyone have info?

Walt Fricke · 12-26-2018, 11:54 AM

Standard hardware store US thread Allen plugs will do the job. I think smaller holes (like the cam carrier squirter tube ends use 1/8" plugs. Don't recall what the larger holes, like the end of the main oil gallery, use, but a usual size works. With the plug out, measure and go to the hardware store with your caliper in hand.

I suggest you use brass plugs. I used aluminum, thinking to save weight of course, and found I had a lot of trouble getting them back out when I went to rebuild the engine again (plugs are most useful for race motors, which get taken apart far more often than our highly reliable street moters) - the Allen would round the in-hex. Not a big deal if you purchase some which are too small or large - Home Depot will take them back if you don't want them in your hardware jars. Then buy the taps that go with them.

I'm inclined to use red Loctite. These are tapered threads, which depend on being screwed in far enough for the taper friction to seal and hold. But you don't want to insert these too far in, especially in some places. The big plug by where the oil pressure sender/cam oil line sits is a case in point. If you put a plug too deep into that hole you will block an internal oiling passage! I found I had to grind a relief on the backside of the plug, and work hard so that the plug was "clocked" so that the relief lined up with the internal hole. This means you might not be able to screw a tapered plug in far enough for its taper. This suggests you do your tapping a bit shallow to start with.

I recall the flywheel side isn't quite as tricky.

A machinist once told me that Teflon tape (or the liquid stuff - the issue with tape is getting some in too far, so a bit gets cut off and swirled away in an oil passage) is intended to reduce the friction in a tapered threaded part, so it will seat fully in, and not as a sealant. I didn't know that. Makes sense, though. But red Loctite must have some lubricating properties, and in this application, if you can't back the plug out come next rebuild, pretty much by definition you have the case apart and can apply heat.

Then, when yo

I

outsider347 · 12-26-2018, 03:35 PM

Tks very much Walt