missing drain plug

[forcenine]

Hello A4ers,
I'm attaching a pic of what appears to me to be a missing block drain plug. I did my best to clean around it but can't tell if there are recognizable threads left. I tried to stick a thin screwdriver in to tell if it was blocked but suspect that it not a viable test for blockage. I did not try starting the motor again as did not want a repeat of the shower I experiences when I posted "water, water, everywhere" last month. This problem of massive water did not happen throughout my working out problems with fuel system and thermostat housing issues but seems to have surfaced at the time of the muratic acid flush. Could I have blown it out then?

Can I expect to be able to screw in either the drain plug or nipple with plug if I purchase it from the catalog? Any other thoughts on how to approach the problem?
Lisa (Forcenine)

[Don Moyer]

Lisa,

Your photo does indeed show the aft block drain, but it appears to be clogged, so I'm not quite convinced that it is the cause of your rather widespread water damage. I'd risk having someone start your engine one more time (if only for a few seconds) while you observe the area closely. It may be that water is jetting back to the area of the drain plug from your water jacket side plate.

Whether or not the drain plug turns out to be the source of the leaking, you can probably take a 5/16" drill bit held by a vise grip and work out the clogged material, and then re-tap the hole using an 1/8" pipe tap. Worst case would be that the hole has corroded too large for the 1/8" pipe tap, in which case you would have to re-drill it to 7/16" and tap the hole using a 1/4" pipe tap. Please don't be confused by these apparent typographical errors. The ID size designations of tapered pipe threaded fittings (1/8", 1/4", etc.) date back to the 1800's when lead pipe was used in homes and the wall thickness of pipe was very thick.

Don

[forcenine]

Don,
The slightest crank on the engine revealed water coming out of the aft drain pictured above. My theory is that the hole WAS blocked, with no cap, until my muratic acid flush which blew the blockage, and alot of water, out. I removed the distributor and alternator to access the hole which was only possible to see by flattening my head against the gas tank (!). Not even a mirror worked. Found a guy at the marina with a tap set who, because of the lack of access was only able to get a couple of threads into it. The nipple would not go, but he did manage to tighten down a plug I had. See pic.

Now, what's my best way to test the plug for watertightness BEFORE replacing dist and altern? (and side jacket while it is revealed) Which pressure flush system would do it? And, do you think there's any hope of backing out the plug and having success with the nipple that would not go before. I hate not to have access via the nipple later, but I'm disinclined to mess with the cap that may have worked for me.

Lisa (forcenine)

[Don Moyer]

Lisa,

You have good instincts. I recommend going the extra mile in trying to reinstall a 6" brass nipple and cap.

This is an 1/8" tapered pipe-threaded hole, and your friend's work suggests to me that the hole will respond well to a little more effort with the proper tools. You can go to any hardware store and pick up your own 1/8" pipe tap. Then get a 3/8" drive socket (at the same hardware store) that will fit over the end of the tap so that you can use a 3/8" by 8" (or so) extension and ratchet to clean up the threaded hole a bit deeper, so that the nipple will go in a little further. As a matter of finesse, do not run the tapered tap into the hole too far or the nipple will end up being too loose. Stop frequently to install the nipple and stop when about 1/2 to 3/4 of the threads of the nipple are buried.

Don

[forcenine]

Don,
I got the 6" nipple into the tapped drain hole and did a flush following your pressure flush directions. It seems the nipple fitting is holding water but with an oozing thermostat housing I just can't tell if water is seeping out the water jacket side panel or not.

I am having a terrible time sealing the thermostat housing completely. I'm using your pre-drilled housing/spacer/gasket system and really need a specific practice to absolutely water-proof it.

On the first install of the housing I used a grey "for thermostat" gasket maker sealant (Permatex) liberally to prevent leaks. Made the mistakes of sealing the upper gasket making it super hard to remove and think I even used "lock-tight" on the in and out npt fittings to ward off leaks. None of these measures prevented leaks, only made it %$#@& difficult to remove.

Before THIS flush, I made new gaskets from grey gasket fabric, wiped on some marine silicone sealant (worrying that the "gasketmaker" stuff was too aggressive) and used only teflon tape on threads. The gasket/sealant combination is just not working even with measured tightening of the studs.

What can I do? Also, is any of this telling me whether I might still have a crack in the block or head?

Lisa (forcenine)

[Don Moyer]

Lisa,

I need to be out of my office until mid-afternoon. If you email your telephone number to me I'll give you a call. I think we need some "real time" conversation and I never learned how to instant message.

Don