I had a couple of requests for this info after my post on hose clamps yesterday. It let's you drain your block without making a huge mess. And if you look closely, you can see my screwdriver at the bottom of the antifreeze drain pan...
The drain hose thing is pretty easy and remarkabley less messy than the normal process. The key to success is the pipe tap operation(see below).
To do this, you need a few things:
1/8" NPT or NPTF pipe tap - either borrow a good one, or buy one at McMaster Carr (http://www.mcmaster.com), where you will get your other parts. Don't use a crappy one from Harbor Freight. McMaster p/n 2553A12, $23.11.
High pressure braided SS chemical hose, 12", 1/8" NPT fittings - McMaster p/n 4468K131, $12.10
Brass pipe cap, 1/8" NPTF - McMaster p/n 5799T25, $3.19
Cold beer or other adult beverage - Market price
1 - Read this whole post and make sure you understand what is going on. If not sure, go find a friend who "gets it", and have them help you. You only have 1 engine block and we don't want to screw that up.
2 - Remove block drain plug and drain coolant all over the floor. Be happy while cleaning up the mess, as this won't happen next time. You can drink one beer at this point, before your start cleaning up.
3 - No more beer! Chase the treads in the engine block with the pipe tap. This is the tricky part, as the threads in the block are not actually 1/8" NPT. They are a metric (or maybe british) tapered pipe thread with 28 threads per inch, not 27 like the NPT. So what you are doing is re-cutting the threads slightly to the US NPT standard. Because this is a tapered pipe thread, the as the tap goes deeper, you get into new metal to cut treads in. The tricky part is not to run the new tap in too deep, or the fitting on the end of the hose will bottom out before the tapers are able to wedge into each other. If this part doesn't make sense yet, go find that friend who "gets it" before you go any further.
4 - With that said, we are going to put the tap in the threaded hole very carefully by hand to get it started. It should thread in just fine, with almost no resistance; you should be able to to turn the tap several revolutions before you feel resistance. Be absolutely positive the tap is going into the hole straight. The tap should snug up as the tapers start to wedge together. Once together, shoot a little WD-40 into the hole and then start turning the tap in, using a small open end wrench on the square at the end of the tap. If you have room, a tap wrench is better, but you probably won't have the space. Turn the tap about 180 degrees clockwise and then 90 degrees counterclockwise to clear the chips the tap is cutting. Make sure you don't push the tap off-center when turning with the end wrench. Then clockwise again and counterclockwise. Do this until you have progressed about 2 full turns on the tap (put a mark on the tap to keep track). Loosen the tap and remove by hand. Use your shop vac to slurp out any chips in the hole.
5 - Take the hose with the threaded ends and do a test fit of the fitting in the tapped hole. Again, be very careful to line it up straight. It should smoothly thread in several turns before you feel any resistance. Tight up the fitting very HAND TIGHT and see how many threads are still exposed outside the block. There should still be a few (4-5 would be brilliant) exposed. See picture below, I see about 3 threads exposed (after full tightening). If you have more than the picture, tap another turn and check again. Each turn of the tap will be the same as 1 more thread in the block. If you have the number of threads shown in the picture or less exposed. Stop now.
6 - Once you have the hole tapped, put you favorite thread sealant on the end of the hose fitting and screw it into the block. I use Permatex Form-a-Gasket #2, totally old school. You should tighten it up pretty tight, but don't go crazy. Once that end is done, you can put the cap on the other end, also using thread sealant (or put the cap on while the hose is still on your bench). Maybe not so tight, as you'd like to take that end off someday.
7 - Use a couple tie wraps to hold the hose close to the block, so it doesn't flop around. Check for leaks when you fire up the cooling system again.
8 - Now you can have another beer.
