View Full Version : Which Tool for the Oil Drain Bolt?

03-09-2005, 06:52 PM
I need to relieve the engine of the oil before turning it over. I can't get the bolt off after being siezed in there for fourteen years, and I don't want to round it off. I would like to replace the square head with a more conventional hex head at some point.

03-09-2005, 07:50 PM
I'm not quite sure whose idea it was to put a square headed bolt on oil pan and transmission drains. I changed all mine to hex head bolts. You can find these at any industrial-grade shop. Just clamp a really big pair of vice grips on the little puppy and start tapping in a counter clockwise motion. Bring the bolt to said shop to match the threads. Do the same for your tranny. I can top off my tranny from the bottom easily now by accessing the side bolt with a shallow socket. p.s., never use teflon tape to secure a seal.


03-09-2005, 08:50 PM
I know the drain plugs on the TRactor (4 Cyl) engines are actually tapered pipe plugs which usually come with a square head. If it's square on the six cylinder engine, it's probably a pipe thread also, which is readily available just about anywhere. I've used a pipe wrench on those suckers when they are really tight which only seems natural since it's a pipe plug. The cast iron plugs generally have the square head. Steel and brass can be gotten in hex heads. Steel hex would be the best choice, but since generic pipe plugs are so cheap, putting a new square head guy on every oil change if neccessary, wouldn't be a big deal. /ubbthreads/images/graemlins/cheers.gif

03-09-2005, 09:28 PM
Most of the big BL companies carry the right wrench for the job, I was lucky to pick up a bunch of square head sockets at a yard sell years ago. I would guess they are still avaible at your local plumber. TR6Bill is right about the vise grips on one that has been stuck for a while. Wayne

03-09-2005, 09:36 PM
When you do get the old plug out replace it with a magnetic drain plug. All of the houses sell them. It's a good way of keeping unwanted bits from circulating.
As recomended a large vise grip (10cr) will grip well but leverage will not be great. You can also use a pipe wrench.

How come the stuff that's supposed to come loose doesn't & the stuff that's not, does ?

Geo Hahn
03-09-2005, 10:43 PM
...never use teflon tape to secure a seal.

[/ QUOTE ]

Why is that? I don't do this on the TR because I see no need but routinely do it on an engine with an aluminum casing and steel plug. Get that one too tight and it's all she wrote.

Is it because a bit of the tape might get in the oil? I sure I have nastier stuff in the crankcase from time to time.

03-10-2005, 01:20 AM
Its a plumbing remnant. I will look around at the local stores to see if I can come up with something. I have a really old style hardware store not far away that may just be the one to have such a tool. With the way the car is sitting on the jackstands, it is kind of hard to get at the bolt under there. Especially since the floor is freezing cold, and there is water trickling in from the cement because all the rain we got in the fall is thawing.

Don't ask, we must really love this to be laying on freezing floor in the ice cold weather trying to get some strange bolt loose....

BTW, I did see the magnetic diff bolt with a hex head in the TRF catalogue. I presume the the thread pitch is the same. I will order one with my next TRF order.

I really like this forum. Everyone responded so well to what seemed like an inane question about an oil drain bolt. I have changed the oil on 100s of cars at work (with normal bolts). I found myself getting annoyed this afternoon, and that is when I put my tool down and went inside. Its supposed to be fun above all else.

03-10-2005, 08:42 AM
Hi all,

Most any good hardware store will have the bolt you are looking for. It can be bought in square head, although 1/2" square is most common now while the TR original is 7/16" square, or in hex head, possbly even an Allen or socket head.

Just go to the plumbing department and look in the pipe fittings. You need a 3/8" NPT fitting (I know, seems much larger than that... plumbing pipe thread fitting sizes are referenced to the inside diameter of a pipe using this thread, not the diameter of the thread). I use brass, since it's less likely to damage aluminum parts and seals well. My local store also offers them in galvanized steel and plain steel.

I've been looking for a set of square wrenches too, if anyone knows a source.



03-10-2005, 10:00 AM
You're right, guess I was thinking of Teflon and gas lines. Refer to "dumb thing" post to check out my infallability issue. I've got so many leaks of oil under my car that I really don't know where they all come from. At least the front 2/3 of my car never rusts. The whole overdrive unit is new and it leaks. Between the oil and Waxoyl, BL knew what they were doing. Who needs galvinized panels? BTW, have any of ya'll discovered Pro Honda Spray Cleaner and Polish. Great little detailing item for cleaning up everything before a show, paint and all. (what's this got to do with Teflon, you ask?)


03-10-2005, 05:28 PM
I sprayed with Mopar rust penetrant yesterday. I got it off with an adjustable pliers and an 11mm open end wrench.

I drained some oil out, turned the engine over and ran compression.