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MG MGA - hot tanking

I know that the engine id tag will disolve in the hot tank but what about all the little brass plugs and stoppers?

Do they disinigrate too?
T McCarthy

I don't know about the brass plugs disolving, but I would remove them so that all of the oil passages can be cleaned out after tanking. It does ruin cam bearing.
Ed Bell

I think the brass plugs should be removed before hot tanking so that the oil gallery passsages get a thorough cleaning. Also good to get gun cleaning brushes to run down those long oil galleries. University Motors recommends replacing 7 of the brass plugs that are removed with NPT pipe plugs. So far I've identified 5 brass plugs for removal, not sure where the other two are right now. Barney's website has a good description of all the plugs, I need to look there. You can remove the engine ID plate easily and reinstall later. BTW, I'm at the same point of an engine rebuild now.

George
G Goeppner

Oh for pitysakes....there is always some little thing more to do.

How do you get the little buggers out? Tap and pull?

George, happy to compare notes. Are you going with any performance upgrades?
T McCarthy

I'm not sure how to get the plugs out, I think drill them. Should remove easily being brass. On the long oil passages, drill out one end and with a long rod you can knock out the two at the other end. I haven't measured the diameter of the plugs, don't know if the hole can be tapped directly or needs a tap drill first. This should all be done before the hot tanking of course. For the ID plate, use a Dremel tool with a cutoff wheel and slot the rivet heads for a screwdriver. I used two cutoff wheels back-to-back. The rivets will (should) back out.
Still planning my machine shop work, not sure what I want to do. I believe the crank is bad (.050" under), so I have to deal with that. Also, one of the pistons looks really weird, having 2 sawcuts on opposite sides of the piston near the #4 ring. Too neat to be done by a PO. Then there's my timing puzzle. The dimples on the timing sprockets were not in line per the manual, and I have the same condition on a spare engine. Someone suggested that I might have Magnette cams in these BP15 engines. Once I get all these basic things sorted out I'll start thinking about upgrades. Definitely interested in port/polish for the head, worth about 7 hp I think. Also happy to compare notes, or at least to have a shoulder to cry on (my wife won't listen to me any more about the MG!)
G Goeppner

Most machine shops no longer offer hot tank services due to EPA/OSHA restrictions. The few machine shops which still offer such services seem to be using chemicals which do not clean nearly as well as previous compounds. More common today is the use of a power washer to clean the surface areas of the block and cylinder head. Cleaning out of oil passages, even if the plugs are removed, is less certain than it once was.

Thus, you do need to spend some time manually cleaning out the oil passages.

The existing plugs are removed by drilling and tapping them to 1/4" UNC. After they are tapped, a cylindrical object, such as a short length of pipe or a socket, is placed over the area around the plug and a socket headed cap screw, or a hex headed machine bolt, is turned into the hole in the plug. As the screw/bolt has the underside of the head hit the spacer, the oil galley plug is pulled out of the block. When completely free, the plug is removed from the screw/bolt, and the next plug removed.

There are five large plugs on the front and back surfaces of the engine block. There are two on the underside. All of these are of just under 1/2" diameter. There are several smaller plugs on the block of about 1/4" diameter. These are commonly left in place, but may be removed by drilling and tapping them with a number 10 UNC tap. The larger plugs can be tapped to 1/4" tapered pipe thread. The hole is sufficiently large that it does not need to be taper reamed using the proper pipe reamer. The existing holes are larger than the major diameter of the reamer.

When tapping the holes, make sure the plug fits just a fraction of an inch below the surface of the block so that gaskets will seal properly. Also, be aware that the plugs will vary slightly in how large they are. Selective fitting can be useful here.

There is only one problem area and that is the upper plug at the right, rear engine surface. This hole goes into the pipe coming out of the block and having a line going to either an oil cooler or the oil filter. Because the large fitting that goes into the hole from the right side of the block extends into the block almost one inch, the plug coming in from the rear must not extend sufficiently far forwards to interfere with the proper fit of the oil line take off. Special car is needed with this one hole to ensure that the plug does not extend too far into the hole, but also does not extend beyond the flat surface at the rear of the block. A little minor grinding/filing is commonly in order when fitting this plug.

Les
Les Bengtson

Bless you Les!

George you can reach me at Tysen@redico.com
T McCarthy

This thread was discussed on 18/08/2008

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