At 01:17 PM 3/12/02 -0600, Rocky Frisco wrote:
>....
>Is there a drain or plug on the back of your block? Might be worthwhile to
>pull that and fish around with a bent coathanger wire. Most overheating
>blocks turn out to be full of rusty crud at that position. Most rad
>flushes don't clean this stuff out until the plug or drain is removed and
>the junk loosened and then flushed out.
Ha, ha, ha, ha, ha, ha, ....... (sorry, couldn't help myself).
For the MG B-series engines the block coolant drain plug is on the right
side near the back, just aft of the distributor mount. MGAs and at least
some MGBs had a drain cock there, but it is mostly useless, as it will
inevitably be plugged. You will generally have to remove the drain cock
just as though it was a plain plug. And then sometimes all the routing you
can do with a coat hanger may still not open the clogged passage. The
drain port is located in a slight depression in the bottom of the water
jacket. I suppose the original intention was that all of the coolant
should be able to drain out that way. In fact there is almost always some
sediment in the cooling jacket, and the small depression for the drain port
is the first place to fill up with debris, which is why it is almost always
clogged. If you want to try routing it out with a heavy wire, bend it a
little so it will try to migrate upward slightly as it enters the block.
The sediment that collects in the bottom of the water jacket can almost
never be cleaned out with chemical flushing agents. In fact it is often so
deep and so stubborn that hot tanking the block will often not remove the
stuff. Any time I have an engine apart for machine work I will manually
route out the sediment. Remove the cylinder head and the water pump and
the core plugs along the side of the block. Use a 1/8 inch steel rod held
with a Vice Grip to reach into the water jacket through the coolant flow
holes in the top of the block, and chip away dilligently at the scale like
stuff in the bottom of the water jacket. With the core plugs and water
pump removed you can see inside fairly well to get a good idea what you're
poking at down there. If you stand the block on end with the front end
down the junk will mostly fall out through the water pump opening. With
about 20 minutes of probing around in this manner I have often been able to
dislodge as much as two pounds of rust and water stone from an old MG
engine block. Then I have it hot tanked.
Now when I reassemble an engine I always toss the drain cock in the novelty
bin and install a blank plug in the drain port. Then next time I feel the
need to open the drain port it's easier to remove the plug that it would be
to remove the drain cock in order to attempt to route out the port. And
you can pretty well bet the farm that with about two years time the port
will be clogged with sediment again, even when you are using 50/50 mix of
glycol and water, and even if you do use a corrosion inhibitor. It beats
me where all the rust comes from, but trust me, it does come.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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