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MG MGB Technical - Drain engine and Radiator

Going to rebuilt the head on my BGT this winter, but not for a month or so. Know I will need to drain the engine at that time, but was wondering if just draining it now (winter storage)would be ok. Will leaving the cooling system empty cause more rust to form?
Bruce-C

A month or so before you start won't make much difference. Some is almost bound to happen - unless you drain it hot then maybe the hot metal will dry the interior passages out! As long as the block is kept dry from weather it should be minimal. Nothing will happen to the rad as it is copper (presumably).

I've not had the head off my 4-cylinder, but when I did the V8 I couldn't get one of the block taps open and so when I removed the heads the coolant level was still above the head gasket that side and so flooded down the rear bores (engine still in car and hence tilted back). Taking the water pump off first may have helped ... or raising the *rear* of the car! I know the 4-cylinder block drain tap frequently doesn't drain any coolant either.
Paul Hunt

I have a '76MGB with the 18V engine and I'm still looking for the block drain plug. If it's just NW of the distributor and to the left of the heater control valve, I'll be darnned if I can figure anyway of getting a socket or a wrench in there to get it off. So I had to drain by opening up the lower rad hose - what a mess! Maybe I need to be pointed in the right direction as the Haynes talks of block taps (which I don't have) and neglects to indicate the location of the drain plug.
TJ Whitehouse

Bruce..

On the four cylinder blocks there is a blanking plug not a tap just to the rear of the distributor. The hole is quite deep and often blocks up with silt, it appears to be a blind drilling but there is a small hole right at the end of the drilling at approximately 3 0"clock. You will need a piece of wire to clear it. Jim
jim soutar

"You will need a piece of wire to clear it."

Don't hold your breath, I've heard of people having the bare block on the bench and still not being able to get anything out of it.
Paul Hunt

My block is currently disassembled and bolted to an engine stand. I still can't clear the block drain hole! About 11 years ago I had the block hot-tanked and the hole was still plugged after that. I wonder if some of these blocks were not drilled when new. Mine is an 18GJ block from a 1970 California roadster manufactured in January 1970.

Is the passage hole to the water jacket near the number 4 cylinder perpendicular to the drain plug hole?

Jim
J Brown

Oh, it's on the bench? Then swing by the hardware store or janitor supply place and get yourself a gallon of muratic acid. Be careful with it, naturally - it's basically dilute HCl. Muratic acid will eat the rust but leave the good metal beneath. Allow it to work overnight, repeat as necessary, rinse well when done.

Hot tanking is a good thing, but it won't get rid of rust.
Sam

Passage hole to water jacket is below the rearmost hole in top of block. Whilst the hole for the "blanking plug " is drilled and tapped it rely"s on break thro into water jacket at maximun depth. You can breath out now Paul, I"ve been successful on many occasions, If you really can"t clear the hole with wire (thick single strand copper is good) remove the rear core plug and clear the silt from above. I"ve just checked three blocks and they all have the breakthro hole at the three o"clock position. Jimm
jim soutar

Not clear on the block drain hole that is mentioned. Anyone have a picture?
Bruce-C

I wanted to drain mine and removed the plug and it was bone dry. I tried to unclog it form the outside with wire,steel rod and whatever else it was solid felt like there was no opening as hardly any debris came out. Luckily I was replacing the head and I went down thru the rear hole on that side of the block with a long thin screwdriver and mallet. Took alot of tapping and repositioning and tapping with the mallet which did eventually work. What a great sound hearing that water pouring out the tap hole.
Mike
MK Mike

Bruce. The blanking plug is to the rear of the distributor and below the main oil pipe and oil guage pipe outlets. Perhaps I have not been specific enough, the hole into the water jacket is at 90 degrees to the blanking plug drilling, right at the very end , i.e. towards the distributor. there is a picture in the manual akd 3257 on page C5 of the cooling system section. Jim
jim soutar

Thanks Jim

Found the picture. Will let the group know what I find. Considering the heater valve hole was nearly plugged when I took it off to paint the engine, I have a feeling the drain hole will be also.
Bruce-C

The drain is shown in the image. As mentioned it's left of distributor and below the oil pressure gauge feed outlet.

Clifton

Clifton Gordon

This thread was discussed between 13/11/2008 and 18/11/2008

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