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MG MGB Technical - No water around Cyl 4

Have had a history of BGT overheating and done the usual things like elec fan, replacing hoses,new head gasket and flushing block, heater, rad etc but finally realised no water is getting round number 4 cylinder. Any ideas to solve the problem - preferably ideas that do not mean removing engine from car.
J I Jones

If you remove your water pump you will be able to see if there is any crud built up at the back of the block by number four.

You can power flush all of it out with a garden hose.
Steven Rechter

JI Jones,

I would be curious to know how you made the diagnosis. If it is packed with crud around #4, I suspect you will have to remove the block drain plug and the freeze (core) plugs from the side of the block and use wire, gouges, water pressure, and air pressure to get the junk out. You might also have to remove the head, but you should have a pretty good chance of getting it out without removing the engine.

Charley
C R Huff

With the head off mine I worked lengths of that clear plastic 'fuel line' type of tubing in and around behind no4 through the top of the block. The sludge I had there was quite concentrated but eventually separated with that treatment. Hosed into the area to remove what was dislodged. Not sure I got everything but ever since the temp gauge runs lower.

Given the tubing commonly takes a curve from storage, that can be used to adopt angles on working lines through the cavity spaces. Ensure oil galleries and bores are covered - I taped the galleries, stuffed cloth into the bores.

The suggestion of Steve's might be a good way to start. Again, hose and/or narrower tubing (adaptors?) should enable some angling to get behind the cylinder. Otherwise, stout wire appropriately shaped could be worked into the space through the pump aperture.

If all that fails, Charley's suggestions are probably the go.

Regards

Roger
R Taylor

There are chemical treatments that work too. I have used Holts "Radflush" but that was 50 years ago!
Anything with oxalic or citric acid will work.
Art Pearse

It's very common for the block drain to be blocked with original casting sand, if nothing else, and no amount of poking with wire will shift it.

I'm also interested to know if it was diagnosed by means other than not being able to get anything out of the drain, and also intrigued by the concept of accessing the jacket round No.4 cylinder by removal of the water pump, which is adjacent to No.1. I'd have thought removal of the head and get direct access was the way to go.
PaulH Solihull

I cleaned mine a few weeks ago and doubt if it can be done properly without removing the cylinder head and welch plugs. The gunge around cylinder no 4 was so hard i had to use a screwdriver and hammer to clear the area around the block drain plug.I used compressed air and water. I don't think any kind of radiator cleaner will work if yours is as bad as mine was.

Ronnie
RA Potter

I did the same as RA Potter a few years ago. I had the head off
and I used a sharpened 3/16" steel rod to chip away at the crud.
I then inserted a telescoping tool retrieval magnet into the coolant ports to grab onto any big bits. Wow. I even hauled out
a big piece of solid wire (similar to clothes hangar wire) from the
coolant passages! After the magnet came up clean, I blew out
the rest with compressed air. My car has been running a few
degrees cooler ever since.
Daniel Wong

Hi Daniel

I think my block was so bad there must have been localized overheating at cylinder #4. Apart from that all the water passages between the head and the block were either completely blocked or only partly open. They were covered by a hard film of goodness only knows what. The motor is running much cooler now but I also fitted a recored radiator which will also help.

Ronnie
RA Potter

1 - taking the water pump off won't tell you anything about what is happening back at #4, so don't bother.

2 - the flow around the back of 4 is slow at best and it is the worst spot for debris to collect.

3 - the debris compacts over time and can become like rock, so poking at it with plastic hoses or trying to flush it out can be futile.

4 - remove the head (yes, it IS a PITA, but it's the only way) and get a long thin pin punch or small diameter rod stock you can probe down to the bottom of the water jacket with and tap the end with a small hammer to break up the crud. It helps to put the drift down further forward, ensure that it bottoms on block material and then wrap a bit of tape around it so you know how close to the bottom at the back you are.

5 - don't get too carried away nor hammer too hard lest you find yourself striking oil. Getting most of the compressed crud out will do.

Good luck flushing out all the chunks of now loose debris you dislodged.....this job really should be doen at engine rebuild time on a bare block after a hot tanking.
Bill Spohn

Hi Bill

Your description is exactly the way I found mine and I cleaned it the same way. Your comments "like rock" is spot on.

Ronnie
RA Potter

This thread was discussed between 03/01/2013 and 11/01/2013

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