Engine block drain tap/passage

[The Satsuma]

Hello,
I know this subject has been covered in several other threads and I have read through the ones of can find but the problem does seem rather puzzling.
The radiator developed a leak and a new one ordered, so we went to flush the cooling system when the block drain bung was removed no water flowed out , when a drill bit was worked into the hole the substance that comes out is black and very dry as though water was never present there, not like the normal brown rusty mud. It was also fairly hard, could it be casting sand? We were just wondering whether anyone had any ideas on cleaning it out, we are thinking of removing the core plugs.
The engine is a 1098cc fitted into a 1967 saloon.
Many thanks..

[philthehill]

The problem you are experiencing is a common one.
The crud you are extracting is just sediment which over time settles into the rear of the block.
As regards removing the visible core plugs - is not really effective in gaining access to the water passage/jacket that serves the drain plug. Only removing the rear core plug (located behind the rear engine plate - so engine or GB out) gives good access to the water jacket at the rear of the drain plug.
Removing the cylinder head and with a screw driver worked down the rear N/S water block to head transfer passage is effective as it intersects with the water jacket directly behind the drain plug
The water jacket goes behind No: 4 cylinder but at its lower end is interrupted by the internal block rear main bearing casting - therefore the drilling for the drain plug does not go right across the block. If you can get a screw driver into the block by 110mm you are well into the main water jacket.
I would suggest that you continue to work at attacking the crud through the drain plug aperture with a piece of stiff (welding) wire with a flat on its inner end.
When through and the water is draining as it should refit drain plug and use a good quality radiator/coolant system corrosion remover/flushing compound as per the instructions on the container.
Having removed the crud from the cooling system you may experience leaks from additional places so keep a eye out for water loss.

[The Satsuma]

Thanks, ah I understand, using a drill worked by hand I believe we have cleared all the way to the end of the pasage, but don't seem to be able to find where it joins the main jacket when poking around with the wire.
What system flushes do you recommend?!

[RobThomas]

My personal preference is Citric Acid powder (cheap for 1kg on Ebay) in a hot engine and a wire curtain thingy in a drill chuck, y'know, the flexible wire stuff they put in net curtains, a sort of coiled flexy that looks a bit like the outside of the choke cable. It will go round corners and won't knacker the inside of the engine.

[philthehill]

The drain plug drilling enters the main water jacket at around 80mm where the water jacket starts to rise to the head transfer passages.
Any branded radiator flush will do the job.
Holts have always had a good reputation so you may want to try this:-
http://www.ebay.co.uk/itm/Holts-Radiato ... Sw42dZDGA7
The citric acid suggestion is also a good way of cleaning the inside of the water jacket.
It appears that you have a good amount of sediment to deal with so just keep plugging away at it.

[The Satsuma]

Thanks I'll take a look at the citric acid!! I see, it's odd we don't seem to be able to get the wire to anywhere but straight in regardless of the shape it's in. Looks increasing like more serious surgery is required , I suppose if we take the engine out to get to the rear core plug at least I can check the clutch. Seems a shame to have to take it apart it starts and drives really well.

[BLOWNMM]

An old inner speedo cable in a drill also makes a good tool for loosening crud and is very flexible.
Bob

[philthehill]

Personally - removing the engine would be the last thing I would do.
As the engine is running well just flush the engine with the rad flush / citric acid and work at getting the crud out. There is no point in making extra work for yourself.
Whilst it is nice to have the facility to drain the block it is not an absolute imperative.
The cross section of the block (rear) in the photo below will show you the relationship between the drain plug passage (middle right) / the water jacket and the rear core plug.
Whilst the photo shows the drain plug passage not meeting the water jacket it does at the lowest point of the water jacket (middle of the picture).

[liammonty]

. Seems a shame to have to take it apart it starts and drives really well.

You don't - it was be madness to take the engine out for that I would follow the advice above.

It's probably been blocked for the past 30 years without anyone knowing, and had no effect, because it doesn't impact on the water circulating around the water jacket, as shown in Phil's photo.

[firedrake1942]

Phil, where did you get that fascinating cross section ?

[philthehill]

Someone on here posted (I cannot remember who) the picture in relation to the oil pressure relief valve seat and I have just kept it for reference.

[firedrake1942]

It looks like a cutaway for either demonstration or teaching purposes.

[The Satsuma]

Okay many thanks, that cross section is marvellous. We'll take the above advice and just keep working on it from time to time.I'll get some of the suggested flushing solutions and give it a run to work with them in!. I was just concerned as I don't know how bad the deposits are and I don't wanna ruin the engine obviously.

[philthehill]

If as you say the engine is running well there is no problem with the deposits already in the engine. You will not ruin the engine in its current condition.
I would stick at it and get that crud out of the drain plug gallery.

[The Satsuma]

Okay many thanks, we've just been out and done a little bit to the car, we think we have the horizontal passage clear, just fiting to get up into the jacket now I'm guessing. We only collected the car last Saturday
Patrick

[geoberni]

Did you get this sorted?

Did you use the Citric Acid?

I've just tried to drain my system down as I need to change a leaking Core Plug, found the same blockage you had.
Eventually managed to clear mine by using about 6" of wire coat-hanger fitted in the end of a 'Dremel' type of Multitool on a flexible drive. It was blocked with hard black gunk all the way to the large chamber seen on the photo above (really useful image that Phill! ).

So now I'll be changing the core plug another time.

[The Satsuma]

Hello
Yes thanks we did get it sorted, we didn't try the citric acid.
We did a very similar thing to yourself, we just spent many evenings poking around with various bits of wire
We did run a couple of different radiator flushes through the system but with little effect!

[svenedin]

Old thread I know but I have just done this job on my engine. The familiar story, I removed the engine block drain plug and beneath was crud so hard I thought for a moment I had removed the wrong plug. I prodded around with coat hanger wire but only got about 3" inside and could get no further. No water drained out. I then took a 100ml syringe with plastic tubing attached and drew up hot, strong, citric acid solution. I put the tubing as far in the drain plug hole as far as it would go and irrigated slowly with the solution. On the second 200ml of citric acid solution, engine coolant start to drain. I rodded out a bit more with the car hanger and suddenly the drain was free. The job took about 30 mins. Tomorrow I will flush through with a garden hose. I did this job because I am going to replace the heater valve tomorrow and the coolant would have been lost anyway.

[myoldjalopy]

Mine is blocked as well and has been for a loooooong time! But it causes no problems, although I may be tempted to try and clear it next time I have to drain the coolant for whatever reason.

[svenedin]

Mine is blocked as well and has been for a loooooong time! But it causes no problems, although I may be tempted to try and clear it next time I have to drain the coolant for whatever reason.

Yes it's not something to rush to do unless another cooling system job is needed. Having that drain free does enable a much better flush through though. I had thoroughly flushed (I thought) but when I got the engine block drain free a lot more rusty water ran through. I am running some Holts radiator flush in the system at the moment so once that's had a chance to work I will drain down one last time. It seems to need both a physical (garden hose) and a chemical clean out.