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Just drained coolant from rad - all very rusty. Drain tap on block clogged with black, oily, carbonated sludge. Any ideas?

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Hi, I recently rebuilt my TR4a engine. The block drain tap is an absolute waste of time! The core diameter of the tap and hole in the block  is only about an 3/16 inch, and even if the tap turns it's going to be blocked with rust and sludge build up after 50 years if the engine hasn't been rebuilt.

The black oily sludge probably means the figure of eight gaskets at the bottom of the liners have failed. Points to an engine strip and rebuild, or at least head off and liners out. Probably needs this anyway if the engine hasn't been previously rebuilt, to clear out the water jacket which gets very clagged up with rust deposits to ensure that the engine won't overheat in the future. Good luck.

Rich

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Hi Roger,

Why did you start this,

Problems? or

Just a Good Idea?

The Drain Tap is almost always blocked, you get a concrete like set behind the liner near the battery, which is a bit of a coolant 'Dead End'

It is possible to get some flow usually, by removing the tap and go digging with an old flat bladed screwdriver etc. if you were just looking to change the coolant then thats where I would leave things, be aware that now that you have turned the tap,  you will likely get a drip once you free the outlet, Try where you leave the handle - jiggle a bit, might stop things.

Oily sludge is a bit of a worry, but you do not know how long its been there, if you have no other problems, e.g. water in the oil etc., then I would not touch anything else.

John.

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Yes Roger, I agree with John here..

 

These engines are incredibly robust.. I remember finding similar to you 30+ years ago and initially being very concerned, bit of poking round as far as you can get with an old pointed welding rod followed by a flush through and everything Has been fine ever since....

 

I definitely would not jump straight to worst conclusions and start rebuild basis only bit of sludge...... (You are probably better off than majority in that the sludge hasn’t even gone rock hard yet!)

 

Agree with Rich though that the Tap is a bit of a waste of time... However, it’s handily located to get your welding rod / latest weapon of choice into the known bottle-neck in the cooling waterway.

 

Good luck, I think you will be OK... and well done for having the energy and enthusiasm to tackle this in Winter!

 

Tony

 

 

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Replace the tap with a blanking plug.  It won't leak like a repro tap.

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Thanks guys, the engine's running well considering it hadn't been started for about 15 years. There's a lot of carbonated sludge around the valve gear, oil was as black as, so drained and refilled with sacrificial 20/50 and a new filter. There was no apparent antifreeze, and water drained from the bottom of the radiator was very rusty - radiator cap very clogged with rusty muck. Water out of the block via the top end of the bottom hose ran clear!!! Seeing as I was about to do a head rebuild - I thought it might be a good idea to drain the block via the tap as it sits lower than the top end of the bottom hose  - if you see what I mean. Tap opened with a little persuasion an a dibble of clear water came out and subsequent probing with a small file (handle end, without a handle!) produced the black, oily gundge mentioned. Dropping the sump will hopefully allow me to see if there's an issue with the figure of eight gaskets - bought a cheap as chips endoscope (£20!) to assist.

Back to the tap - it looks like it will be much easier to get a spanner/wrench to it once the manifolds are off . 

I would appreciate any tips on liner removal and refit, as this is something I've not done before. I'm going to attempt this work with the block in situ, and maintaining existing liners, pistons etc, if at all possible. There's good compression at 155 psi except No 2 which is down to 120 - but i'm thinking this might be a valve issue.

Thanks.

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43 minutes ago, peejay4A said:

Replace the tap with a blanking plug.  It won't leak like a repro tap.

Now there's an idea. I wonder what size / thread etc.

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Roger

Our Cumbria Group Motto is;- 

                          'If it ain't broke don't fix it'

I went down the road you are looking at 30 years ago, bought new everything for an unknown engine, then when I had got stuck in and everything apart, it certainly did not need pistons or liners.

Having bought said items, I duly fitted them, the ones I took out of my car, have run in a fellow group members car for at least 15 years now with out issue.

Couple this to the fact that you may be replacing stuff that does not need replacing with new items that may not be as good as original, adequate but not as good and its work that needs careful thought.

I understand the urge to 'Do the Engine, ' satisfying and nice to think you won't have go there again for sometime but, I would say give it some thought.

If you pull the head and sump for a look, and are undecided about removing the liners, make sure you clamp the liners down, easy to 'Crack' the figure of eight gaskets, by rotating the crank a little, then you have to go the whole job.

John.

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Hi Roger,

If you want to remove the liners insitu then ensure that the crank has been cleaned of its surface oil - this always drips where you don;t want it.

cover the crank so that it remains clean.

Remove the pistons upwards - note where they have come from etc etc.

From underneath using either a hard wood or Ali drift and a decent hammer/mallet punch the liners upward on the bottom skirt.

Move the drift around the liner circumference to give equal lift. If you are going to keep the liner then note its position - 1, 2, 3, 4 and radial location in the block you can turn them 90' to equalise wear.

If the Fo8's are still in place have a look at their condition - clue to leaking etc.

You can now clean the block internals from above - hence the cover over the crank. Pay particular attention to the seating area for the Fo8s. Make sure all the corrosion is removed.

You may now have some bad corrosion in the seats.

The best repair is to get the seats machined. However you could also fill them with something like JBWeld and flatten down - it needs to be flat and even. and square to the liner.

Good luck

 

Roger

 

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If I had to do such an extend of work, I would not hesitate a second an take the engine out of the car.

It provides easier access to all area’s for cleaning and inspection and will give a better quality job.

And the clutch can be inspected too.

Just my 2 cts.

Waldi

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1 hour ago, John Morrison said:

Roger

Our Cumbria Group Motto is;- 

                          'If it ain't broke don't fix it'....................

John.

Alternatively, you can fiddle with it until it is.........:rolleyes:

Cheers, Andrew

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Like Roger says cover the crank and anywhere you don't want rust and bits of grit to get. Cling film (sandwich wrap) is very useful pre cut lengths about 16" long and wrap around the crank, it clings to itself like a bugger as we all know, one of the only times you'll find that useful.

These engines will respond to remarkably little attention to continue to run well, a little fettling and poking will clean out the majority of the **** from the water jacket through the drain tap hole and if the liners are removed I use a 90 deg drill and a small drill bit to open out the drain DON'T snap the drill here. For road use that will do, flush out the block again to remove loose bits, a full engine out chemical clean and clean of the block is even better but won't show any benefit for a road going engine, it just makes you feel better.

The trouble with a bought car is there is no previous knowledge for you to base any rebuild upon, I would nail it all back together after your rooting around and get a seasons running on the engine (unless the cars condition determines full rebuild...in which case what are you doing with the engine ?)  

Mick Richards

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5 hours ago, Fireman049 said:

Puzzle find the block drain hole?

Tom.

DSCF0225 - Copy.JPG

Yikes!

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Again, many thanks everyone - superb tips! 

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18 hours ago, rogerowen said:

Just drained coolant from rad - all very rusty. Drain tap on block clogged with black, oily, carbonated sludge. Any ideas?

Put an air line on it from the outside and blow it back into the block.  I have a piece of plastic pipe that fits over the end of the nozzle and then I ram my airline into it.  This may be a problem if you don't have a compressor!

Rgds Ian

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In days of old we used to fill the cooling systems with a strong mixture of caustic soda and water. The cars were run for well over a week and

when the drain taps were opened you wouldn't believe the rubbish that came out!

The system was then thoroughly flushed out with clean water. We never had any problems using this method.

In those days Bluecol anti freeze was terrible stuff if left undrained for a long time. It created  thick brown sludge.

Tom.

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Hi,

when I bought my TR4A the tap on the engine was broken off  - and sealed anyway.

I put the broken thread out, cleaned the drill (while I had to change the 8 seals) and pluged it.

Years later I fitted a ball valve for some experiments with the thermostat and water pump housing.

Draining works very well - if you do it from time to time.

Ciao, Marco

  

Edited by Z320

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Hi,

When I tried to remove the brass original tap, surprise, surprise it sheared off! My solution was to run a 1/4 BSP tapping size drill (8.8mm or 11/32ins) and run a 1/4 BSP tap into the hole to clear out the brass tap thread core and cleared out the drain hole into the block.

I purchased the 1/4 BSP tap on e-bay cheaper than a replacement repro brass tap!  I then used a taper 1/4 BSP steel plug with PTFE tape from my local builders merchant.  Job done.

Rich

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I know we discussed that already and I have been told I'm wrong,

but on my TR4A the thread is 1/2"-20 UNF (d =12.7), what is very unusual for a "liquid tap",

and not 1/4" - 19 BSP (d = 12.9 mm), what should be correct for that usage.

That's the reason for my brass adaptor (on the pencil).

Ciao, Marco

 

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Replace the tap with a blanking plug.  It won't leak like a repro tap.

Now there's an idea. I wonder what size / thread etc.

I've previously  experienced issues with the drain tap - bought a repro one which was worst than useless, it leaked on test before I installed it in the block, the old one leaked slightly.

I used a blanking plug instead, can't recall the thread size, but it was a standard brass plumbing part. I wrapped plumbers tape around the thread and it's water tight.

I had some brown gunge out after poking a wire hook into the aperture and then flushing with 'Irontite' Thoro-Flush.

Rob

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