Head Removed - How do I clean coolant passages in block?

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halfbob
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Head Removed - How do I clean coolant passages in block?

Post by halfbob » Fri Jun 19, 2020 9:25 am

Good morning,

Finally got into the engine bay of my 77 Roadster and been busy removing items in preparation for lifting Engine out. Decided to take the Head off whilst Engine still in situ so I could get it's 3rd party refurbishment underway and take a look at the state of things inside (the car has sat under a tarp for 30 years).

I'm new to all this and it's my first ever Head removal but friend's who are "in the know" say I shouldn't be too alarmed at the black deposits on top of the pistons and inside the Combustion Chambers. The Bores are clean and not scored and the Head Gasket seemed to have done it's job with integrity. However, I am concerned at the "rusty limescale" type deposits in many of the visible coolant passages. When I removed the Radiator there was a fair amount of coolant that came out and from the lack of colour or smell I suspect it was plain tap water, which is notoriously "hard" in our area. The "spigot" on the Thermostat Housing for the Top Hose had completely disintegrated.

Is there anything recommended that I can pour in and leave to dissolve any of these deposits? I've trawled the Internet and seen recommendations ranging from Vinegar to Calgon. Any advice much appreciated.

Thanks

Ian Fozzard
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Re: Head Removed - How do I clean coolant passages in block?

Post by Ian Fozzard » Fri Jun 19, 2020 12:29 pm

I think this depends on how bad this is. B series engine blocks are renowned for getting blocked with rusty deposits even if you have conscientiously used antifreeze. The rearmost drain hole is frequently blocked and no amount of poking with wire will unblock it.
My engine is blocked in that area, but all I have ever done is backflush with a hosepipe as best I can. Seems to be cooled adequately.
For a thorough job you need to take the stripped block to an engine reconditioner who can immerse the whole thing in a bath (acid or alkali, I'm not sure). I don't think most folk go to that trouble though, so your decision depending on how bad it is.

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Dave Wheatley
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Re: Head Removed - How do I clean coolant passages in block?

Post by Dave Wheatley » Sat Jun 20, 2020 9:06 am

Brick cleaner has been suggested for many years to clear out cylinder head and block deposits. I've never tried or needed it, but here's some info.

https://www.google.co.uk/search?source= ... CAg&uact=5

Whatever you use, don't let it get into the oil though.
Last edited by Dave Wheatley on Sat Jun 20, 2020 9:17 am, edited 1 time in total.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

Ian Fozzard
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Re: Head Removed - How do I clean coolant passages in block?

Post by Ian Fozzard » Sat Jun 20, 2020 9:14 am

Dave, that's generally hydrochloric acid I think. Fairly nasty stuff so you would need to be very careful. Not sure how this might affect machined surfaces - eg cylinder bores etc. but if you were getting the block rebored and machined then it probably would be OK.
Engine reconditioner presumably know what they can immerse a block in and not do too much damage!

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Dave Wheatley
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Re: Head Removed - How do I clean coolant passages in block?

Post by Dave Wheatley » Sat Jun 20, 2020 9:22 am

True Ian.

Ideally of course, the stuff should be used before the head is removed. Bit late for the op.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

halfbob
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Re: Head Removed - How do I clean coolant passages in block?

Post by halfbob » Sat Jun 20, 2020 9:58 am

Thank you all for your comments. Yes, I agree it would have been better to deal with this with the Head still on; first lesson learned :D

Dave Wheatley
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Re: Head Removed - How do I clean coolant passages in block?

Post by Dave Wheatley » Sat Jun 20, 2020 10:50 am

If you do go down the chemical route, let us know what you used and how you did it.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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Peter Cresswell
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Re: Head Removed - How do I clean coolant passages in block?

Post by Peter Cresswell » Sun Jun 21, 2020 11:07 am

Generally speaking I would advise against trying to clean out the block at home, unless it has been done professionally in the last few years. Not only are the chemicals required to do it successfully hard to buy as an individual, you will have the problem of disposing of the stuff after cleaning out has been done, and to be successful the chemicals need to be hot. You also have the problem that if the sediment has been there for some time it will have become very hard (which is likely in this case - 30 years under a tarp!) and needs a lot of agitation to move it. Far better is to use the services of an engine reconditioner even if you just want to get the block clean and free from oils to paint it. It does mean stripping it down though to get this done.
When I had my block machined just a few years ago, I asked them to clean the block out, and they dipped it in a hot chemical bath and they had a long stemmed thin rotary wire brush to break up the sediment that collects at the bottom. They have the same problem with Triumph TR blocks and A/B Series block so were well used to dealing with the cleaning process. I think they charged £25 to do it as I was having other work done at the same time.
An alternative, if you can find one, is to have the block cleaned in an industrial Ultra-Sonic cleaning machine. Not many engine reconditioners have these, but many people who prepare race cars do particularly if they also have engine overhaul facilities.
A further point here as the car has been unused for 30 years. I would suspect the piston rings will need replacing as they may have become 'set' in the position they have been sat at through lack of use, and at the same time it gives a opportunity to check the state of the main and big end bearing. After all if you are doing quite a bit of work to recommission the car, you don't want to be taking the engine out again after a few months if some thing that could have been checked, wasn't.
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965

halfbob
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Re: Head Removed - How do I clean coolant passages in block?

Post by halfbob » Wed Jun 24, 2020 6:48 am

Peter Cresswell wrote:
Sun Jun 21, 2020 11:07 am
......A further point here as the car has been unused for 30 years. I would suspect the piston rings will need replacing as they may have become 'set' in the position they have been sat at through lack of use, and at the same time it gives a opportunity to check the state of the main and big end bearing. After all if you are doing quite a bit of work to recommission the car, you don't want to be taking the engine out again after a few months if some thing that could have been checked, wasn't.
Thank you, Peter, for your reply. On reflection I think I will take that route. To my untrained eye the Engine seems in good order. It cranks very smoothly by hand and the bores are in good condition. However, as you point out, it would be sensible to get it thoroughly checked out at this stage rather than have to remove it again later.

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B Faiers
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Re: Head Removed - How do I clean coolant passages in block?

Post by B Faiers » Mon Jun 29, 2020 8:55 am

If you are keen to go down the DIY route you could take out the core plugs and get a lot of the muck out by poking with something like a bicycle spoke and sucking with a thin tube attached to a vacuum cleaner. On an engine of this age it is good practice to replace the core plugs anyway, as they have probably rusted a good way through.

With the engine out of the car you can turn it upside down (take care not damage the surface of the block) and let gravity help you.

If you are intent on getting the block 'hot dipped' and you are keen on originality, remove the engine number plate before you hand the engine over to the reconditioner as the acid will destroy the aluminium plate.
1964 MGB Roadster
1958 MGA Coupe
1926 MG 14/28 Bullnose
2012 MG 6TSE
2003 MG ZS180

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