12G202 Head. Beyond salvage?

[svenedin]

Could you please post a current part number for the stub with hexagon.

Hello Phill

10M227 from ESM.

On their website the part is shown without the hexagon but they sent me one with the hexagon which I was very pleased to receive. Maybe check with them on the phone to be completely sure.

Stephen

[philthehill]

Thank you for the above info.
I think that I have been here before as regards the bypass hose stub!
I wanted the part number for general circulation on this site but it appears that the stub with hexagon is no longer available.
Thankfully I have several of the bypass stub with the hexagon purchased some time ago from Bullmotif.
There is also a corresponding slightly shorter stub with hexagon which screws into the water pump of the Cooper 'S' etc to take the other end of the bypass hose. I have several of those also.
https://www.ebay.co.uk/itm/174322272913 ... R5KE15_aYg

[Bill_qaz]

Glad you got it sorted, so annoying when wrong spec parts are supplied.
Yes carbon build up can cause running on, back in the day decokeing was a common procedure.

[svenedin]

Glad you got it sorted, so annoying when wrong spec parts are supplied.
Yes carbon build up can cause running on, back in the day decokeing was a common procedure.

Yes very annoying getting the wrong spec parts. Happens way too often.

De-cokeing? Indeed. My mother tells the story of how my father thought it was OK to leave an engine on her bedroom floor when she still lived with her parents. It was a DKW engine. He wanted to de-coke the engine. She still married him of course! The apple has not fallen far from the tree….

[svenedin]

Thank you for the above info.
I think that I have been here before as regards the bypass hose stub!
I wanted the part number for general circulation on this site but it appears that the stub with hexagon is no longer available.
Thankfully I have several of the bypass stub with the hexagon purchased some time ago from Bullmotif.
There is also a corresponding slightly shorter stub with hexagon which screws into the water pump of the Cooper 'S' etc to take the other end of the bypass hose. I have several of those also.
https://www.ebay.co.uk/itm/174322272913 ... R5KE15_aYg

Phill I followed the eBay link. That company is the same company I got my bypass adapter from that did not fit!!!

Stephen

[philthehill]

Here is a link to a bypass stub/adapter with hexagon:-

https://www.ebay.co.uk/itm/285451426265 ... R-DDy6zaYg

[oliver90owner]

De-cokeing? Indeed.

Flat-head engines were regularly decoked. I have seen 4000 miles recommended as service intervals. Head gaskets were often re-used a couple - or even several - times on side valve engines.

Along came OHV engines and pressurised cooling systems, so the procedure became more complex and far less re-use of head gaskets. Engine designs (particularly the carburettors) improved, thus allowing more mileage between decokes. Regular valve grinding was usual when a decoke was felt necessary (and was likely the root cause of the need for the decoke).

The adoption of fuel injection and hardened valve seats on all petrol engines has virtually removed any coking problems in more-modern engines. Diesel engines and some spark-ignition engines had hardened exhaust (at least) valve seats a lot earlier (1920s?) (and engines with aluminium heads, of course).

These days, feeding the engine with a water mist is often used instead of a dismantling job, if coking occurs. Generally, oil-burning is the usual problem nowadays whether coked inlet valve heads or piston rings/cylinder bores. Occasionally bore glazing due to too-light loading had to be dealt with. Bedding in the rings on new engines can be problematic (just ask John Deere on that one).

Most claimed ‘motor mechanics’, these days, are actually only ‘fitters’ - only changing parts, not repairing them - but still needsing a modicum of skill.

I’m not a mechanic but I have scraped-in crankshaft bearings, modified pistons for older engines, etc in my time.

[svenedin]

De-cokeing? Indeed.

Flat-head engines were regularly decoked. I have seen 4000 miles recommended as service intervals. Head gaskets were often re-used a couple - or even several - times on side valve engines.

Along came OHV engines and pressurised cooling systems, so the procedure became more complex and far less re-use of head gaskets. Engine designs (particularly the carburettors) improved, thus allowing more mileage between decokes. Regular valve grinding was usual when a decoke was felt necessary (and was likely the root cause of the need for the decoke).

The adoption of fuel injection and hardened valve seats on all petrol engines has virtually removed any coking problems in more-modern engines. Diesel engines and some spark-ignition engines had hardened exhaust (at least) valve seats a lot earlier (1920s?) (and engines with aluminium heads, of course).

These days, feeding the engine with a water mist is often used instead of a dismantling job, if coking occurs. Generally, oil-burning is the usual problem nowadays whether coked inlet valve heads or piston rings/cylinder bores. Occasionally bore glazing due to too-light loading had to be dealt with. Bedding in the rings on new engines can be problematic (just ask John Deere on that one).

Most claimed ‘motor mechanics’, these days, are actually only ‘fitters’ - only changing parts, not repairing them - but still needsing a modicum of skill.

I’m not a mechanic but I have scraped-in crankshaft bearings, modified pistons for older engines, etc in my time.

Interesting. My parents generation talked of a decoke as a regular piece of expected maintenance. They were talking about pre-war and early post-war cars so yes sidevalve. The DKW was 3 cylinder, 2-stroke (a very rare car now). I was actually surprised how little coke there was in my engine considering its age, mileage and how long it is since the head has been off (minimum 34 years).

I’m no expert with these things at all but I had noticed that the engine had a tendency to almost (but not quite) backfire when using engine braking on a steep hill. An examination of the old head shows more than one valve that is not flush with its seat (not absolutely closed). There was also the oil leak which didn’t seem too bad until I removed the head and occasional running on presumably caused by coke.

It’s definitely a job that was worth doing and overdue but it took months to get the refurbished head back and I had to find a good head after the one I had in the garage turned out to be too corroded.

Stephen

[philthehill]

The DKW 3 cylinder 2 stroke car was very successful in motorsport.
For those who are unaware of the DKW car here is a taster:-
https://www.youtube.com/watch?v=IbSM-h_nmi8

[svenedin]

The DKW 3 cylinder 2 stroke car was very successful in motorsport.
For those who are unaware of the DKW car here is a taster:-
https://www.youtube.com/watch?v=IbSM-h_nmi8

Wow! Thanks Phil

[oliver90owner]

I have a Munga with the 900 cc 3 cylinder two stroke engine.

[svenedin]

Head is back on. I ran engine up to temperature static. No leak. Took car for a short gentle run, no leaks.

I’ve made a silly mistake though. I forgot to fit a thermostat! When the car is completely cold I will drain the coolant and fit the missing thermostat. This is annoying because I have to disturb 2x head nuts to remove the heater pipe to fit the thermostat.

There’s an exhaust to manifold leak as well but that was bound to happen.

The rocker clearances are set and checked. Top end is a little noisy compared to before, presumably due to refurbished rockers and new valves which need to bed in.

Stephen

[philthehill]

So long as you did not re-torque the head after the first heat cycle and you drain the coolant out of the block you will be ok.
I would re-route that heater return pipe soonest though. A bad design and a failure by BMC.

I have just picked up on your query of the nuts with interlocking rings - the interlocking rings indicate a Unified thread. You will find the interlocking ring theme on quite a few of the Minor threaded parts.
There are also notched nuts/bolts/screws which indicates a 'American National Fine' (A.N.F.) thread.
The Unified and A.N.F. have the same pitch and TPI but have different root and tips to the thread.
There is also a wheel bolt with a platform head which is used on some early axles to denote a A.N.F thread.
There used to be in the early Minor wksp manuals (Morris Minor. Issue 2. Pt No: 37720) a General Information section No:8, No:9 which had illustrations relating to the threads.
The General Information section is well worth obtaining.

[myoldjalopy]

Phil you say "A bad design and a failure by BMC." So the question must be 'Why did they alter the previous arrangement of having the heater hose run from the rad along the engine bay floor?'

[svenedin]

So long as you did not re-torque the head after the first heat cycle and you drain the coolant out of the block you will be ok.
I would re-route that heater return pipe soonest though. A bad design and a failure by BMC.

I have just picked up on your query of the nuts with interlocking rings - the interlocking rings indicate a Unified thread. You will find the interlocking ring theme on quite a few of the Minor threaded parts.
There are also notched nuts/bolts/screws which indicates a 'American National Fine' (A.N.F.) thread.
The Unified and A.N.F. have the same pitch and TPI but have different root and tips to the thread.
There is also a wheel bolt with a platform head which is used on some early axles to denote a A.N.F thread.
There used to be in the early Minor wksp manuals (Morris Minor. Issue 2. Pt No: 37720) a General Information section No:8, No:9 which had illustrations relating to the threads.
The General Information section is well worth obtaining.

Thank you Phil for the information about the markings on nuts and what this means. I saw a decent early workshop manual at an auto jumble this Summer but I didn't realise it had more information than the reprint that I have so I didn't know I wanted it. I do now.

I am not sure the earlier heater pipe that goes on the manifold will fit with my manifold and its PCV valve. I will keep an eye out for that pipe though (it is not interchangeable with the later heater pipe).

Yes I drained the coolant and I had not re-torqued. The thermostat is in and all is well. No antifreeze was wasted as I had only used water in case of leaks and more draining down!

I have noticed a few things. The compression is considerably higher now. It is quite hard to turn the engine over on the starting handle. It was quite easy before. The top end is noisier but I am assuming that is the new parts that need to wear in together. The idle is much more even and regular. In fact it is very regular indeed. Sounds much better at the tailpipe end.

There were a few issues I haven't mentioned during this saga. The thermostat housing leaked out of the top through one hole and so did the heater valve through one hole. I took them off, removed the studs and put a little Permatex thread seal on the end of the stud that threads into the cylinder head. On reassembly the problem was cured. Both heater tap and thermostat housing had new gaskets of course, the thermostat the better blue gasket (not cork).

No leaks of any kind so far.

I would like to thank everybody who helped me with this task. Your help was invaluable and much appreciated. I have gone from a novice who had never replaced a head gasket to somebody who has done it 3 times

Stephen

[Bill_qaz]

This is the piston and bore grading marks we discussed earlier in the post.

Screenshot_20230927-204029_Microsoft 365 (Office).jpg (91.01 KiB) Viewed 13119 times

[svenedin]

This is the piston and bore grading marks we discussed earlier in the post.
Screenshot_20230927-204029_Microsoft 365 (Office).jpg

Yes although on later engines like mine there is no diamond, just the number.

I was really nervous starting the engine after all that work! It was fine

Here is a short video after my work. The idle is a bit high. The reason for such a pathetic attempt to rev the engine was that the throttle lever was too hot to touch!!

https://youtube.com/shorts/FDSditd0WOs?feature=share


Stephen

[philthehill]

Just to put an modern perspective on the bore markings:-
BMC had a surplus of pistons of various grades so was able to match pistons to bore very easily.
Nowadays engineering companies do not hold stocks of various grade pistons so the block has to be bored to suit the piston(s) as supplied.
In theory you could have for a Minor four different bore sizes to suit four different pistons.
Quality control is everything.

[oliver90owner]

Just as another couple of asides.

I never fit the rad cap - if at all- tightly, until after the head had been re-torqued. A small precaution (and as far as I know, never required), but just another point of being on the ‘safe’ side if ever there was a possible issue.

I always attempted to loosen the cylinder head, before serious dismantling, (particularly on diesels with head studs) by operating the starter motor after slightly loosening the head fixings. I’ve encountered too many heads stuck down with sealant, over the years. Likely it helped on occasions.

[JOWETTJAVELIN]

Just as another couple of asides.

I never fit the rad cap - if at all- tightly, until after the head had been re-torqued. A small precaution (and as far as I know, never required), but just another point of being on the ‘safe’ side if ever there was a possible issue.

I always attempted to loosen the cylinder head, before serious dismantling, (particularly on diesels with head studs) by operating the starter motor after slightly loosening the head fixings. I’ve encountered too many heads stuck down with sealant, over the years. Likely it helped on occasions.

Not advisable at all and certainly not with liners.