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MG MGB Technical - Cylinder removal

I have a 71 B that sat for 23 years. I cant get the engine to turn. I have soaked them with oil, kerosene, coke, penatrant, etc. No good. I have the engine out and the heads 0ff, oil pan and extraneous bits. Once i get the crank out, whats the best way to try to get the cylinders out? I already assume i will need to have the head bored. I am hoping the rings are rusted and the pistons still good. Any thoughts? Thanks.
rj horizon

rj,

I think you have some parts and terminology confused. If you don’t have a book, you should get one, and if you have one you should study it a bit.

The head does not get bored. It gets a valve job. You say you have the heads (plural) off. There is only one, so are you sure it is the head that you have removed?

The cylinders in MGs don’t come out. They are part of the block. If you had an old Triumph, the cylinders do come out, but let's assume you still have the original MG engine. Assuming that, the cylinders are what gets bored. They are the big round holes under the head and there are four of them.

I am guessing that the things you are trying to get out are the pistons, which fit in the cylinders.

If the block is bored, which it probably needs since the engine is stuck, then your existing pistons don’t fit anymore and you need oversized pistons. But, it is likely that they need replacement anyway.

The technique of getting stuck pistons out depends upon how stuck the engine is, and where it is stuck. I did have one once that was only lightly stuck between the pistons and cylinder, but was frozen up solid at the wrist pin between the piston and rod.

Getting the pistons out of the block may take light tapping with a hammer and wood block if they are just barely stuck, and in that case the pistons might still be good. Don’t tap anywhere on the outer quarter inch of their diameter or you will likely crush the ring land. Also, knocking them out might expand or break your ring land. Heat can help, but it is not easy to get it where you want it. I have built fires in the cylinders with diesel fuel and rags. Like I said, this is if they are lightly stuck.

If they are stuck hard, you may need a short piece of a 4 x 4 (preferably oak. It may need the corners trimmed so that it will fit in the cylinder. Then you can beat on that with an 8 or 10-pound sledge hammer. I have seen this done once by a very large friend who was very good with a hammer, and it still took him 45 minutes and many pieces of 4 x 4.

Charley
C R Huff

I free'd up a frozen VW aircooled engine (they do have 2 heads!) using a mallet and a piece of round wooden fence post. I found it was ideal for the job as it sat nicely into the cylinders so I could whack it with the persuader. Before I took the heads off I filled the cylinders with diesel and left it soak for a couple of days. This engine was badly siezed though.
R Kelly

You are correct CR. I don't know where my head was when I wrote that. Sure does make me sound like a jerk. Didn't even have a beer. Oh well...cylinder, piston, heads, head, etc. Repeat.

That was my thought, block of hardwood and a hefty hammer.

I am putting all of the pieces in bags and labeling them as I go. Now I am beginning to wonder what I wrote on the bags......
rj horizon

rj - "I don't know where my head was when I wrote that. Sure does make me sound like a jerk." Don't despair, most all of us started out that way and learned as we went - it does get better and more understandable. Cheers - Dave
David DuBois

Rj, you could be faceing a danting task. with luck you can pound the pistons with a peice of hardwood and a large hammer until you get a little movement. use plenty of penetrating oil. I have had piston stuck to the point that we chisled them out in peices. The block will need to be bored of its not over the size already and you will need a set of pistons. Send me a email and I'll might be able to help out.
Jim Pelletterie

RJ,

You didn't sound like a "jerk" at all - just somebody making his way along the learning curve. All of us have been there, and a lot more of us haven't gotten there yet. Or rather, you sound like me at times when I do know what I'm talking about but do not know the correct terminology.

I have a badly stuck 18 GB block for my '65 B. When I took the head off, it appeared that antifreeze had leaked into #4 cylinder - the cylinder walls look like they have a severe case of acne. My view is that on any rebuild, the engine is going to have to go to the machine shop anyway - so why not just let them extract the piston with a hydraulic press?
If you miss with that hammer and strike the block mating surface instead, you're going to do some extra damage that will, at best, cost you more than pressing the piston out; at worst, will ruin the block, depending on size of hammer, power of stroke, and where it hits.

Otherwise, the machine shop can press or break the piston out, and resleeve the cylinder(s). I don't see any point in messing with it myself.

FWIW,
Allen
Allen Bachelder

If the piston rings have rusted to the cylinder wall, then the pistons will most likely be already useless. Removing them with a press will surely break the rings, which will then ruin their grooves in the piston. If the block has been disassembled, you can simply dissolve stuck pistons with muriatic acid. That way damage to the bore will not extend beyond the extent of surface rust. Just be sure to set the block on wooden rails out of doors before you pour the muriatic acid into the bore(s) as the fumes that result are toxic!
Steve S.

Opps! Don't use muriatic acid (hydrochloric acid) as it will produce hydrogen embrittlement of the cylinder walls! Use phosphoric acid instead.
Steve S.

rj,

Okay, now I see your problem. No Beer!

The absolute minimum for a stuck engine is a 6-pack (make that a 12-pack if you have a helper). And that's if things go well. You may as well get a couple cases while you are at it, and save a return trip to the store.

I suggest you avoid the possible pitfall of doing half or three quarters of a rebuild. Once you are in for boring and new pistons I think it't a good idea to "go all the way". Otherwise you risk losing your parts and labor investment from an early failure of something you didn't replace.

Also, when you put it back together, make sure you use the right oil pump gasket. I had to learn that one the hard way. There is one for the 3-main bearing engine and one for the 5-main bearing engine. Match the gasket up to the pump because matching it to the block can lead you to pick the wrong one. I think it is also possible to put the wrong pump in, which can make the pump quit entirely when the gears disengage. My GT had the wrong pump in it when I got it, but I'm not sure that it was a 3-main pump, but the oil pressure went to zero about a week after I bought it.

Cool hint with the muriatic acid, Steve. I've never heard that one.

Good luck,
Cheap Charley
C R Huff

"it does get better and more understandable"

Then time takes over and it gets more difficult again ...
Paul Hunt 2

Steve,

I suppose it depends on how stuck an engine is - which one might not find out until sufficient force had been used to break the rings and ruin the grooves. But I have never rebuilt an engine without replacing the pistons with new ones anyway, and where the cylinder walls are so seriously damaged as in my case, I still don't see any point in trying to deal with this myself.

Charley,

I agree emphatically about "going all the way", but I've never heard of using beer to free stuck pistons. Does it work better than phosphoric acid? Do you pour it in the mechanic, or do you eliminate the middleman and pour it directly into the bores?

Thanks,
Allen
Allen Bachelder

Allen,

This is not a time to eliminate the middleman. The beer should be poured into the mechanic, and into the helper if applicable. It steadies the hammer hand and turns hard work into a social event. Be sure not to pour the phosphoric acid into the mechanic.

Charley
C R Huff

Guys, thanks for the positive feedback. I am getting close.

I have a new question in relation to the same activity. My manual tells me to replace the oil thrower behind the crank pulley of the timing chain with its concave side away from the engine. Then in another sentence they say to make sure the side of the oil thrower stamped with the F is facing away from the engine.

Attached is how it was installed, F facing away and the concave side "facing" the engine. Is the manual incorrect or am I screwed up again.

The dictionary defines concave as the inside of a sphere which is how I always understood it. Hence, shouldn't the manual state concave side facing the engine? I have the Bentley manual, section A.10.

I am talking 71 B. The seal is not felt but neoprene on the timing chain cover also.

I am going to put the beer in the mechanic and acid in the block. Never the other way around. Maybe this would make more sense then.



rj horizon

RJ,

My 'original' workshop manual shows the oil thrower fitted as yours, saying that the 'F' marking should be visible (ie away from the engine).

Back to the pistons - are they out yet? If the rings are rusted solid to the cylinder then the rings are dead and the cylinder needs a rebore. If you need a rebore then you'll need new pistons. Therefore, does it really matter if you damage them?

Steve S.,

Why would hydrochloric acid be any worse than phosphoric acid with respect to hydrogen embrittlement? Isn't the B-series block made of cast iron? Is hydrogen embrittlement really a big issue with cast iron? Anyway, aren't components (usually welds) heated up to liberate the hydrogen to prevent embrittlement, and if so - and if embrittlement were an issue - wouldn't running the engine produce more than enough heat to let the hydrogen go? Just curious.

Neil
Neil22

RJ,

I've read read a bit more...

For a dual roller system, book says F marking showing.

There is a note in bold that says that the early type of cover and thrower must be used together, and that thrower must fitted with concave side facing away from the engine.

Then later, in the section about the single row chain it says that the F marking should be showing, diagram has the thrower with the concave towards the engine.

Moss parts book says double row chain pre 18V (1971), single row chain thereafter. But the thrower changes early in 18GB engine. The diagram is of a big thrower, shown with concave pointing away from the engine. Factory parts book says the same.

Mine's fitted like yours, seems to work okay!

N
Neil22

I will reassemble the thrower as it came apart. I think thats the safest way.

Next step is to get the crank out and prepare to work on the pistons. Probably next weekend. No time during the week and to damn cold out there. 40 in the barn. I will check into the acid scenario.

I am assuming a bore job and new pistons along with all the other replacements. Bite the bullet. Don't want to have to do this again in the near future.

Thanks again everyone for the great advise.
rj horizon

Neil22-
1) Hydrochloric acid impregnates the cast iron with hydrogen, phosphoric acid doesn't.

2) The B Series bolck is made of cast gray iron.

3) You should more properly address this question to a metalurgist. I've never heard of heating a weld in order to liberate hydrogen from the metal. If such a thermal practice was sucessful, I doubt that the engine would reach a high enough operating temperature to enable the process to take place.

RJ-
Do you have an Email address?
Steve S.

rj,

You mention that you have a 71 model. You should check the engine number on the aluminum tag on the side of the block to see if it matches a 71 model. Often old Bs have had an engine swap. My 68 has a GK engine, which, if I remember correctly, did not exist until 70 or so.

This will become increasingly important when you start ordering parts.

Charley
C R Huff

Steve S. Email is westect@comcastdotnet.
rj horizon

RJ,

I might able to help. Check your email.

Steve Mc
Steve Mc

Steve,

I think you'll find that any acid would have the same effect, given that all acids have a hydrogen component (being part of the definition of being an acid in the first place. I think the whole 'hydrogen embrittlement' thing is a red herring.

FWIW,

Neil

Neil

Neil- Being neither a chemist nor a metalurgist, I'll have to take your word concerning hydrogen being a part of any acid. It is widely knowm amongst engine builders that hydrochloric acid is a no-no for removing rust from cast iron blocks. You'll never see it used at any engine rebuild shop in the baths used for that purpose. Nor will Machinists or Tool & Diemakers use it for rust removal on any ferretic (sic) metals. Having been a Journeyman Tool & Diemaker, I'm sure that this not a "red Herring". Phosphoric acid is what is used. Why phosphoric acid doesn't produce the problem of hydrogen embrittlement is something for the experts in such matters to explain.
Steve S.

Neil-
I consulted a metalurgist and have managed to paraphrase his explanation into layman's terms for you:

Hydrochloric acid reacts with the iron oxide (rust) to form soluble ferric chloride, thus leaving a clean exposed metal surface. However, it then also reacts vigorously with the iron to form ferric chloride and hydrogen. If you leave an iron engine block in a bath of hydrochloric acid long enough you’ll just have a bath of ferric chloride (and enough hydrogen for another Hindenburg!) On the other hand, phosphoric acid reacts with the iron to form ferric phosphate, which adheres to the surface. This protects the surface and slows down the reaction, so it is more or less self-limiting. Phosphoric acid reacts very slowly with iron, thus hydrogen emission is much lower.
Steve S.

Steve,
What did he say about hydrogen embrittlement?
Neil
Neil22

Neil22-
Reread my previous posting. In essence, the less hydrogen that is produced by the chemical reaction, and the less violent that production is, the lesser the chances of hydrogen being forced into the iron. The coating of ferric phosphate (which has a dark purple hue) helps to prevent this from happening.
Steve S.

FWIW, some views on the oil thrower issues discussed above.

As Neil says, the thrower changed in April 65, not long after the introduction of the 18GB engine. I believe one of the changes in that engine was the introduction of the neoprene timing cover oil seal - previous one being felt.

My Moss parts book shows the oil thrower Neil describes from his Moss publication, as does my Leyland service manual. However, in the Leyland manual it is a component of the three bearing crankshaft. The five bearing shaft being shown separately. The Moss parts list acknowledges the two parts though, correctly nominating one of Clausager's car numbers as the change point.

My Leyland manual also contains the warning Neil mentions regarding 'early' timing covers being used with the oil thrower concave face outwards - away from the motor. This is just as the three-bearing crank oil thrower is drawn.

I conclude the reference to 'early' is to the three-bearing motors, G and GA - those with the felt timing cover oil seal. There being no issue regarding double/single chains.

RJ's proposal to fit the thrower showing the face stamped F is exactly what I did on my GG engine. It is also as I found the thrower on a GB engine I disassembled in 06.

Regards
Roger

Regards
Roger
Roger T

This thread was discussed between 23/02/2008 and 06/03/2008

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