Lurch Engine rebuild – M116 sleeving

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CraigB
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Lurch Engine rebuild – M116 sleeving

Post by CraigB » Sun 29 Jan, 2017 9:11 pm

Long time between drinks but back getting Lurch's original engine together. My main mentor since a young age/ godfather / expert machinist cousin has been pretty crook but at a recent visit he said “when are we gonna do those blocks of yours” and so I was there within days!

Thought I would start a new thread with sleeving in the title because its something I haven't noticed on here. Pistons are bloody expensive but the original Mahle items are top quality and have a long life. So if you bore and then sleeve back to original bore size, then you can save that piston cost – if they are still ok, ring grooves not worn etc.

So in Lurches case, the engine was in good shape but had an overheating issue that led to what seems to be a blown head gasket or two. Joe had a 560 engine sitting there and his plan was to fit that so wasn't worried about the old engine. When I pulled the heads, two of them had fluid in them that had been sitting there for years and there was deep corrosion on those bores. And yet the other 6 original bore cylinders were good and pistons were good. My options were rebore and full set of oversize pistons or two sleeves.
DSCN1693.JPG
I don't know what normal price of sleeves is but I got a couple of 'surplus' ones for $50 for the pair. They are 'spun' cast iron and apparently you don't want to drop one because they will shatter like a glass.

Before starting I had to mark and drill a couple of stands to bolt the base of the block to so the cylinders were vertical. These get turned around to do the opposite bank.
DSCN1692.JPG
The workshop is very low key, my cousins back shed, but is made up for with his depth of experience. The reboring tool is ancient and grips with a clamp in one of the other cylinders and is centred with these 3 internal pins/jaws that you expand into the cylinder being bored. There is a cutting bit, along the lines of that in a lathe that rotates and the machine slowly descends to a set depth. We set that depth to leave a few mm at the base at the standard bore size. I guess there was about 5 cuts with a smaller step for the final cut.
DSCN1691.JPG
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Next step is to drive the liner in that is at a specific interference fit. It shouldn't move, but to be sure it is sandwiched between the head and that step we left at the bottom of the bore. Also a ring of loctite 602 I think it was is put on the base and top of liner before the last bit driven home. The liner then gets a finishing bore to size and then honed.
DSCN1695.JPG
Last step will be to have the block face skimmed complete with the liner.

Doing it seems remarkably simple, but that is with the experience of precise measures and that 'sixth sense' that experienced machinists seem to have. Its not something you want to make a mistake on! Even with me doing all the lifting it is still a bit rough on my cousin with his health so it will happen in bursts with next on this Wednesday. He seems to think we will knock Lurch off quickly and then it is on to Gloria's engine (the original '72 350sl engine). That one was quite worn in all bores with significant ring groove that made it hard to get pistons out. I managed to swap a pair of heads for a set of good oversize pistons, so that will get the straight rebore treatment. Then if we get that all done, next job on the list is an Amilcar engine that needs white metalling – the 'dark art' that also goes on in his back shed!
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Craig Baulderstone
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Re: Lurch Engine rebuild – M116 sleeving

Post by Giles » Mon 30 Jan, 2017 2:29 pm

Nice work Craig. Will you be adding a manual gear box to go with pedal box I sent you?

Regards,

Giles
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Re: Lurch Engine rebuild – M116 sleeving

Post by CraigB » Mon 30 Jan, 2017 3:24 pm

Yes its all a bit confusing and i change my mind almost as often as i change my undies. Only a couple of weeks ago the 560 was headed into Lurch and now back to original again. The 560 and intended use for pedal box was for the other white slc i have intended for rallying. It may go through a preliminary step of being an auto though. My intention is to go full programmable injection so I think i will stay with the original plan of the white car so i am not chopping things around on Lurch. The temptation to bolt it up to Lurch is that the rest of the mechanicals are so good on it with 560 discs etc and i wasn't sure of the future of this 350 engine, but full steam ahead now on the 350.
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Re: Lurch Engine rebuild – M116 sleeving

Post by Bartman4800 » Tue 31 Jan, 2017 5:02 pm

Craig,

A good write-up but I am a bit confused about the whole deal.

I would have thought that the pistons, being an alu alloy, would wear quicker than the nodular cast iron cylinder wall.

Are you saying it's quite the opposite and you reuse the original pistons in the new sleeves?


Regards, Bart
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Re: Lurch Engine rebuild – M116 sleeving

Post by cuisses » Tue 31 Jan, 2017 5:50 pm

Bartman4800 wrote:Craig,

A good write-up but I am a bit confused about the whole deal.

I would have thought that the pistons, being an alu alloy, would wear quicker than the nodular cast iron cylinder wall.

Are you saying it's quite the opposite and you reuse the original pistons in the new sleeves?


Regards, Bart

I thought pistons were not supposed to touch the walls - that is the job of the piston rings, hopefully with a bit of oil in there as well?

In any case, I am impressed you can do this in a "shed".
David Williams

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Re: Lurch Engine rebuild – M116 sleeving

Post by Bartman4800 » Tue 31 Jan, 2017 6:09 pm

cuisses wrote:
Bartman4800 wrote:Craig,


Regards, Bart

I thought pistons were not supposed to touch the walls - that is the job of the piston rings, hopefully with a bit of oil in there as well?

In any case, I am impressed you can do this in a "shed".
I don't think so. The rings float around the pistons (the grooves are deeper than the height of the rings)

If you have too much clearance at the crown, you get piston slap...

And the skirt surely touches..


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "missus car"
2002 VW Passat V6 30V Station Wagon (my new commuter bus)

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Re: Lurch Engine rebuild – M116 sleeving

Post by CraigB » Tue 31 Jan, 2017 6:43 pm

Not the issue on lurch because bores not worn and piston fine in corroded bore that is being sleeved. But now i am not sure about pistons from Gloria. Will check tomorrow. But hard surfaces wearing with rings expanded under tension is rings and bore. There will be some side force with alloy and ultimately wear but I have a feeling that is much lower force, even though with softer metal. Have you seen race engines with hardly any skirt at all on pistons. And of course pistons aren't round but oval with a grind for longevity vs friction (my cousin also has a piston grinding machine with something like 4 different settings for the ovality) - ie. a race grind has a small amount of piston face contacting bore, but wear out much quicker. So i think that is basically what David is saying, although it is in contact the aim is to minimise that contact. So they must wear of course but i got the impression they still had a life that outlived that of the hard contact of bore and rings. But more educated response after tomorrows session and a lecture from my cousin.
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Re: Lurch Engine rebuild – M116 sleeving

Post by CraigB » Wed 01 Feb, 2017 11:32 pm

OK - I have an answer i trust but not the science behind it, so maybe David can help us out. For some reason the harder material wears more than the soft and the example my cousin gave, based on years of experience, take a piston that has wear you can feel in the gudgeon to piston and put a new gudgeon in and it will feel like new. All he could suggest was that the softer alloy took up grit from oil etc and that ground away like sand paper on the hard metal - but just a guess.

Skirts don't generally wear, but you are right Bart that it is the land (the bit above the top ring) that will wear and cause piston slap. When i showed him a selection of pistons from two of the engines, both were fine in the lands. The very worn engine he could see there was some slap signs, but the land itself not too bad and in a fresh bore would be fine. He could see the rings were very worn though and you could see all black on the rod and under piston etc from all the blow by. I never saw that car running but was told it was taken off the road because it was blowing so much smoke. Still, much easier to bore than put in 8 sleeves given that i have the oversize pistons I sourced.

So regardless, you have to check the pistons for wear and sounds like in particular the land and can measure land vs lower on the piston. But using my pistons as one example, there is a good chance they may not be worn and in a fresh sleeve work well. But depends how much you can get oversize pistons for and how much it costs to resleeve. Creates some interesting options though.

Lurch is done though and now i need to bolt up the front alloy cover and take to have the block faced so the cover is all faced to that same level for the heads to bolt up to all nice and flat.
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Re: Lurch Engine rebuild – M116 sleeving

Post by cuisses » Thu 02 Feb, 2017 12:35 am

Maybe the "softer" aluminium is not so soft after all. Aluminium is very reactive with oxygen and always forms a tough oxide layer, which prevents further corrosion. (Iron also gets an oxide layer, but this is porous and peels off, and hence iron rusts, but aluminium does not).

Hardness of aluminium is 2 to 2.9, iron 4 to 5, but aluminium oxide is 9. The pistons are aluminium alloy, but presumably still get an oxide coating,
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Re: Lurch Engine rebuild – M116 sleeving

Post by Honey500 » Thu 02 Feb, 2017 9:10 am

Interesting read Craig sounds like good progress.

Looking at the beginning of the thread you talk of the sleeves being cast iron. I wonder if the wearing has to do with cast iron being Strong/hard but being brittle, i.e. shattering if dropped.

David would the oil on the piston srop the aluminium oxidizing?
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Re: Lurch Engine rebuild – M116 sleeving

Post by CraigB » Thu 02 Feb, 2017 9:31 am

That sounds like a good explanation. And i guess different manufacturers use different alloy. My first car was a Morris Oxford (there- I said it out loud!) extremely low mileage (10k miles?) old ladies car that was seized. I pulled the engine with dad and took it to my cousin. I guess the wear was so slight and tolerances tight, plus I remember cousin saying Morris use particularly long skirts on their pistons, but we ended up breaking most of them knocking them out with a bit of hardwood. Bores came up fine but i needed a set of pistons. I ended up buying very cheaply an accident damaged Wolsely 24/80, which was an australian designed and built engine that was basically the morris 4 with 2 more cylinders added. (and nearly 40 yrs ago so started my habit of buying whole cars to get parts!). When i stripped the motor the pistons were ever so slightly bigger bore (but had shorter skirts that the Oz development must have thought appropriate). My cousin ground 4 of the pistons (I think that ovality thing is called cam grinding or a cam grind?), also there was a bit of wear in I think the top piston groove and that also got cleaned up to fit an appropriate ring size. Cousin worked at Adelaide Engine Service and they had data on individual rings for everything and just picked the appropriate part. (also that reminds me of something he said yesterday, when AES closed there was an auction and whole racks of pistons were bought and chucked straight into scrap metal bins.... Including a brand new set of oversize Stutz Bearcat pistons amongst many other rare parts)

Anyway, it all went back together and ran fine for many years of 'teenager abuse'

But the point of that story mainly was that while these high mileage Mahle pistons had no wear in ring grooves, the Wolsely did and i have seen other pistons with visible wear and no doubt a different alloy.
Craig Baulderstone
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Re: Lurch Engine rebuild – M116 sleeving

Post by AMG » Sat 04 Feb, 2017 3:55 pm

So you put a stepped liner into the 2 bores on Lurch's motor?
Just curious if they are like Rover v8 ones, with a step in the bottom and one in the top (prevent slip in both directions) but I guess the loctite does that anyway.

heard so many stories form the LR guys about the v8 'steam engine' - I think it's quite possibly because the build quality was just garbage and people also are reluctant to take their time when doing a 'quickie' reco on the short block.

Should be a very strong motor again once you're done.

I could never quite get over just how free-spinning that m116 3.5 v8 was. It was truly a remarkably smooth engine. Stunning, when you consider it was 42 years old and had 300,000km on it.

And nothing like the P.O.S. rover v8 I ended up with in the RRC. (I'm pulling it out soon, it's really on it's last legs.. worn cam, rockers, yeah... I don't even want to bother rebuilding it, even though it's probably a 900 buck job)
Current:
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
1992 300CE-24 6sp. man. Perlblau / Iceblau "Gretel"
1992 Range Rover Vogue SE 4sp auto Ardenne Green "Oswald"
2012 Renault Sport Megane RS265 Trophy 8:08 6 sp. man. Liquid Yellow "Jean Rédélé"
Previous:
1986 560SEL Anthracitgrau "Schultz" - In Mercedes Heaven
1987 190E 2.6 4sp. auto Signalrot "Sabine" - which now resides/owns Andrew M's Garage
1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.

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