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1983 380 SL
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Discussion Starter #141
Dropped my block off at the machinist this morning. I'm waiting for him to give me a price to repair #6 cylinder.
Just like S&K he did not have the ability to do the final hone on an ALUSIL block but unlike S&K he had no problem repairing the cylinder and having me do the AN-30 hone.

We discussed the fact that pistons for an '83 380 aren't exactly growing on trees these days so he agreed that no matter what he eventually does... probably sleeve it... he would adjust the final size for the only pistons I have available... two category 1's and two category 1+.

I'm thinking about which thickness sleeve to use... the most common sizes being .062, .093 and .125. Inasmuch as a 2nd repair size is 1 mm over standard and 1 mm = approx. .040, then a .062 sleeve would require a bore size only .022 thousandth of an inch greater than a 2nd repair bore size (which is acceptable). Even a .093 would only require a .053 bore over standard.

We'll see what he says. :unsure:
 

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'85 300tdt (sold),'64 220b,'63 220Sb ,85 monte carlo ss 406SBC(4 sale),1976 vega wagon(sold)
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Dropped my block off at the machinist this morning. I'm waiting for him to give me a price to repair #6 cylinder.
Just like S&K he did not have the ability to do the final hone on an ALUSIL block but unlike S&K he had no problem repairing the cylinder and having me do the AN-30 hone.

We discussed the fact that pistons for an '83 380 aren't exactly growing on trees these days so he agreed that no matter what he eventually does... probably sleeve it... he would adjust the final size for the only pistons I have available... two category 1's and two category 1+.

I'm thinking about which thickness sleeve to use... the most common sizes being .062, .093 and .125. Inasmuch as a 2nd repair size is 1 mm over standard and 1 mm = approx. .040, then a .062 sleeve would require a bore size only .022 thousandth of an inch greater than a 2nd repair bore size (which is acceptable). Even a .093 would only require a .053 bore over standard.

We'll see what he says. :unsure:
You may want to talk to him about the pistons as well. They have a coating on them to keep galling between the aluminum pistons and bores at bay. The other consideration is piston to bore clearance. The clearance in an iron block is different than the alloy block. Things shrink and grow differently when made of different metals.
I would personally sink the small bore long stroke low compression 3.8 in a nearby lake to hold a floating dock in place and find a good running beat up worthless 420sel to grab the engine from. Do the head gaskets while swapping all your intake and injection goodies.
 

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1983 380 SL
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Discussion Starter #143
You may want to talk to him about the pistons as well. They have a coating on them to keep galling between the aluminum pistons and bores at bay. The other consideration is piston to bore clearance. The clearance in an iron block is different than the alloy block. Things shrink and grow differently when made of different metals.
I would personally sink the small bore long stroke low compression 3.8 in a nearby lake to hold a floating dock in place and find a good running beat up worthless 420sel to grab the engine from. Do the head gaskets while swapping all your intake and injection goodies.
The tolerances for the block to piston are super tight primarily because aluminum has a higher coefficient of expansion than steel, so as the block heats up the gap between the aluminum block and the steel piston gets larger. I'm not overly concerned about piston wear... my 107 is not my daily driver nor will it ever be. The occasional Sunday top down drive in sunny weather and a once in a while trip to a gtg is all I'll be doing. If I was concerned with longevity I'd be putting a pre-computer Chevy small block, a 327 or a 350, into the hole where the Mercedes engine currently resides.
 

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Well, pistons are aluminum first of all. I suggested a 4.2 because it's about 60-75 hp up on a us 3.8. Unfortunately a gen 1 or 2 small block Chevy doesn't go in that hole without reengineering the steering or the oiling system on the Chevy. You can cut all you want off the pan but that oil pump is still right where the drag link lives. LS or Ford would be easier.
 

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1983 380 SL
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Discussion Starter #145
Well, pistons are aluminum first of all. I suggested a 4.2 because it's about 60-75 hp up on a us 3.8. Unfortunately a gen 1 or 2 small block Chevy doesn't go in that hole without reengineering the steering or the oiling system on the Chevy. You can cut all you want off the pan but that oil pump is still right where the drag link lives. LS or Ford would be easier.
Hmm, you are correct about the pistons... my bad. Brain fade.
As to the small block Chevy into a 107... I wouldn't be the first to do it and I'm not actually contemplating doing it. I was merely emphasizing my point about not getting too anal with the 380 rebuild.
 

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1983 380 SL
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Discussion Starter #146
While waiting for the machine shop to finish the block I finished the initial cleaning of the heads. The Formula 88 Degreaser in a Home Depot bucket with a 1500 watt heater works pretty good.

Here's picture of a head before cleaning...
MercLeftHeadCaptiveHeadBolts.jpg


Here's the same head after cleaning (different angle).
MercHeads1stCleaning.jpg
 

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1983 380 SL
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Discussion Starter #148
Very nice! The Formula 88 did a great job.
Thank you. I still have some more cleaning to do... but a dip in a clean water bucket right from the hot Formula 88 bucket, followed by a wipe down with paper towels and the bulk of the old oil and crud just wiped right off. Some of the carbon buildup on the exhaust ports require a light scrubbing with a brush but other than that the process is almost painless.
 

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1983 380 SL
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Discussion Starter #149
The machine shop where I brought my block called and now I've got a bigger problem. They cannot remove the scratches via simple honing, they must bore the cylinder to the 1st repair size which is approx .020 over (in metric that's .5 mm over). I can't find a 1st repair size piston (88.5mm). Does anyone have or know where I can get a 1st repair size piston for a 116.962 engine?

If I can't locate a 1st repair piston they can insert a sleeve but the extra work involved in boring and honing the sleeve to match the size pistons I have available (1 and 1+) would cost hundreds of dollars.
 

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Discussion Starter #152

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Hmm, you are correct about the pistons... my bad. Brain fade.
As to the small block Chevy into a 107... I wouldn't be the first to do it and I'm not actually contemplating doing it. I was merely emphasizing my point about not getting too anal with the 380 rebuild.
Yes not the first but like I said, complete steering reengineering. Either rack conversion or a sketchy handlebar shaped draglink. Maybe put the engine at an unreasonable height. Trust me, I've got measurements thinking about putting a very healthy 406sbc I have in my 450slc. It's nowhere near dropping in. I was mentioning the 4. 2 because you probably already spent more talking to a machine shop, let alone having work done, than you can buy a 420sel for. I know I could get one under 1000 right now. Probably 500 if you want to drive a little. And it's free power.

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The machine shop where I brought my block called and now I've got a bigger problem. They cannot remove the scratches via simple honing, they must bore the cylinder to the 1st repair size which is approx .020 over (in metric that's .5 mm over). I can't find a 1st repair size piston (88.5mm). Does anyone have or know where I can get a 1st repair size piston for a 116.962 engine?

If I can't locate a 1st repair piston they can insert a sleeve but the extra work involved in boring and honing the sleeve to match the size pistons I have available (1 and 1+) would cost hundreds of dollars.
I've got a 3.8 that jumped time here I would sell pretty reasonably if you really want to rebuild yours. I've even got a "ran when I started taking parts" car sitting here.

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I've got a 3.8 that jumped time here I would sell pretty reasonably if you really want to rebuild yours. I've even got a "ran when I started taking parts" car sitting here.

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And I’ve got a running driving dual-row-chain 1981 380sl that could be sold for its motor or sold whole, or used to take the fuel distributor to test the one at your shop. That’s three possibly 3.8 motors in Delaware for you, all very reasonable I’m sure.


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Discussion Starter #156
I thank everyone for their thoughtful input and suggestions... after much soul searching I've decided on a course of action with the best possibility of producing an acceptable outcome at the least cost.
The machine shop has given me an estimate of $400 to bore the badly scratched #6 cylinder to a size that will allow the insertion of a sleeve. I will provide him with 2 pistons from the 4 I recently purchased on eBay. One is a category 1 piston and the other is a category 1+. He will decide which one to use.

I have decided not to replace the rings on any of the pistons as they all appear to be in good shape and the compression tests were good on all cylinders (except #6, which is being repaired) and the engine was not burning any oil even with the badly scored #6, but there was moderate blow-by which may have been from #6... I have now way of knowing for sure. I will be replacing all the bearings and seals as it would make no sense not to do so while the engine is out of the car and totally dismantled. I'll also do the TimeSert repair. I have yet to figure out how to do that without using the drill termplate but I'm confident that I'll find a way.

I'm going to attempt to lap the valves using the old fashioned method which I have done with success many times in the past. It's not as good as regrinding at 2 angles but it is good enough for my purposes. My 107 is not my daily driver and other than the occasional gtg I won't be putting extensive mileage on the vehicle at anytime in the foreseeable future.

That's it... now I wait for the machine shop to do it's thing and then I'll begin the arduous task of putting this engine back together. If the engine runs as well as it did before I tore it down... without the infernal ticking... I'll be very pleased.

There's so much to do that it's a bit overwhelming at this point, but I have the entire winter to get it done. Small steps... one task at a time... any by April I should be on the road again... maybe.

I'll be posting progress reports along the way and very likely asking numerous questions as I go.
 

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Jyuma, you are making a big mistake by re-using the old rings in old bores. The rings match themselves to the bores over time, and now neither the bores nor the rings are round. You will very likely have poor compression and high blowby & oil consumption if you just put everything back together. At the very least discuss with the machine shop if they can do the final fine hone and subsequent lapping with the compound per the Mercedes documentation. This will provide a more or less correct bore surface that will be far more round than the as-run condition. It is better to be a little bit too big but round with new rings than to put old rings back into an old bore.
 

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Discussion Starter #158
Jyuma, you are making a big mistake by re-using the old rings in old bores. The rings match themselves to the bores over time, and now neither the bores nor the rings are round. You will very likely have poor compression and high blowby & oil consumption if you just put everything back together. At the very least discuss with the machine shop if they can do the final fine hone and subsequent lapping with the compound per the Mercedes documentation. This will provide a more or less correct bore surface that will be far more round than the as-run condition. It is better to be a little bit too big but round with new rings than to put old rings back into an old bore.
I considered that but the machine shop cannot do the final hone... they don't deal with it. I will do a final hone with AN-30. Also... I have not changed the ring orientation on the pistons, they are in the same orientation they were when I removed them. I also marked all the pistons with what cylinder they came from. They're going back to the same holes they came out of. I agree it's a gamble, I guess I'm just a risk taker.
Having said all of that... I'll reconsider your advice and ask the machine shop if they can true up the remaining 7 cylinders without needing to go to the first repair size... that would be a game changer as I have been unable to locate even 1 first repair size piston let alone 8 of them. I emailed MAHLE and they got back to me to ask what country I was in so they could forward my email to the appropriate location. I haven't heard from them since.

If the machine shop can true up the cylinders without the need to go .020 over, I'll replace the rings.

Thanks
 

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Can I ask what the reason for spending money on this particular engine is? It sounds like your throwing money at 1 cylinder and then hoping for the best with the rest of them. Are you doing all the guides and timing chain, gears,tensioner, cam oilers, valve seals, guides and everything?
 

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1983 380 SL
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Discussion Starter #160
Can I ask what the reason for spending money on this particular engine is? It sounds like your throwing money at 1 cylinder and then hoping for the best with the rest of them. Are you doing all the guides and timing chain, gears,tensioner, cam oilers, valve seals, guides and everything?
Good questions... the reason I'm spending money on this particular engine is because I'm the original owner, it's been my car for 36 years and I want to keep as much of it as original as possible. I realize I can't do that with consumables like bearings and seals but certainly the block is not generally considered a consumable.

The dual chain conversion was done 22 years ago. Twenty years ago I parked the car and never even so much as cranked the engine again until 2018. For all intents and purposes the dual chain and sprockets are 2 years old.
The guides and tensioner are new... I replaced them last year.
Cam oilers are new... I replaced them when I replaced the guides last year.
Valve seals and guides will be replaced before I bolt the heads back on.
I'm not sure what you mean by "everything" but certainly everything that should be replaced (at a reasonable cost), will be replaced. For me to have all the cylinders bored to 1st repair specs would cost thousands of dollars if it means replacing 8 pistons with 1st repair pistons... even if I could get them, which so far looks like I can't. I'm willing to roll the dice on going with what I've got but if it doesn't work out I'm prepared to pull the engine and do it all over again (actually I'm planning to run the engine on a test stand before putting it back in the car).

I agree... with any other engine this would be a no brainer... but the devil I know is better than the devil I don't know, and buying someone else's almost 40 year old engine is definitely the devil I don't know. Hey, who knows... maybe in the end I'll be forced to do it... but not before I've exhausted every possibility of salvaging the original engine. :)

Thanks for your input... it is most appreciated.
 
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