M70 Rebuild Thread.

[dragon850]

Starting a new thread about this rebuild we are doing in the donor $300 engine that will be used to swap an engine in my Supercharged 850 That has unknown damage.

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Took advantage of some labor day sales today on fcpeuro. Ordered, complete top end reseal gasket set, complete bottom end reseal kit, head gaskets, head bolts, 24 valve guides, timing chain and tentioning spring, 24 new hydraulic valve lifters. Anything else you guys think I need?

[BMSman]

Do you plan to remove the Pistons? And if not did you already do a leak down test.

I will be curious what this ends up costing as I'd like to do same myself.

[dragon850]

I do not think I will be removing the cylinders, we will inspect the cylinder walls and check the hole diameter.
Usually the bottom ends on M70 are rock solid, I have seen rebuild threads on M70 engines with over 250k miles where the cylinder walls look brand new.
As far as the cost, well... It is starting to add up even with the super deals I got yesterday:
FCPEURO:

Description	Unit price	Qty	Amount
BMW Head Gasket Set (750iL 850CSi 850Ci 850i) - Elring 11129059239 Item# ELR-818720	$189.99 USD	1	$189.99 USD
BMW Cam Follower (318I Z3) - Ajusa 11331712010 Item# CRP-85000900	$10.11 USD	24	$242.64 USD
BMW Valve Guide - CRP 11121709860 Item# CRP-11121709860EC	$4.59 USD	24	$110.16 USD
BMW Short Block Gasket Set (750iL 850CSi 850Ci 850i) - Elring 11119059235 Item# ELR-818453	$139.99 USD	1	$139.99 USD
BMW E12 Torx Head Bolt Socket - CTA 9259 Item# CTA-9259	$15.99 USD	1	$15.99 USD
BMW Engine Timing Chain (850Ci 850CSi 850i 750iL) - Iwis 11311710155 Item# 11311710155	$57.99 USD	1	$57.99 USD
BMW Engine Timing Chain Tensioner (750iL 850Ci 850i) - Genuine BMW 11311307053 Item# BMW-11311307053	$9.99 USD	1	$9.99 USD
Promotion (Labor Day 10% Sale)	-$76.68 USD	1	-$76.68 USD

Subtotal $690.07 USD Total $690.07 USD Payment $690.07 USD

PLUS from Autohaus AZ:

11121729247 Cylinder Head Bolt Set; 14 Bolts for 1 Cylinder Head $23.58 2 $47.16

11121729897 Cylinder Head Gasket; Left (Cylinders 7-12); 1.64mm $35.22 1 $35.22

11121729893 Cylinder Head Gasket; Right (Cylinders 1-6); 1.64mm $31.52 1 $31.52

Parts Total:	$113.90
Refundable Core Total:	$0.00
Shipping & Handling:	$0.00
Total Before Tax:	$113.90
Sales Tax*:	$0.00
Order Total: $113.90

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Is it worth wrapping the exhaust manifolds in heat resistant exhaust wrap? I have seen it done on may performance cars but not on 850.

[B10 BITURBO]

I really recommend using studs,, thats my opinion,, it is an aluminum block,, i think can get studs that are almost the same dimension,, 10x110 is oem bolts

here is a comparison,,,

http://www.summitracing.com/int/part...0-1b/overview/

[jrthemessenger]

Hey guys, I'm in the middle of rebuilding my M70 engine as well. I bought the Head Gasket Set KIT from Dealer directly ($339) which includes ALL the gaskets and seals), except for the Head gaskets which were and additional ($262). I also purchased the lifters "Alignment element" $384 @ Autohaus AZ. The two sets of springs per valve $212.00 @ BWW dealer. The cylinder head bolts ($58), water pump $135@ PartsGeek, and thermostat $63 @ dealer. The pistons and cylinder walls look great and it passed the leak test as well. By the way my 850 had 239K @ the time. I will post again once is all done and on the road :-)

[dragon850]

Can you elaborate what is the advantage of using studs over head bolts?

I really recommend using studs,, thats my opinion,, it is an aluminum block,, i think can get studs that are almost the same dimension,, 10x110 is oem bolts

here is a comparison,,,

http://www.summitracing.com/int/part...0-1b/overview/

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Yeah, this is what I read over and over again, cylinder walls are bullet proof. So you did not touch the bottom end? Why did you decide to buy the springs, I am not aware that they are prone to wear. Upon inspection several rockers are worn, kind of a wavy feel to them, so those will be replaced.

Hey guys, I'm in the middle of rebuilding my M70 engine as well. I bought the Head Gasket Set KIT from Dealer directly ($339) which includes ALL the gaskets and seals), except for the Head gaskets which were and additional ($262). I also purchased the lifters "Alignment element" $384 @ Autohaus AZ. The two sets of springs per valve $212.00 @ BWW dealer. The cylinder head bolts ($58), water pump $135@ PartsGeek, and thermostat $63 @ dealer. The pistons and cylinder walls look great and it passed the leak test as well. By the way my 850 had 239K @ the time. I will post again once is all done and on the road :-)

[dragon850]

Did some laboring on the labor day Took the upper and lower timing cover off, for the lower cover important to note that it's also held my 4 bolts underneath the lower oil pan so you have to turn the engine and unbolt it.
Cams looked good without any obvious signs of wear, no scoring. It was apparent quality oil was changed often. All banjo bolts were tight except for one that was finger tight but not backed out at all. On that side #2 cylinder cam lobe had some discoloration.
Several rockers had a wavy pattern when you run your finger over the surface, I will be replacing them. Other rockers did not look worn at all. Very minimal crude deposits inside the head.


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Timing chain tensioner, it had a worn in grove from the timing chain also was a bit wobbly probably will get replaced. Right timing guide was cracked.

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Removing camshafts.

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Finally the heads are off, holy molly what is that black crap on valves and pistons?? LOL, lots of carbon deposits. Looks like who ever drove this car was a slouch, , never gave this engine a proper full throttle cleaning! Any ideas on the best way to remove the deposits from pistons?

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Head gasket was not blown. Looks like engine was never overheated.

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Cylinder walls looked very good and had no visible scoring

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Heads will be going to machine shop to get hot tanked, checked and fully rebuilt.

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We soaked valley pan bolts for about 5 hours using liquid wrench, as a result all bolts came out without incident, however they were covered in gunk.

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[B10 BITURBO]

Can you elaborate what is the advantage of using studs over head bolts?




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I can not say 100% sure,, but on other BMW aluminum blocks it is well known that the threads will not hold,, and then you have a serious problem,, if you use studs the force is just on the stud and the nut have no problem at all,to tight down and you are not wrenching/screwing the bolt via the aluminum block and the friction is by then none at all.

[dragon850]

So you get your engine all taken apart do hours and hours of work, THEN when you go to do the last pass on tightening the head bolts one gives way. Why? steel bolts, aluminum female threads in the block that have been through many thermal cycles. The aluminum fractures at the thread wall. So how do you repair the threads in the block in the one bad one.
A: (Take everything back apart?)
B: With the head on, you tap to 11mm?
C: Go find another block?

I don't know the answer?

It's REALLY bad news. Helicoil? Time-sert? I D K !!!

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" Right timing guide was cracked. "
Yep. Mine too. very common.

Did this actually happened to you? Is this bolt failure common at all? I have never seen this on an M70 but you are making me worried a bit!

[Timm]

Are the head fixings on the M70 stretch bolts like they are on the V8's?

[dragon850]

Just ordered this gasket removal wheel for aluminum: http://www.ebay.com/itm/261959353305...%3AMEBIDX%3AIT
Can I use it also to remove carbon from pistons or is there a better solution for that?

[dragon850]

What is the best method of removing carbon from the top of the cylinders??

[Mikekugel]

What is the best method of removing carbon from the top of the cylinders??

Ed, Nothing is ever easy huh. The best thing to do is most likely the hardest thing. Take each piston and rod out, and glass bead the tops, and clean the ring grooves, and install new rings. This is a Boosted application right. perhaps Sealed Power has a set of rings that would be right. Perhaps some kind of plasma coating might be applied to the piston tops,,,just saying,,mission creep. I like the idea of studs versus head bolts for your application. New main and rod bearings, and an oil pump look see are in order. Perhaps stronger rods? Billet crank? You are pushing the engine way over it's design criteria. Dang these things can get expensive,,but we love them. Hope to get together at the Legends next August, or sooner. Mike

[dragon850]

As far as I know bottom ends are good for 600 reliable boosted HP and are virtually bullet proof naturally aspirated. I know a person with a Dinan twin turbo 750 500hp, after 130k miles he did a complete top end rebuild, bottom end still looked great! (were talking 100k boosted miles). Not planing to do the bottom end, just possibly take apart the oil pan to clean it and adjust the chain. Cylinder walls look and feel nice and smooth.
I did some research and looks like the best solution for melting away and removing carbon is CRC Gasket Remover like this: http://www.amazon.com/CRC-05021-Tech...gasket+remover Just ordered a can.
If I can't get the SC 850 on the road by next August despite my best efforts, I will surely part it and I will be meeting you there in a CL65

Ed, Nothing is ever easy huh. The best thing to do is most likely the hardest thing. Take each piston and rod out, and glass bead the tops, and clean the ring grooves, and install new rings. This is a Boosted application right. perhaps Sealed Power has a set of rings that would be right. Perhaps some kind of plasma coating might be applied to the piston tops,,,just saying,,mission creep. I like the idea of studs versus head bolts for your application. New main and rod bearings, and an oil pump look see are in order. Perhaps stronger rods? Billet crank? You are pushing the engine way over it's design criteria. Dang these things can get expensive,,but we love them. Hope to get together at the Legends next August, or sooner. Mike

[Fatandre]

I have heard steam cleaning could do the job

[wokke]

I've done 10 engines meanwhile and never had any issue with worn out threads in the block. What I had though was popped off bolts heads twice. Seems like BMW had some poor quality.
And yes Tim, the bolts are stretch bolts and I highly recommend to use quality bolts and not some super cheap "on sale" crap. Seeing that the thread owner is going to install USD35,- head gaskets makes me wonder how long they'll last.
I once made the mistake to order complete gaskets sets (upper & lower) from AJUSA. They were on sale and extremely cheap (luckily, because I dumped them). The upper oil pan gasket was a cork one like the one from the lower oil pan.
And the rest didn't make a better impression on me either.

I do recommend to pull the pistons and actually clean them in some hot solvent. No need for any further disassembly but it definitely makes sense to clean the piston ring grooves. Especially sticky oil removal rings cause excessive oil consumption.
DO NOT REMOVE the rings as they break easily and then your screwed.

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..... Take each piston and rod out, and glass bead the tops, and clean the ring grooves, and install new rings. This is a Boosted application right. perhaps Sealed Power has a set of rings that would be right. Perhaps some kind of plasma coating might be applied to the piston tops,,,just saying,,mission creep. I like the idea of studs versus head bolts for your application. New main and rod bearings, and an oil pump look see are in order. Perhaps stronger rods? Billet crank? You are pushing the engine way over it's design criteria. Dang these things can get expensive,,but we love them. Hope to get together at the Legends next August, or sooner. Mike

NEVER glass bead the pistons, not even the tops. Those pistons are coated and if you glass beat the top you can dump them afterwards.
I've seen a lot of M70/S70/M73 bottom ends with high mileage and none of them needed new bearings. Especially the mains looked like brand new every time.
Rod bearings on the top are worth a look, especially if FI is planned.

[B10 BITURBO]

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I've seen a lot of M70/S70/M73 bottom ends with high mileage and none of them needed new bearings. Especially the mains looked like brand new every time.
Rod bearings on the top are worth a look, especially if FI is planned.

This is from my engine... driven ,, close to 250.000 km the last owner took good care of all engine service,, but have no clue before that






As you can see,,, they are not in the best shape,,, the main bearings are cheap,,, but the rod bearing are NOT........ and afaik only as oem

i really recommend changing both,, as everything is open,, and you will have a good conscience,, (( hi hi hi ))

and i also agree with Wolf about the AJUSA,,, do NOT buy it,,,

buy Victor Reinz..Elring or those top brands everybody know,, and i also recommend the lower oilpan to be sealed,, not just the kork seal,, but gasket seal

these steel pan have habits to leak after been taking occasionally of the engine,, so gasket seal is often recommended

[wokke]

fully agree with all what you say Sveinbjörn.
And bearings are indeed only available from BMW directly. Even my contacts to Kolben Schmid and Mahle didn't help when I needed them.

[B10 BITURBO]

fully agree with all what you say Sveinbjörn.
And bearings are indeed only available from BMW directly. Even my contacts to Kolben Schmid and Mahle didn't help when I needed them.

I dont know if you believe this ,, but i had to pay,, with the highest discount possible ,, over 800€ for the rod bearings,,,,,, holy shxx,,,,,,, at the Icelandic BMW dealer

[affa]

Fine choice. I used the same wheel. But if still go easy on it as it is abrasive.

Are the pistons coming out? If not please pack some cheap grease into the cylinders / piston gap before you go at it. You wouldn't want the abrasive going into the cylinders. I believe GM had a bulletin on scotch brite / roloc grit killing engines from a gasket change.

[affa]

I used plastic grit in my blast chamber. Does a great job and doesn't hurt anything.

I did put tape around the rings first. What wokke said...

[dragon850]

I've done 10 engines meanwhile and never had any issue with worn out threads in the block. What I had though was popped off bolts heads twice. Seems like BMW had some poor quality.
And yes Tim, the bolts are stretch bolts and I highly recommend to use quality bolts and not some super cheap "on sale" crap. Seeing that the thread owner is going to install USD35,- head gaskets makes me wonder how long they'll last.
I once made the mistake to order complete gaskets sets (upper & lower) from AJUSA. They were on sale and extremely cheap (luckily, because I dumped them). The upper oil pan gasket was a cork one like the one from the lower oil pan.
And the rest didn't make a better impression on me either.

I do recommend to pull the pistons and actually clean them in some hot solvent. No need for any further disassembly but it definitely makes sense to clean the piston ring grooves. Especially sticky oil removal rings cause excessive oil consumption.
DO NOT REMOVE the rings as they break easily and then your screwed.

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NEVER glass bead the pistons, not even the tops. Those pistons are coated and if you glass beat the top you can dump them afterwards.
I've seen a lot of M70/S70/M73 bottom ends with high mileage and none of them needed new bearings. Especially the mains looked like brand new every time.
Rod bearings on the top are worth a look, especially if FI is planned.

Thanks for the input, note the gaskets and bolts are Victor Reinz(yea they are $35 ea.), they are just on a VERY good sale. The only thing from ajusa is the hydraulic valve lifters.
I will remove Cylinders for soaking and look at the bearings.

[fursideup]

That will be fun! I better clean off the pool table so you have a place to lay all those pistons, caps and bearings out.

[bmw528e11]

When you planning to do that? I might swing by on Saturday morning?

[NevadaMike]

Have you considered CO2 (Dry Ice) blasting? You should be able to find a place in the Bay Area. I've also found that regular old paint thinner (not lacquer thinner) does a pretty good job dissolving that carbon. Be sure to get the deodorized kind, you'll thank me.