M112 engine "rebuild kit" list

[broly]

hi all,

would one of the experts here could give me a list of seals etc that should be replaced for anyone contemplating rebuilding their M112 engine.

thanks.

 

[Wombat457]

Hmm, I geuss that depends on the extent of the "rebuild"; however, look at it like this - for every part (pretty much) you remove you will also be removing a seal or gasket. IE" Exhaust Manifold = exhasut manifold gasket, sump = sump gasket, head = head gasket and so forth. So figure out what you will be removing and that wwill pretty much tell you what gaskets seals you'll need for the most part.

 

[s5tuart]

hi all,

would one of the experts here could give me a list of seals etc that should be replaced for anyone contemplating rebuilding their M112 engine.

thanks.

I can't help but good luck with the project. If you can do a video or even still photos of progress it would be very interesting.
I love the M112 and 113 engines.

 

[LostKiwi]

As above it depends what you remove.
If it's an engine out rebuild always replace engine rear main seal, gearbox input seal and front timing seal. While you're at it check frost plugs and replace if necessary.
Two Rules of thumb.
The harder it is to get to the more it's recommended to change it whilst in that area.
Also the harder it is to get to the more I would recommend using genuine parts.

 

[broly]

bump.

found this gem of a thread here:

To ring or not to ring.

Hi. I have a 2003 S55 AMG, it has covered 125000 miles. I am about to have a Kleemann upgrade on it, Pulley, throttle body, decat, cams, etc. So, Before all this, I am going to have a rebuild done on the engine, Mains and big ends, seals. I have decided not to have the bores honed, as I...

forums.mercedesclub.org.uk

i don't want to put the cart ahead of the horse quite yet, hoping to hear good news on monday.

a wise man that is weighing the possibility of supervising me for this rebuild suggested that i read up on the mercedes pistons, bore, etc

looking at WIS/ASRA for the M112k and M112, they're identical, which i guess isn't surprising.

however i think the M112K pistons are made with stronger alloy to accommodate the extra pressure, no?

i assume the block material is the same?

i fired up my M112 and it actually sounds very good.
- puffs a lot of smoke but the misfire doesn't sound bad. in fact, after having not started it for years it sounded fine until i kept letting it run and i hear this very faint 'tick'.

i can't speak until i see the bores and cylinder walls, but i think it should be okay.

let's hypothesise a little bit (hey it's what we do right?):
assewm:
- the M112 block meets the WIS/ASRA specifications of:
- "reuse crankcase" (AH01.00-P-0300-01VA)
- "Standard Marking X" for cylinder bore measurement (AH03.10-P-0001-04MM)

- the M112k pistons meet the WIS/ASRA specifications for:
- vertical clearance (AR03.10-P-7311-01V)
- end gap (AR03.10-P-7311-02V)
- visual inspection (AH03.10-P-0001-04MM)

then i assume it's safe to use the M112k pistons in the M112 block without getting the block machined?

really eager to hear the experts like lostkiwi chew on this.

 

[broly]

@LostKiwi ping sorry for the direct mention, i didn't realise the forum supported that

 

[alexanderfoti]

M112 engines are a dime a dozen and are very reliable. My choice would be to swap the engine unless you have any other reason not to?

 

[broly]

M112 engines are a dime a dozen and are very reliable. My choice would be to swap the engine unless you have any other reason not to?

i was really against this because of the "numbers matching" thing lol. plus it'd be a learning experience.

but what bout the differences in oil pump and such @alexanderfoti ?

i noticed the SLK32 and C32 have different oil pumps, which lead me to believe it's due to the chassis and not the pump mechanism itself, as the mopey bois suggested all M112s use the same oil pump spray mechanism: https://www.crossfireforum.org/foru...rential/22544-m112-m112-amg-engine-specs.html

i really want the numbers to match lol.

 

[alexanderfoti]

Ok fair enough, but you will pay probably a £3,4000 premium for thenumbers to match.

Yes the pumps are different due to different sump designs as you say.

 

[broly]

Ok fair enough, but you will pay probably a £3,4000 premium for thenumbers to match.

Yes the pumps are different due to different sump designs as you say.

@alexanderfoti are you talking about labour etc? or just parts?

since the c32 engine uses the same oil pan as the 320 4matic, then should i just use the c32's oil pump?
- or should i use the e320's? surprised they have the same pan but different oil pump.

i may drop it in but i don't think it's a wise idea because, from personal experience, it seems that the engine should be checked to make sure it isn't burning or eating oil.

in my E320 it was fine until 120k km, then we had to make a little bit of a fuss for a just-out-of-warranty goodwill repair.

around 290k it seemed to happen again but i redid the entire valve covers and air intake, and it seemed to be better.

then for some reason it started misfiring when i was away from home for a bit. now it runs pretty good but the smoke in the exhaust. i think its the valve stem seals.

 

[LostKiwi]

Many years ago I had a C240 in W202 form. I had it from new (picked up from the factory in Sindelfingen) and after about 60k miles it started consuming oil at an incredible rate. Dealer fixed it by sorting a blocked breather. If you have oil consumption issues check there first.

 

[broly]

i don't know if it's consuming oil at an alarming rate, but i can hear the misfire. it's very slight, but it's there.

and the smoke in the tailpipe is not consistent. it's almost as if it's triggered by a certain cylinder in the powerband.

for example revving the engine until ~3k rpm produces no smoke. but once you hit the 3k mark it will smoke quite a bit, but then stop, and then smoke again. almost as if it's triggered by a specific cylinder.

nonetheless, this whole situation is a good learning opportunity and that's how i'd prefer it be framed. it's not "how do i get my car back and running ASAP" because i could have done that ages ago with the exact same M112 from a different car many years ago.

i don't want to do that. i want something cool lol

 

[Malcolm Johnson]

Personally i would get another engine, my old work car w221 flashed up amber and as i was looking for somewhere to park in single lane road works it turned red and seized 10 secs later. Catastrophic oil loss. Seized lower end. My indie said get new engine. Bought a new unit from a scrapped e320 from Dronsfields
That was 9 nine years ago, indie had to alter sump. Car has been a drive ornament for 5 years now. 4 years work use after swap. You need a trusted indie.

 

[Steve@Avantgarde]

The breathers vent into the rocker boxes. If they leak excessively or block then the engine can consume oil as LK has said.

I've never known a M112 or M113 to mechanically wear pistons or rings. We get the occasional valve seat issue on M155k (which is a cousin of the M113K) but that is always down to incorrect fuel being used. The 112/113 family is an absolute bullet proof bunch.

 

[broly]

The breathers vent into the rocker boxes. If they leak excessively or block then the engine can consume oil as LK has said.

I've never known a M112 or M113 to mechanically wear pistons or rings. We get the occasional valve seat issue on M155k (which is a cousin of the M113K) but that is always down to incorrect fuel being used. The 112/113 family is an absolute bullet proof bunch.

i agree with what you're saying, but the valve seals aren't an unknown thing with the cars either.

i'm not saying it's terribly common. but if the breather horses were sorted out already, and it puffs the way i've said, i think it would be the valve stem seals.

no one here has had that issue? i thought it was known. i wasn't alluding to piston or ring wear, but just being prepared for that possibility.

i may need to focus more on the electric bit since mercedes' body wire harness style is new to me, and i'll have to run a fresh plug for the intercooler pump and also the magnetic clutch, but i don't think this will be bad since i have the tools and mercedes (unlike HANDA) seems to provide the wire/terminals via EPC.

i get what you guys are saying. and if this car is for me then i shouldn't care bout "numbers matching". really it doesn't mean anything anyways on newer cars since i just learned that the VIN isn't on the block, it's an engine number.

i don't know when that changed but i guess it's more for ("even") older cars.

 

[B777]

Following…
My G320 with M112 engine started burning oil.
I changed and cleaned valve cover gaskets , breather gaskets and hoses, right side valve stem seals, EGR valve and seals, MAF sensor and seal, camshaft sensor, crankshaft sensor, clean injectors, changed spark plugs.
It’s only getting worst at now 1L of oil every 200 km…

 

[Uncle Benz]

A common issue that causes these engines to smoke is a blocked oil drain passage the allows oil to return to the sump from the rear of the right hand cylinder head. It’s like a U bend, hidden behind the crank rear main oil seal cover. Gets blocked with oil sludge, keeps the right hand head full of oil if revs have been used which speeds the oil pump sufficiently to pump a lot of oil up there quickly and it can’t drain back.

 

[Uncle Benz]

Circled it here. @broly. Your description fits this fault exactly

 

[B777]

Thanks Uncle Benz !
When I changed the EGR valve and associated hoses, I did clean that tube.
Maybe I should do it again because I used engine flush on the last oil change…

 

[Uncle Benz]

Thanks Uncle Benz !
When I changed the EGR valve and associated hoses, I did clean that tube.
Maybe I should do it again because I used engine flush on the last oil change…

To properly clean it out you really need to remove the gearbox, the flywheel and the plate that hold the crankshaft rear main oil seal. It’s a bit of work, but leaks from the rear main seal are common on these too, so it’s an ideal opportunity to replace that while you are there