M103 3.0 to 3.6 Build Discussion - PeachParts Mercedes-Benz Forum

ptoro01 · #1 10-24-2006, 09:07 PM

So the mystery has been out there, will a 350SDL crank fit into an m103, what else is needed to make this work and what will it actually do? Instead of a 350SDL crank for the conversion, would a C36 bottom end work better.
The last few threads date back to 2002 about this when most of us simply dismissed it under the fact that its too expensive.

Chime in if you have done this or if you have done research and you got stuck somewhere. And hey, if anyone wants to send spare parts my way, I can put them in the spare engine I have.
Let the brainstorm begin!!
Pete

newbenz2 · #2 10-24-2006, 09:17 PM

I thought the 350sdl crank fit in the m104... Thats what I'm doing to my 104.... To my knowledge the m103 doesn't accept the 350sdl crank.... the crank will bring a m104 2.8 to a 3.6...
Kevin

300EVIL · #3 10-24-2006, 09:19 PM

Hi Pete,

From what I have "heard", from more than one sorce, the M104 3.2 block with the 350SDL 0M603 crank and M104 2.8 rods was used to make the AMG 3.6L M104. I have not personally performed the calculations to confirm this, but it sounds about right. The 3.0 M103 has a bore of 89.0MM and a stroke of 80.25MM. The M104 3.2 is 89.9 X 84.0 and the M104 3.6 is 91.0 X 92.4. This means that the 3.6L displacement is an enlargement of both bore and stroke. According to Ortolan, the 3.0 M103 will make 3.4L with C36 parts using stock (I think) pistons. Do the math and that should come out right. As for the crank, I don't know but it may need some alterations on a crank lathe in order to fit an M103/104. I suggest you contact Ortolan and ask him for the measurements of his C36 crank and rods to make sure.

Ortolan · #4 10-25-2006, 06:22 AM

While researching the project I read that increasing the bore of the M103 left the cylinder walls too weak. Apparently the Brabus 3.6L had a very short lifespan. This is why I elected to leave the bore alone and only increase stroke. The increased stroke also reduces the chance of detonation at the same compression ratio.

brabus3.6 · #5 10-25-2006, 08:54 AM

Quote:

Originally Posted by Ortolan

While researching the project I read that increasing the bore of the M103 left the cylinder walls too weak. Apparently the Brabus 3.6L had a very short lifespan. This is why I elected to leave the bore alone and only increase stroke. The increased stroke also reduces the chance of detonation at the same compression ratio.

From whom did you hear of the 3.6's apparently short lifes[an & what do you deem to be short? I have a Brabus 3.6 which has done over 130,000 miles, still going string (touch wood). I've done all the top end work (valve stems & guides, head gasket) due to a head gasket failure at around 100k but this is a common M103 fault. The car does consume some oil, in the region of a quart every 700 miles but tuned engines are such and I'm using Mobil 1 15W-50 Fully Synthetic, I may switch to a semi-syn as I've heard this will cut back consumption and may be better for an older engine.
The torque increase from boring the engine should not be overlooked. This really increases low down torque significantly well still having an apetite for the heady heights of 6550RPM. Do it!

Ortolan · #6 10-25-2006, 08:47 PM

Re: short lifespan of Brabus 3.6L M103.
http://community.190revolution.net/drivetrain-performance-modification/12350-300e-320e.html?highlight=brabus+m103

ptoro01 · #7 10-25-2006, 11:33 PM

very interesting, so the brabus version that im looking to build is rather unreliable in the long run. Since these engines are so easy to come by, would a rebuild every 100k be such a huge issue or do they last less mileage?

Ortolan · #8 11-25-2006, 12:45 AM

I dropped my 300CE off at the workshop today, along with the C36 crankshaft and rods.
By next weekend I should know if the parts will work in my M103 block.
If everything is a perfect fit I'll order new bearings etc and aim to have the car back on the road by Xmas.
I'll keep everyone posted.

Incidentally, the custom suspension I purchased from ebay.de worked a treat.

http://cgi.ebay.de/Fat-Grip-Performance-Fahrwerk-Mercedes-E-Klasse-W124_W0QQitemZ230053203239QQihZ013QQcategoryZ70154QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Ortolan · #9 11-30-2006, 05:31 AM

Update: I went down to the workshop on my lunch break today and the engine and transmission are now completely disassembled. The first thing that caught my eye was the engine block upside down on an engine stand with the crankshaft sitting in the bearings.
I ask if that's the AMG crank and the mechanic says "yep, it needs different bearings but it looks like it should work fine". (a little bit unfortunate because the stock bearings look to be in brand new condition!)
He still needs to test if it will work when the crank, rods and pistons all come together (will hopefully know by tomorrow).

The next good news I got was that the block has been (partially) prepared for piston oil sprayers. I had read in an old thread that this was the case with M103s but it was a relief when this was confirmed. I have a set of 6 sprayers from an OM603 en route from Germany which should be here in 2 weeks.
The block needs to be sent out for the cylinders to be honed, which is going to set the timetable for completion. The head also needs to go out but there's enough of these that the shops work on a no-wait changeover basis. I'm still optimistic for an Xmas completion date.
The oil & water pumps need replacing along with the inlet valves and a few other minor parts. Two of the pistons have very light scratches due to the rings wearing away but the damage is so minor I'm not going to replace them.

This car is a bit of an enigma. I purchased it as an import from Hong Kong with unknown history. The odometer has less than 90,000km on it. The leather interior, metallic paint and many other components are in almost new condition and support the reading while other parts are very worn down and suggest the previous owner rolled the numbers back.
I took a bunch of pictures but forgot the camera at work. I'll post them all tomorrow evening.

Ortolan · #10 12-01-2006, 02:37 AM

D'oh, stupid gallery limits.

Anyway, here's 12 pics in reduced file size:
http://www.peachparts.com/shopforum/vbpicgallery.php?do=hall&u=31501

Ortolan · #11 12-01-2006, 08:37 PM

$%#!!

Just got off the phone with the mechanic and received some very bad news.
He attached one of the rods & pistons to the crank and put it back in the block to test clearances and found that the rod impacts the block by a fair margin.
THE C36 CRANKSHAFT AND RODS WON'T WORK IN THE M103!!

Now I'm at a loss as to how to proceed. I guess my options are:
1. Continue with the M103 rebuild using stock parts, turbocharge that and sell the C36 parts.
2. Put the M103 back together and sell it as a long block. Buy an M104 long block locally and use the C36 parts and machine the pistons to lower the CR, then turbocharge that.

t walgamuth · #12 12-01-2006, 08:44 PM

either option sounds good.

the c36 motor in the car sounds good though. a two door would be sweet with that motor.

tom w

waybomb · #13 12-01-2006, 09:55 PM

Is the piston at the correct height at TDC? (yes)
Does the piston skirt hit the crank throw at BDC? (no)

You sure you don't have enough room in the block to take a little off if the two conditions above are met?

Ortolan · #14 12-02-2006, 12:06 AM

One side of the cylinder could probably be machined but the problem is that the other side is where the oil nozzles must be mounted.
http://www.peachparts.com/shopforum/vbpicgallery.php?do=big&p=1491

Ortolan · #15 12-02-2006, 12:54 AM

My mechanic says he has found an early model M104 short block soon to be for sale which should fit the M103 head. I told him I was pretty sure the M103/M104 ends were not interchangeable but he says this particular block should work. He's going to call the lead MB technician in Australia on Monday to get confirmation.
I don't want to get my hopes up as this question has come up numerous times and each time the verdict has been that under no circumstances are the M103/M104 ends interchangeable.
My mechanic told me that there's not a single M104 for sale anywhere in the country at the moment (the one he found is still in the wrecked car and won't be removed for a few weeks yet).