nick 55

I could tell you that I had to refer to my workshop information, but I would be lying. I spend a pretty good amount of time tinkering on cars and can pretty well figure things out by now.

Nick

bp95gsx

YOU DO NOT HAVE TO REMOVE V12 ENGINE TO DO MOUNTS. At least I didn't. My first time I did the job in 4 hours. I can do it in 2 hours now.

NEMES1S

Were you workin on an sl600 or sl65? That doesn't soound too bad to me, if it only takes an afternoon I think I can handle it....assuming I find one to buy first.

EXECMALIBU

The MB factory rep said that it is the only way!

I know MBUSA hates to pay the big bucks (13+ hrs plus misc small parts) to the dealer for the R+R of the engine..

So please let us know your secret on an SL65 so we can advise our mechanics or for the DIY guys!

EXECMALIBU

John,

You stated...

"YOU DO NOT HAVE TO REMOVE V12 ENGINE TO DO MOUNTS. At least I didn't. My first time I did the job in 4 hours. I can do it in 2 hours now."

Were you just goofing?? or is this a real possibility?

Please let us know what you figured out on how to change the mounts without taking out the engine...

nick 55

Please educate me, as I can do S600 mounts in about 2 hours, and SL mounts are decidedly more involved.

Nick

V12Godspeed

I think he may have referred to the S600 mounts since he owns one. that could be the confusion. correct me if I am wrong.

NEMES1S

^ that was my thought.

Welwynnick

This is one of the best threads I’ve read, and I hope my namesake still visits here and realises how appreciated this is.

Engine mounts have joined the most discussed V12TT topics – like coil packs, ABC, and IC pumps, and I wonder if/when I’ll have face up to replacing them in my 151k mile car. I wanted to scope the job – see if I understand it right.

My understanding is that the turbos block access to the top of the mounts, so you have to remove the engine. Aside from the sheer scale of the task, it sounds like removing the engine is similar to other cars, except that it’s complicated by the ABC, charge cooling, alternator cooling, aux radiator, and space available.

The procedure described in the first post is very concise, and could only be written by someone who knows what they’re doing. If I could paraphrase it further though (and tweak the order for clarity) I think it boils down to this:

• Remove covers & disconnect battery
• Disconnect suspension arms and steering rack
• Remove bulkhead and cooling fan
• De-pressurize and drain all the fluids
• Disconnect all wiring and pipes to engine
• Remove exhaust & propshaft
• Support subframe and transmission, and unbolt from chassis
• Lower the engine/subframe assy
• Unbolt engine mounts from subframe & lift engine
• The key task – unbolt engine mount arms from the block
• Replace engine mounts

The lines in bold are just used in this procedure.

The pictures show the car in a workshop on a hoist, so I was wondering if it’s really a DIY job at all.

Question 1: would anyone contemplate doing this without a ramp or pit?

And looking at what removing the engine achieves – getting access to the engine mount arms – are there any other methods? Notice that when you remove the engine, the turbos still block access to the mounts – but with the engine out you can access the engine mount arms. So it’s not the access to the mounts that matters, but access to the mount arms. Maybe there are other ways to do that, so all the fluid systems aren’t disturbed and the engine can stay in place?

Question 2: Can you remove the turbos without having to remove the engine or the cylinder heads (which is presumably a lot of work)?

Question 3: Couldn’t the subframe be dropped without removing the engine? In this case, the abbreviated procedure might be:

• Remove covers & disconnect battery
• Disconnect suspension arms and steering rack
• Unbolt engine mounts from subframe
• Support engine & subframe independently
• Lower subframe from chassis
• The key task – unbolt engine mount arms from the block
• Replace engine mounts

The lines in bold are unique to this procedure.
The end result is hopefully to get access to the engine mount arms, but look at all the things that wouldn’t have to be removed or disconnected:

• Fan
• Bulkhead
• Wiring
• Cooling
• Heating
• Air con
• Oil cooling
• Charge cooling
• Transmission cooling
• Alternator cooling
• ABC
• Exhaust
• Propshaft
• Transmission
• Engine

Without wishing to sound lazy, all that represents a lot of work, and a lot of risk of something going wrong. Ever dropped a nut or socket in a V12TT engine compartment? I’m fairly familiar with it (my knuckles bear witness to that), but I’m sure I’ve overlooked something, otherwise those clever WIS people would have used this procedure instead. My concern is with the ABC suspension, which is jammed in everywhere. Although the pump’s on the engine, I’d say that ABC was a chassis system rather than an engine system, so most of it should stay put when the engine is removed, right? And in any case, if you have to remove something to remove just the subframe, then surely you’d have to remove it remove the subframe and engine?

I dunno, what do you think?

Nick

benz_addict

Just did this myself on my S600. Your post very extremely helpful. Thanks again!!

Welwynnick

I can't believe its been a year and a half since I've been looking for an excuse to try that procedure. There has to be reason why you can't do it - something I haven't thought of.
If its too easy to be true, it can't be true - or can it?

Mercedes must have thought of this when they wrote their procedures. I thought it was something to do with the assembly sequence: maybe the engine can only be dropped in from above when the subframe has already been installed? Maybe they have to be connected together first, before being fitted from beneath?

I think what I was specifically afraid of was that long list of hydraulic and cooling connections to the engine: perhaps MB fastened some of them to the subframe? Transmission cooling and PAS and ABC connections spring to mind.

Well, I tried it this weekend, and yes, there was a hydraulics complication, but it was easily overcome. I took lots of pictures, which will help to explain what happened when I've got a bit more time.

Nick

ttboost

You dropped your engine?

V12TTenthusiast

The S and CL V12s don't need the engine to be dropped but the SLs do

Welwynnick

No, the engine stayed exactly where it was, but I dropped the sub-frame.

Welwynnick

I’m not sure it’s as simple as that. For one thing it may depend on which motor mounts are fitted. The early type (like non-turbo cars) have three nuts on top, right up against the turbos. The later type have two bolts that are accessed from below, but I don’t think the SL got them. The other thing is that the CL & SL sub-frames are different. The motor is mounted further back on the SL, with the mounts just behind the steering rack, instead of just in front of it. Not sure whether that makes any difference.

Nick 55 said in another thread that you can remove the rack on the S & CL to access the mounts, so I actually tried that out of curiosity before removing the sub-frame. Its rather tricky as there’s so little room. I reckon that if you just wanted to remove the rack, it may be easier to first drop the subframe THEN remove the rack (just don’t unbolt the suspension arms). Once the rack is out, access is improved enormously, though the top bolts on the mount arms are still hidden behind the turbo waste-gate and diverter valves.

Two issues:
Disconnect both the feed and return lines to steering rack
Manoeuvre subframe around ABC pipes – lower front first

Four options:
1. Remove Rack. Keep suspension & subframe in place, but remove steering rack completely
2. Lower Subframe. Keep suspension and steering arms connected, support engine and lower subframe
3. Remove Subframe. Disconnect steering & suspension, support engine and remove subframe
4. Remove Engine. Disconnect steering & suspension, remove engine & subframe



Whichever way you do it, the steering column and PAS return line have to be disconnected.

Nick

Welwynnick

Isn't it great what you can do at home with a good set of tools and some stands .....



The blue stands are supporting the engine sump, the blue jack is supporting the rear of the subframe, and red jack the front, which has to come down first.

With the subframe out of the way (and the rack, the heatshields and covers that go with it) access to the motor mounts is much easier.

I was so pleased to see this little sucker out of the car at last.



So to answer my earlier question:- Yes, you can do it at home.

Nick

Welwynnick

And here's a few views of the bottom of a V12 that you might not have seen before. The subframe, rack, motor mounts and RHS exhaust are all out.

This is looking straight up at the RHS turbo, with the diverter and wastegate valves at the bottom, and alternator below that.
The pipes on the left are the tranny cooling and the nightmare ABC pipe that always fails



This is the same side, but taken from the front, looking back and slightly upwards.
Steering column on the left; turbo just above; alternator top right:



Here's the other side, looking straight up; front is to the left.
The water feed and oil return pipes the bottom of the turbo are easy access, but the top connections are still difficult.
The other pipes are the PAS feed pipe (bottom) and return pipe (top - the one that hides behind the subframe heat shield).
You can see three of the four motor mount arm bolts the bottom.
The forward top bolt is still obscured by the AC compressor, oil pump pipes and turbo valves.
I undid it with a 3/8" E14 socket on a fine-tooth ratchet, running horizontally between the motor mount arm and the exhaust manifold.



Nick

Welwynnick

Just a thought for those who really do want to drop the engine, but don't have a lift:

Perhaps the engine can be dropped by lowering it with a crane? They don't cost too much.

Support the car on jack stands
Disconnect everything that has to be disconnected
Support the engine from above
Undo the subframe bolts
Lower the engine & subframe to the floor
The transmission would either be supported by a jack, or maybe pivoted on its own mount?

I don't know if this would work, but I got thinking about it while doing various "engine out" type activities on mine, with the engine in place.
What happened was that I went ahead and drained and disconnected pretty much all the things that I was trying to avoid disconnecting.

Just a thought, Nick


PS. One other thing before I forget. I've taken lots of parts out of my car, and I've started weighing them, out of curiosity. Yes, really.

I noticed that both the W140 and the W221 have pressed steel front subframes, but the W220 is all alloy. Does that make it much lighter? Well, considering it holds the engine, steering and lower suspension, I was surprised how light it was when I removed it. You can pick it up with one hand, and if you have a good grip, one finger will do.

After the W140, Mercedes obviously tried hard to make the W220 lighter, and you can see that in all the interior trim. But (along with TRUE double glazing, which was wonderful) I think one of the things that really distinguished the W140 was its isolation from the outside world - very obvious subjectively on the few occasions I drove one - but also very tangible.

Both the W140 and the Maybach had suspended (rubber mounted) subframes both front and rear, something that big, old Jaguars featured. Its a heavy and expensive solution, but it uses the mass of the subframe and its compliant mountings to the body to filter out NVH very effectively. Its gone out of fashion now, and though rear subframes are always mounted in rubber bushes, modern cars have hard-mounted front subframes.

I think its a shame; I used to have a lovely old Jag XJ6 that made the roads feel like they'd been carpeted, and the W140 was very similar. Presumably, the W220 uses the hard-mounted subframe to supplement the rigidity of the bodyshell. Had they used the old approach, the bodyshell would have been heavier. But how much heavier? The additional structure can't weigh any more than the subframe itself, so how much does that weigh? How much weight did they save? Well, curiosity just got the better of me:

W220 S600 front subframe: 23 pounds
W220 S600 front brake disc: 35 pounds

Wow.

Edit: Isn't the internet wonderful? I noticed tonight that the W163 and W164 ML-class also have a suspended front sub-chassis. They also have a great reputation for refinement.

SL65MONSTA

can the SL mounts be replaced with out removing engine???

aeroman

I'm just glad I have a warranty. No way would I try something like this.

SL65MONSTA

apparently its a matter of jacking the engine up a little and its a tight fit to get it in , but is possible

aeroman

I'm still not trying it.

wlelandj

Wow, great info and write up! You've convinced me...to not try this at home. Speaking of motor mounts, did anyone notice in Speedriven's new catalog that they have billet motor mounts listed for the SL65? I haven't priced stock motor mounts,but Speedriven's are listed at $1k.
-Leland

Edit: Whew, basically under $100 per for OEM. Maybe the $1k includes install?

Welwynnick

In England we're fond of saying: "a fool and his money are soon parted"

Do you have any equivalent sayings in the US?

Nick

FxFormat

I'm getting ready to do this, my SL 600 has 77K miles and nothing in the carfax says these were done, i do feel a little vibration in the cab so looks like i'm going to be changing out all 3 mounts.

Anyone successfully do this on an SL 600 without removing the engine? Really want to find an easier way.