I'm starting the process of replacing the (very much in need of replacing) motor mounts on my 300td. Unfortunately I've gotten stymied on the very first step - loosening the 8mm allen bolt from the bottom...

The motor mount is so crushed that I think the bolt head might be sitting against the steel of the frame. I've attached a picture of the situation.

I read a bunch of other accounts of removing the bolts and it seemed like the process was to clean out the head of the bolt as much as possible, and hit the allen key into the bolt to make sure to get a good fit, and then use a breaker bar to put as much pressure on it as possible. All I ended up with is the head slowly rounding out (I stopped before it got too bad I think).

I rented an impact wrench from the local tool lending library, so I'm going to go back at it tomorrow morning, but I guess the question I have is: should I lift the engine enough for the bolt to not sit on top of the frame anymore?

Attached Thumbnails

 

I've only done four now, but none of mine were sitting on the frame like that. All 4 were centered in that hole and up.

Wait for an expert to chime in, but I expect they'll say lift it up a bit.

Don't use a cheap hex key socket, use a quality tool so you get a good tight fit.

__________________
Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Put a 2x4 under the oil pan and then jack the engine up......then undo the bolt, right now you can get it out because all the weight of the engine is on the mount....causing the bolt to sit on the frame......chances are.....you will need a helper to move the engine around while you are underneath attempting to remove the bolt and reinstall the mount......with motor mounts that bad, check your oil cooler hoses for rub through.....your trans mount is also probably trash....

__________________

you need to get an official NAPA or better brand 8mm hex short socket, in 1/2" drive with an extension on there...
you need STEADY PRESSURE, NOT IMPACT!!! but ONLY with a TOP quality hex socket.
TOP QUALITY!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The 8mm bolt just bolts the Aluminum arm to the rubber mount.

There are 2 6mm small bolts one each side of the rubber mounts, these bolt the rubber mount to the frame.

Use a 6mm Allen wrench with the short end cut down to fit into each bolt. there is not much room to get into these.

Be sure to have the hex holes CLEAN. maybe go to a car wash and blast the area clean of grease and gunk.


Some times valve grinding compound works on the 8mm hex bit to grab the hole. if it is rounded out. maybe drive in a 10mm triple square bit. The McParts stores sell these in a 4 bit set. the ridges of the bit might be enough to grip the bolt.
I also read of driving a Socket over the head of the bolt, forget the size. and the tight fit will grab it.

Drilling off the head of the bolt is another option.

If you can`t get the bolt out, remove the 2 6mm bolts on either side of the mount. then remove the 4 17mm nuts on the Aluminum arm and lift it out. then put it in a Vice to work on. might be enough room to wiggle it out.

I have an arm with a stuck bolt, I just replaced the arm from one I got at PNP.

Back in 97 before I understood how these things go together, I had a bolt that rounded out. NO problem, right? I used a Saws All and cut the arm off. Then when I got it out I felt kind of stupid looking at what I did.

Good thing for PNP.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Ok fair enough - no impact, just steady force. The 8mm driver that I have is from a Husky set. I haven't given it a go yet - I was using a large allen key before (not nearly enough I'm realizing now)

x2 on - you will need a helper to move the engine around while you are underneath attempting to remove the bolt and reinstall the mount. I recently had the identical situation and that's route I went after attempting it by myself. The motor mount came out in pieces.

I'm sorry, but I just imagined you as a pushy salesman. TOP QUALITY SOCKET! A#1 BEST IN TOWN I'LL TELL YA WHAT SON, I EVEN USE THESE SOCKETS TO BRUSH MY TEETH!!

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Yeh but it's true .... manufacturing tolerances and quality of steel on cheap tools will either cause busted knuckles or damaged fasteners and more work....sometimes both.

__________________
Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

I was working this today, on my 240 D, because they've never been done. Both 8mm bolt holes were exceptionally clean.





Sprayed with penetrant too.

I ran an SK top quality Allen, on a 12" snap-on ratchet (your point of needing 1/2" drive noted; I have 3/8). Both bolts moved the slightest bit, like let's call it one degree, then wouldn't go any further.

As I hadn't read your comment here on constant pressure (which is why I'm replying here, as it's good guidance), I put my 3/8" impact on it. That's good for what, 200ft-lb max, likely less?

So I stopped. I have an 18" or so 3/8" breaker. Obviously I can extend it with a pipe.

Question is, how much is too much? Is there a good rule of thumb for when I'm going to do damage?

When I did mounts on my '82, the bolts came out easily. I was expecting the same since this car is so clean and low mileage.

Id hate to ruin the bolts. Kent from Washington says that a rough idle or a compressed mount can beat the threads such that they're damaged and don't want to comply. The only complaint on this car is that at slow idle it's rough in drive with AC on. Fast idle and driving it is smooth as glass. But if this theory of Kent's is true, there could be damage on the threads.

I'd expect these to come right out. I'm surprised they won't. How long of a breaker is typically used?

Thanks!

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Those look fine.

My mounts on my 300D were meh. Not quite smooshed jello but not new either.

I was worried the sockets wouldn't be friendly. They were and came out without a problem. I was really surprised.

You should be fine too. Just throw some penetrating oil on them and attack with a regular socket first.

They should pop off without a problem.

__________________
-Typos courtesy of my mobile phone.

That's what I did. Car is jacked up, high quality 8mm is in there.

But given that my 82 was a breeze, its curious that both moved a bit and stopped, and that neither show any sign of budging with 200+ lbs of force (me) on a 12" ratchet. So I dont want to go too far and cause more problems...

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Awesome! I just finished replacing the two motor mounts and shocks. It was probably the dirtiest thing I've ever accomplished actually. I'll post some pictures when I've uploaded them. One of the mounts was so crushed that it ended up mostly in pieces. The other mount was better, but still worthy of replacement.

The 8mm bolts came out with a good bit on an angling ratchet wrench and breaker bar and lots of patience. The 6mm bolts were barely in place (I got kind of lucky there I think).

The difference is amazing!! I wish I had taken a before video, but it shook the whole car so badly it hurt. Now it's smooth as can be. Of course, now that it's not shaking anymore, I can hear this pretty awful noise coming from the engine at low rpms, but one thing at a time for now...

Ok a gratuitous picture of a ruined motor mount... That's what happens when you spill biodiesel while changing a filter kids...

My primer pump was leaking on my mount. It turned the mount in to the most disgusting jello mold in history. Was very glad to get both replaced at once. Now, when changing lines and filters, I cover that mount with a plastic bag, and then over that a small catch using a small disposable aluminium pan.

__________________
1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

The Baja Arizona Oil Burners Send a message if you'd like to join the fun
Left to Right - UberWasser, Iridium, Stuttgart-->Seattle,, mannys9130

Visit the W123 page on iFixit for over 70 helpful DIY guides!