Bottom Bolt of Motor Mount - PeachParts Mercedes-Benz Forum

Graplr · #1 06-01-2008, 07:47 PM

Help please. I changed the motor mounts. I can't get the bottom bolts back in.

I have an 84 300SD so the bottom bolt holes aren't exposed. I have to go through the frame. I don't know if this is the case on 123's and others.

Any suggestions on how to get the holes to line up?
Thanks!
-Ryan

Chad300tdt · #2 06-01-2008, 08:34 PM

When I did the mounts on my w123, I let the weight of the motor down on the mounts and the mount arms centered themselves in the mounts. Then I jacked the motor up slightly and the bolts went in easy.

The bottom bolts are accessed through the frame cross member on a w123 as well.

Diesel911 · #3 06-01-2008, 09:05 PM

I had the same problem. In my case the lack if alignment seemed to be caued by the fact that I jacked up only 1 side of the car at at time causing the engine to pull moro to the lower side even though the lower side already had the new motor mount installed. After putting jacks stands on both sides and some raising and lowering of the eignie the hole aligned enough for me to get the bolt in.
Also useful for this sort of thing is if you have a long tapered punch that will go through both holes. You shove it through the hole and the tapered part helps with the hole alignment.

tangofox007 · #4 06-01-2008, 10:10 PM

Get someone to shake the engine while you line the bolt up. And don't use the torque specs for that bolt in the Haynes Manual; it's way too high.

Jimmy Joe · #5 06-01-2008, 11:39 PM

This might help you:
My mounts were completely shot and thus, the engine was not where it was supposed to be, it seemed. So, when we tried to get those holes aligned, it was a serious 'no go' on one side. We pried, we pulled, we cursed; but only one side would line up (drivers).
Got in and bumped the motor by putting her in gear, No go.
So then I jumped behind the wheel and drove her down the hill and back. The hole got closer! Then I just drove the tar out of her for a few miles, and bingo, my friend managed to get that bolt started!
(Huge thanks to Charmalu for major help and support!)

Be careful, but you might consider taking her for a spin to 'settle' the motor in the right spot. Mind you, we had the driver side bolt in; and that is the most important side I assume, as those pesky oil cooler lines are right there, and if you don't have that side secured, you might be risking some serious issues bu burning through a line with your power steering belt.

Graplr · #6 06-02-2008, 10:04 AM

Thanks for all the advice.

I finally ended up getting them in last night.

I ended up tying a rope to the engine hoist bracket (or whatever it's called

) and pulling it forward while someone else lowered the engine.

Since the passenger side hole was misaligned back, that got the passenger side in place. I started the bolt on that side just enough to keep it threaded. Then I raised the engine just a tad. It was just enough for the driver side to come up. Since the driver side was over to the outside I pushed the engine in as someone else lowered it. That got the hole aligned. I put that bolt in and then tightened the passenger side.

This was quite an ordeal!

But I can't believe how smooth my idle is. Even when it is stone cold, I can't feel any shake at all!

Along with new mounts I put two new engine shocks and mounting kits and I did a valve adjustment as well. In the 30k I've had this, it is by far the smoothest it's ever been!

Chad300tdt · #7 06-02-2008, 11:53 AM

Congratulations Graplr! As long as you don't have a leaky primer pump or turbo drain, they will last a very long time.

dannyF · #8 07-01-2008, 05:17 PM

I am in the middle of the same job - took me over a year to get one of my bolts out on the engine mount b/c it was stripped - but finally I was able to drill it out. I hope I didn't strip the threads for the new bolt....

However, I only see one engine shock. There is none on the driver side that I can see. Am I missing something? Thanks!

Chad300tdt · #9 07-01-2008, 05:29 PM

Quote:

Originally Posted by dannyF

I am in the middle of the same job - took me over a year to get one of my bolts out on the engine mount b/c it was stripped - but finally I was able to drill it out. I hope I didn't strip the threads for the new bolt....

However, I only see one engine shock. There is none on the driver side that I can see. Am I missing something? Thanks!

The engine shocks on both sides are attached to the mount arm that goes between the motor mount and the motor.

When you drilled out the bottom motor mount bolt, you should have used a 1/2" bit. It drills just the head off the bolt and then you can unscrew the bolt shaft with your fingers since there isn't any tension on it anymore.

Here's a pic of the bolt I had to drill out of mine. I drilled until the bit hit the thick washer and then unscrewed the shaft with my fingers.

Here's the thread I posted that shows the torture I put myself through

Stripped motor mount bolt - HELP needed ASAP

dannyF · #10 07-01-2008, 06:38 PM

Thanks, Chad. I already drilled the head off, though, but had drilled into the bolt - ended up being a 3/8 incher to get the head off, but the remaining bolt is hollow, if its still in there....

However, I only have one engine shock and it is on the passenger side. From these posts it seems that some cars have 1 and others, 2. I am definitely not seeing the other one in the spot where it should go on the driver side. Also, my stubborn-side engine mount has a different support than the other one. The 'stubborn side' has a bolt on top of the housing on the opposite side where the stubborn bolt came out and that bolt attaches it to some other support part of the car- I am not sure what that is about.... That is the passenger side, btw.

dannyF · #11 07-01-2008, 07:22 PM

I realize I was mistaken - I do have 2 engine shocks. The second was in a different location that I found when viewed from above.... They are now both loosened. Thanks for the note, Chad.

dannyF · #12 07-19-2008, 05:18 PM

Does anyone know the torque specs for the motor mount arm on an 84 300 SD? These are 17 mm nuts, btw.

Johnhef · #13 07-19-2008, 06:40 PM

Guys, for future reference, use a prybar to help get the holes lined up