GregMN's 1991 W126 350SDL Has A New Home - Page 13 - PeachParts Mercedes-Benz Forum

Diseasel300 · #**181** 11-20-2019, 09:48 PM

YAAAAAAAAAAAAY! It lives! What an ordeal, such a rollercoaster!

Squiggle Dog · #**182** 11-20-2019, 10:07 PM

Quote:

Originally Posted by Diseasel300

YAAAAAAAAAAAAY! It lives! What an ordeal, such a rollercoaster!

Thanks again for the head! Some parts of The Diseasel are living on.

Diseasel300 · #**183** 11-20-2019, 10:17 PM

Quote:

Originally Posted by Squiggle Dog

Thanks again for the head! Some parts of The Diseasel are living on.

Indeed they are, it makes me happy that they could help someone else.

Squiggle Dog · #**184** 11-25-2019, 09:58 PM

The cooling flush was done. I used a Prestone Flush 'N Fill Kit and the old lower radiator hose to make sure it was rinsed thoroughly. Zerex G-05 coolant went in.

The engine mounts were in dire need of replacement. The right side engine mounting arm was resting on the metal edge of the mount, and a lot of noise and vibration could be felt through the body. The engine was also resting lower than it should, and probably part of why the oil pan smacked the ground pulling into a parking lot.

Diseasel300 sent us the nearly new Lemförder engine mounts that he had on his 1986 W126 300SDL. Unfortunately, I discovered the engine mounts were another feature exclusive to the 350SD/L. For whatever reason, they changed the mounting holes so the ones from his car wouldn't work. So, my roommate ended up buying some from the dealer. The W123 part number ones we got from Diseasel300 are on top, and the 350SDL-specific ones are on the bottom (and they are side-specific due to different shore hardness of rubber).

The right side engine mount isn't accessible from on top. Fortunately, the entire job is able to be done from the bottom. First, the engine mount shock absorbers must come off. They are worn out and need replacing.

The mounting arms are detached from the mounts by the hex key bolt which is accessed through a hole under the mount.

Then the engine is lifted up so the heat shields can be removed and the bolts holding the mounts to the body can be accessed.

Squiggle Dog · #**185** 11-25-2019, 10:14 PM

The bolts securing the engine mounts to the body are now able to be removed.

The old mounts are on the left, and the new ones are on the right. That is the flattest mount I've ever seen! The center was actually touching the body of the car, and the engine mounting arm was resting on the metal edge.

We also got the heat shields from The Diseasel. The right side heat shield from my roommate's car was cracked from the mounting arm crushing it against the collapsed mount, so it was much needed. The left side one was pretty good. The left side one from The Diseasel looked like it was in good condition, but might have gotten crushed by the head during shipping. If that's the only damage that happened, I'll take it. So, I ended up using the original left side one, but it was covered with a thick layer of hardened waste vegetable oil that I had to burn off with a torch. Then I painted them.

The left side mounting arm was missing a bolt, so I found one in my spare hardware stash. Unfortunately, I discovered that the original bolt had sheared off and was still inside the hole.

The mounts and heat shields are installed! One day we'll replace the engine shocks. The new mounts made a huge difference. The engine used to be so loud and the body would vibrate. Now it is so smooth and quiet, and it also solved the problem of the engine nearly stalling after being revved up and let go. Apparently running a diesel engine with bad mounts can actually break crankshafts and main bearings from the shock force.

Squiggle Dog · #**186** 11-25-2019, 10:47 PM

The underside of the engine was filthy from the front crank seal leak. I cleaned it up because so I wouldn't have to keep fighting grime every time I worked under there. Unfortunately, there is a lot of hardened waste vegetable oil all over that won't seem to come off, and will be haunting my dreams. The J-B Weld oil pan repair is still holding up after over two years of daily commuting.

There was some rust-through on the crossmember that needed addressing.

The steering system needs a full rebuild; the steering box is leaking, and the ball joints are bad.

The subframe mounts are falling apart.

Both of the boots of the center link are torn open and full of water. One of the boots of the right side tie rod is ripped off.

We're hoping he can get by on these parts for another year because it's going to cost a lot of money to replace them--and he's already spent a lot on emergency repairs.

Squiggle Dog · #**187** 11-25-2019, 11:03 PM

I noticed the exhaust pipe was on crooked and the nuts were loose. I removed the nuts and clamp and tried to straighten the pipe, but it wouldn't bend at all, so I tightened up the nuts. There seems to be a vacuum connection missing from the back of the turbocharger, so I'll have to investigate.

The flex discs are cracking and due for replacement. The tunnel insulation is falling down and causing the front flex disc to rub on it. The three-piece driveshaft (another special 1991 model year feature) was replaced with new not long ago, but the flex discs weren't replaced at that time.

The differential vent is rusted and probably clogged. I should tend to it before the seals blow out from overpressurization. The fill plug looks like it's never been removed. I wonder if there is any oil in there. Scary!

Usaguy · #**188** 11-25-2019, 11:26 PM

Quote:

Originally Posted by Squiggle Dog

The flex discs are cracking and due for replacement. The tunnel insulation is falling down and causing the front flex disc to rub on it. The three-piece driveshaft (another special 1991 model year feature)

all 350 diesel w126 had a 3 piece driveshaft.

while you have the driveshaft out check your U-joints for easy rotation and lube the splines before torquing back everything to a factory torque specs (at least one of the splines has to be moving while driving)

Quote:

Originally Posted by Squiggle Dog

The differential vent is rusted and probably clogged. I should tend to it before the seals blow out from overpressurization.

Good idea also judging by the crossover pipe you have an ASD diff.

May require a special fluid and is a nice option in snowy climate (not so much in AZ unless in flagstaff)

Squiggle Dog · #**189** 11-25-2019, 11:38 PM

Quote:

Originally Posted by christuna

all 350 diesel w126 had a 3 piece driveshaft.

while you have the driveshaft out check your U-joints for easy rotation and lube the splines before torquing back everything to a factory torque specs (at least one of the splines has to be moving while driving)

The driveshaft was replaced with a new one not long ago, so it should pass the test. I'd like to get new flex discs on it soon, though.

Quote:

Originally Posted by christuna

Good idea also judging by the crossover pipe you have an ASD diff.

May require a special fluid and is a nice option in snowy climate (not so much in AZ unless in flagstaff)

Yeah, this car has ASD. I've already rebuilt the tandem power steering pump which runs it, and used the proper fluid and bleeding procedure. I think the sphere is bad, because it makes a hissing noise every few seconds and the ASD light is always on. But, it's likely the valve body might need a rebuild. Like they say, it's just more stuff to go wrong.

Usaguy · #**190** 11-26-2019, 12:29 AM

Quote:

Originally Posted by Squiggle Dog

Like they say, it's just more stuff to go wrong.

Yeah I get away with an open diff and rwd because they do a good job with clearing the snow where I live but if I lived outside an HOA I would most likely need functioning ASD

Squiggle Dog · #**191** 11-26-2019, 05:29 PM

It's interesting to note that the local Mercedes-Benz dealership wanted $6,381.26 to replace the head gasket and timing chain. That's not including the cost of a new head or a used one and the costs associated with machining and a valve and lifter job. A local independent Mercedes repair shop wanted $3,042.24. I did it for a few hundred dollars factoring in the low-cost used head.

Diseasel300 · #**192** 11-26-2019, 05:56 PM

Quote:

Originally Posted by Squiggle Dog

It's interesting to note that the local Mercedes-Benz dealership wanted $6,381.26 to replace the head gasket and timing chain. That's not including the cost of a new head or a used one and the costs associated with machining and a valve and lifter job. A local independent Mercedes repair shop wanted $3,042.24. I did it for a few hundred dollars factoring in the low-cost used head.

Exhibit A of why old cars require a DIY owner. Most people would scrap the car over a cost like that, if you're capable of doing the work yourself, you can keep the car on the road. The shop has to make a living and it's a pretty involved job, on a car like this, that shop rate is more than the value of the car.

vwnate1 · #**193** 11-27-2019, 11:09 AM

Wow, a lot of work done and as so often, more revealed needing attention .

This is a fine car and will reward your friend with a fantastic driving experience .

IIRC that old veggie buildup comes off the soakings of the purple degreaser .

83w126 · #**194** 11-29-2019, 03:55 AM

Quote:

Originally Posted by Squiggle Dog

I'd like to get new flex discs on it soon, though.

That would definitely be a good idea, having one break is likely to mean a destroyed tailshaft housing on the transmission, holes punched in the floor, and possibly blown airbags and seatbelt tensioners.

Squiggle Dog · #**195** 02-25-2021, 03:32 PM

It appears I haven't updated this thread in a while. Back in December 2019, I installed a new antenna grommet, as the old one was letting water into the trunk.

I decided it was time to check to see if there was any gear oil in the differential. The fill plug was a mass of corrosion and it took a lot of effort to remove. Fortunately, there is oil in there, though it's old and muddy looking.

The differential breather valve was coated with waste vegetable oil and was clogged so the pressure inside couldn't release (which will cause oil to blow out of seals as the internal temperature rises).

I soaked it in biodiesel and cleaned it up and removed the rust. Then I put a coat of rust converter on it.

The breather is back in place so the differential can vent.