GregMN's 1991 W126 350SDL Has A New Home - Page 7 - PeachParts Mercedes-Benz Forum

Squiggle Dog · #91 11-07-2018, 05:44 PM

Since the car spent most of its life in Minnesota, it acquired some rust issues. One of which was the left side subframe mount rusting off of the car. The previous owner had a bracket fabricated to replace it, but it would keep coming loose because some raised areas from what was left of the mount were keeping it from laying flat, and when the bolts were tightened, the box tubing would crush and the bolts would loosen again.

The bracket would come loose and then it would cause the bolt and plate in the mount ahead of it to loosen and fall out, so the front suspension of the car would come loose and move around.

Here is the backside of the bracket showing where high spots were keeping it from resting flat against the body.

I drilled out the holes larger on one side and used a length of 3/8" inner diameter, 1/2" outer diameter steel tubing and a sledge hammer to pound the box tubing back to its original location.

I cut off the rest of the old subframe mount and ground the area flat so the bracket would have a good mounting surface. I then treated it with Corroseal rust converter. I cut some of the 3/8" inner diameter, 1/2" outer diameter steel tubing down so it would fit in between the sections of the box tubing to prevent it from crushing when the bolts were tightened.

I used four metric M8-1.25 90mm 8.8 bolts with washers, and four M8-1.25 tension nuts applied with red threadlocker to keep them from coming loose.

I scraped the rust scale off of the bracket and used rust converter on it. Now the front suspension is a lot more secure.

300D85 · #92 12-22-2018, 11:07 PM

Quote:

Originally Posted by jay_bob

I thought the US market W124 and S124 (1987 only) were fitted with a 6 cyl OM603 up until 1989. From 1990-1994 they got the 5 cyl OM602 and were badged 300D-2.5.
In 1995 they got the N/A OM606 engine that was then used in the W210.

From what I have learned the OM603s had the EDS but it only worked on the ARF valve on the turbo. The wastegate was pressure operated. They had a pressure switch in the manifold that opened a switchover valve in the manifold to ALDA line that dumped the boost if it became excessive.

Starting in 1990 with the 2.5 liter/5 cylinder OM602 they expanded the electronic controls by adding a MAP sensor and vacuum operated wastegate.

So chances are if the OP has a transplanted engine from a W124 it is likely from an 87 to 89 model with the pressure operated wastegate. If the person doing the swap was diligent they would have brought over the EDS computer from the W124 donor along with all the associated control hardware.

original post
GregMN's 1991 W126 350SDL Has A New Home

Quote:

The original 3.5 liter "rod-bender" 603 engine was replaced with a 3 liter engine from a 1990s W124 300D.

Squiggle Dog · #93 12-23-2018, 12:08 AM

Quote:

Originally Posted by 300D85

original post
GregMN's 1991 W126 350SDL Has A New Home

I misspoke when I wrote that years ago--the engine is actually out of a 1987 W124 300D.

Squiggle Dog · #94 09-07-2019, 12:39 AM

The 350SDL is still being daily driven to work by my roommate. I did a front and rear suspension and steering rebuild on my daily driver, a 1980 W116 300SD, but when I got it to the dealership they refused to do an alignment because the front end was slightly too high and the steering damper was leaking. But, one of the Mechanics had a 350SDL like my roommate's!

Also, my roommate was on his way home from work and he got rear-ended at a stop light. A guy in a Dodge truck ran into the back of a Ford Fusion, and it pushed the Ford into the Mercedes. The front bumper and lights of the Ford were smashed up, but there was no damage to the Mercedes other than a bent trailer hitch cover and it pushed the right side of the rear bumper in about an inch, but the bumper shock expanded out on its own, which restored the bumper to its previous position.

At a later date, I was inspecting the engine and noticed that the belt tensioner pulley was severely tilted and the bolt had worked itself out, but fortunately I caught it before it fell on the ground. The belt itself was in poor condition, as the non-drive side was polished smooth and there was a split in it. I put the bolt back in with thread locking compound.

A few days afterward I got woken up by a call at about 6:30 AM because the car overheated on the way to work. I drove out to look at it and saw that the fan blades had hit the radiator and broken.

I loaned my car to my roommate so he could get to work and rode home with his 350SDL on the tow truck. When I looked at the radiator, it was apparent from where the coolant was leaking. The fan blades had sliced open the bottom of the radiator.

The cause of the problem was the single bolt that holds the fan clutch to the water pump (poor design, if you ask me, compared to the 4 bolts which an OM617 uses) loosened. So many bolts are coming loose on this engine!

Squiggle Dog · #95 09-07-2019, 01:02 AM

After removing the radiator, I placed cardboard over the condenser to protect it from damage, securing it in place with clips.

The fan blades were in rough condition, but the clutch seemed to be fine, although it feels like someone rigged it so it's always locked.

The part number on the original fan blade is 606 200 00 23. Several websites show that this part number has an MSRP of $78 and is no longer available in genuine Mercedes. I found a new aftermarket (ACP GERMANY) fan blade for just over $20. It was advertised as the same part number as the original fan blade (606 200 00 23), though the blades are narrower than what was on the car, and the ends of them are rounded instead of square.

However, when the fan blade arrived, the receipt showed part number 606 200 01 23, instead of 606 200 00 23. So, I went back to the website, and it indeed shows the correct part number of 606 200 00 23. Then I looked up the part number on the sticker on the part, which is 0759.0205, and cross-references to the correct 606 200 00 23 part number I need on several different websites.

So, it seems this must be the correct replacement fan blade for the vehicle, but I just wonder with the blades being narrower and the edges more rounded than the original blade. It seems to work, though.

I went to install the clutch into the fan, but one of the tabs was in the way.

So, I broke off the offending tab with pliers. (Shhh...)

Squiggle Dog · #96 09-07-2019, 03:35 AM

The engine compartment was covered with a thick layer of oil and dirt from a badly leaking front crank seal. It took me what seemed like days to clean it.

After I removed the crank pulley and balancer with the six bolts, using a 13mm socket on the flywheel to keep the engine from rotating, I loosened the large crank hub bolt and used a steering wheel puller to remove the hub.

The hub had a deep groove worn into it from the crank seal. Unfortunately, unlike the OM617 which uses a $10 spacer ring, on the OM603 the entire $300 hub has to be replaced. Obviously that wasn't happening, so I decided that I would install the new crank seal 3mm deeper than flush so the seal would ride on an unworn part of the hub. Otherwise with that groove worn into the hub, it would leak even with a new seal.

Squiggle Dog · #97 09-07-2019, 03:45 AM

Here's the old and new seal. The new seal was quite different than the old one; rather than having a rubber inner lip with a retaining spring, it had what felt like paper with ridges on it. The part number on the seal was also different than what was on the packaging.

I used a 2X1.5" PVC pipe bushing and a 3/4" washer (the biggest I could find) with the crank bolt and one washer as an installation tool. I filed and sanded off the lettering at the bottom surface so it was smooth against the seal.

I put oil on the inside and outside edges of the seal and carefully pressed it into place using a 27mm socket and ratchet.

I used the depth gauge on a set of calipers to get it driven in exactly 3mm from flush on all sides. Only about another millimeter too far and the seal will touch the timing chain!

The seal installed 3mm deeper than flush.

Squiggle Dog · #98 09-07-2019, 03:57 AM

The water pump was leaking, as was the thermostat gasket, so I replaced them. We found a good price on a Laso-made water pump. Comparing it next to the original, they are nearly identical.

Even the impeller vanes are of the same design; I have heard that often aftermarket brands have inferior vanes.

Just about all the bolts I worked with required soaking in Evaporust. I then painted them with silver paint. The instructions that came with the water pump said to not use sealant on the gasket, but my roommate said he wanted it sealed up really well, so I put a light, even coat of black RTV on both sides of it.

I installed a new Wahler 80C thermostat and gasket. There is a notch in the thermostat, into which the tab in the housing fits, to correctly clock it.

Fortunately the aluminum housing is in great condition. Its location is somewhat inconvenient.

Squiggle Dog · #99 09-07-2019, 02:25 PM

I installed a new belt tensioner spring and damper. I used red thread locking compound on the tensioner bearing bolt threads and black RTV at where the bearing meets the engine (since the hole goes all the way through into the crankcase). I was able to spray a little lithium grease into the pulley bearing through the broken spots of the seal. I had to borrow a torque wrench that would go up to 320 Nm/236 ft-lbs so I could tighten the crank hub bolt. I put black RTV on the washer that touches the hub and a little on the bolt threads at that washer to prevent oil from creeping out.

The water pump and crank pulleys were rusty. The crank pulley was very rusted and the surface was heavily pitted after rust removal. I painted them with black engine paint.

The pulleys and new belt are installed. When I installed the fan, I used blue thread locking compound and made sure it was extra tight so there wouldn't be a repeat performance.

A new fan shroud was ordered.

We also got a new radiator mounting kit as it was missing one of the lower mounts, which explains why the radiator was tilted. It was also missing the upper rubber mounts entirely, and the clips were rusted.

Squiggle Dog · #**100** 09-07-2019, 02:39 PM

The coolant expansion tank was cracked in several places, and they are difficult to find.

Fortunately my roommate had a spare that was in better condition, though it had some cracks which I covered with epoxy. I replaced the O-ring for the coolant level sensor. The connector was glued to it from years of coolant leakage and corrosion, so it required cleaning.

I realized there is a grommet into which the bottom of the tank rests, and I didn't order one. But, it turns out the grommet on the top of the oil filter this car uses worked perfectly.

What a goofy lower radiator hose! The OM603 is a bizarre engine.

My roommate ordered a new German-made Elaplast brand upper radiator hose, but received a ÜRO brand instead. We tried using a Gates hose, but it was too narrow in diameter and way too long. So, we used the ÜRO hose, but it was also too long and needed to be cut down on both ends. The diameter was correct, though.

Squiggle Dog · #**101** 09-07-2019, 02:55 PM

We got a new all-aluminum radiator from Champion for only about $175 and free shipping. Had it been only a year or two earlier, we would have been in a bad situation, as buying used was the only option--and finding a good used radiator to fit this car would have been very difficult. New radiators for this car haven't been available from Mercedes for years, and aftermarket ones weren't offered, either.

It fits really well and there is no plastic to break. The only downside is that the fan shroud rattles at the bottom because the brackets are too big--the designers made them the same size as stock and didn't factor in that the plastic tanks were wider and the fan shroud rests against them to bring its tabs out to the edges of the brackets.

I did a coolant flush with oxalic acid and then ran washing soda to neutralize it. The cooling system should be nice and clean. I filled it with a 50/50 mix of Zerex G-05 coolant and distilled water. I didn't notice any oil in the cooling system, or coolant in the oil, which is good. The car drives fine, but idles poorly. It sounds like it has a rod knock, so I'm concerned about that. But hopefully it gets him to work and now I have my car back.

ROLLGUY · #**102** 09-07-2019, 05:10 PM

As usual, you are doing an awesome job! Your roommate should be very happy to have a mechanic as thorough and competent as you to fix his car. Many of us on this board are impressed with your wok. Thanks for sharing it with us!

cleeves · #**103** 09-07-2019, 05:58 PM

Enjoyable and fascinating, thanks.

H

vwnate1 · #**104** 09-07-2019, 10:55 PM

Thank you for the informative and detailed post .

? Could you elaborate on the evaporust stuff a little bit ? .

I've been using a dilute Phosphoric Acid mix of a few decades now but I've seen the Oxalic Acid and wondered if it was too strong, if you're using it in aluminum I'd think not .

? Can't you shim the rattly lower tabs with thin rubber or something ? .

Squiggle Dog · #**105** 09-07-2019, 11:40 PM

Thanks, all!

Quote:

Originally Posted by vwnate1

Thank you for the informative and detailed post .

? Could you elaborate on the evaporust stuff a little bit ? .

I've been using a dilute Phosphoric Acid mix of a few decades now but I've seen the Oxalic Acid and wondered if it was too strong, if you're using it in aluminum I'd think not .

? Can't you shim the rattly lower tabs with thin rubber or something ? .

I get Evaporust at O'Reilly Auto Parts. If you soak something rusty in it for long enough, it will come out rust-free; usually this is only a few hours, and scraping and wire-brushing helps accelerate the process. But, it's expensive, so if you have to remove rust from large parts, oxalic acid (Savogran Wood Bleach) is more economical, but slightly less effective and kind on finished surfaces.

Oxalic acid does work pretty well as a rust-remover, though. I've soaked things like copper heater cores in it, too. It cleans aluminum nicely as well, but I've found that sometimes if you mix metal types, the metal particles of one type can plate themselves to the different metal.

Oxalic acid is what was used as an effective cooling system cleaner for decades until the laws changed. Evaporust would work well, too, but it's a lot more expensive. Maybe half a cup of oxalic acid powder in a cooling system, run for about 15 minutes and then drained after the engine cools tends to be effective, though if the system is very rusty, it could be left in for longer. I always neutralize it by running Arm & Hammer Washing Soda (soda ash, NOT baking soda) with water in the cooling system before I run water a couple more times to rinse the system.

The lower radiator shroud tabs that are rattling can be shimmed, but I don't know how to do it yet in a way that the shims won't fall off.