1991 300d basket case volume 2

[bfrinkus1]

Howdy folks, back again. You gave me such fantastic help on my first post, I'm back for more. Quick refresher, I purchased a cheap 1991 300d 2.5turbo with 225k and got exactly what I paid for. Trying to make quality repairs to get her back on the road and keep her there for another 225k.

-I saw the serp belt with shoulder wear, quick visual indicated tensioner arm cocked sideways. I removed arm and will be replacing it. However, I was troubled by wear to the bolt that holds the arm to the block. Picture attached, please advise if this is as bad as it looks.

-Obviously the fan/clutch assembly had to come off, but before removal I saw that it looked very wobbly when rotating. Part of a fan blade damaged and wrong bolt securing fan/clutch to water pump pulley. Pics attached. Please tell me correct allenhead bolt (length, pitch, etc) to replace the incorrect hardware and tell me if you think fan blade damage is bad enough to require replacement. (Note: I could be wrong, but wobbling appeared to be caused by incorrect hardware, not fan imbalance).

-There is metal cover on the vacuum pump that is leaking oil at the bottom. I gently tried prying cover off to see if there was a gasket underneath, but it didn't seem to want to come off. I've read that these cars tend to have problems with the vacuum pump...do I have to replace pump to fix leak, and SHOULD I replace pump just as a precaution?

-My ABS light is on and I was advised to check charging voltage. With no accessories on, it's charging low 13s at idle, mid-high 13s revved up. With all accessories on, it's charging 12.5 at idle and mid 13s revved up. This seems low to me so I removed it for inspection. Brushes on regulator look great, so I took it to my local automotive big-box retailer. They tested and said it was fine. They also said that it was only supposed to be a 70amp unit, is this correct? I plan on taking it to a specialty alternator/generator shop for additional testing on Monday, but wanted y'alls thoughts on this.

-I'm pretty sure my AC compressor is shot (clutch engages and turns when I put R134 in it, but it does not generate any suction or discharge pressure), but I also think system has a small leak (system only had 10psi when I first checked it). I injected UV dye, but haven't found the source of the leak yet. Are there any common places these things leak that I should make sure to check?

You guys (and girls!) are awesome, thank you for your valuable insights.

Many thanks,
Brad

[bfrinkus1]

I took the alternator (that I thought to be undercharging at idle) to a reputable alternator/starter rebuild shop. They told me that not only is it ok, but that it's really good! I may be looking too hard for problems that aren't actually there...

I'm going to make sure my battery cells are full, and top them off w/distilled water if they're not. I'm gonna load test it and if the battery checks out solid, I'm going to put the alternator back on and leave the starting/charging system alone.

I'm still welcoming any advice from you vets on correct fan/clutch bolt size, what caused damage to tensioner bolt, and vac pump oil leak.

Many thanks!
Brad

[Benzkid_300D]

I'm not a specialist on 1991 300D's but I believe that they are indeed supposed to be a 70amp unit... And you voltage is about average... If you want higher volts Some people like to upgrade to modern 110amp units which when mine eventually goes I will be doing

Not at all an expert on A/C and how it works boggles my mind but mine works great so if it ain't broke don't fix it

[whunter]

This is what the tensioner looks like.
It appears yours has ripped out a chunk of the timing cover.
The part number should be MB# 6010150601


















W124 602 Timing chain R&R procedure question








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[Jeremy5848]

A 70 Amp alternator is correct and normal. Larger ones are available but not necessary unless you have lots of high-current accessories (driving lights, big stereo, etc.). Your measurements sound reasonable.

You should plan to replace that broken fan. The bolt is listed in EPC; you can get a free subscription. The clutch may be OK but get the fan and bolt replaced first. The pivot arm may need replacement but the spring is likely OK and the shock may be OK.

The cover does not come off of the vacuum pump. I'm not sure about leaks, can you post a picture?

Jeremy

[whunter]

The fan blade and clutch have been superseded.
It appears the clutch was wrecked by the wrong bolt.
The new clutch will NOT attach to the old fan blade, the changed the diameter.

Hydrostatic clutch
MB# 6062000022


Also requires:

Fan blade
MB# 6062000023


Bolts, x3
MB# 914020006017

The center bolt is
MB# 000912010078




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[whunter]

The vacuum pump is MB# 0002303565
There are NO repair parts available, never have been...
Call Phil for the best price.

OM603: Vacuum pump explosion, bearing intact! Injection Pump Timing device wrecked




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[whunter]

Originally Posted by bfrinkus1

I'm pretty sure my AC compressor is shot (clutch engages and turns when I put R134 in it, but it does not generate any suction or discharge pressure), but I also think system has a small leak (system only had 10psi when I first checked it). I injected UV dye, but haven't found the source of the leak yet. Are there any common places these things leak that I should make sure to check?

You guys (and girls!) are awesome, thank you for your valuable insights.

Many thanks,
Brad

The A/C compressor MB# 0002301111 is roughly $300.00 USD.


I would first suspect a bad expansion valve and/or evaporator, as both are common.




W124 (124.290) Evaporator, Vacuum Pod, and Bulb Replacements
W124 (124.290) Evaporator, Vacuum Pod, and Bulb Replacements


.

[whunter]

Originally Posted by bfrinkus1

My ABS light is on and I was advised to check charging voltage.

With no accessories on, it's charging low 13s at idle, mid-high 13s revved up.

With all accessories on, it's charging 12.5 at idle and mid 13s revved up.

This seems low to me so I removed it for inspection.

Brushes on regulator look great, so I took it to my local automotive big-box retailer.
They tested and said it was fine.
They also said that it was only supposed to be a 70amp unit, is this correct?

I plan on taking it to a specialty alternator/generator shop for additional testing on Monday, but wanted y'alls thoughts on this.

You guys (and girls!) are awesome, thank you for your valuable insights.

Many thanks,
Brad

The ABS light is probably a damaged wire or sensor.

13.5v - 14.5v is good.



.

[winmutt]

Before you do anything try sourcing that timing chain cover. GL.

[bfrinkus1]

First, a big thank you to those trying to help! Some updates:

-I have previously run into the damaged timing cover, thank god that's not what I'm dealing with here...just damage to the bolt going THROUGH the timing cover.
So here's what I've figured out: It appears the last idiot that worked on this thing threw away the shim/that goes between the tensioner arm and timing cover (extra parts!). In addition to misaligning the tensioner pulley with the serp belt, this put the back of the tensioner bolt DIRECTLY into contact with the timing chain (multiple measurements confirmed bolt impeding approx .075in into path of timing chain). When they started the engine, the timing chain chipped the piece missing from the end of the bolt (it's hard to tell in the pics, but there are no chafe marks indicating long term erosion of bolt by light contact with the chain...piece is pretty clearly chipped off from a one time event). They were exceedingly lucky that it didn't break the timing chain. I determined I needed a shim at least .075in to prevent contact of bolt with timing chain (this would also center belt on tensioner pulley). To account for measuring errors on my part and any unforseen movement of timing chain, I fabricated a shim of .11in to prevent any possible contact with timing chain, and belt still rides completely on pulley. At present time, I believe I have this problem solved, although putting in a new timing chain just got put on the to-do list.

-The fan clutch bolt fiasco, caused by the Mr. Einstein that worked on this thing last...
Since Albert couldn't find the correct metric bolt to reinstall the fan clutch, he forced a SAE bolt in there (if I ever meet this guy's Mom, I'm going to punch her in the face). Since the threads in the water pump are probably already shot, I'm not going to further stress them by trying to reinstall a metric threaded bolt, no matter how "correct" it is. I purchased an SAE allen-head bolt that I hope will do the trick. When water pump requires replacement, I will upgrade to the correct metric bolt.

-Thank you for the help regarding the non-repairable nature of the vacuum pump. $300 for a new vacuum pump stings a little, I may keep an eye out for a used one in the junkyards. Am I correct I should watch for one with torx bits on the front cover to indicated it is a later model part of revised design?

-Warning lights annoy the crap outta me, but I may have my hands full with legitimate mechanical issues before I get to tweaking the details on this car. The ABS light may have to wait...

-Still confused on the AC system. Even though the AC clutch would engage and turn, I got no response in system pressure. However, with car OFF, I could turn clutch by hand and see 5psi response from both suction and discharge guages from just one twist of the wrist. I definitely have a slow R134 leak, I appreciate the tip about the evap core and expansion valve, I will inspect them for leakage.

whunter, you are a walking parts catalog. I appreciate the time and effort you went to finding me part numbers and corresponding pics. Truly above and beyond!

Thank you all for your time and insight!

Best,
Brad

[jbach36]

Since you took the fan off, obviously replace the serpentine belt, and replace the little shock absorber thing. GET A GOOD OEM ONE, not a cheap one from China, or they fail pretty quickly, and cause strange noises.

I think I already told you, you might as well do all the normal repairs while you're doing it, otherwise you'll be repairing stuff piecemeal, especially if you don't know when the last time something was fixed or replaced.

Change the Shut Off Valve, read up on that, and how to block off air flow in case of a runaway diesel. This can blow your engine up and cause physical harm, so figure out what you're doing before you do it.

Change your glow plugs.

Clean your injectors with Molly Lube or whatever it's called. Simple to do once you do it. Like many things, going into it, seems like a big deal, but when you're done, it's like, gosh, that was easy.

Replace your rubber fuel lines, super simple to do. Be careful of the plastic fuel lines, so you don't crack them. Speaking of which, get the clamps to hold your lines in place that you're supposed to have anyways. Many of them break off over the years, your lines shake, which can be bad. They're cheap, but hard to put on.

Replace all your pitted aluminum fuses with the good copper ones. Might cost you all of $12 for new fuses. Keep spares, just in case.

Many of your vac hose lines are probably old and brittle. Rather than driving along and having problems, replace what you can now. They're cheap.

Replace the windshield wiper rubber grommets at the bottom of your reservoir if they're dry rotting. You'll be driving around with no wiper fluid just when you need it, which can be dangerous.

How old is your radiator? While the fan is off, might want to replace that, and of course the hoses.

Are the small hoses under the radiator for the transmission cooling leaking? If so, replace them while you have all that off; easier to get to.

A lot of problems on these cars are because of the rubber dryrotting, so replace what you can.

Lube your sunroof rails with the proper grease. I don't think you need the big 5 pound tub of MB grease, but a very light grease will do, and/or some lithium spray. Ask other members what they think about that. You don't want oil on there, as it attracts dirt. Know how to manually wind the sunroof back should there be a problem. That's in your trunk area.

If your fuel gauge isn't working properly, there's an easy fix, disconnect your battery, take out some of the back matting of the trunk and take off this big round thing, pull it out, and clean it off. Your float is probably stuck, simple fix if you have a rotozip or dremel.

A/C probably leaks, get all that fixed.

Stuff you don't see that should be changed, are your flex discs, where the transmission meets drive shaft. Definitely check for cracking. Could be big problems if you don't fix that, and it goes. Strut rubber under the hood, check that.

Other than that, some things just give out in their own time, depending on when it was fixed last, like tie rods, etc.

Almost forgot, at 200k, the timing chain and rails should have been replaced. If this hasn't been done, or if you don't know, then do it. You don't want the chain breaking while you're buzzing along as 70 mph.

Replace all your fluids of course. Suck the stuff out of your power steering reservoir. It probably leaks, too, so use some Prestone fluid with a special stop leak stuff in. It doesn't ruin the rubber. Use a baster like for cooking, to suck all that old fluid out, and pour new in. Change all the brake fluid, oils, you name it, and don't forget the rear axle that many people forget.

Basically, once all the rubber's replaced, and parts with rubber like the Shut Off Valve, you're good for another 225k

[jbach36]

Read the DIY articles on this forum, and go to YouTube to see stuff you need.

[bfrinkus1]

Many of your suggestions have already been done, or are on my "to-do" list. However, I had not thought of a few things you mentioned and have added them to the list.

Thank you for the time and thought you put into the suggestions. Sounds like you've been there yourself?

Best,
Brad

[amotion578]

Bumping from the dead because my OM603, 87 300D turbo suffered this EXACT failure (hole in timing chain cover- literally I double taked on the picture because it looks identical to the one I took), I was looking for the PN and here it is.

Praise the car gods for working picture links (found via google image search!)