Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #16  
Old 10-06-2003, 03:43 PM
Moderator
 
Join Date: Dec 2001
Location: Southern California, U.S.A.
Posts: 8,538
About the 3.0 liter six cylinder diesel engine in the later W126 cars - I know that most here on this site are concerned about cracked heads and overheating on this engine, but I've discussed this with the legendary Enrique at Mr. MB Motors in Southern California, and he swears that the newer engine is a better engine than the five cylinder, and doesn't have a high failure rate of cracked heads and overheating.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".
Reply With Quote
  #17  
Old 10-06-2003, 03:49 PM
mplafleur's Avatar
User Friendly
 
Join Date: Sep 2001
Location: Lathrup Village, Michigan
Posts: 2,939
I've got a clamp-type tool, but the clamp is the wrong size. It's an AVL 875 and the manual is in German.

Thomas,

I'll lend it to you if you can send it back with the right clamp and a translated manual.
__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

Reply With Quote
  #18  
Old 10-06-2003, 03:59 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
RLeo is always smarting off in GERMAN.. lets make him translate it... LOL
Reply With Quote
  #19  
Old 10-06-2003, 04:21 PM
R Leo's Avatar
Stella!
 
Join Date: Mar 2003
Location: En te l'eau Rant
Posts: 5,393
Der Unterschied zwischen gescheitem Deutschem, das von den Computern und von Deutsch übersetzt wird, die intelligent gesprochen wird, ist sehr groß.
__________________
Never a dull moment at Berry Hill Farm.
Reply With Quote
  #20  
Old 10-06-2003, 04:26 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
THAT DOES IT ! Send the manual to Randy....
Reply With Quote
  #21  
Old 10-06-2003, 04:44 PM
mplafleur's Avatar
User Friendly
 
Join Date: Sep 2001
Location: Lathrup Village, Michigan
Posts: 2,939
I just got off the phone with AVL. They have an office a few miles away that they didn't have when I bought the unit. Someone there is going to try to find a translated manual as well as the correct size clamp.

6.35mm right? or is that what came with it and I need 5mm?

What size is that inj line?
__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)


Last edited by mplafleur; 10-06-2003 at 04:51 PM.
Reply With Quote
  #22  
Old 10-06-2003, 05:58 PM
jbaj007's Avatar
Registered User
 
Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
6.35 mm is 1/4" inch and I heard that is not for our cars. I assumed 6 mm. from another website, but I'll throw a "mic" (pronounced "mike" ) on a line tonight and let you know what I get. I'll bet AVL will get back to you with the exact answer for Mercedes as I thought it's a German company. Dieselmota (something like that) is a guy (on some BBS's and on eBay) who imports a lot of German stuff, including AVL stuff. He'd know the size.

Edit (later that evening) I measured 5.95 mm., so I assume the 6.0 mm. is the one to buy?
__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Last edited by jbaj007; 10-07-2003 at 02:51 AM.
Reply With Quote
  #23  
Old 10-06-2003, 06:45 PM
Thomaspin's Avatar
pindelski.com
 
Join Date: Jun 2001
Location: CA
Posts: 531
Enhancements added

I have updated the slides for Dave M's comments. Thanks again Dave.
Reply With Quote
  #24  
Old 10-06-2003, 06:52 PM
gsxr's Avatar
Unbanned...?
 
Join Date: Aug 2001
Location: USA
Posts: 8,018
Quote:
I assume you still have to pop the valve cover to determine chain stretch. What's the key test to determine if the engine has overheated - compression? And why is the six so prone to overheating?
Yep, still pop the cover to check stretch. But on the 603, it's easier & cleaner, IMO - no linkage to mess with either.

As to how to test for past overheating, there's no test that I know of. There is a rudimentary test for the result of overheating - the dreaded cracked head. To test, open the radiator cap with the engine COLD to release any pressure and equalize the system. Then fire it up, warm it up, and drive the car hard - numerous full throttle trips to the redline. Run it as long and as hard as you want. Then park it overnight. The next morning when COLD (same ambient temp as previous day, approximately), pop the hood and squeeze the upper radiator hose. It should be soft and squishy, as if the cap were removed. If so, the head is probably fine (assuming there is ZERO coolant loss). If it's rock hard and tight as a banjo string - can't pinch at all - there's an excellent chance the head is cracked. Figure $900 for a used head, $1800 for a new one (bare), and either a couple hundred bucks in tools as DIY, or ~$1000 labor at a shop. I like these engines so much, I think it's worth it, if the problem happens during ownership just eat the cost and fix it. The new heads are stronger and shouldn't crack in the future.

Why do they overheat? Well, the cooling systems are the common fault, often from not using MB coolant and not changing it frequently enough. Also the fan clutch has a finite life span as they slowly spew the silicone fluid out and stop working properly. You can re-fill the original fan clutch (with metal blade), the new replacement clutch (from the OM606, with plastic blade) may not be refillable. Well, nobody has figured out how to refill the new one - yet. Keeping the fins clean to ensure good airflow is required, and testing operation of the electric fan & it's triggering senders is a good idea as well. When shopping for a car with a 603, pay attention to the temp gauge. They should stay under 95C in most driving, maybe up to 100C on a hot day, idling with the AC on. They should rarely if ever get to 105C (full load up a steep hill with the AC on or something), and it should cool down (under 100C) as soon as load is removed. Mine are very stable in the 90-95C range unless under load, but always drop right back.




HTH,
__________________
Dave M.
Boise, ID

1997 E420 - 155kmi (Bugeyes)
1994 E420 - 145kmi (Blondie)
1993 500E - 193kmi (Lollipop)
1992 400E - 189kmi (Stinky Dirty)
Check out my website photos, documents, and movies!

Last edited by gsxr; 10-06-2003 at 07:07 PM.
Reply With Quote
  #25  
Old 10-06-2003, 07:12 PM
gsxr's Avatar
Unbanned...?
 
Join Date: Aug 2001
Location: USA
Posts: 8,018
Quote:
About the 3.0 liter six cylinder diesel engine in the later W126 cars - I know that most here on this site are concerned about cracked heads and overheating on this engine, but I've discussed this with the legendary Enrique at Mr. MB Motors in Southern California, and he swears that the newer engine is a better engine than the five cylinder, and doesn't have a high failure rate of cracked heads and overheating.
Paul, I agree with Enrique. The OM603 is a much better design in MANY ways over the OM617. Much more refined, quieter, less maintenance, more power, better MPG. But it just won't tolerate abuse and/or overheating like the OM61x, which was almost impossible to damage! Anyway, the 1986/87 six-cylinder 3.0L engines (OM603.96x) all came from the factory with cylinder heads that were weak - not strong enough in certain areas to withstand temporary hot running conditions. They will eventually crack. MB fixed this on later 3.0L engines (not shipped to the USA), as noted in the service manual, by making the castings thicker in some places. But all these USA 3.0L engines (86/87) ARE prone to cracking! I personally know of a good half-dozen or more, mine included. The fact that there were FIVE redesigns of this head (six part or casting numbers), and also FIVE redesigns of the head gasket (again, six total part numbers), shows that MB realized there was a problem with the original design back in 1986 and worked to perfect it as years went by.

The 1990-95 six-cylinder 3.5L engines (OM603.97x) all have a stronger version of the head, and these very rarely have head or gasket problems. However as you probably know, *all* those 3.5L engines had weak connecting rods, which oval out the cylinders, requiring a MUCH more expensive fix - which is NOT a DIY project like the head. Luckily, the 3.5L engines provide good used heads for the 3.0L! :p They're scarce and not cheap ($800-$1200 typically, used, with cam & lifters if you're lucky).

Now, the OM606 engine used from 1995-up in the USA does seem to be a much better engine, with no head or bottom end problems that I'm aware of. Perhaps that is what Enrique was referring to!? On a side note, I have heard of very, VERY few OM61x heads cracking, or gaskets failing. Check this forum and you'll find lots of threads on OM603's cracking, but few if any 616, 617, 601, 602, or 606.


Regards,
__________________
Dave M.
Boise, ID

1997 E420 - 155kmi (Bugeyes)
1994 E420 - 145kmi (Blondie)
1993 500E - 193kmi (Lollipop)
1992 400E - 189kmi (Stinky Dirty)
Check out my website photos, documents, and movies!
Reply With Quote
  #26  
Old 10-06-2003, 07:12 PM
Thomaspin's Avatar
pindelski.com
 
Join Date: Jun 2001
Location: CA
Posts: 531
Dave

Thanks.

Do the fan clutches on the OM617 leak also?

I'm religious about cooling system maintenance and always use MB antifreeze, BTW. Really saw the benefits on the trip last week (2,500 miles in 5 days) where the engine would pull like the proverbial horse up steep mountain passes, while registering a modest increase in coolant temperature from 87C to 89C, a/c off.

Taking her up to 4,750 rpm (105 mph), with a little more on tap, on a level road, saw no increase in coolant temperature.

I'm on my third water pump (201k) and use one with the MB logo, preferring to believe tales of aftermarket pumps being less effective, although I have seen no compelling proof of this.

Come to think of it, I now have over 250k km during my ownership so I guess I'm eligible for the lapel pin. Got the grille badge with 153k miles on the odo (250k km).
Reply With Quote
  #27  
Old 10-06-2003, 07:25 PM
gsxr's Avatar
Unbanned...?
 
Join Date: Aug 2001
Location: USA
Posts: 8,018
I honestly don't know much about the 617 clutches. I don't think they leak, they seem to be a different design. The 603 clutches are always wet after a few months, and they collect dust and grime all over the face. You clean it off, and it's back a few months later. I've never seen that on my 617 clutch. Also the 617 clutch is easy to check with the "roar" test, plus it stops instantly if you kill the engine with the clutch engaged on a hot day. Not so on the 603, never roars, and just stops slower - never seems to fully lock. At least with the newer 606 clutch (which both of mine have). Kinda odd, and makes it hard to test!!

On a related note, my 617.952 runs at incredibly steady temps - 85-90C almost all the time. Even in brutal summer heat, whether idling or climbing mountains, I can't get it over 95C. Very, very stable. To me that indicates an excess of cooling capacity with things in working order (I have recent radiator, clutch, t-stat, etc). The OM603, even when perfect, will run hotter. High speed runs using max power will drive the temps to 100-105C even on level ground with cool ambient temps. That's the price you pay for 20% more horsepower with basically no increase in radiator area (I'm assuming). It shouldn't run towards the red (110+) unless something is wrong though, and it should cool down within minutes after the load is removed. At least my 603's behave that way!

__________________
Dave M.
Boise, ID

1997 E420 - 155kmi (Bugeyes)
1994 E420 - 145kmi (Blondie)
1993 500E - 193kmi (Lollipop)
1992 400E - 189kmi (Stinky Dirty)
Check out my website photos, documents, and movies!
Reply With Quote
  #28  
Old 10-06-2003, 08:05 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
They must leak... the instructions say they are supposed to be stored Vertically even at the parts store....
Reply With Quote
  #29  
Old 10-06-2003, 11:57 PM
Registered User
 
Join Date: Sep 2003
Location: Alberta, Canada
Posts: 17
Sorry to interrupt the flow of info guys, but I'm fairly new at diesels, can anyone explain to me or point me in the right direction on how you determine the amount of timing chain stretch one has on his vehicle? Thanks...
__________________
"Life", is the art of drawing, without an eraser.
Reply With Quote
  #30  
Old 10-07-2003, 01:07 AM
wbain5280's Avatar
Registered User
 
Join Date: May 2001
Location: Northern Va.
Posts: 3,386
Quote:
Originally posted by gsxr


The 1990-95 six-cylinder 3.5L engines (OM603.97x) all have a stronger version of the head, and these very rarely have head or gasket problems. However as you probably know, *all* those 3.5L engines had weak connecting rods, which oval out the cylinders, requiring a MUCH more expensive fix - which is NOT a DIY project like the head. Luckily, the 3.5L engines provide good used heads for the 3.0L! :p They're scarce and not cheap ($800-$1200 typically, used, with cam & lifters if you're lucky).



Regards,
I'd still like to know what the newer and better engine number is for the 3.5L engines. OM603.97what?

There is one at work here, W126, a white one, and I just love the car.

Thanks

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 03:53 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page