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  #1  
Old 04-09-2009, 10:13 AM
126 Guy
 
Join Date: Sep 2005
Location: Queens, NY
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Unhappy 90 300SEL engine issue. Oil leak & headgasket

My relatives 300SEL has started to leak oil heavily & using about 4 quarts of oil every week and oil has mixed with the coolant. I know it must be a definite headgasket and possibly cracked block?? They bought the car used 2 years ago without knowing its service history or knowing what problem areas to look for.. OUCH.

The car now has 140k miles, The body and interior is still in great shape & the transmission is perfect. What would they be looking for in cost for a motor rebuild or replacement motor? I do not know too much about the 3.0 straight 6 engine, I have all V8 W126's.

Any help would be great.

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  #2  
Old 04-09-2009, 08:49 PM
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Quote:
Originally Posted by Two560Two View Post
My relatives 300SEL has started to leak oil heavily & using about 4 quarts of oil every week and oil has mixed with the coolant. I know it must be a definite headgasket and possibly cracked block?? They bought the car used 2 years ago without knowing its service history or knowing what problem areas to look for.. OUCH.

The car now has 140k miles, The body and interior is still in great shape & the transmission is perfect. What would they be looking for in cost for a motor rebuild or replacement motor? I do not know too much about the 3.0 straight 6 engine, I have all V8 W126's.

Any help would be great.


M103s eat up heads (valve guides) and gaskets... I can't recall one instance where the block has failed FYI. The head must come off for the gasket replacement, and you're going to get a large snowball effect happen... many things will need to be replaced at the same time so parts cost will increase. Do NOT fail to have the head rebuilt at a machine shop, it will need stem seals and guides at least.

Will you be doing the repair (doesn't sound like it) or farming it out to a shop?

If to a shop... be ready, it won't be cheap due to increasing labor cost and cost of parts.
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I'm not a doctor, but I'll have a look.

'85 300SD 245k
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  #3  
Old 04-12-2009, 04:15 PM
126 Guy
 
Join Date: Sep 2005
Location: Queens, NY
Posts: 523
I was planning to tear the motor apart myself for inspection then start from there but I am still factoring out the cost of the whole engine rework vs. what the car is worth. I might just do a custom V8 sleeper swap with a newer mercedes 5.0 V8 & transmission & possibly making custom headers and a nice sounding exhaust
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  #4  
Old 04-12-2009, 10:43 PM
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Thats a bummer, but yeah it definitely sounds like the headgasket is shot.

I have a 300SEL as well (1988) with 156K, but thankfully I dont lose any oil or coolant. I dont have any service records with my car, but I am assuming it may have already seen some sort of replacement since I am not leaking or burning any oil. I just hope it stays that way.

Good luck.
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  #5  
Old 04-14-2009, 04:56 PM
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Question

So you'd rather spend time/money putting a Bent 8 into a car versus fixing what's already there? I'm not following this logic at all.
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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #6  
Old 04-14-2009, 07:50 PM
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Personally, I really like the m103 motor. Sure, it's a bit leaky, revvy, and so on, but there sure is a lot of room to work on one in a w126.

Just make sure that coolant is not getting into your oil galleys. That will rust the crap out of things and make the motor worthless.

If you do have coolant in your oil then ACT FAST before things rust.

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