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1985 380sl
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26 Posts
Discussion Starter · #1 ·
I just traded my old Coleman camper for what I believe to be a pretty decent '85 380sl. I am looking for a good place to possibly buy some engine parts. My car runs and drives but has a lot of miles, 334,xxx, and it smokes. I'm trying to decide if I want to rebuild the engine or replace it. I am also interested in whether or not I can replace the current 3.8 v8 with a larger v8 from a different model MB. Any info would be greatly appreciated.
 

· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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1993 600SL, 1973 450 SL,1998 SLK 230,2018 C300, 2019 Ram 1500 Laramie, 1968 Firebird,
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Don't even think about rebuilding that engine. You'll have 3 to 5 grand in it. I doubt you could do it for less. And those 3.8's weren't particularly desirable. ! Find a takeout, preferably a 4.5, 5.0 or 5.6. Rowdie can fill you in on all the nuances. Unless you have cash to burn, or a major love affair with the car or your own machine shop that's your only way out !
 

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560SL,380SL,E350
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4,406 Posts
I just traded my old Coleman camper for what I believe to be a pretty decent '85 380sl. I am looking for a good place to possibly buy some engine parts. My car runs and drives but has a lot of miles, 334,xxx, and it smokes. I'm trying to decide if I want to rebuild the engine or replace it. I am also interested in whether or not I can replace the current 3.8 v8 with a larger v8 from a different model MB. Any info would be greatly appreciated.
I find this very inspirational - that is the highest mileage I've seen on a 116 engine. the PO must have taken very good care of it. I am rebuilding an engine that I believe has ~100K EXCEPT for the holes and bearings, and I hope to get 250-300K before it needs a short block rebuild.

Do you know if it ever had a valve job? Does it smoke all the time or just a lot on start-up?

Unless the car is in INCREDIBLY well maintained condition (and at that mileage, things that you don't think wear out do), I doubt if it is worth a rebuilt engine. It is getting tougher to do, but there are still engine blocks from late 80's/early 90's SEL's with <125K miles that can work, if the oil pans and oil filter pedestals are swapped. The 420SEL has a 380's M116 short block bored out a bit and with a little higher compression. You won't wind up with a performance car out of this, but it will be drivable and a little faster than a 380...

Swapping in a 560 is much more involved because of the control systems involved - people on the W126 forum have done it but actually acquiring a 560SL or SEL is easier...
 

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1985 380sl
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26 Posts
Discussion Starter · #6 ·
Alright, you guys have so far been a big help.
First, I will get my profile filled out so you know more about me.
Second, I don't know if it has ever had a valve job. I have a lot of service records for the car but they all seem to be from a later owner since they start in the early 2000's. One of the receipts does say it needed valve seals and should be running 20w-50.
Third, this is going to be a weekend toy for my wife and me, not a daily driver.

I am mechanically inclined (I actually own a tool repair business and have rebuilt one other engine in the past) so I think I could handle valve seals. I know a decent machine shop in my area and I'm sure they could do guides for me. I just want to get a little advice before I spend that money.

I did add a quart of Bardahl engine oil treatment and it cut the smoking down pretty good. Any more advice would be greatly appreciated.:)
 

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560SL,380SL,E350
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4,406 Posts
Generally, when the valve seals on these go bad, the valve guides are not far behind.

Replacing the heads on these engines is not trivial and rebuilding them is not that easy. Even if you pulled them and had the heads done, there are a lot of "while you are in there" parts that can easily add up to (another) high three figures. Most of the rubber and vacuum lines will not survive being disturbed while the heads are removed. Then, there is the issue of helicoiling (actually, timeserting) the block because the screws holding down the heads screw into the raw aluminum in the block. Sometimes, you can get away without it; sometimes, you might be tightening the last bolt, you can't get to torque, and now you have to do the inserts anyway AND you ruined a $60-$90 head gasket. I've done the time-serts with the required jig (which is a fairly rare and expensive tool) and I don't see how anyone could do this while the engine is in the car.

The W126 forum is worth looking at and searching through because they have a lot of hard-core engine guys on there. One guy with a very respected shop trusts only a very small number of machine shops because of longevity issues. Anyone can do a valve job. Far fewer can do a valve job that lasts 150K miles.
 

· Registered
1985 380sl
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26 Posts
Discussion Starter · #8 ·
Took the 380 to the muffler shop to have the hacked up exhaust system repaired. Now it is much quieter. Someone before me had done a terrible job of "fixing" the exhaust.

Once I got it home I was able to get a better look at the car and check out all the little intricacies of the car. I noticed the sun visors are missing (weird), the door locks don't want to lock, and the round chrome over the trunk lock button is missing. Now I can't open the trunk! Any ideas of how get it open? The tumbler is still there but I can't get the key to go in far enough to actually turn it.

Also, in the instrument cluster there is a dial that has a 0,1,2, and 3 on it right above the oil gauge. What does this tell me?

Thanks guys! Your being very helpful and I appreciate your patience.
 

· R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s ALL SOLD
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32,794 Posts
That is your oil gauge. Pressure reading in bars. 1 bar = 100kPa = 14.7psi I think.
Sun visors self-destruct. They were cheap crap.
Door locks operate off vacuum. You probably have a leak. What does the economy gauge read at idle? It should be pegged to the left.
 
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