1968 280SL Engine Head Cracking

[Bill Aldridge]

I've owned my 280 SL since 1980, and in about 1990, I experienced oil in my coolant.  I ended up pulling the head and taking to the #1 rated Engine/Head shop in Portland, Or.  They did a pressure test, and discovered a crack, which they welded.  They advised these Mercedes heads have a problem with cracking because the aluminum becomes brittle.  Further, that rebuilders will stencil a Letter, starting with A for the revision of rebuild/weld.  MMMM?

They completely rebuilt the head and I installed it, and all was great.   Fast forward to about 2005, after the car had been in storage for about 10 years, and when I started it, yup...water in the oil.

So, Is there any truth to "rumor" of these heads being brittle, and prone to cracking?  If so or not, or if anyone has a similar experience, may I ask for your feedback.  Thanks,

Bill

[Vander]

In my personal experience no the heads are not brittle, there is a minimum thickness specification the head needs to be which will tell the machinist if there is enough material to work with.

Not saying there is not another issue, but 10 years in storage will cause condensation to form in the oil. I have seen some Mercedes sit so long, they condensate and mix with the oil turning a milky white.

I would recommend changing the oil, filter, and the filter upper seal. Drive the car, put some miles on it and then re-check it.

[rwmastel]

Per usual, Vander gives good advice.

If I understand your post, this is your timeline.  Please correct me if I'm mistaken.

1980: purchased car, used the car (Regular basis?  About how many miles per year?)
1990: oil/water mix, cracked head, rebuilt the head
1990-1995: used the car (Regular basis?  About how many miles per year?)
1995-2005: car sat unused
2005: oil/water mix found
2005-2023:

Curious about the last 18 years.

[MikeSimon]

You should never run a car that sat for 10 years without changing the oil first. If the car just sits, oil and water- even from condensation- does not mix into a milky white. That only happens if you pump the oil through the system by running the engine. When sitting, the water, being heavier than oil, settles on the bottom of the sump. If you have enough water/moisture in there the mix will get to your main/rod bearings and they will fail.

[Bill Aldridge]

rwmastel, et al:  Did you receive my reply to the Date range?

[rwmastel]

Bill,

No, I don't see it in this thread.  Just your first message and the one above.  Even your profile next to the message says 2 posts.  Did you get distracted from writing?  I've found that if you get pulled away from your computer or phone while drafting a message, come back later and finish & click "post", you've timed out and your message can be lost.

[Bill Aldridge]

Dang...I put in two pictures of my 280, which may have been too big.  In general, my timing was off a bit.

1985: The first head crack & repair.  I drove the car only in good weather, so maybe 6,000 miles/year.
1988: Divorce: She got the 300CD and I got the 280SL. 
1988-1995: Drove only in Sunshine, so about 1,000 miles/year.
1995: In spring, checked all the fluids, including oil condition and fired it up as usual, and discovered the oil in water after a few minutes.
1998: Moved it to a friend's garage for storage
2004: Got married!
2005: Move car to my garage for storage since then.  Too many rental houses to fix up and rent, work, etc..
2023: I want to get it back on the road, but want the engine rebuilt, as well as the transmission.  I've learned a lot of people are recommending Metric in California, and a few have also refereed me to Burback Motors, in Portland, OR.

It now sounds like my head is an anomaly.   Thanks for your questions! 

[Bonnyboy]

I would expect that the head cracked from running out of coolant and overheating rather than being made of brittle material. 

Nice car beside   - 69 Barracuda?

[Bill Aldridge]

It never got hot, I’m a gauge watcher!  😀

Yes, 1969 Formula S, 340, 4 speed console , owned since October 1971, cousin bought it new. 

[Benz Dr.]

These heads are far more prone to warping than they are to cracking. I can't remember ever having to repair any cracks but I've fixed plenty of corroded or warped heads.

[Bill Aldridge]

I am working on securing a Portland Shop to pull the Engine and send it down to California for rebuild.  During this process, I was advised this supposedly "best machine shop in Portland", (which I used for the weld job) wasn't used by any of these shops.  Interesting.

Now, I need to find a worthy shop to rebuild my 4 sp auto transmission.  I'll check out previous posts, but if all y'all have "the best shop" on the tip of your tongue...I'd be thankful.

[rwmastel]

Many people recommend Sun Valley in Pacoima, CA, but I'm sure there's others to consider.
https://www.mercedesdismantlers.com/

Reading their web site, it says "We sell our transmissions on an exchange basis."  Is there anything uniquely identifying our transmissions to our chassis?  I don't recall any transmission number, like there is an engine number.  Or, a chassis or production number being stamped on the transmission.

[Pinder]

Rodd

   on my 1970 280SL data card box 11 Getrlebe-Nr  : 006310    and it matches the stamped number on my gear box. This is a 4 speed stick.

Regards

[Benz Dr.]

Many people recommend Sun Valley in Pacoima, CA, but I'm sure there's others to consider.
https://www.mercedesdismantlers.com/

Reading their web site, it says "We sell our transmissions on an exchange basis."  Is there anything uniquely identifying our transmissions to our chassis?  I don't recall any transmission number, like there is an engine number.  Or, a chassis or production number being stamped on the transmission.

The 230SL and the 280SL are different units.

[rwmastel]

On my 1970 280SL data card box 11 Getrlebe-Nr  : 006310    and it matches the stamped number on my gear box. This is a 4 speed stick.

OK, that's box 6 on my data card.  So, I wonder if in "matching numbers" cases if Sun Valley will give you back your own transmission?  I think I'll give them a call, because that's who I was planning on using.

[MikeSimon]

Isn't the tranny number on a riveted plate?

[Bill Aldridge]

Rodd,

Thank you for the heads up on the Transmission Shop.  I'll wait to hear your comments based on your phone call.  Bill

[rwmastel]

Thank you for the heads up on the Transmission Shop.  I'll wait to hear your comments based on your phone call.  Bill

Just got off the phone with Mark from Sun Valley.  Great guy to chat with.  (Note:  There is a Sun Valley Transmissions up by San Francisco/Oakland and they only do American cars.  You want the one near Los Angeles.)  They aren't doing as many classic car transmissions as they did years ago, but they still do them and know them well.  I asked basically what they do, and he said:
- Completely disassemble, inspect, and clean everything.  All gears, mechanisms, and everything comes out.
- Check fluid coupler for leaks.
- Re-machine drums if needed.
- Send out bands for relining (great place in Arkansas that has best materials).
- New clutch.
- Replace all gaskets, seals, o-rings, etc.
- Lubricate all the internals in case the transmission has to sit a while and wait for the rest of the project to complete.
- Factory parts only, no aftermarket.
- Bench test for 30 minutes.
- 3 day process for technicians to complete (compared to 1 day process on modern transmissions).
- 2 year, unlimited mileage warranty.
- For classic cars, they will rebuild your transmission and return it back to you.  No exchange.
- $2550 for the automatic in my 230SL.

If you're getting your engine rebuilt by Metric Motors, they are about 10 minutes away from each other.  You can crate everything together on one pallet and ship it to Metric, and then Sun Valley will drive to Metric and pick up your transmission.

Isn't the tranny number on a riveted plate?

Yes.

[Bill Aldridge]

Rodd,

That price is very inexpensive! Thank you for the long exploitation, and yes I would want mine rebuilt and not exchanged.   I'm going to call Mike at Metric and ask his thoughts...for us Both!  Did Mark say anything regarding any differences in a 230-250-280 4 speed automatics?

I'm getting some large estimates for some of the pieces (if need of repair) from Burback.  Anywhere from $500 to $5,000 on the transmission! Up to $5,000 for fuel injection? 

I'll nail them down on these estimates, as a lot has to do if the cores are good.  The radiator and oil cooler at $4,200 or $4,400 to rebuild/replace? 

I know it's expensive, just want all these bits to be in the ball park.

[rwmastel]

Did Mark say anything regarding any differences in a 230-250-280 4 speed automatics?

I did not ask.