Head gasket or ??? - PeachParts Mercedes-Benz Forum

bgiovan · #1 12-15-2010, 08:13 PM

Picked up a 1979 300SD (W116 body) this past weekend 150,000 miles orig in really great physical shape (no rust, interior near immaculate). The only caveat is the previous owner had it overheat (badly they said) and rather than do anything about it, they sold it (to me thankfully).

No coolant in the oil as far as I can tell however with antifreeze replaced the thermostat never opens and the thing overheats within a 5-10 mins with the volume of white smoke increasing as time goes on.

So two things are in play here (at least). The (dreaded) Klima I is not working properly and needs to get addressed. The other is...is this a head or a whole motor?

Car starts and idles fine. When running for a couple of minutes the pressure really builds up in the expansion tank and when you crack the expansion tank the motor stumbles a bit. Put the cap back on and it regains its composure (but of course the pressure is building).

I have a 1980 in my garage torn down to the studs but motor and trans still in place. 175,000 miles and motor known to be fine.

I'd obviously rather not have to transplant the entire motor if possible but not too sure what my best course of action is.

Hopefully fellow Detroiter Roy will chime in here. I sold my 1987 300SDL to a guy who wanted it more than I wanted to keep it and this 1979 will be my daily driver.

Looking for suggestions. Don't want to spend a bunch of $ if I don't have to but conversely don't want to cheap out only to have to redo something later.

TIA. Happy Holidays!

Brian Carlton · #2 12-15-2010, 09:00 PM

Quote:

Originally Posted by bgiovan

The other is...is this a head or a whole motor?

Car starts and idles fine. When running for a couple of minutes the pressure really builds up in the expansion tank and when you crack the expansion tank the motor stumbles a bit. Put the cap back on and it regains its composure (but of course the pressure is building).

Odds are very good that you've got a blown head gasket. Of course, when you remove the head to do the gasket............you've got to ask yourself if you want to spend $150. or $1000.............or any amount in between.

The possibilities for doing the "while I'm in there" are seemingly endless.

bgiovan · #3 12-15-2010, 09:13 PM

Yeah Brian that is what I fear...the "while I'm in here I might as well just..."

Sending out the head and dealing with that is a given. I've resigned myself to that at least. I guess what would be a top 10 list while I'm in there with #1 being most important to hit while I'm there and #10 being "if I can get to it and not bankrupt"

Thinking timing chain is pretty obvious. I've never pulled the head on one of these so not too sure what I'll find. I guess get it off and judging by the condition of the head I'll know what lies ahead.

What other damage could have been done aside from the head?

I guess the saving grace here is that I have a known good motor in the 1980 so the head work will not be for naught. But I want to do it in the least amount of moves!

Brian Carlton · #4 12-15-2010, 09:19 PM

Quote:

Originally Posted by bgiovan

Yeah Brian that is what I fear...the "while I'm in here I might as well just..."

Sending out the head and dealing with that is a given. I've resigned myself to that at least. I guess what would be a top 10 list while I'm in there with #1 being most important to hit while I'm there and #10 being "if I can get to it and not bankrupt"

Thinking timing chain is pretty obvious. I've never pulled the head on one of these so not too sure what I'll find. I guess get it off and judging by the condition of the head I'll know what lies ahead.

What other damage could have been done aside from the head?

I guess the saving grace here is that I have a known good motor in the 1980 so the head work will not be for naught. But I want to do it in the least amount of moves!

My "while I'm in there" list included the following:

Replacement head (original was cracked)

New exhaust valves, valve seats, valve guides, valve seals, prechambers (at Metric).

New head bolts.

Bosch rebuilt starter.

New gasket for oil filter housing.

I spent over $1200. on it.

Turning the key at 0°F in a hotel parking lot and having it run like it was 70°F: PRICELESS

GregMN · #5 12-15-2010, 09:28 PM

I can swap out the drive train in about the same amount of time as R & R a head.

I would swap in the known good engine.

bgiovan · #6 12-15-2010, 09:31 PM

Yeah Greg, that had crossed my mind also and as I type I'm starting to lean in that direction. Put the known good motor in it and take my time to completely rebuild the other one. Only problem is the good motor is still in place in the 1980, in the garage, and its freaking 10F outside. Couldn't do this in June right?

Let me ask, I've heard it both ways...easier to pull just the motor or both motor and trans and reinstall as one?

bgiovan · #7 12-15-2010, 09:39 PM

Brian, what is the link to Metric. I've heard that name before but can't quite put my finger on it. Thanks!

Brian Carlton · #8 12-15-2010, 09:42 PM

Quote:

Originally Posted by bgiovan

Brian, what is the link to Metric. I've heard that name before but can't quite put my finger on it. Thanks!

http://www.mercedesengines.net/

My strong advice is to use them if you decide to do any work on the head. Plenty of folks ignored that advice and found out the hard way how much oil a 617 can really consume if a moron does the job.

bgiovan · #9 12-15-2010, 09:47 PM

That's what I heard also. Too funny. This place is about 15 mins from my sister's house in LA. Sounds like I have a parts runner!

Brian Carlton · #10 12-15-2010, 09:48 PM

Quote:

Originally Posted by bgiovan

That's what I heard also. Too funny. This place is about 15 mins from my sister's house in LA. Sounds like I have a parts runner!

Definitely........out there, you've got no decision.

However, people on the east coast don't want to spend the extra $130. for round trip shipping of the head.

Worst savings of money they ever did.

bgiovan · #11 12-15-2010, 09:51 PM

I've got an office in LA and travel out there with some frequency. In fact going out in January. Wonder how the TSA will feel about me taking a head as a carry-on?

bgiovan · #12 12-15-2010, 09:54 PM

Just did a mapquest for grins. It is 4.6 miles away from my sister's house. Hilarious!

DieselPaul · #13 12-15-2010, 10:25 PM

A guy came and bought wheels from me, he had just put a Metric head on a 300TDT, he had fantastic things to say, the head was immaculate and the thing ran perfect.

Have you tried running the car without the thermostat? sounds like the thermostat is bad if its not opening when the motor is hot. A stuck thermostat will make for pressurized lines and overheating. Been there, done that. Just take the thermostat out and see how it runs.

Edit: I just reread your original post, yeah that sounds like HG.

bgiovan · #14 12-15-2010, 10:34 PM

I see you're in C-bus so you know the hell we're living thru this time of year. Need heat now so want to get that resolved while the head is out for repairs. Another project for a warmer time of year is to get the climate control sorted. Acquired a Euro 1978 280SE gasser a couple of years ago. Has manual climate control and crank windows. Main reason for that acquisition was to yank out the dreadful Chrysler Airtemp/Klima I and put in good old standard manual climate control. That's one devil on one shoulder. The other says I need to keep it as is and just bite the bullet and do the Unwired Tools conversion http://unwiredtools.com/accii.asp

Head now and heat. My main two concerns. Then tackle the overall climate control in the spring. Judging by the looks of things, being a Florida car with a responsible owner, the AC compressor looks brand new so I'm thinking it's had some really recent work. Who knows?

For now...head!

GregMN · #15 12-15-2010, 10:42 PM

Easier to pull the engine and transmission as a unit. That is how the factory service manual says to do it and that is how I have done it 4 times.