[akimball442]

I got a free '73 450SL from my Uncle last year. I drove it up from NC after changing the oil and putting new tires on it. It sat since 1995 prior to that, and made the 800 mile trip in the pouring rain with little trouble, averaging 14 or so MPG. The car has approximately 190K. It's in very good shape- physically. The interior is above average, and the exterior is outstanding. Completely rust free southern car. Both tops are perfect, and all the trim is perfect.


Now that the car is safely home, it needs a ton of work.

This is going to be a long post, because I have a lot of questions/concerns.

I pulled it out of the garage last weekend, after I added transmission fluid to it because it would not move. The transmission fluid was found on the floor. So that's probably a hose or a bad gasket, I'm not really worried about that.

Last year before I put it up, it developed a violent shake when accelerating. There's also an occasional loud clunk that I can't seem to nail down. I'm not sure whether or not this is flex disks, center bearing, both... or:

Is it engine related? The engine seems to run fairly well- but this problem seems to only occur at lower RPMs. If you're going say 40 mph and push the pedal down, it'll shake like crazy accelerating. If you put it in manual 2nd gear at the same and the engine revs up, the acceleration is smooth. So maybe it's a motor mount?

About the engine. I know in the 126 forum, a lot of the guys talk about timing chains. Does this engine need the timing chain and guides replaced at an interval? I can be pretty sure if it has ever been done, it was a long time ago.

I am sure it should have the spark plugs changed, I've read on here to only use the old style plugs. Can anyone suggest a brand and part number for the correct plugs? I do not want to cause any damage to the electronics.

The electrical system is a nightmare, but I'll deal with that on my own- I'm not scared of wiring, motor-vehicle wiring is my thing.

I'm a competent mechanic with plenty of good tools, I'm not afraid to buy more if I need them. I'm also not scared of any job. But I have limited knowledge about this particular car, and I know from my other MB's that making a mistake would be more costly than just doing it right the first time.

I'm most concerned about the chassis/driveline noises, then the engine mechanical stuff.

Thanks

 

[isthisdave]

Plan on doing ALL the frame, mount, suspension, and driveline rubber. Even if your Uncle was a maintenance fanatic, sitting for nearly 15 years will have dried out every mount and bushing made of rubber. The clunk does sound like a motor mount, but I would determine its source and severity before driving the car again. A flex disc failure can be catastrophic.

Timing chain, tensioner, and upper guide rails should definitely be considered unless you can be sure Uncle did them. Yours may be early enough to have the original metal guides. Don't replace them with the new style plastic unless they are excessively worn.

Spark plug recommendations are like arguing about BBQ technique. There ain't no one answer. FWIW, I ran Bosch platinum in my '78 SLC for nearly nine years with nary a problem. Why some think newer technology an anathema I don't understand.

Congrats on the acquisition, and good luck!

 

[ussun]

I had the same vibration, it drove me crazy. It did end up to be the transmission mount.

About your timing chain yours is the the double row type and I don't think you should have any issue with it. They really are long lasting and all the single row guys scare you into getting done. But when I had mine all check out, my Indy MB guy said it looked "as new" so it was a waste of time and bucks.

It really does sound to me that you need to do is really check out your mounts.

Oh yay where in NY

 

[rowdie]

Definitely pull the valve covers off and check the chain, tensioner and guides. Mine was so loose and the guides so worn that the chain was slapping the head. '73 450SL and same was happening with the '72 450SL parts car.

 

[ScottinSoCal]

If you're going say 40 mph and push the pedal down, it'll shake like crazy accelerating. If you put it in manual 2nd gear at the same and the engine revs up, the acceleration is smooth. So maybe it's a motor mount?

Chances are good you need new motor mounts - the ones on there are either collapsed and ready to break, or broken already. They probably don't have anything to do with the shake; that's likely the transmission mount, as Dave pointed out.

About the engine. I know in the 126 forum, a lot of the guys talk about timing chains. Does this engine need the timing chain and guides replaced at an interval? I can be pretty sure if it has ever been done, it was a long time ago.

How long ago only counts on the guides, if they're the plastic ones. Miles and driving style count for the chain. You should get it checked. These engines are interference engines, and if the chain is loose enough to allow it to jump teeth, the pistons come up and slam into the valves. You wind up with a large, greasy paper weight where your engine should be.

I am sure it should have the spark plugs changed, I've read on here to only use the old style plugs. Can anyone suggest a brand and part number for the correct plugs? I do not want to cause any damage to the electronics.

Plugs and plug wires should be the original type. I got my from GermanStar, and the wires from another online vendor. I don't remember which.

 

[akimball442]

Is there a procedure for checking the timing chain? I know on some of the engines you set it to TDC and line the cam marks up... then see how many degrees stretched it is on the balancer pulley.

Is it different on this engine, if not, how many degrees are allowed?

 

[roncallo]

I got a free '73 450SL from my Uncle last year. I drove it up from NC after changing the oil and putting new tires on it. It sat since 1995 prior to that, and made the 800 mile trip in the pouring rain with little trouble, averaging 14 or so MPG. The car has approximately 190K. It's in very good shape- physically. The interior is above average, and the exterior is outstanding. Completely rust free southern car. Both tops are perfect, and all the trim is perfect.


Now that the car is safely home, it needs a ton of work.

This is going to be a long post, because I have a lot of questions/concerns.

I pulled it out of the garage last weekend, after I added transmission fluid to it because it would not move. The transmission fluid was found on the floor. So that's probably a hose or a bad gasket, I'm not really worried about that.

Most likely pan gasket to tight (lucky you) or trans front seal (not so lucky you, but a $5.00 part if you can do it yourself)

Last year before I put it up, it developed a violent shake when accelerating. There's also an occasional loud clunk that I can't seem to nail down. I'm not sure whether or not this is flex disks, center bearing, both... or:

Is it engine related? The engine seems to run fairly well- but this problem seems to only occur at lower RPMs. If you're going say 40 mph and push the pedal down, it'll shake like crazy accelerating. If you put it in manual 2nd gear at the same and the engine revs up, the acceleration is smooth. So maybe it's a motor mount?

You need to determine if this is misfire related of mechanical. A miss fire will not make a clunk but from 100's of miles away this sounds like 2 problems. Flex couplings and center bearing should be inspected as well as all mounts including the trans mounts.

About the engine. I know in the 126 forum, a lot of the guys talk about timing chains. Does this engine need the timing chain and guides replaced at an interval? I can be pretty sure if it has ever been done, it was a long time ago.

Your engine is an early M117 iron block. The timing chain should be replaced every 100K miles if the car was maintained well. Your engine originally came with phenolic backed metallic chain guides. If they have never been changed and are still serviceable you should not change those because the replacements will be cheep troublesome plastic. If they have been changed to plastic and you don't know if it was done less than 10 years ago then you should change these. I only change the tensioner on condition.

I am sure it should have the spark plugs changed, I've read on here to only use the old style plugs. Can anyone suggest a brand and part number for the correct plugs? I do not want to cause any damage to the electronics.

I cant speak for the early 107's but for the 560SL's the original copper core non-resistor plug is no longer available over the counter. There is a Bosch Copper plug available from MB at a huge price which is in my car now. From personal experience I have found no appreciable difference between the MB Bosch plug and the Bosch Platinum +4 available cheaply anywhere and that I used previously. I have seen many wives tales of negative stories about the Platinum +4 in other MB engines, but for the Alloy M117 5.6, I personally have seen no difference and I do believe I can go 60K miles as I do with my Fords, instead of 30K with the Bosch copper. With both plugs I can beat the advertised highway gas mileage of 17 if I go on a long trip. I have only run the Platinum +4's in the 1/4 mile and ran a 15.075, which is about a 0.5 seconds faster than any published data I seen for the 560SL. The car is bone stock with no resistor change or anything special, but I did do I first gear start.

The electrical system is a nightmare, but I'll deal with that on my own- I'm not scared of wiring, motor-vehicle wiring is my thing.

It's all relative. The electrical system in the 73 450SL is not a nightmare. The electrical system on a 1996 SL600 is a nightmare, see photos of all the wiring I had to install.

I'm a competent mechanic with plenty of good tools, I'm not afraid to buy more if I need them. I'm also not scared of any job. But I have limited knowledge about this particular car, and I know from my other MB's that making a mistake would be more costly than just doing it right the first time.

The 73 450SL was complex for its time but by today's standards it's as complex as 1993 Ford Taurus. But it does come from a different country where they do things differently.

I'm most concerned about the chassis/driveline noises, then the engine mechanical stuff.

Thanks

 

[roncallo]

Is there a procedure for checking the timing chain? I know on some of the engines you set it to TDC and line the cam marks up... then see how many degrees stretched it is on the balancer pulley.

Is it different on this engine, if not, how many degrees are allowed?

Look at post number 4. That will make a very distinct clunking noise the first time you start up in the morning. As the timing chain wears the noise will be heard when you start up at times of less than overnight rest. So if you hear the timing chain noise ever, its time for a new chain. Generally maintaining the car will get you about 100K miles without reaching ever getting to the noise stage. The markes are really just for assembly and to make sure you are in the ball park but they will also shift and when they are ~1/8 off you can assume the timing chain is stretching.

 

[rowdie]

Look at post number 4. That will make a very distinct clunking noise the first time you start up in the morning. As the timing chain wears the noise will be heard when you start up at times of less than overnight rest. So if you hear the timing chain noise ever, its time for a new chain. Generally maintaining the car will get you about 100K miles without reaching ever getting to the noise stage. The markes are really just for assembly and to make sure you are in the ball park but they will also shift and when they are ~1/8 off you can assume the timing chain is stretching.

I believe it is referred to as the death clatter. I had started hearing it on the '73 and luckily discovered a note about it by Tom Hundt on Mercedes Benz Tinkering. That was before I found the Forums.

 

[isthisdave]

Is there a procedure for checking the timing chain?

Why yes, there is.....


M116/117 Timing Chain Replacement

 

[akimball442]

It's all relative. The electrical system in the 73 450SL is not a nightmare. The electrical system on a 1996 SL600 is a nightmare, see photos of all the wiring I had to install.

Haha, perhaps I should be more specific. The wiring in THIS car is a mess. It's by no means difficult, I hope I didn't imply that. There's just some issues that need attention, like a cobbed up battery cable that needs to be replaced, and some fuses that continuously blow because of shorts in the fog light circuit... etc.

I'm not scared of the electrical system at all. It's very simple.

The SL600 wiring would be a project I'd enjoy

As for the timing chain, I think I'm going to just add it to the list. I don't want to wait until it sounds like it's going to come apart. The car is 36 years old, and it's possibly original. None of the service records indicate that it's been replaced.

It's going to be a busy summer

Thanks for all of the replies and information. I know more than I did yesterday.

 

[roncallo]

The SL600 wiring would be a project I'd enjoy

Are you sure. I went to hell and back last year with this and I don't recognize you as the gate keeper.

 

[akimball442]

Are you sure. I went to hell and back last year with this and I don't recognize you as the gate keeper.

Haha, I just love electronics.

I am a certified mechanic, I work for a bus dealership. The buses, like everything else, have gone to complete multiplexed electrical systems, much like your later model SL, and any new MB model starting with the model year around 1992. I think after 92, every model that was redesigned had the multiplexed electrical systems. The same is true for GM around that time, with Cadillac. Those systems moved to all of the lower end cars in one form or another with the 96 model year, and OBDII requirements.

Having said that, I don't think that any of it is necessary. The simpler systems were certainly more reliable, and inexpensive to repair in the event of a problem.

As long as there are cars, there is going to be government intervention, in terms of fuel economy requirements and emissions control. This is true among passenger vehicles and commercial vehicles alike. So the electronics underneath the hood are going to become more and more complicated as time rolls on. I think auto manufacturers should leave it there.

In my opinion, it's not necessary to consult a computer before lowering a window, and that's how multiplexing works. A direct wire to the window regulator seemed to work for 50 years...

But I don't mind working on the stuff. All circuits,when broken down, are very simple.

Still, you'll notice in my profile that the newest vehicle I own is a 1988 model Mercedes. I would still rather drive it than work on it.

 

[ussun]

I'm sorry, but john I just cann't look at this pic without laughing my as off.

 

[akimball442]

Why yes, there is.....


M116/117 Timing Chain Replacement

Perfect!

 

[roncallo]

I'm sorry, but john I just cann't look at this pic without laughing my as off.

Yeah, where was akimball442 when I was in the belly of the beast.

 

[daryn]

Damn Roncallo that's wild. I saw pictures once of a guy who put a r129 500sl engine into an SEC and it showed two handfulls of wiring on either side of the engine that needed to be sorted. That looks like patience maker.

 

[akimball442]

Yeah, where was akimball442 when I was in the belly of the beast.

I would have been happy to help

 

[Red_560SL_87]

Aaron

I will call you when I have electrical problems. If you ever drive the 450 down to the city drop on by. Would love to see it.

Bobby

 

[akimball442]

Feel free. I'd be happy to help. I don't expect you'll have too many electrical problems with the SL though. 80s' MB's seem to have very solid electrical systems.

I think my SL just had a few too many corner gas-station electrical repairs. Check the fluids, pump up a tire, twist and tape a wire....

There are a few people in NY. To answer an earlier question, I'm located in central upstate NY, between Utica and Syracuse.

I'm thinking there may have to be a NY MB GTG one of these days.