1972 350SL Questions - PeachParts Mercedes-Benz Forum

DieselPaul · #1 03-23-2011, 12:34 PM

I just bought a 1972 350SL, which supposedly is a euro, it has euro bumpers and hubcaps, aside from that I don't know how to prove it is a euro. It has federal headlamps.

The car was parked, running, two years ago. However it has not been started since, I bought the car as a non runner and towed it home. My plan was to pull the valve covers and rub some oil on the cam lobes, pour some oil down the chain, and probably change the oil totally. With the valve covers off the cams look pretty good, no obvious wear, though everything is very dry. The chain also looks good, but when I touched it, you can pull up on the top half of the chain, like pulling it up away from the guide rail. It is tight on the bottom side of the cam gear. So the top half has play, and the bottom half is tight. Is this normal? I've never had an OHC mercedes V8, so pardon my ignorance.

Also, can anyone tell me what spark plugs this motor takes? It has a set of bosch platinums in it right now, which I can't tell if they look worn or not, but regardless I don't believe platinums were OE on a '72. When I had the two plugs out I sprayed some fogging oil into the cylinders.

The car came with a list of about $9,000 worth of stuff it needed from a European Indy in town, including $1,600 for a driveshaft... the flex discs just look iffy. Things like a leaky steering box and mentionned, and the A/C compressor, etc but there is no mention of anything on the motor so *hopefully* the motor is in running order.

dugald · #2 03-23-2011, 05:14 PM

All SLs of that age had "euro" bumpers and hubcaps, whether sold in Europe or NA.
I believe the euro-market car had a 350 engine and the NA a 450, even though both were originally badged 350SL. The engine number should distinguish between them but I don't remember the respective engine codes.
You can ask the MB Classic Centre to decode your VIN.

Bogeyman · #3 03-23-2011, 05:32 PM

VIN beginning with 107044 is a USA model with 4.5 liter engine. If it begins with 107043 it is a euro model with 3.5 liter engine.

bwostosh · #4 03-23-2011, 06:34 PM

You can certainly beat those prices.
Plugs W7DC Bosch or NGK equivalent.
Can you do the work yourself?
Steering box, motor mounts driveshaft?

DieselPaul · #5 03-24-2011, 04:48 PM

VIN is 107 044. So it is a US car.

I oiled the cams up today, and put in a new set of NGK plugs. It started for a second then died, it was running on the fogging oil in the cylinders.

When cranking it makes nearly 45psi of oil pressure, which I imagine is a good sign.

However it does not run, I popped the plugs out and they are bone dry. I gather I am not getting fuel, I am off to work now though and don't have time to try to diagnose more.

The good things are it isn't locked up and it is sparking because it did run briefly.

Also, a guy walking by who claims he used to work for MB said these motors go through timing chain tensioners, and my original post mentions I notice so slack in my chain, but no obvious wear. Is it possible I need a tensioner? Where is it on the car? People talking about them online seem to make it sound easy to get to, but I can't find a photo.

rowdie · #6 03-24-2011, 05:37 PM

2 Bolts. Guides are metal and should not be a problem.

Walrus · #7 03-24-2011, 08:29 PM

Quote:

Originally Posted by DieselPaul

...tensioner? Where is it on the car? People talking about them online seem to make it sound easy to get to, but I can't find a photo.

http://www.startekinfo.com/StarTek/outside/11883/?requestedDocId=11883

Online manual at this link

Previous rant deleted...

Edward Wyatt · #8 03-24-2011, 09:04 PM

I would get rid of the platinum plugs and use NGK BP5ES plugs, you can get them for about $2.00/ea and they are non resistor and work very well. Sorry, didn't read all the way through before posting

One thing to be very wary of is the rubber fuel hoses under the air cleaner, they can and will leak. Usually they leak on cold start and quit when the engine warms up.

Edward Wyatt · #9 03-25-2011, 02:58 AM

Quote:

Originally Posted by DieselPaul

VIN is 107 044. So it is a US car.

I oiled the cams up today, and put in a new set of NGK plugs. It started for a second then died, it was running on the fogging oil in the cylinders.

When cranking it makes nearly 45psi of oil pressure, which I imagine is a good sign.

However it does not run, I popped the plugs out and they are bone dry. I gather I am not getting fuel, I am off to work now though and don't have time to try to diagnose more.

The good things are it isn't locked up and it is sparking because it did run briefly.

Also, a guy walking by who claims he used to work for MB said these motors go through timing chain tensioners, and my original post mentions I notice so slack in my chain, but no obvious wear. Is it possible I need a tensioner? Where is it on the car? People talking about them online seem to make it sound easy to get to, but I can't find a photo.

Try seeing if you can hear the injectors clicking, but first check the fuel pressure by using a "t" fitting on one of the fuel hoses under the aircleaner. You should have around 28-30 psi, if not whack the fuel pump with a rubber mallet. Chances are it's stuck.

If you do have fuel pressure, and the injectors are silent then you might consider cleaning the trigger points in the distributer.

My money is on the fuel pump, imho.

JimFreeh · #10 03-25-2011, 05:58 AM

Quote:

Originally Posted by dugald

All SLs of that age had "euro" bumpers and hubcaps, whether sold in Europe or NA.
I believe the euro-market car had a 350 engine and the NA a 450, even though both were originally badged 350SL. The engine number should distinguish between them but I don't remember the respective engine codes.
You can ask the MB Classic Centre to decode your VIN.

A quick give-away is to look for bumper guards.
If present, then it's a US delivery car.

Jim

DieselPaul · #11 03-25-2011, 11:00 PM

Updates!

I DID put the NGK plugs in it before I tried to start it, so we are good on that front.

The car will now fire like 2 or 3 times if you try to crank it after its been sitting on the charger for a while. I tapped the pump with a hammer before this started happening.

I had my girlfriend crank the car while I was under the hood, I hear the injectors clicking.

Laying under the car I don't really hear the pump. I would believe the pump may be moving a minute amount of fuel and thats why it can kind of start for a second. But I'm not getting fuel through the injectors, and the tap trick didn't fix it, so I think its time for a pump.

Uploading pictures now!

DieselPaul · #12 03-25-2011, 11:04 PM

As I picked it up,

Washed,

Let the waxing begin!

DieselPaul · #13 03-25-2011, 11:10 PM

The chrome is coming back well

Edward Wyatt · #14 03-26-2011, 09:50 AM

That's one sweet looking 350SL, kudos to you for saving it from a user-uppper owner.

The injectors clicking is a real good sign, but please look over the short fuel hoses that run to each injector from the fuel rail. They are about an inch and a half long and tend to weep on cold starts. One of the reasons MB switched to CIS injection in 1976 was because of the numerous engine fires from thes hoses leaking and owners not replacing them every few years. I hate to soud like a nervous nellie, but I once saw a 1972 280SE 4.5(same motor) burn to the ground in front of me because of that and when I had a similar model myself I found that three years was the lifespan of the hoses.

Graham · #15 03-26-2011, 10:43 AM

Quote:

Originally Posted by DieselPaul

Laying under the car I don't really hear the pump. I would believe the pump may be moving a minute amount of fuel and thats why it can kind of start for a second. But I'm not getting fuel through the injectors, and the tap trick didn't fix it, so I think its time for a pump.

I would remove the pump and filter first. The pump may need cleaning but I doubt it is bad. The pump can be cleaned and the filter should be replaced anyway. There is a thread on Benzworld on how to dismantle the pump.

With these cars, when you turn the key on, the pump only runs for a few seconds and then stops. It only starts up again once the engine starts. To check the pump, you need to jumper the fuel pump relay. The relay is located near the fuse panel in the passenger foot well. The other way, is to connect 12v power directly to the pump terminals.

If you do either of the above and remove the return line to the tank from the exit of the fuel pressure regulator or damper. You can run the pump and check that it has proper flow (1Litre in 30 sec).

You should check your fuses - there is a fuse for the fuel pump. If the fuse is good, your problem could also be the fuel pump relay. Jumpering it will overcome this temporarily. (Pins 1 & 3 need to be shorted on 5 pin relays, I believe)

This thread shows where my 72's relay is as well as other stuff:

http://www.benzworld.org/forums/r-c107-sl-slc-class/1481216-testing-fuel-pump-early-djet-107s-2.html