New member needing input

[rwolak]

Hi, i'm a new member to this forum and am in the process of looking at a '73 450SL for possible purchase. The car has 114K miles and has been stored in a garage for the past 14 years. I have a lot of experience with old BMWs (E9 & E24) but would like to know what to look for in this Benz? I know they are prone to rust but I'm more interested in the mechanicals. oh, by the way, I could probably buy this car for $5000. Is the price worth it, assuming the car is in reasonable condition?

TIA
Bob

[ctaylor738]

When you say "stored" do you mean "not driven"?

[rwolak]

Yes, basically the car sat in, what i've been told was, a heated garage since 1990. I don't know if it was ever started. The car was purchased as part of an estate sale and the new owner is selling the car. It was driven from the garage to the current owners location. I guess my biggest concern is, if the car wasn't moved since 1990, what are the chances that leaks from seals, gaskets, etc. could start occuring once the car is driven on a regular basis. I know this does occur, but am wondering if anyone in the Mercedes world has had experience with this.

[ctaylor738]

There's plenty of experience.

I would say that first on the agenda is to find out if the motor will turn over. If it is frozen there is a very good chance that you will get it running but that it will need rings or another engine.

Gas turns to peanut butter after a few years.

Next, you will have to clean the entire fuel system including tank, filter, pump, metal lines, fuel rails, etc. You will need to replace the rubber and fabric lines that connect the stuff in the rear. The pump may be clogged and beyond repair.

You can then change the oil, I would try heating up what is in the crankcase with a heat gun first, and you need to hope that the pickup screen is not clogged because you need to lift the engine to get the pan off. You can then start the engine and find out (if it has oil pressure) that it smokes like crazy because the valve seals are dried out.

Then you will almost certainly have to replace the brake calipers and hoses and do a thorough flush.

Then you can drive the car and see if the transmission still works and find out what leaks.

Coolant hoses will need to be replaced.

Then you can sort out the suspension issues.

Then, if the car is in average condition, you will have a $5000 car. And a lot of satisfaction that you brought one back.

[rwolak]

Really appreciate the input. I know the engine turns over because the current owner drive it to his house. However, the car apparently is not running now because of a weak spark condition. Plugs, wires, points, rotor, cap and condensor have all been changed. If I'm not mistaken, the current owner said he also changed the coil. As far as I know, there isn't much left in the ignition circuit that would cause a weak spark. If you, or anyone else has any ideas, i would greatly appreciate any input. I still haven't seen the car so I don't know what condition (physical) it is in.

TIA
Bob

[ctaylor738]

The '73 ignition (I think) had a transistor box - a big silver thing on the left fender, which can go bad. I think the power supply to the coil has two ballast resistors that reduce the voltage to the coil and they have also been known to fail.

[benzzmann]

my advise to you , dont buy this car, 73 450 SL has the worst electronic fuel injection system, they change them in 76 to mechanical

[rwolak]

All have provided good advice.

BENZMAN--when you say they have the worst electronic fuel injection system, what seem to be the problems with them?

[benzzmann]

you might want to check the trigger points, thats why the car wont cranck, its outside the distributer

[rwolak]

for asking so many questions, but I am completely new to the SL. I've done a lot of work on BMWs, but never MB. Also, since I'm only looking at this car for possible purchase, I don't have a manual.

When you say "trigger points" are you referring to a sensor on the crank for timing? Now to ask the stupid question----would you happen to know where these "trigger points" are located?

Again, any help is greatly appreciated!!!

TIA

Bob

[ctaylor738]

There is a second set of points (2) under the ignition points. They basically tell the injection system how fast the engine is turning to regulate fuel flow. They can get gummed up from oil vapors.

Try a search - tons of posts on them

[Richard Wooldridge]

Hi there,
That model car has a contact on the starter solenoid to bypass the current dropping resistor in the supply line to the transistorized ignition module when starting, it could be that the contact isn't making when the starter is engaged, which would make for a weak starting spark.
The distributor actually has FOUR sets of what Mercedes calls "release" points under the ignition points plate. They cause the injectors to fire in pairs of two. If one set of points doesn't make contact, the engine will miss on two cylinders because two injectors aren't working.
I would jumper out the ballast resistor while cranking and see if the spark is then hot enough to fire off the engine. Don't leave it jumpered as the ignition module could be damaged if it is left jumpered for any length of time while running.
I wouldn't be afraid of the earlier injection, it works well when in good shape.

[rwolak]

Sounds like the trigger points, at least, can be cleaned. Since the car has sat since 1990, its a good chance they have "hardened gunk" on them

[benzzmann]

Sorry for not getting back to you sooner, kids are home for spring break, the trigger points are located under the ignition points in the distriputor plate, I am sure if you clean them might work since the car sat that long, good luck