Mechanic woes

[Hornnumb2]

Ok I have a 1980 450SL that has been sitting for 10 years, So far we have flushed the tank and replaced the full pump to get it to run. It drives but doesn't have the power it should. I have been to 2 different garages and one told me that the timing chains are streched causing the loss of power and the other garage told me it has 2 fuel pumps and to check the other pump? I couldn't see another pump, does anybody know if that is true and where it is located. Thanks for any suggestions...Michael

[t walgamuth]

fuel filter? air filter?

tom w

[t walgamuth]

also check ignition timing.

tom w

[450slcguy]

Originally Posted by Hornnumb2

Ok I have a 1980 450SL that has been sitting for 10 years, So far we have flushed the tank and replaced the full pump to get it to run. It drives but doesn't have the power it should. I have been to 2 different garages and one told me that the timing chains are streched causing the loss of power and the other garage told me it has 2 fuel pumps and to check the other pump? I couldn't see another pump, does anybody know if that is true and where it is located. Thanks for any suggestions...Michael

1980 - One pump, one timing chain.

[ctaylor738]

One pump.

Chain stretch is easy to check, as is timing, mixture, and fuel flow. Lots of posts on all of these.

Is your air sensor plate moving freely? If it is sticking, the engine will not get enough fuel when you hit the throttle. Another possibility is that the warm-up-compensator is not providing enrichment under load. Re timing - what sort of advance are you getting at 3000 RPM? Are you getting a good snap from the vacuum advance when you blip the throttle?

[Earlybird]

Try some injector cleaner and check your vacuum to see if there are any leaks. If that dosen't work, attach a fuel pressure meter just before the fuel injection system and compare the actual PSI with the PSI in the book. If you are low, Keep looking at the fuel pump, the fuel filter and the return line pressure regulator.

[MattBelliveau]

I would imagine that after sitting for 10 years, an entire tuneup would be in order.

[page62]

Probably clogged injectors, or a weak spark.

Apparently you ran into 2 mechanics that were talking out of their you-know-whats...

[KCM]

Originally Posted by Hornnumb2

I have been to 2 different garages and one told me that the timing chains are streched causing the loss of power and the other garage told me it has 2 fuel pumps and to check the other pump? I couldn't see another pump, does anybody know if that is true and where it is located.

The 560SL does have two pump. The mechanic got his models mixed up.

Do a full tuneup before jumping to conclusions: filters, plugs, timing, fluid changes, maybe spark plug wires depending on their condition. Check the belts, distributer cap, and rotor while your at it. Injectors might very well be clogged. Run some injector cleaner through it or take the injectors out and clean them. How is the muffler? If it is rusted up, might be falling apart inside and restricting the exhaust system. Check for any cracked hoses in the intake and injector system that might be sucking air past the air sensor plate. Good luck.

[kip Foss]

Modern fuels do not last. They start getting gummy after a few months and after 10 years have probably set up like glue. I would go through everything that contained fuel from the tank to the injectors, fuel distribution valve included.

Where are you located? There is a German certified MB mechanic near San Antonio, Tx. that rebuilds fuel valves for about $250 last I heard.

[cth350]

The warmup/enrichment compensator has to be cleaned and probably replaced, as a used one is cheap enough. The thing makes a huge difference in the car's performance. Sluggishness and a positive unwillingness to accelerate are symptoms of this part being screwed up.

The way to tell is with a pressure gauge. Any mechanic that doesn't know that shouldn't be working on this car for you.

As I'm typing this, the banner at the top of the page is advertising the Unwired Tools UTIC regulator. That's a very effective replacement part and is much cheaper than a brand new factory part.

Start with a used one or getting yours cleaned by somebody that knows what they're doing.

-CTH