AboutRon Expertise I can answer questions on W114/ W115 /W107/W126 Mercedes models 1967-1985. I have rebuilt many of these cars and have problem solved many issues. I have access to much of the technical data and have deailed instructions on fixing the most common issues.
Vintage US and other foreign cars as well
Expert: Ron Date: 6/27/2008 Subject: 1979 Mercedes 450sl
Question QUESTION: I have owned a few classic cars but never a foreign model. I just purchased a 1979 mercedes 450sl for $2500. It appears to run very well. But, there are a couples of holes in the exhaust pipe just before it enters the muffler. The engine has 175xxx miles. The heater is not working but the owner provided the heater part. Everythingelse seems to be working. If you were just buying the car. What things would you check and what are common issues with this year and model?
Thanks, in advance
ANSWER: rust is the first thing, under carpets, floor boards, trunk wells, then I would turn my attention to anything rubber under the hood, these gals run hot and rubber gets brittle, they are prone to vacuum leaks and this is the ususal culprit. Depending on the service history many other items should be checked including plugs, injectors. Heater issues are common, did he give you a new servo? Exhaust is easily fixed, give it a good going over and let me know what you find, I have rebuilt several so I can probably help
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QUESTION: I am having a problem with acceleration. The compression has been checked it's fine. Newer spark plugs wire and caps and rotors. Heater is removed but no apparent vacuum leaks there. idles ok but around 3 rpm's it hesitates. I will replace the fuel filter near the tank. No apparent vacuum leaks. I have heard that cam shafts are a problem with this unit. But, i have been told that it idols to well to be a camshaft. Any recommendations?
ANSWER: hesitation on acceleration can be due to several factors. Changing fuel filter is a good start, but you may also be having a fuel delivery issue.
Have you had the injectors out, checked and refurbished? Do you have good fuel pressure?
When you really step on it do you get any smoke? What color?
What color are your plug tips?
Has the timing been checked? Running advanced of what is recommended I have found to be benificial
If I were to bet , I would say injectors and timning.That is where I would start.
Good luck
Ron
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QUESTION: timing is on the mark. have not had the fuel pressure checked yet. I am not sure what the recommended fuel consumption is but I know it is not running effiecently. Plugs, are white at the tips and the vehichle really doesnt smoke. When we were working on it yesterday and getting on it you would maybe see white smoke. It has super Bosch plugs in it from the previous owner. I will replace the plugs just to be safe and make sure it has the right gap. I have been told by a mercedes person that the Bosch platnums do not run well in this year. I will use the basic bosch plug. What is the likely hood of the fuel pump or electrical? When we figure it out I will also let you know what the fix was..
Answer I would cross reference original plugs and go with those,do not use platnums, these engines are designed to run hot, so plug match is imperative. I would also advance timing about 5-10 degrees, the plugs are indicating a lean performance. Have you adjusted your ECU?
Could be fuel pump, but more likely fuel regulator. Take one step at a time.....'Ron
