20th Jul 2008, 17:19

To the poster from July 9 '08: I have a 79 450 SL w/140,000 miles. Mine exhibits the same fluctuations in oil pressure and has for a while. According to my original owners manual, it is normal for this to happen.

18th Aug 2008, 20:07

It is my belief that the oil pressure may drop down at idle speed when the engine is at operating temp, but that it should be at, or about, "3" bar when the engine is revved to 1500 rpm.

Also SAE 20W 50 engine oil is recommended for summer use. This oil is available in Canada and elsewhere from Castrol.

You get even better protection if you use diesel rated engine oil that has better anti-wear additives and a better ability to carry impurities.

Fuel consumption?... I have found on my fuel injected 1980 SLC runs between 18-22 MPG (Imperial gallon) highway and anything from 12-14 in town, obviously less in stop and go.

On 350 and 450 engines the timing chain can be a substantial prob if it brakes... ruins the engine.

A new chain can be threaded onto the old one and wound into the engine carefully. Don't try this at home unless you know what you are doing... If the timing slips the engine will not run well and may be ruined... Take to someone who knows what they are doing. A new chain is about 75 times cheaper than ruining an engine. On older engines the gears may need replacing.. a costly job. Don't forget the oil pump and drive drive chain while you are at it.

Overheating?...Yes but only in very stop and go driving. Suggest install a manual override switch for the fan.

1980 450 slc Euro model. Dieselman.

8th Dec 2008, 12:01

My Father-in-law gave me a Silver 1979 450 SLC to keep it in the family. I had about $4000 worth of work done in southern California and shipped it to southwest Florida. It runs well, runs cool and handles beautifully. It has about 260K miles on it. I had the window switches replaced in Florida.

The odd thing about this car, is that while running the A/C and making a right turn- water drips on your right foot! This is a harmless condensation / leak issue, and I'm told the car has always done this since new! (It is a German model.) The electric antennae has stuck in the "up" position. Getting out of the car is a little slow going if you are over 6 feet tall.

A fantastic classic.

Randy in SW Florida.

30th Mar 2009, 20:48

Unfortunately, the 450SL/SLC belongs to a time of old generation engines with the least amount of electronic engine control, coupled with a heavy body and a full hydraulic automatic gearbox, which all together result in a generally poor fuel consumption figure. If you average something like 5-6 km/L, then that's normal, you might be lucky to hit 8 km/L on the open road cruising without the air conditioner on.

The good news is that it isn't infested with unrepairable entire-assembly components, including a platoon of computers and sensors which are difficult to diagnose and expensive to fix.

30th Apr 2009, 11:21

Hi all.

My 1980 SLC (bought a month ago) gives a strange vibrating noise when I'm driving beyond 80km/h. I was told this could be because of the car not being driven in excess of this speed for some time, partly due to the fuel price, and that the injectors are clogged. Any other reasons for this?



16th Aug 2009, 20:13

Hello all,

I'm in South Africa, I have purchased a 1979, Mercedes 450SLC which is without a gearbox. Please help with the details of a good mechanic for this vehicle. And a place where I can find the parts.

Thanking you in advance


5th Dec 2009, 13:48

I have a 1979 SLC and love it to death. This is my second one and I want to change its appearance with chrome wheels and a paint job. It has 14 inch tires and I would like to step it up to 16" in chrome five or six spoke. I'm getting mixed comments like nothing over 15" or I will have tie rod wear within a year. Can someone help me find rims and give me a true answer as to what I can and cannot do?

Thank you.


30th Mar 2010, 16:06

HELP, 1980 450 SLC The car starts up great, runs great, for a while 15 miles, then it starts to chug chug like it's out of gas. What?

3rd May 2010, 23:31

I have inherited a 1978 450 SLC, my dream car... I have eventually found a mechanic and body work specialist to work on the car. Do we have a M/Benz 450 Club in South Africa? dean@bold.co.za

19th Nov 2010, 22:54

My father has a 1970 450SLC that he would like to sell. Where is a good site to put it for sale? It is silver and is in good condition.

7th Jun 2011, 10:29

Hi there.

I read that it can be the 'idle air control valve'. See link http://www.ehow.com/facts_7974179_mercedes-450sl-problems.html

23rd Jun 2011, 14:58

I bought my '79 450 SLC in 1980. It had never been titled, as it was driven for 1700 miles by a Mercedes executive. Found out it was a European car when I had to replace a radiator. Have just over 134000 miles on it, and still love it.

About 5 years ago, I had it all taken apart and cleaned up and restored at about 20k. To me, it was worth it. It stays in storage now through the winter months, and still looks great. We do have three other cars, but in the summer it gets to work out. Not the fastest off the light, but over 70 nothing can step out quicker, although I have kept it under 150.

2nd Aug 2011, 17:57

I have a 79 450 SLC that I just purchased. I am having trouble with getting the trunk to open. I had it open twice and now I can't seem to get it open. Doors and fuel tank door all open well. So, I don't know if that eliminates a vacuum problem or not. Any suggestion?

14th Sep 2012, 20:58

Hi. You can do a lot of things with your wheels/tyres - but any changes to the standard factory set up will affect the handling; sometimes dramatically. The original set was 205 70 R14.


11th Nov 2012, 21:20

Hi, I too have a 450SL (C). Actually a 1975 with 40,000 KM from BC. I live in Winnipeg. I'm just storing it outside for the winter, and need to know how you check the antifreeze. FYI I put it on a concrete pad, jacked it up carefully and put blocks under the frame so the tires are off the ground, and put a cover on it.

Any ideas on the antifreeze? I don't want a cracked block in the spring...

Thanx, Chris.

20th Feb 2014, 04:43

I also had the same dash light problem, and found a thread that suggested turning the dimmer up and down until the lights work, and then leave it in that "sweet spot". Good luck, it worked for me.

13th Mar 2014, 16:59

Hi, my dad is giving me his 79 450 SL. I live in SW FL and would like to know if you ever found a decent honest mechanic to work on the car? Let me know. Thanks, Bob.

24th Feb 2015, 04:57

Mine, a '79 450 SLC, made a loud vibrating noise intermittently when doing in excess of 60 mph, and after starting would continue at lower speeds. The automatic air/con kept the heat high also, but once the vibration had stopped and restarted maybe six times, it has gone and the temp control now seems to work as it should. I believe that one vacuum actuated vent control was jammed or stuck from lack of use. The wind pressure and my willingness to put up with loud annoying vibrating noises until something happened allowed the problem to resolve itself. I also think the last owner sold his car because of the fear of repair costs. Lucky me...

24th Feb 2015, 15:20

Maybe an electric lower coolant hose heater. Test your antifreeze with test strips. Piece of cake. Start it every few weeks if you can.

21st Apr 2015, 16:03

Please call me at 954-540-7031. I have the same dash light problem and can't find the fuse box. It's a 1978 450 SL.

22nd Dec 2015, 19:18

Thanks for the article. What indications of problems are there for the timing chain? Does it give any warning(s)?

Re oil -- 10W 40 is our normal (1980 450SLC), which is used daily for 8 miles to and from the office/store. What problems are there if the oil is mixed with the diesel oil? I am just about 3/4 quart low now.

Thanks, Bob Gurin, samcat@bellsouth/net

7th Mar 2017, 15:55

I would sell on eBay... I bought my 1979 450SL on eBay... you can ask what you want and set a reserve price... the buyer will pay shipping.

7th Mar 2017, 23:19

Condensate tube is clogged.

8th Mar 2017, 16:37

The questioner was almost certainly already aware of eBay, and over six years later the car is likely long gone anyways.

10th Mar 2017, 19:53

I didn't have the SLC; I had the SL 2 Top Roadster. If well kept, these are a very attractive car with great styling. I never had the soft top up. Hardtop I never used. Always ready to pull in and out of the garage for fun. To me, the further back you go in time the better looking they got. Like the XKE. This car, although small, always seemed very solid and even heavy for its size. I dated my wife with one of these. And ended up later giving the car to her to drive. A good excuse to go out and get another fun car for yourself. Worked for me.