To the poster from February 24th: it sounds to me like your engine bearings are shot! The fact that your oil pressure gets lower and lower, especially at lower rpm's, until finally stalling I think is an indication that as the oil viscosity decreases with increasing temperature, and lower engine and oil pump revolutions can no longer provide pressure through the oil galleries, the bearings experience increased friction to the point of stopping crankshaft revolution. Basically, with such low oil pressure, the crankshaft is "trying to weld itself" to the bearings. My family once had a car (of a different make and model) that exhibited these symptoms. Oil pressure was normal when first started, but when it warmed up, oil pressure dropped to the point where the oil pressure warning light would actually pulse in rhythm with the engine when idling in gear at stop signs. Unless you are prepared for a total engine rebuild, try adding some Slick 50 or other friction reducing additive to the crankcase oil. Or you could go the other route and add very high viscosity oil conditioner. The one strategy is to introduce teflon to the metal surfaces to greatly reduce friction. You may still experience low oil pressure, but the metal surfaces will have very low friction against each other. The other strategy is to use such a thick, viscous oil that it will keep oil pressure throughout the system. Your engine is probably shot anyway, so it's your choice of which route to go, because it's only trying to prolong the inevitable failure.
I just bought a 1979 450 Roadster at an auction and I am not a Mercedes specialist so I have a few questions.
1. Why would my 450 have rectangular headlites verses dual headlites like the owners manual indicates?
2. This is a california car and must be set for high altitude operation. I live in Manitoba Canada and I find the car runs very rich when starting it hot.
3. It seems quite gut less for a large V8.
Your comments or suggestions would be appreciated.
For the gentleman who purchased the 79 450 Roadster, the square headlights are common on European models where as the u.s. models came with the double round head lights. They may have been changed by the previous owner. Another sign of a European model is that the front and rear bumpers do not have the shock absorbers and mount closer and directly to the body. This makes for a cleaner and less cluttered appearance, in my opinion. I own a fully restored 1979 450 SLC and love the European look. Mine is also a european model and I will be shipping it back to the states soon. Respectfully, Charles Shank or daddyshank@hotmail.com.
I recently purchased a 1978 Roadster that I had previously owned. The problem I have is the idle is much too high. The engine idles at around 2K RPM. I have looked for the obvious vacuum leak, but cannot find one. Any ideas?
I am looking at purchasing a 1979 450SL which has been sitting for 4-5 years. What can I expect to do prior to initial start up?
ericmuhlbaier@bellsouth.net.
I am interested in a 1979 slc and the owner want $1100 dollars and to my knowledge everything works why would they want this amount of money do they not know what they have.
I have bought a 1979 450sl with 58,000 km. Original owner sold me the car. I am going to put it away for the winter (Calgary, Alberta). What special things do I need to do. As well, anybody have ideas re hanging the hard top from the ceiling in my garage??
I own a 1979 mercedes 450 slc that is having a problem with the interior dashboard lights. the headlights go on, but I cannot light up my dashboard. does anybody have any suggestions.
I have just purchased a 1979 450Sl Roadster with 106K miles previously used as a daily driver. I am experiencing some issues that I need to consult:
Oil pressure: when the engine is warm and sitting at a stop light the oil pressure goes all the way down to zero, however, there is no noise from the engine and it seems to run fine. When I shift into neutral and accelerate, the oil pressure gage moves up and down at the same rate as the tachometer. When the car is operating at highway speeds the oil pressure, indicates maximum pressure,. At start-up when the engine is cold, the oil pressure indicates maximum pressure as well. Someone told me they thought that the oil gage in the dashboard needed replacing. I was also told that the oil tube going to the oil gage might be clogged and may need replacing or unclogging. Any ideas on what this oil pressure issue could be, and how to resolve it?
Rough Idle: The engine runs rough at idle speed; it seems to run fine at highway speeds.
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.
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.
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.
Hi All.
I'm from South Africa and also recently purchased a 1980 450SLC. For a 30 year old car it's in good condition. Is there something I can do about the gas (petrol) consumption issue?
Brgs
Christopher
punte05@webmail.co.za
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.
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?
Thanks.
Christopher.