Points to check when buying a UK 91-95 SL500 - PeachParts Mercedes-Benz Forum

LeaUK · #1 05-17-2003, 03:41 AM

Hi all

Have actually started looking at cars in the last two weeks and would like your advice on specific points/checks to look for and what procedures you recommend when buying from private owners.

I'm sure this has been covered before and using the search I have found a few but hoped you wouldn't mind repeating and adding.

Here's my thoughts so far:

1) Check service history and phone garage - ask garage about mileage at last service and any known repairs etc...

2) Phone previous owner

3) Can a check on the VIN plate yield something usefull - if so is this just a call to a MB dealer?

4) What's Carfax and is it available in the UK

5) Will and Authorised dealer provide a detailed Inspection report - for a cost of course?

6) Check engine compartment for oil

7) Check sound of engine - no rattling or 'nasty noises'

8) Check hood operation and for dampness inside

9) Take car for drive

10) Is their a Insurance database I can check for previous claims?

11) I have access to a engine code diagnostic tool - I guess this would be very revealing too?

Bet there's loads I've missed so I would be most grateful if you can advise too.

Much thanks
Lea

spinedoc · #2 05-17-2003, 06:03 PM

Just a quick by the way, go for a 1992 or newer. The 1990 and 1991 did not have a diagnostic connector, makes the dealer have to troubleshoot the old way, by the book!! Gets expensive.

jjrodger · #3 05-18-2003, 08:53 AM

Sounds like you've thought of everything. Carfax is the same as HPI only a more detailed. A dealer should do a pre-purchase inspection. Good luck, just done 2,500 miles in mine in a week with no problems at all, only pleasure.

LeaUK · #4 05-19-2003, 02:29 AM

Thanks guys

I'm sure pre 93 do come with a diagnostic connector but maybe not! I know they have fault code identification but perhaps this is by the old LED flashing trick? Uhm, I'll have to check that one more thoroughly as you're quite right - the diag connector is a MUST have!

JJ - is Carfax available in the UK?

Does anyone know if you can look up the car's insurance claim history on the net yet?

Cheers
Lea

LeaUK · #5 05-20-2003, 07:07 AM

Just for others who may be interested - CarwatchUK has a great checklist
http://www.carwatchuk.com/help_and_advice/default.asp
http://www.carwatchuk.com/help_and_advice/checklist.asp

well worth looking at!

jjrodger · #6 05-20-2003, 02:12 PM

Learoy:

I have the UK brochure and specification sheet for the R129 dated August 1989. This is the first brochure and spec (Car did not review the then new SL until November 1989).

It clearly states that the 500SL enngine has a diagnostic connector. I do not know whether this will provide info your machine can read; I do not know whether this is what we all understand a diagnostic connector to be here in 2003. However, in 1989 Mercedes-Benz UK said that its 500SL motor comes with a diagnostic connector.

Let me know if you want the full spec sheet and I will endeavour to get it scanned for you.

spinedoc · #7 05-20-2003, 10:09 PM

When I brought my 1991 to the dealer for an ASR light they could not pull the codes because the diagnostic connector or system did not allow for it. They had to trouble shoot the old fashioned way by the book. Now maybe I got ripped off here, but they seemed pretty certain that there was some kind of difference between the 91 and 90 models that they upgraded in the 92 on up.

Possibly I misunderstood, maybe someone with a bit more tech expertise than me can tell me.

jjrodger · #8 05-21-2003, 02:50 AM

I don't doubt you for a minute Spinedoc. I don't really know what a diagnostic connector is, anyway! We've posted recently on the differences between the various incarnations of the 32-valve V8 fitted to the 500SL, so maybe the answer lies there.

suginami · #9 05-21-2003, 05:13 PM

1996 and later cars all had to have OBD-II, which standardized not only the connector plug, but also standardized diagnostic trouble codes among all car manufacturers. The same code number means the same thing for all cars. Further, more systems were connected to the engine control module so you get more and better information. OBD-II also allows the tech to retrieve live data.

Thus, one can assume that it would be the most safe to buy a 1996 and later car.

FWIW, some cars before 1996 might have come with OBD-II. I know that the E class first came with OBD-II in 1996 with the introduction of the W210 chassis. I might be wrong, but I believe the C class cars came with OBD-II in 1994. Don't know if the R129's got OBD-II sooner that 1996...

suginami · #10 05-21-2003, 06:29 PM

It just occurred to me that I do know that Mercedes released in 1993 W124's a pre-OBD-II system, a OBD-I 1/2, if you will.

My 320E has a diagnotic box in the engine compartment, mounted near the battery. It has an LED light, with a button that allows you to activate flash codes. Diagnostic Fault codes that are tripped by systems that affect smog emissions are connected to this LED light. There are several numbered sockets that allow a tech to plug in a computer to scan different systems. Independent techs will frequently use a hand held machine made by a company called "Baum" that allows them to retrieve the codes. Live data can also be retreived via this system. I have been told that nearly all the data that OBD-II stores is available in this sytem.

So, to make a long story short, there is no reason to assume that Mercedes limited this to 1993-1995 W124's. It is just as likely to be available on R129's, possibly several years earlier.

spinedoc · #11 05-22-2003, 12:03 AM

All I know is when my mechanic was explaining the lack of a diagnostic connector he was pointing under the hood, near the passenger side.

LeaUK · #12 05-23-2003, 01:43 PM

Hi guys

Thanks for your comments. Trying to work out the injection system and diagnostic versions for the 500 is proving more difficult that expected. I think the only way to clarify is by the VIN number as this states actual date of manufacture.

Next move is to contact Mercedes direct and just ask!

Cheers - I'll keep you informed.

slsmag · #13 07-19-2003, 01:25 AM

I see that this thread drifted in to the ether several months ago, but for the benefit (hopefully) of others, maybe this will help... (and if anything I post is wrong, please post a correction!)...

From the mid-80's to the mid 90's, Mercedes, Porsche, Audi, BMW and many others used Bosch fuel injection and management systems. These are controlled by the Bosch LH controller.

The LH controller sarted off as having some basic diagnostics built in to it and gained capability (including 'memory' to store fault codes) over the years.

Each year brought improvements, and a new LH controller... requiring the special Bosch diagnostics tools to read the diagnostics.

The last version of Bosch "Hammer" (as it is called) had adpaters available for it that allowed it to read the more current LH controllers (through around 1995) as well as the basic LH controllers from the mid 80's.

But the LH controller is an ENGINE/FUEL controller. It could tell you if an 02 sensor or temp sensor was failing, but it was not hooked up to systems like the ABS, SRS, etc. (Spinedoc - this is likely why your MB mechanic told you he could not do a simple diagnostic on the SRS system in your '91 500SL).

In the early '90's, MB, like all manufacturers, started engineering new electrical systems that could take advantage of the coming OBD standards for diagnostics. Since nearly everything on the car is controlled by one sort of computer or another it was relatively easy to create monitoring systems that read the engine controller signals as well as measure temperatures, rpms, voltage flows, compression in each cyliner, hydraulic pressures, spark effectivness, amperages, even alarm systems and power accessories - and report all of this data to a central diagnostics hook-up: OBDII.

Hope that helps a bit.

- michael
'98 SL500 BLK/PAR

LeaUK · #14 07-19-2003, 04:06 AM

Hi Michael

Thanks for expanding further on this one as I'm sure these threads do help others. In fact I know they do as I've used this forum extensively in the 6 months before purchasing. But just for your info I've taken the plunge and she's a 500SL 119.972 '93 (registered) probably '92 manufactured as there's no cat ;-)

She's an LH 4.1 and I'm off to profile the engine soon as I have access to a diagnostic reader so I'll keep the forum up to date with my findings

Just for interest, the '95 SL500 119 982 engine came with Motronic - guess that's fully OBDII?

Cheers
Lea

spinedoc · #15 07-19-2003, 07:22 AM

Michael thanx for the clarification. I would be curious as to the specifics of the systems used in those earlier autos. But not as curious as I used to be since I upgraded to a 96!!!