Questions About Possible 1984 380SL Purchase

The dealer I'm talking to about a 1984 380SL has a number of cars on his lot and is not too interested in working on this SL for now because it's low profit compared to other cars. While this may sound like a dodge, I can
understand this, since in my own business, whenever I have a choice, I focus on high dollar issues and small projects that could make 1/2 or 1/3 as much often are let go or left on the side for a long time.
Today I took the car out for a test drive. There is almost no rust on this car. The climate controls even seem to be working, but I wasn't clear about the AC (didn't turn it on until later). (I know heat/AC is not one of the biggest issues, but this is one of the few issues I'm unsure of in terms of repair cost.) The one issue that could be a deal breaker at this point is that it's running rich. He says he's checked the injection control unit (that's on the passenger side, under a floor board, or somewhere near there, right?) and the warm up regulator. He has not checked the cold start valve or the injectors themselves.
My first question is about the injection issue. I'm no expert on this, but if it's running rich, my understanding is that it would either be injectors (unlikely), the controller, the oxygen sensor, the warm up regulator, or the cold start valve. Is there more? I know if it were too lean it could be a bunch of things (rust in the line, pump problems, leaks, etc.), but how risky is it to get a car like this under these conditions (with two items checked and not sure what else it is)?
I'll be taking it into another mechanic for a check before I get it. Are there things they can quickly or easily check to narrow it down? If I could be sure it would be something below a certain cost level, I'd be much more inclined to buy this car, since most of it is in great shape. I just don't want to buy a car with a problem that could grow into many thousands as the mechanic gets more into it and finds more wrong. Any comments on this situation, what to look for, what could be checked to rule out some sources, and so on, would be greatly appreciated.
The other issue is the AC. This is not as big a deal, since I tend to leave the top down most of the summer, but it would be nice to know about. I had a 1988 Jeep truck that needed an AC recharge a few years ago and they had to retrofit the AC to work with the newer gas (instead of freon). If the AC on this, which I understand worked a year or two ago, needs recharging, is it a matter of just recharging it, or will it have to be retrofitted (assuming it isn't)? If it needs retrofitting, is that expensive?
Thanks for any help!
Hal
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The engine problem of running rich are usually of several problems... yes on warm up regulator and fuel distributor... both high ticket item. No on cold start valve but doesn't hurt to change them as it is nearly 23 years old. If it were me, I'd do a compression and leak down test. This will tell me if engine is still in good shape or not.
Alot of rubber items on this engine needs to be replaced at this time of drying out and leaky... which is part of vacuum system and that also controls emission.
A/C can be recharged with R12 as the price of R134a and R12 is practically the same today... so why bother retrofitting. Just replace all the seals and it should be trouble free.
In light of all above problems, it will be a costly repair... so if I were you, I would bargain all the way down on the price range. It will cost you alot ot fix it. I am not sure on the convertible top condition now.. but if it were original, yes, you will eventually need to replace them.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tiger wrote:

The mechanic said he's checked the warm up regulator and the injection control unit. (What's the "official" name of the injection control unit? I can't find it in parts listings and in the MB service manual.) Even if it's the fuel distributor, I'm getting a low enough price I could deal with replacing it. (I found the part for about $1,100). If I knew that *was* the actual problem, I'd be okay with it. I just don't want to deal with a cascade of failures/replacements, like replacing the fuel distributor, then a sensor, then something else, and so on. Is there any way to easily narrow down that problem quickly to a few parts or rule some out? If I can get parts eliminated during the pre-purchase inspection, it would help a lot.
Any estimate on how much a compression and leak down test will cost? I will have someone else inspect it and go over everything with me so I could probably have them do this when they inspect it.

I didn't even think of mentioning this. Surprisingly, most of the rubber tubing that I could see is in pretty good condition. I've been working on a 1973 450SL and had to replace a lot of tubing. There are serious rust issues, though, which is why I'm looking for another SL.

I'm not clear on a lot of this, since I've never dealt with AC issues like this before, but isn't R12 something they're moving away from? I thought the intent was to move away from all freon. Am I wrong on this (good chance on this topic)?

It's already bargained down fairly low -- I'm ahead of you on that! With the price I'm looking at, if I have to, I could afford to replace something as expensive as the fuel distributor. I know the top is something like $800 for a new one and is a full day job to install. That's one item I want to be sure is included in the pre-purchase inspection.
I know there's work to do and that it needs fixing up. I don't mind that, since I would be restoring it over the next several years. I just don't want to run into a multiple part replacement problem this quickly -- a few paychecks from now it would be easier to deal with! ;-)
Thanks for all the information and help!
Hal
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Follow the numerical notations...

1111....No real answer as I can tell you... you also have to consider the price of the cat converter too as it is probably way past its prime. The car has electromechanical fuel injection... it is sort of like half fuel injection and half carburator in layman's term... The actual control of fuel is fuel distributor... electronic part controls the emission part but it is mainly the fuel distributor that does the precise metering depending on the accelerator. Tell them to lean them out as much as they can to see if it can pass emission test. Any competent MB mechanice can do it... others will not know about how to do it.

2222.....Well, US does not make R12 anymore... however, other country start to produce it... which is why it is still available. Now, there is no need to move away from R12... Heck, even if you can't get R12, you could have someone put in R401... an R12 replacement used in refrigeration... Not designed for car, but it works...

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tiger wrote: ...

Does the cat converter get old over time or mileage? This has about 125,000 miles on it.
I have a good mechanic I usually go to with my 1973 450SL who will probably be the one giving this a pre-purchase inspection. I'm hoping they can do some general or simple checks and rule out some parts and limit the possibilities so I can at least have a guess on what is wrong. The price is low enough I can accept dealing with some work on the FI system, just not something huge lie $5,000.
After test driving it for about 10 minutes, I did let it cool a bit and stuck my finger up the exhaust pipe. There was some soot, but no grease or anything sticky. Before the test drive I don't think there was soot -- at least not much.
...

So I can get R12 in the US, then? It's just not produced here? So what you're saying is that other materials have gone up in price, so there really is no difference in price, is that it? Could you elaborate more on the R401? Does it work with any problems or long term damage? Is it legal to use it in the AC in this car? Will a mechanic look at me like I'm screwy if I suggest it?
Thanks for all the info and help!
Hal
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Let your mechanic do preinspection on the car before purchase.
As for R12, yes, made in other country and imported to US. R12 is widely available... it is just some shop who deals with newer car don't buy R12 because they almost never use it. Yes, the price of R134a used to be like $3 a pound has risen to the point where price of raw R12 and R134a is now same or identical.
Don't bother with R401... R12 is not that hard to find or buy.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Just to finish this off (and sorry for top posting, but this is rather short), I did NOT buy the car described below. The pre-purchase inspection turned up too many engine issues. What I could see of the car was in good shape, but it needs some serious work that only someone with experience could see. I did find a much better deal, a 1985 380SL in excellent condition. I found the car on the Internet last Thursday night, reached the dealer on the phone 11 am Friday morning, test drove it, had it inspected by a trusted mechanic, and bought it and took possession by 5:15 that evening. Here's some pics, including a few of the problem spots:
http://halblog.com/images/1985-380SL/index.html
Thanks for the help!
Hal
Hal Vaughan wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Great find Hal! Glad you got the right car.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.