newbie needs advice - PeachParts Mercedes-Benz Forum

ScottieInBoca · #1 08-16-2010, 01:51 AM

Just got an 1981 380SL. Got some issues that I am not sure how to approach - or if they are even worth bothering with.

1. A/C -- air is lukewarm and comes from both front and top dashboard vents. I can live without a defroster - is there some way to access the system to divert all the air to the front vents?

2. Dashboard - shot but covered with one of those molded plastic covers. Is it possible to obtain a replacement or recover the original?

3. Cruise control is non functional.

4. idles high - but tends to stall at stoplights if I lower the idle any further. Previous owner said higher idle was set to address stalling caused by A/C.

5. Fuel gauge is oddly functional -- slightly less that 1/2 a tank = empty

6. economy gauge is non-functional.

If anyone can point me to the appropriate threads, or has relevant advice on any of these issues, I would be most appreciative. I can turn a wrench, and don'r mind going to a pro for a bigger issue - if the fix is worth it.

Thanks in advance

Scottie

nobby · #2 08-16-2010, 05:00 AM

Your high idle, economy gauge, vent controls yell VACUUM LEAK to me.

Star chipping away.

nobby · #3 08-16-2010, 05:01 AM

More..........

nobby · #4 08-16-2010, 05:03 AM

Your fuel gauge empty at half indicates a malfunctioning fuel sender.
You can access this from the soft top boot under the white plastic cover.
It can be removed and cleaned successfully................most times.

Jack M · #5 08-16-2010, 10:27 AM

Hi This is from Rocky Raccoon, from a post that I had in February. From what I have read in years of posts the vacuum system is almost like the heart of these cars. Primarily because the rubber deteriorates and the vibration allows them to move off of the fittings. So take a bit of time , use a inspection mirror an follow each hose from beginning to end and replace those that slip around a bit. every slight leak adds up to decreased performance and items that don't work. good luck J

Hi This is from Rocky Raccoon, from a post that I had in February.
The fault is probably not at the economy gauge or it's vac hose. You do however have a massive vac leak. Based on experience, I would look at the main vac source hose.

Between the intake manifold and the firewall at the approximate center of the engine you will find a small pipe with a right angle rubber fitting attaching to the vac hose. That hose leads along the top of the firewall to the U.S. driver side where it terminates in a three-way connector. One of the hoses in that connector goes to your vac gauge.

The right angle fitting on the intake manifold is in an area of high heat and oil vapor and is usually the first to deteriorate. It is hard to see and hard to reach unless you have tiny hands. The rubber connectors are available from the dealer at low cost or an assortment can be found at most big box auto part stores. Inspect all your connectors under the hood.

meltedpanda · #6 08-17-2010, 03:45 PM

buy a mityvac and start testing the vacuum system, could be a line or a bad pod . Your AC most likely needs recharged , probably R12 so you will have to have system purged and retrofitted to r134A ( others may disagree, but trust me) The dash R/R is not for the faint of heart but can be done, caps , when done will look fine. I do have a spare dark brown dash . get your vacuum sorted out before you start to deal with engine specs.

ScottieInBoca · #7 08-20-2010, 10:25 AM

Been poking around the vacuum system as suggested. What a pain in the ass. Anyone in south Florida who has done this or any decent mechanic who will not rape me to get it straight?

francotirador · #8 08-20-2010, 10:48 AM

Quote:

Originally Posted by ScottieInBoca

Been poking around the vacuum system as suggested. What a pain in the ass. Anyone in south Florida who has done this or any decent mechanic who will not rape me to get it straight?

I recommend trying to follow the directions posted hereon. You'll be happier and better off after you've learned some of the system yourself. I've done many repairs to my 126 that I would never have even thought about attempting before reading these boards. It's quite rewarding. Oh, and even if you have someone just repair the vacuum leak you have issues with right now, something will come up later. Well, that's unless you have them update the whole system. Then you can talk about rape.

meltedpanda · #9 08-20-2010, 02:19 PM

you really at least need to isolate your vaccuum leak, start at the fire wall , apply some vacuum see if it holds, if not use compressed air ( low pressue) and see if you can hear where you are open, Cold really be just a loose line, unlikely but possible

ScottieInBoca · #10 08-21-2010, 09:37 AM

OK guys -- I feel like I might be a little above my head with this vacuum system. Looks like a bunch of spaghetti in squid ink. However, I am going with your advice and plan on trying to tackle - at least some of it - this weekend.

Aside from the previously posted schematics, is there another walk through somewhere on the site? I tried to find it by searching various variations of 380SL, vacuum, R107, etc. but didn't find what I thought I was looking for.

Any other insight, advice ... would be appreciated. And, of course, if anyone is in South Florida that has attacked this mess who wouldn't mind lending a hand - beer and pizza would be on me!!

Scottie

meltedpanda · #11 08-21-2010, 10:42 AM

OK scottie, bring it on up to KY and I will help. I'll will work for beer and pizza lol
Seriouisly , do you have a vaccuum guage? If not you will never figure this out.
If you do then connect to the line that goes to the intake ( should be a Y connector somwhere) and with the car running , see what you vacuum is. If it is non existant or below say 10mm/hg then you have a leak in a line or a line off. You can also check the vaccuum draw on the pull off line of the distributor
Do you have vaccumm door locks? The drivers side door valve is a common area of failure, as is the line to the reserve vacuum tank ( in fender well) . There is some isolation of these varrious routes by one way valves but you have to determine what is working , what is not
Another area lines tend to fall off is the ACC in the dash

RadioTek · #12 08-22-2010, 01:05 AM

Sorting out vacuum issues involves a schematic (provided), a large stock of vacuum tubing of appropriate sizes and compositions, a goodly assortment of fittings, and above all: patience.

If you are the type to worry at a problem until it is fixed, this is a good place to start. Just follow each circuit from beginning to end, replacing the tubing as needed, and go on to the next one.

Budget a couple of days to go through the whole thing. It may not take that long, but just in case...

Also, you might want to invest in a couple of the plastic ramps that will raise the front end up about 8 to 10 inches. They will come in handy if you do any work on the car yourself, and your lower back will thank you.

Take a deep breath and do it one step at a time. There is a unique feeling of triumph that comes from hunting down and fixing a problem. Enjoy it.

garland · #13 08-23-2010, 05:42 PM

If you are in Boca Raton, Fl you might try Bill's Auto at 5331 N Dixie. I bought my 92 SL500 from him a couple years ago. He works on a lot of the older Mercedes and I think he is pretty fair. No affiliation, but I own the furniture refinishing shop next door to him.

rowdie · #14 08-23-2010, 11:52 PM

How are you adjusting the idle?
It is controlled by the air slide valve and is not adjustable. Take it off and clean it.
Economy gauge is a simple vacuum gauge. Far right at engine off. Far left at idle. Varies after that with acceleration.

Get the mighty vac with the gauge on it. You can also measure vacuum with it.

There is a vacuum line at the pass side rear of the engine between engine and firewall. Kind of hard to see and it is a rubber elbow. Seems this one fails overtime due to heat and oil more often than others. It is a major source of vacuum for the system.

ScottieInBoca · #15 08-26-2010, 12:04 PM

I got the vacuum meter even got the mityvac. Spent a couple hours pulling off the airbox and tracing lines. Some had vacuum, others did not. I tried to make heads or tails out of the schematics, but had little luck. With vacuum tubes going in and out of harnesses, changing color on me, and dropping into inaccessible places it was hard to track any individual line - or even understand what it was for or what it was supposed to do. Even those I got to seemed to do strange things - like go into a 4 way splitter (that I couldn't find on the schematic) that only had three lines attached - a very apparent issue, I think!!

In the end, I think I am going to have to bite the bullet and go to a pro.

Thanks to everyone for their advice and input.

Scottie