Priest008

Hello all, like many, I came here due to issues with the car and have not managed to find much help from mechanics. My dad owns a 1985 Mercedes 380sl. It drove really well when we bought it around 4 years ago, however this past year some strange things have been happening. First, right next to the speedometer is a needle which goes up and down and reads "Economy", it worked fine but around a year ago it got stuck on the red part but we thought it must be nothing as the car kept on working fine. We kept on driving it like that for a few months until recently, around 4 months ago the car started acting really weird. My dad was driving one time and it just stopped, and after firing it up again he managed to keep going. We started having issues with the car and it seems that every time we tried starting it would start and just die off again, so we had to stay accelerating to keep the engine going. What started happening was that when we went to accelerate the engine would just die. Then if we'd manage to get the car to warm up it would work fine. We took it to a cowboy mechanic who played around with the air/fuel mixture and it worked fine for a few minutes then died again. What was happening was that the car would work fine when warmed up but now recently even when its warmed up the car always seems like its a bout to die on us. I noticed that in Neutral the car tends to stay on AT TIMES.... not all the time, it has moods. But always when put into Drive and Reverse, it starts to shiver (especially when you touch the accelerator) and then dies. We're lucky sometimes that after starting the car 20 times it works.

Now just to describe what it does....Recently we found a foreign body in the Air filter, a mechanic seems to have forgotten a plastic cup! We removed it and now the car starts up no problem but the minute you move the gear into Drive position, the car starts to shiver and dies. Rather than a shiver feeling as if its chocking from a lack of petrol, its like its not firing right and it just stops in the middle of the street, and after its done that the first time in Drive, it starts malfunctioning even in the Neutral position. One mechanic suggested its the spark plugs, the other suggested its the high tension cables, another suggested its the fuel pump and the 4th mechanic suggested its an electric issue..... these all cost money to stay paying around with. Now this past weekend the oli pressure gauge went crazy, it went right up and over the numbers and every time we start the car it goes up all the way past the numbers, whilst before it was regular.

Has someone ever had such issues? Thank you so much.

myway

Economy gauge is a simple vacuum gauge. Normal to fluctuate when driving. Should peg left at idle. If it is peg right either the vacuum tube has fallen off or you have huge vacuum leak.

Priest008

rocky raccoon

myway is correct. You have a massive vacuum leak and that IS your engine problem. All of your hard vacuum lines are connected by soft rubber connectors. I'll bet that they have never been replaced. The hot, oily environment in the engine compartment tends to make them deteriorate. Obtain a kit of new connectors from a parts source and methodically examine each one. Look for hardened or split connectors and replace each one. If the vacuum line can be easily moved while in the connector, that one is hardened and not sealing.

A good father-son afternoon project. Bring beer.

One more thing. Try to restore any adjustments made by the "cowboy mechanic". The air-fuel mixture on your car seldom to never needs attention. He probably messed things up.

Priest008

Thank you very much for your detailed explanation! You're wonderful! Could I ask you though:
You said
"If the vacuum line can be easily moved while in the connector, that one is hardened and not sealing."
Where is this vacuum line? And what is this kit I need to buy? There is one kit for all these seals?

Thank you

rocky raccoon

An underhood examination will reveal a large number of hard plastic vacuum lines. They are small in diameter, may be color coded and could be mistaken for wires except they are hard, and by now given the age of the car could be brittle so handle carefully. These lines operate a number of auxiliary functions for example, door locks and transmission shift controls and go to the ECON gauge.. They snake all over the engine and behind it between the engine and the firewall. The vacuum source is the intake manifold and that is why a large vacuum leak will affect the way your car runs.

The vacuum lines are connected together and to the auxiliary equipment they control by the use of soft rubber connection points. A complete kit can be ordered from the dealer or from one of several on-line parts providers for our old cars, including ebay. You may even check a general parts house such as O'Reilly's. They come in straight, angled, Y and X configurations.

Look closely under the hood. Can't miss them. Get the vacuum system in shape. You will be amazed at how much better your car will run.

Priest008

myway

Might want to check wiring to the WUR. How old is the O2 sensor? Did this car sit for an extended period?

rocky raccoon

May want to check the items myway suggests but if the warm-up regulator has failed, it would probably not start at all. If the O2 sensor is bad, it will probably start but run rich. In any case, check and repair one thing at a time or you will get wrapped around your own axle and never know what the problem was.

Priest008

UPDATE.... so gentlemen, the car was in the mechanic's hands for some time and I told him about the vacuum leak, he said thinks it's not the case. He changed the spark plugs to these new plus 4 plugs which apparently make it run better he changed the oil filter and a all high tension wires and the car is now running much better. The economy gauge has now started to function but only goes half way from Red to the middle, it doesn't start from the god part and works its way up, no. It is stuck on the red bit and then moves to the middle. The oil pressure stays playing up and down. I drove the car myself today and it drove beautifully, like it had done when I first purchased it. I bumped into a friend whose a mechanical engineer and he came for a drive, half way through a I was driving and let go of the accelerator the car decided to turn off. I pulled over and started it again. It did this a couple of more times to me. My friend said its "hunting" and told me the same thing about the vacuum lines and so I asked him if he knew how to check them. So we bought carb cleaner and I told him to finally check these vacuum lines. We sprayed the stuff around and nothing much seemed to change, there was a very slight change in sound at one point but very slight. Anyhow, if I change them, is this the kit?
https://www.ebay.com/itm/For-Mercede...2:pf:0&vxp=mtr

Thanks

myway

Sill a vacuum leak. Your "mechanic" should do a smoke test. He should also use the correct spark plugs and wires for your vehicle. Tell him to read. The kit you linked is for the injectors. Use Mercedes parts for that.