85380SE

I posted this on the S-Class board, but I later found this board and wondering if I should have posted this here. Oh well - here goes.....

First off.... Hello! I had a membership here before, but had not been here in awhile and have changed my email, so my other username is history. I was "86560SEL". Anyway, I have posted this about my 85' 380SE on the other MB forums and thought I would get some "freshened" advice here.

1985 380SE (with 268K) missing at idle and when initially shifting gears- vacuum leak? Spark plug wires? "OP" or "OVP"? relay?

I had posted here before about the sudden stalling my 380 sometimes does after the engine is fully warmed after I place it in gear or stop at a traffic light. I have been told it could be the idle control valve.... checked that and it is fine. Idle goes up when it is disconnected. I have not yet tried to check for vacuum leaks, as mentioned here and recommended to me by some here. I was told to start the engine and spray brake cleaner around (on cold engine) to check for leaks. I was told by a local MB indy repair shop that it may be a vac leak and how to check it (by spraying the brake cleaner around the cold engine), but I have not yet checked. Is brake cleaner the best thing to use?

Well, to update, strangely, the engine has NOT been stalling, but when I first start it of the mornings, it idles smoothly, until about 3 minutes, then it will start "missing", or after I start to accelerate after it has idled, it will start missing/spluttering. There was one occasion where it was like it was "choking" and putting out gassy smelling smoke (black) from the exhaust. Its like it was getting too much gas. If I hold the accelerator steady when in park, it misses, but upon acceleration, or even in gear at steady acceleration, it smooths out. It will do this now until the engine almost completely warms up, but recently, it is missing more often (even with engine fully warmed), if the engine is idling in park, or when it will first upshift into the next gear- then it will smooth out again. BTW - when starting- it ALWAYS starts very easily and quickly... no matter the temperature. In fact the first start of the day is even quicker than the rest of the day- which is still almost instant. Also- it will miss a little when it is idling in park or neutral, but when I shift it into gear, its smooth as silk.

It did this slightly last winter, but only if the temperature dropped below 40°. During the summer it did not do it, but it was doing the stalling. Now the stalling is gone, but it is running very poorly when the engine is cold if the temperature drops below 60°. It has been getting a little worse every week. I have a feeling it is only going to get worse and worse.

Does it sound like this could also be a vacuum issue causing this as well, or could something else be causing this? I was also thinking possibly plug wires. I have already replaced the spark plugs last summer, when it was only a minor issue. That did not seem to help and whatever is causing the miss when in park, or when the gears first change is getting worse. Also, I on the highway upgrade that I have to drive up every morning when I leave, I have to take the engine up to 3000 rpms to gain speed. It seems like there is a point when it hits 3000 rpms ( I think in 2nd or 3rd gear - I will check), for a moment, its like something is holding it back.... like an A/C compressor has kicked in (but my A/C belt is removed. I go ahead and let it shift into the next gear and it will miss for about 2 seconds, them smooth out again. The car has 268K, so I know its getting worn out, but when it was running smoothly, I had sufficent power and had more confidence in it.... now I am not very confident, even though it has never left me setting stranded. YET. Also, I have a bad thermostat.... that may be causing some of the problems? On the highway, it drops to about 55°-60C (engine) when the outside temperature is below 50°F. However, in town it goes back up slightly and if I let it set and idle in gear (for an extended period- say, 10 minutes) it will go up to 110°C. My auxillary fan is on the fritz (blows fuses), so thats no surprise. But you would think that in the winter (when it was below 50°f that evening), that it would not go near 110°C.

I was also told it could be the temperature sensors faulty and it was telling the engine the wrong temperature, hence the poor running?

Any other suggestions? I do not have a fortune to spend, so I cannot afford to replace this and that to see if that is the problem, only to still have the issues continue. I was told by someone else that it could be the intake gasket??? I am at a crossroads. Oh, as a sidenote- when I first start it after it has cooled down, it makes a "sawing" noise as the oil pressure gauge is going up to "3"- which is fairly quickly. It stops as soon as the needle gets to "3" and I never hear the noise again for the rest of the day. Is this my timing chain/tensioner about ready to go out?

Please help.

Thanks in advance!

C32AMG/02

The variation in engine temperature is one problem; the coolant temperature sensor controls the Electro hydraulic pressure actuator (fuel quantity) in KE systems. Test the sensor with an ohm meter cold, low resistance about 500 to 1000 ohms, high resistance at engine operating temperature about 7000 to 12.000 ohms. Usually located around the thermostat housing, two pin connector.

Change the thermostat and make sure you have the right amount of coolant in the engine, not low and no Green antifreeze, use MB.



The engine will run lean with a plugged fuel filter, check the filter if it looks old and rusty change it. Check and clean the coil wires. Especially if the cover is missing. Also check and clean the wire connection on the ignition controller /EZL.


Vacuums leak are hard to identify, the best method is with a smoke machine,
Check the vacuum lines and hoses for cracks.

Two very important relays which if defective can cause a drivability problem, the fuel pump relay and the OVP relay, remove them and check the spade connectors for corrosion, carefully remove there protective covers and also inspect for corrosion, if so change them.

85380SE

Thanks so much. I will check all of this, or have my mechanic check is as soon as I get a chance.

coolant sensor.... should I just go ahead and replace it, or are they rather costly and should I test first? I am not sure if I have one of those meters... I will see if grandfather or dad has one.

Coolant- I KNOW that it currently has the green coolant in it. Is there any other recommended coolant I can use other than MB?

Do you know where the fuel filter(s) are @ on this car?

What is a "smoke machine"?

Are those relays located in the fuse block?

Seems like the big problem now is not the stalling. It only seems to do that when the outside temperature is above 70°. My main problem now seems to be a miss when idling in park (smooth when in gear) and when it upshifts, it will "miss" for a couple of moments, then it smooths out.

Oh, something else- when I start the car for the first time of the day, I hear a "RRRRRRT" sound (in the engine compartment) as the oil gauge moves up. The oil gauge goes up the same moment that the tach does, so I am not sure if the sound is connected to either one of those things or not. I have no clue when my timing chain/tensioner was last changed and someone said it could be one of those fixing to go out.

Many thanks again! I appreciate it! I need to get this car back up to par, as it is my work car (truck uses too much gas) and I may have to be doing some traveling for work.