1987 560sel issues - PeachParts Mercedes-Benz Forum

jeffrylebowski · #1 04-26-2010, 10:02 AM

My 560 has a few nagging issues and any input would be helpful.

1. When cold, I have trouble starting the car. When I turn the key, the car will not fire and a whining sound comes out of the engine. Usualy after a few turns, the car will start.

2.When it does start it idles extremely low for the first few seconds, almost like it's going to stall. Then after a few seconds the rpm's climp up to around 800 and it idles a little rough. Almost feels like there is a miss.

3.I have a stuck spark plug. A mechanic has told me he'll probably strip the threads getting it out but assures me a heli coil can be inserted rather easily and we can get a new plug in there. Has anyone dealt with this issue and if so, are there any hazards I should be aware of. Hopefully this is the cause of the miss.

4. When cold, the idle will surge until I get up to temperature. I believe it is the Idle Control Valve and can part one out from a local auto wrecker.

5.I have noticed I can't get the passing gear to kick in very often. Am hoping it is related to the stuck spark plug which may be dead. Any other thoughts on this.

So a few things and just need a little guidance on where to start. I'd like to get her fixed up for the summer.

rsmartin · #2 04-26-2010, 11:19 AM

all those things could relate to vacuum leak as well

johnathan1 · #3 04-26-2010, 12:05 PM

I would test the cold start valve. Without extra fuel being injected, most gas engines are very hard to start when ambient temps are low.

Also test the kickdown switch.

As far as the spark plug...it sounds like your mechanic already knows how to handle it. Only other option is to replace the head.

jeffrylebowski · #4 04-27-2010, 11:02 PM

Thanks for the thoughts guys. How would I go about testing/locating the cold start valve?

jeffrylebowski · #5 05-04-2010, 11:19 AM

Yesterday I had a little time to get under the hood and took out the idle control valve and gave it a good cleaning. This morning the idle seemed a little better as the rpm's immediately jumped up to 1000 then settled in at 600. There is still a slight surging of the idle but at least the feeling of stalling is gone for the moment. When I took off the air filter housing, I noticed a big crack in one of my air intake hoses. Will this affet the idle? I put some electrical tape around it as a quick fix and will order another one today.

The thing that is bothering me is that I still have the starting issue. It took 4 turns to get going and that same whining sound came from the engine when it did not start. If it is blocked cold start valve, would their be no fuel delivery upon ignition?

As for the cold start valve, I stil don't know where to look to find it. Each time I open the hood it's an adventure.

This forum is great and thanks to the many who have helped along the way.

tinypanzer · #6 05-05-2010, 05:34 PM

Cold start injector is a good first check. Temperature sensors are important too.

Air leaks are common on that motor, especially if you're never replaced the injector cups and O-rings and the little plenum donuts that mate the intake manifolds.

As for the stuck spark plug, you can try freezing it with liquid refrigerant. You can use a can of "Duster" held upside down so it will dump fluid. Be careful not to give yourself frostbite. With the block still warm (not hot!) dump some liquid refrigerant down on top of the spark plug. After a few seconds when its good and cold, try breaking it loose with a wrench. Keep in mind that if it does strip out as your mechanic said it would, you are now somewhat stranded. However, I have been successful with this approach before. The warm (not hot!) block is still somewhat expanded with heat, and freezing the plug shrinks it enough to un-seize it from the threads.

IMPORTANT - if the ceramic breaks during this process, you must vacuum out all the little pieces before you continue to remove the plug! Don't let them into the cylinder!

hbofinger · #7 05-07-2010, 03:05 PM

Stuck plug - you might consider "freezing" the plug to try to get it unstuck. This means using a combination liquid wrench or something of the sort and Radio Shack electronics cooler (spray that is used on electronic components to rapidly cool them for troubleshooting). You will want to rapidly cool the plug while not having the stuff touch the head itself. I have not done this on a plug, but have done this quite successfully on stuck bolts. Make sure you replace the plug after you get it out...

Oh - there is a product that actually does both of these steps for you (local Benz dealer pointed this out to me). One of the more difficult to find liquid wrench-type solutions does this, but I don't know the name off hand.