[Fine Business]

I'm replacing my water pump and I found a broken plastic line (vacuum?) crossing the front of the engine behind the fan. The line (blue arrow 'A') comes from the box shown in the first picture and runs over near the firewall and ends in a blue cap on another thing-a-ma-jig (picture #3).

I'm curious what it is, and wondering why it didn't trigger a code.

Is this plastic line a Mercedes only item or can I get it at a typical American parts store?

Also what looks like a plug on the bottom of the box (Blue "B") is cracked, is that just a plug? (again, Merc item?)

 

[Fine Business]

That plug at blue 'B' has a screen in it so it's not a plug but some kind of atmospheric vent. I'll pick one up somewhere.

I patched the broken line finished up the water pump job flushed the radiator and started it up and everything looked good so I topped off the coolant, put away my tools and then when next I started it... "CHECK ENGINE ELECTRONICS" DISPLAY APPEARED AND "CHECK ENGINE LIGHT LIT UP.

WTH!

The only engine electronics I touched were the temp/sender on the thermostat, the electric fan plug and one sparkplug that I pulled to verify that the plugs were new as the PO said they were.
Also I repaired the broken air pipe mentioned above. I mentioned it because I was surprised that it didn't cause a code. so I fixed it and got a check engine display.

I went for a test ride and it feels fine.

I'm an hour away from a Merc dealer, so I guess I'll have to go looking for someone locally who can check the codes.

Is this car ('96 I6) a standard OBD2 scan or needs some kind of special Merc scanner?

 

[Kajtek1]

Any OBDII scanner should read you the codes.
Your engine is grandfathered in W210 from W124, so it is still having vacuum logistic system.
You need to find someone who would have exact, or work on exact model, so this is not going to be easy. I would find vacuum diagram and make sure everything is working.
Hook up vacuum gauge into the system to make sure you have no other leaks.
Are cabin duct flappers operating without a problem?

 

[71_340]

Any Autozone or O'Reilly store will scan the codes for you and clear them.

I looked up the P/N for the black box and all that comes up is a "Magnetic Valve". Where do the other lines go to? It might be a purge valve for fuel vapors.

 

[Fine Business]

Thanks guys.

AFAIK all the flappers work normally. I don't use all the buttons so there may be a non responsive function that I haven't noticed.

I don't know how specific the dash error messages are. Do you think a vacuum problem could give an 'engine electronics' message?

I'll have to learn how to troubleshoot a vacuum system.

Now I'm guessing that if the 'Magnetic Valve' box has openings to the atmosphere then the broken line may not have been a problem (bleeding away the vacuum).

Another thing that I noticed is that one of the vacuum lines going into the plug/coil area was pinched closed by the engine cover on top of it. I replaced the pinched part and thought I was doing good.

I have no idea what all this stuff is doing.

 

[Kajtek1]

The line venting to atmosphere likely is tank vent.
In the past the cars had vacuum operated logic systems (yes, before electronic era they build pneumatic computers) and your engine might have mix of those with electronic.
I did restore vacuum system on 1987 diesel and it had like 250 components. Not something you can fix on try by error mode.
Read the codes, write them down and erase. Then check your vacuums for leak and go from there.

 

[tirona]

the box you are wondering in first post is the switchover valve. even though is connected to vacuum lines, the switchover valve is mostly electrical where electrical signals transfer vacuum signals in the lines. those lines go to egr valve, fuel pressure regulator, air intake, brake boost ...., just follow them and you will see where they go. you should replace all those lines considering age, mine were all crumbling to the touch so i replace what i could. vacuum line is very cheap.

I don't know how specific the dash error messages are. Do you think a vacuum problem could give an 'engine electronics' message?

yes

Another thing that I noticed is that one of the vacuum lines going into the plug/coil area was pinched closed by the engine cover on top of it. I replaced the pinched part and thought I was doing good.

I have no idea what all this stuff is doing.

this vacuum line goes from the switchover valve to the egr valve (look in attached picture circled in red). if original that line will crumble as soon as you touch it because of the heat exposed in the last 18 years, so most likely you damaged it. that could be what's triggering your cel.

 

[Beverly Sharp]

?

Is this an example of "leave well enough alone?"
Hemersam

 

[Fine Business]

WOW good information all, thanks... as far as leaving well enough alone... had to fix the water pump so its more like not being able to let sleeping dogs lie, or opening a can of worms.

The lines are in remarkable shape if original but I saw several rubber hose patch connectors over what must have been breaks in the past.

The water pump, hoses belts etc are all Mercedes parts and in very good shape so it looks like the car was well cared for by dealer maintenance.

 

[Kajtek1]

Those plastic tubings last forever - I have seen them 30 years old in good condition.
It is rubber couplings and tees that like to dissolve.
Per my experience - each car that passed 10 years will require a number of rubber and plastic parts exchanges. Waiting for them to fell down or spending some time and money on repairs before massive failure will happen is personal decision.

 

[kstreufert]

A couple of years ago the vacuum tubing on my 96 SL320 (exact same M104 motor) started to completely fall apart. I picked up several feet of vacuum tubing from the dealer and replaced it all. The tubing gets very brittle with time. It is a quick and easy job that will save you a lot of aggravation.

 

[Fine Business]

Yes, new plastic pipes in the engine room is next.

I took off the bottom covers getting ready for an oil change and there is a lot of oil under there so I want to give it a good cleaning. I was thinking of an off hours trip to a car wash with some degreaser.

Are there any precautions I need to take, or horror stories I should be aware of before I do it?

 

[tirona]

brake cleaner works best for cleaning old oil, much better than degreaser and also it dries quick. m104 is not picky on oil type or weight, but dont fill it to max and if previous owner used dino then dont switch to synthetic or it might develop a leak. mb lowered oil capacity by half quart in these engines since it might have contributed to leaking. so keep level between min and middle on min-max spectrum on dipstick.

 

[Fine Business]

It definitely leaks but I haven't seen any drops under the car so I can live with it. Gonna go Dino with it (half qt. low too).


Yeah good point, brake cleaner works fast. I use it a lot.

A word of warning though on brake cleaner.

Brake Cleaner = Phosgene Article

Keep the brake cleaner off hot engine/exhaust parts. If it boils it makes poison gas!

 

[Starguy1]

Yes, new plastic pipes in the engine room is next.

I took off the bottom covers getting ready for an oil change and there is a lot of oil under there so I want to give it a good cleaning. I was thinking of an off hours trip to a car wash with some degreaser.

Are there any precautions I need to take, or horror stories I should be aware of before I do it?

Be very careful about spraying water directly on top of the engine. It will get under the ignition system cover and fill up the spark plug holes.

 

[Fine Business]

Yeah, not going there... just doing the down-under stuff. Then I want to check the oil pan etc bolts .


I noticed I have an open inspection hole at the bottom of the torque converter. Its supposed to have a cover on it right?

 

[tirona]

I noticed I have an open inspection hole at the bottom of the torque converter. Its supposed to have a cover on it right?

the openings at the tc housing have small black plastic covers but they fall off, but no need to get new ones. i didn,t know there were supposed to be covers there since my e320 didnt have them, but my s320 had them.

 

[Fine Business]

this vacuum line goes from the switchover valve to the egr valve (look in attached picture circled in red). if original that line will crumble as soon as you touch it because of the heat exposed in the last 18 years, so most likely you damaged it. that could be what's triggering your cel.

I checked the engine codes today and had;

P0400 (EGR Recirculation Flow Malfunction)
The line that I fixed (was crimped) goes to EGR. and the other line that was broken goes to the "EGR Vacuum Check Valve" (the blue cap thing-a-ma-jig in picture #3 above PN0021408460)
Both of those lines come from the mystery "Magnetic Valve" box.

First I'm going to replace those air pipes. If that doesn't fix it, is the EGR valve (my car has two) something that can be cleaned/repaired?


The other code was P0411 (Secondary Air Injection System Incorrect Flow Detected)
Looks like air pump / check valve related - whatever(& wherever) that is.

Any thoughts or suggestions on this one? I did some searching and it looks like smog pump is expensive is my original one repairable? can this do damage if left alone?

 

[tirona]

I checked the engine codes today and had;

P0400 (EGR Recirculation Flow Malfunction)
The line that I fixed (was crimped) goes to EGR. and the other line that was broken goes to the "EGR Vacuum Check Valve" (the blue cap thing-a-ma-jig in picture #3 above PN0021408460)
Both of those lines come from the mystery "Magnetic Valve" box.

First I'm going to replace those air pipes. If that doesn't fix it, is the EGR valve (my car has two) something that can be cleaned/repaired?


The other code was P0411 (Secondary Air Injection System Incorrect Flow Detected)
Looks like air pump / check valve related - whatever(& wherever) that is.

Any thoughts or suggestions on this one? I did some searching and it looks like smog pump is expensive is my original one repairable? can this do damage if left alone?

egr valve is same as air pump check valve, so both codes point to same thing. make sure all lines and hoses are in place and not cracked, air pump is under alternator if i remember correctly. you can clean egr/air pump check valve with carb or brake cleaner if you need to.

 

[Fine Business]

Thanks.