99 e300td , diagnostic -missing - PeachParts Mercedes-Benz Forum

oldwheels · #1 06-29-2008, 12:08 PM

My 99 e300Td started missing while on a trip. I am a bit ignorant on diesel trouble shooting so I'll ask you gurus.

Symptoms

Start and runs great when cold. Smooth - no missing.
After warming up will start losing one cylinder. When hot cylinder will runn partialy or not at al. Nost of time runs partialy.
Highway speed is okay with normal power or close to it.
Check engine light came on and is staying on.
130K miles
No leaks, filters always changed.

If I need to do compression check what special tools are needed? I assume I pull the intake manifold.

Please pass you r knowledge along.

I'm suspecting a bad valve seat.

TMAllison · #2 06-29-2008, 12:13 PM

Pull the codes to narrow things down.

Does it start to run rough after ~2 minutes? And which cly is missing?

oldwheels · #3 06-29-2008, 12:28 PM

How can I isolate a cylinder?

TMAllison · #4 06-29-2008, 12:30 PM

The ECU will sometimes do that via code. not always.

By feel, or by sound using a mech's stethoscope or 18" screw driver pressed against your ear.

Additionally, you can crack an inj line one at a time and find the one that "doesnt" effect idle.

DieselAddict · #5 06-29-2008, 02:29 PM

I would isolate the cylinder (as mentioned above) and pull the injector out and have it tested. I haven't heard of any diesel having this symptom because of a bad valve seat. That's a more common problem with gas engines.

aklim · #6 06-29-2008, 08:40 PM

When you changed the filter, did you change the O-ring on the mesh filter? Are there any bubbles when it is running? Wouldn't hurt to take the injectors out for a test at a Bosch diesel shop

oldwheels · #7 06-30-2008, 09:57 PM

Yes, I changed the o RINGS

I 've been reading my manual. Pretty vague on easy to find info.
Has any one here ever pulled an injector out of one of these engines?
This things runs bad now. It is consistant missing.

TMAllison · #8 06-30-2008, 10:08 PM

First, you need to get your CEL checked out. You might have 10 different problems rather than just one for all we/or you know.......

Go to AutoZone (they will do it for free) or other MacParts store. Thats the starting point to getting "good" help. Prior to knowing the codes we only know what you tell us and are oftentimes influenced by your bias......The other way to do this is for us to guess until one of us guess "right".

Again, does it start running rough 2 minutes after start up?

ps: to remove the inj's you need MB socket #606 589 00 09 00 and a new replacement with heat sheild; or a pop tester to reset its pressure, and/or inj nozzle pending whether the one tested had a bad spray pattern or not.

aklim · #9 06-30-2008, 11:56 PM

Quote:

Originally Posted by oldwheels

Yes, I changed the o RINGS

I 've been reading my manual. Pretty vague on easy to find info.
Has any one here ever pulled an injector out of one of these engines?
This things runs bad now. It is consistant missing.

Any air leaks from the hoses? While running you should see bubbles.

You are going to need to read the codes before we can go any further. Either that or we can spend your money throwing parts at it till we get lucky.

oldwheels · #10 07-01-2008, 06:15 PM

, I done some diagnostics,
went to Autozone, only one code. P0300, ( ramdomly missing on multiple cylinders"

Cracked the fuel lines on the injectors while idling. No. 1 cylinder is the culprit. No differance in idle speed. The rest made a big differance.

Do ya think I should put in an injector??

aklim · #11 07-01-2008, 06:17 PM

Quote:

Originally Posted by oldwheels

, I done some diagnostics,
went to Autozone, only one code. P0300, ( ramdomly missing on multiple cylinders"

Cracked the fuel lines on the injectors while idling. No. 1 cylinder is the culprit. No differance in idle speed. The rest made a big differance.

Do ya think I should put in an injector??

When you cracked out the #1, did it flow fuel? Hopefully it did. That gives hope the injector is dead.

Before I do IP work, unless it is leaking because of U:SD, I would first take ALL the injectors out and have them tested and/or cleaned.

TMAllison · #12 07-01-2008, 06:49 PM

Quote:

Originally Posted by oldwheels

Do ya think I should put in an injector??

I do, although it is strange that it runs fine cold and gets worse when up to operating temp. Must be a dribbler when fuel thermo heats fuel up to a certain point?

You could put a new one in, or pull all six and have all of them serviced at a inj shop. They would replace the bad nozzle(s) if that was needed. The latter is probably a better way to go although more expensive.

You'll need the MB inj socket (606 589 00 09 00), 6 heat sheilds and likely new cloth braided return lines as they like to leak after being pulled off and reinstalled.

aklim · #13 07-01-2008, 06:51 PM

Quote:

Originally Posted by TMAllison

You could put a new one in, or pull all six and have all of them serviced at a inj shop. They would replace the bad nozzle(s) if that was needed. The latter is probably a better way to go although more expensive.

I would take them all out just so I could check pressure and spray pattern and see how far behind the others are.

TMAllison · #14 07-01-2008, 07:05 PM

Quote:

Originally Posted by aklim

I would take them all out just so I could check pressure and spray pattern and see how far behind the others are.

Def has merit.

nhdoc · #15 07-02-2008, 06:27 AM

While he's isolated which cylinder is causing the problem he hasn't necessarily been able to conclude it is the injector by this method. At this point it could be fuel (injector or IP) or low compression and I don't like the "cold smoothness" since having the GPs on for the first few minutes can mask a low compression condition in one cylinder. Once the heater goes off that one starts to miss. I have heard of this before.

He can simply swap injectors with another hole...if the miss moves then he's definitely pinpointed it as the injector. I suppose if the problem didn't move then I'd do the compression test to know whether it was low compression or a problem with the IP at #1 that was causing the miss.

The OP lives close to me, in fact he's coming to my house later to borrow my injector socket so he can pull it out...we'll get to the bottom of it.