1995 E300 - Questions on Injectors/Idle - PeachParts Mercedes-Benz Forum

KrustyKustom · #1 04-09-2016, 11:22 PM

I have been lurking here a while and finally decided to be a member as there is so many good conversations going on here. I recently purchased two months ago a one owner 1995 E300 that I have been trying to buy for 3 years. Long story but he finally sold it to me and I have been having a blast going through it mechanically to learn it and start to list what items I want to replace for longevity and reliability. It runs great but it does have a little lumpy idle, not bad but not glass smooth. I can see one of the crankcase breather hoses that attach to the intake has a small crack in the rubber but I am really thinking it is a injector/nozzle. I get a haze of smoke at night in a following car when I give it a little throttle but during the day no noticeable smoke. At idle and the engine is cold or not super hot it has a secondary occasional "rattle" that goes away when fully warm or if slight throttle is applied.

The owner has meticulous (every receipt and fuel fill up since new) records and I went through them and in the 288k miles it has on it there is no significant injector pump or injector work done. It has had glow plugs 4 times (all 6) and the return fuel hoses have been done about 3 times but that is the extent of the fuel delivery system work. Should I consider the nozzles for replacement? I really want to get that idle as smooth as I can get it. When the AC is on and it is idling when the compressor kicks in or out it has a fairly good "bump" on the idle as well.

I am going to replace the vac pump as well as a preventative, I have already replaced the shock tensioner, tensioner arm, belt, idler and all fluids including the rear end oil. I have a really slight weep of coolant on the passenger rear side of the head, once it warms up it does not weep. In looking at a head gasket I think it is the o-ring in that back corner. So the head will need to come off at some point as well. No oil in coolant or coolant in oil.

Fun car to tinker on and I have two other new MB diesels that I only do maintenance on but something in this I-6 engine speaks to me. Its a blast to cruise around in.

thanks for any suggestions,

Chris W. · #2 04-10-2016, 08:58 AM

My injectors are original and untouched. Rattle when cold and backing off throttle is normal. Light haze of smoke is normal. Don't be afraid to give it an "Italian tuneup" from time to time. Floor it and let it run up through 3rd gear at least. Agree with new vac pump at this point. Sounds like a nice car - enjoy it.

Rgds,
Chris W.
'95 E300D, 463K

KrustyKustom · #3 04-10-2016, 10:21 AM

Thanks for your input Chris. I have not really "romped" on it yet, I have gotten it to 3k rpm and it actually surprised me for a non turbo it actually had good acceleration when the motor starts to breathe.

I am enjoying the heck out of this car which only confuses my buddies and wife. One of my buddies calls my car "Bushwood " in honor of caddyshack, my kids call it Stinky Pete!

I will have to post some pics

Sent from my SM-G920V using Tapatalk

barry12345 · #4 04-10-2016, 01:01 PM

In the extensive records you have. If the injectors have never been checked at least they are well overdue for at least a check. At least you have the extensive records that came with the car to go by.

renaissanceman · #5 04-10-2016, 03:36 PM

See my thread about the rebuilt injectors with Bosio nozzles done by Greazzer. My idle is now so smooth...similar to this youtube video where the guy sets a cup of water on the crossover pipe and starts his 603 cold.

https://youtube.com/watch?v=xXwO6B1vthY

jt20 · #6 04-10-2016, 08:53 PM

I understand the urge.

having just done this, I would suggest you measure your fuel consumption and acceleration before doing this. its really not worth the hassle if it is functioning well.

I had some weird noises that I had to figure out and injectors were my best option before digging in deep. MPG was not so great either.

get more data first.

make sure you don't have any air infiltration into the fuel system. this will cause your described symptoms and its notorious on these engines / fuel system. research "om606 orings"

tmallison has some great info in his posts. you can get orings from mcm_aster_carr

babymog · #7 04-11-2016, 07:39 AM

If you have idle issues, look for leaks first. Even a tiny seepage at the delivery valves or injectors will cause rough idle. Unlikely you have a leak upstream of the IP (air) or you would likely have hard starting.

Zulfiqar · #8 04-11-2016, 03:41 PM

you say the idle is not smooth, is the ELR working? - ELR is the electronic idle control, there is a connector on the pump near to the manual idle adjust screw, check to see if its connected and if its connected, remove it and verify the engine idles slower.

my car has absolutely zero change in idle speed, no matter if I run the A/C, turn the wheel, have the defrost running - or all at once.

KrustyKustom · #9 04-11-2016, 09:19 PM

I am going to check for that plug and see. Is that a solenoid based device?

Mine does have idle change when the compressor kicks in. As far as the idle goes It is not bad and once warmed up its livable, I just think it can be better and since this car does not have to be my daily driver I do not mind looking some of these things over through the course of a few days if need be.

The cars records and overall condition blow me away. Not a leak on it aside from that first 15 min warm up coolant drip. I have not had to add any coolant in the 300 miles I have put on it so far.

Man, everything around that IP is busy and buried. May best be seen from below?

KrustyKustom · #10 04-11-2016, 10:17 PM

I just scoped out under the intake manifold for the plug in question. Incredibly there is a plug that is not plugged in! It has a white/blue wires going to it. I did find the idle control and it appears to have a blue/blue plug going to it. Anyone have a look at theirs and see what color wires go to the idle control?

That area is so compact and hard to see what is what I am going to have to lift it and have a look from the bottom.

I appreciate the suggestions...

benedict · #11 04-12-2016, 12:17 AM

You'll have a spare plug on the OM606.910. This spare plug is for the OM606.912/962 injection pump's rack position sensor which our .910 does not have.

The rack position actuator (red thing at the end of the IP) is controlled by the ELR relay (003 545 5205) located behind the battery on right hand drive cars but possibly reverse on US versions.

So, easy way to test for operation is to unplug the above relay and you will hear the revs drop or remove cross-over pipe and unplug the wire going to the back of the IP. Default idle is 570 RPM +~- 40RPM but if the control circuit is working correctly, the idle should come up to 630 RPM +~- 20 RPM the change is obvious but you must do the test with a warm engine 60-80C. The ELR controls a few other things such as AC clutch and temp sensor. Higher the temp, faster the revs to assist the water pump circulation when stationary.

Maxbumpo · #12 04-12-2016, 03:01 PM

I agree with having the injectors checked / serviced. Other possible culprits: worn / dead engine mounts (three: two up front on the sides of the engine, third is at the back of the transmission right before the drive shaft.

Last place: rebuild the delivery valves on the IP, when the copper crush washer inside gets worn, they can cause a rough idle.

renaissanceman · #13 04-12-2016, 03:04 PM

Having done both, here are my observations:

Engine mounts: vibration
Injectors: gentle rocking back and forth

How much blowby on this engine? My 603 has essentially none, so I assumed good compression and jumped straight to injectors.

Zulfiqar · #14 04-12-2016, 04:17 PM

benedict explained it perfectly

your case maybe due to damaged wiring too, this year had the biodegradable wiring in it whose insulation crumbles away. Reason for me say this is when I bought my car its idle control was dead, meaning everything worked except the idle. Very lumpy and harsh.

my case was a misconfigured connector for the ELR cube. Once I fixed it, the idle is extremely smooth no matter if the engine is started dead cold, or I switch on other things like A/C or defrost etc even on a cold engine.

The OM606 engine whilst idling makes a clicking noise only - its very quiet and almost mouse quiet when the hood is shut closed and you have its barrier blanket pasted on the underside.

connerm · #15 04-12-2016, 05:05 PM

Check fuel tank strainer too. Blow out the fuel lines. Replace all of the rubber pieces on the intake. Plastic pipes should be fine. Check the big bushing on the tensioner arm for wear.