1995 E300 rough Idle

[lebstyle007]

Hi I have a 1995 e300 Diesel that i just bought, in idle it runs very rough, the hwole car shakes, and the acceleration from zero is very very sluggish, gets even worse when the A/C is on ( it will barely move)
but once you get to a certain speed and rpm ( over 70km/h) it runs smooth, specially on the highway.
it seems like it is missfiring in idle up till 1500rpm, then is smooths out if you press the gass in neutral.
Any ideas?

[Cr from Texas]

Start with the routine maintenance items. I'd first assume the valves need to be adjusted and go from there. Probably also need to change the fuel filters but I don't think that's your problem.

[tankowner]

Originally Posted by lebstyle007

in idle it runs very rough . . .the acceleration from zero is very very sluggish

And the problem is . . .??? This is a diesel right?

Just kidding, these NA diesels are rather slow on the take off, but your problem sounds extreme. So this in not just another '95 E300 with nailing issues - the whole car is shaking, huh? Is it that it's seems starved for fuel and that is what is causing the rough idle? Is the engine stumbling?

Check your fuel lines and make sure they are okay without any air bubbles visible in the clear plastic lines. I doubt that is your problem though if things improve with speed.

Like Cr from Texas said - start with the easy and cheap things and go from there.

Originally Posted by Cr from Texas

I'd first assume the valves need to be adjusted and go from there.

The valves on this model are supposed to be self-adjusting.

Anybody think this could be an IP timing issue??? (I don't have any experience with that so I will leave it to someone else to say.)

[Cervan]

i dont know the engine in the 1995 e300... If its the 603/606 it may be the infamous head cracking issue. but i would make sure that there is no chocolate milk in the radiator (oil residue) And your not mixxing water in your oil. What color is the smoke? Do you see any bubbles in your fuel pick-up line? The valves in the inline six are hydraulic self adjusting.

[Number_Cruncher]

First thing to do is to replace the fuel filters, both pre and main. Check that there is reasonable flow from the feed pipe - i.e., that the tank strainer isn't blocked.

It's allways worth replacing the O ring seals on all the low pressure fuel lines, and rnewing the injector leak off pipes, to avoid fuel leaks, and to eliminate air from the system.

If the problem persists, then, get the injectors out, and do a compression test. While the injectors are out, get them tested for opening pressure, dribbling, and spray pattern.

Unless abused by a previous veg burning owner, the IP is extremely unlikely to be the root cause of the problem.

The valves on OM606s are self adjusting, driven by hydraulic tappets, so, there's nothing to adjust. However, valve seat recession is not unknown, but, this will be picked up by the compression test.

[If I were a gambling man, I would back that the answer will come from the compression test]

[tankowner]

Originally Posted by cervan

i Dont Know The Engine In The 1995 E300...

606.910

[TMAllison]

It runs so its getting some fuel; after changing out both fuel filters I'd look to the resonnance flaps'egr valves and their electro-vacuum controls to make sure its getting sufficient air.

Compression testing would be way down on my list as you don't mention that it is hard starting.

I would also check your motor mounts.

[lebstyle007]

when i first start it it runs rough and doesnt idle high then go low, it stays at about 550 rpm all the tme at idle.

when u drive and hit about 50kms/hour it drives perfect, even in idle when its shaking and i press on the gas in park it runs rough till the rpm hits about 1500 to 2000.

I put some lucas injector cleaner for diesel in the gas tank and drove it on the highway for about 2 hours, when i was back i could tell it was running a little smoother, but still rough, and the acceleration improved, but still sluggish, but when the A/C is on, it gets worse as usual.

i did change the fuel filter in the engine compartment, but i had this problem before and after.
seems like its not getting enough diesel at idle, so when i give it gas the pressure goes up and it gets enough.

but when driving over 50, it drives perfect and smooth.
I left the car at the diesel mechanic today, tomorrow I will check with him if he found something wrong, but he told me might be a bad injector, so he might do a compression test on it.
I dont know much about diesels, its my first one.

[Cervan]

Originally Posted by lebstyle007

when i first start it it runs rough and doesnt idle high then go low, it stays at about 550 rpm all the tme at idle.

when u drive and hit about 50kms/hour it drives perfect, even in idle when its shaking and i press on the gas in park it runs rough till the rpm hits about 1500 to 2000.

I put some lucas injector cleaner for diesel in the gas tank and drove it on the highway for about 2 hours, when i was back i could tell it was running a little smoother, but still rough, and the acceleration improved, but still sluggish, but when the A/C is on, it gets worse as usual.

i did change the fuel filter in the engine compartment, but i had this problem before and after.
seems like its not getting enough diesel at idle, so when i give it gas the pressure goes up and it gets enough.

but when driving over 50, it drives perfect and smooth.
I left the car at the diesel mechanic today, tomorrow I will check with him if he found something wrong, but he told me might be a bad injector, so he might do a compression test on it.
I dont know much about diesels, its my first one.

may be injectors.

[Number_Cruncher]

>> Compression testing would be way down on my list as you don't mention that it is hard starting.

Yes, ... and no. If there are 2 or 3 good cylinders with good working glow plugs, the engine will probably start without too much aggro, but still run like a donkey.

The specific problem I'm thinking of is inlet valve seat recession, which, as per Wingas's recent OM606 thread, can give you good compressions on some cylinders, and bad compressions on others.

If the injectors are coming out anyway, it's a perfect opportunity to do a compression test. It's not expensive at this point, with the injectors out, as you've already done most of the prep work.

[lebstyle007]

the mechanic told me he took it apart and did a test, he told me injector number 6 isnt working at all, and number 5 is on its way out.
but he recommended i change all of them or he said they will rebuild them.
but im not sure if i should rebuild all of them, or just the 2.

but i know i can buy them new for the same cost as the rebuild.

any recommendations?
thanks

[ds190]

Leb, don't forget about the pre-filter, which should be replaced also. It does not come with the O ring needed for it, so you have to order that as well.

[TMAllison]

Glad you are getting to the bottom of it. I dont think you mentioned mileage?

I'd pop and spray test all of them, replace nozzles on the bad ones and re-balance all if your mech can do that for you. Otherwise its probably easiest to just replace them with rebuilts.

Sounds as if you had a couple of dribbler's at idle.

[husk]

Did your Check Engine light come on? If so did it display error code P0300? I have a simliar problem in my 606.962 in that the CEL comes on sometimes, and displays this code which leads me to believe its the injectors. I have been running Diesel Fuel Additive and whenever I do add it the CEL does not come on and I get about 60 more miles to the tank than not adding it (from 420 to 480). When the CEL does come on though I do not notice a huge loss in power, it pretty much feels the same. I am trying to decide if its time to replace the injectors or not. EDIT: Did the 95's have OBDII?

[TMAllison]

Originally Posted by husk

EDIT: Did the 95's have OBDII?

95's were OBDI.

HUSK - Didn't M.B.DOC address that code for you previously?