To check or not to Check (Timing)

[grim 140]

I just purchased a 1995 S500 That Has The M119 engine.
I am here because of the extreme helpfulness I see in this Forum.
I purchased this S500 for a great price because The guy could not keep it running past about fifteen minutes.
It would then sputter and run rough then die. I purchased Knowing that I could fix it (I hoped)
Well I did. It turned out it needed the whole gamut. Wires,Sparkplugs,Caps,rotors,Fuel filter,crank shaft position sensor and even the insulator bowls.
I made sure to that I used the correct Sparkplugs (this seemed to be an issue I see that people are always saying to make sure of)
It runs now except it has a slight miss all the time.Not bad but noticeable enough to bother me. I have checked for Vacuum leaks found two fixed them. I also checked fuel pressure fantastic.
By the way I noticed the miss it has before I did all of this to it.My question is could it be an timing issue??
Turns over strong no noise for the typical timing chain guide noise.It has a 133000 miles on it.
Its a clean car no rust.You can tell it was maintained even though there is no records to check with.
Also it has the new upper engine harness. No lights on the dash either. So my next plan is to take the valve covers off and check the timing.
Just wanted people thoughts before I went ahead with this next bigger step.

 

[grim 140]

Also forgot to add I installed new ignition coils also.

 

[gsxr]

A slight miss is probably not due to camshaft timing, it's more likely to be either ignition or injection. If you only notice the miss at idle... have you checked motor mounts? They are usually shot and can make it feel like the engine is missing at idle (generally is smooth at speed).

For a new M119 purchase I would pull the lower oil pan and inspect for chain rail debris. If there is any debris, definitely pull both valve covers and inspect the upper chain rails. If the pan is clean I'd still like to pull the covers and inspect the rails anyway. Or at least pull the passenger side, and while you're at it measure chain stretch for grins. Don't be surprised if the chain is ok.

BTW, welcome to the forum!

 

[RicardoD]

Does slight miss mean same thing as “occasional stumble at idle”? I have that too and recently changed spark plugs and wires like you did. However, I gapped my spark plug to spec 0.8mm and wisdom on this board says to gap to 1mm for better smooth idle. I know member lowman did this and it took care of his idle smoothness.

 

[grim 140]

The engine miss is noticeable if your at idle or driving.Its just not smooth and no surge.
If its ignition what else could it be the EZl? Don't those just fail complete or if its injection related do you mean the fuel injectors possibly clogged?
As for motor mounts I dont see any over the top movement when doing the brake torq test.
Of course I would not doubt they are probably going to need to be done soon anyhow.
So I take it the oil pan could be the easier of the two (valve cover) for checking for chain rail failure.
As for spark plugs I will check that out also.
Thanks to everyone for the quick response back earlier

 

[gsxr]

The engine miss is noticeable if your at idle or driving.Its just not smooth and no surge. If its ignition what else could it be the EZl? Don't those just fail complete or if its injection related do you mean the fuel injectors possibly clogged?

Since you have replaced everything I doubt it's ignition related, but it wouldn't hurt to open the gap up to 1.0mm as Ricardo mentioned. The EZL either works or it doesn't, so that's not the problem. Since it's a new purchase, I'd run a bottle of Red Line SI-1 injector cleaner in 1/2 tank (~13 gallons) of top-tier fuel, and run it near empty. That should clean out the injectors. Who knows what gas the PO had been using.

As for motor mounts I dont see any over the top movement when doing the brake torq test. Of course I would not doubt they are probably going to need to be done soon anyhow.

Even with bad mounts you won't see major engine movement up top with the brake torque test. They are hydraulic mounts and collapse over time. On the W124 chassis you can measure the distance from oil pan to engine crossmember to determine if they are shot, but I don't know the measurements for the W140 chassis. Unless you can see a date code on the mounts indicating they are recent, they are probably due for replacement. Only get the OEM/Boge mounts (last I heard, Lemforder mounts were still reboxed OEM Boge, and less than half the cost of OE/dealer mounts).

So I take it the oil pan could be the easier of the two (valve cover) for checking for chain rail failure.

I can't remember on the 140 chassis if the lower oil pan is easy to drop like on the 124... but I think so. (On the W210 it's a PITA, can't access the front pan bolts.) If you do drop the pan, replace the O-ring for the oil level sender in the side of the block, it's a very common leak and the O-ring is only a buck or two. The new style / larger oil sump rubber pickup is another cheap upgrade while the pan is off. If the pan is totally clean that is no guarantee the rails are ok, but it means there's a much better chance they are ok. But if you find a pile of plastic in the pan, then you know you have to pull the valve covers. The valve covers aren't too hard to R&R on the W140, but if the PCV hoses are fossilized you may break some in the process (they should be soft rubber, not hard plastic). If you pull the valve covers only use OE/dealer gaskets (search the forum for info on Naperville, a dealer that sells below wholesale with free shipping). The aftermarket Reinz gaskets have been reported to not fit as well and there is also no difference in the price.

If the misfire persists you may want to consider a compression test for grins. Also, if the car was neglected or sat for a long time, it just may need a good old Italian tuneup...

 

[nocfn]

And new mounts. Like Campari - its good for what ails you ....

 

[grim 140]

Okay I did the 1 mm spark plug gap did not make a difference.
Motor mounts yeah I think they are going to have to be done but the miss is still there.
From what I can tell from the info I gathered from the PO.
I gave him a call a little bit ago( He's cool)
This mercedes did sit for awhile like maybe a year or two
Before he got it.He had it for about 4 months.
It was almost empty when I drove it home.
I stopped at a Shell station and put the 93 Vpower in it.
About ten bucks just to get it home.

So with this new info I think A proper Italian tune up maybe just what it needs and some redline.
I have to first go to the DMV and get it platted with a temporary.
So I will get back to u Guys in about a week.
Also The oil pan bolts are hidden some under the cross member.
Thats going to suck but since I have to lift the motor.I might as well do the Motor mounts to.
Any other thoughts let me know.
I will get back to everyone thanks!

 

[nocfn]

Get mb or get lemforder mounts from fcpeuro. They are reboxed oe

 

[Klink]

Expired and/or Mickey Mouse motor mounts feel just like a rough running/missing engine in this car. Believe it or not, they will also make the car feel like it has weak front shock absorbers, especially on washboard pavement. The mounts can be consumed by time as well as mileage.
There is a date code on the motor mounts. You may need to get in there with a mirror and flashlight to see it. Look for the "W" with some numbers. The number closest to the W will be the week they were made and the other numbers will be the year. I don't have a good picture here to post right now. Suffice it to say, if they are, say six years old or older, replace them before you go nuts looking for a engine roughness. Some don't even go five years if the vehicle is driven aggressively, or covers a far higher than average mileage.

EDIT: See attached photo. 16W01 means they were manufactured in the 16th week of 2001.

 

[grim 140]

I will definitely check.
Also going to the DMV tomorrow.

 

[grim 140]

Still working on the italian tune up...Honestly It seems a little better??
I will give it more time. Also tomorrow I will do a compression test on the motor.
Will let everyone know the results of that to.

 

[grim 140]

All right Compression test done.
Perfect! With in spec.
I been taking it up on the freeway now doing about 80..85ish thats as fast as I will go with having to worry about the Police.
Doing stretches of at least 45 minutes at a time. I would say I have about 2.5 hours into it so far on the Italian tune up trial.
Still a miss happening. In the mean time I am taking it into a Garage Tomorrow that works on Mercedes and foreign cars only. Just having a Scan done to see if it thing pops up or gives us a clue.
As to what is going on.?? It does not seem to lack power or anything when you give it gas it gets up and moves.
Will keep everyone posted on the scan.

 

[grim 140]

No resolution yet still working on it.

 

[grim 140]

Problem not found.
The car is in perfect working order Sensors and computers are behaving like they should.
Timing is on. I was told go and drive that car because it has sat before I purchased it.
So I guess that is what I will continue to do. I was not charged because they could not find anything wrong with it and yes they had the mercedes diag system and bells and whistles. So I will keep posted to everyone and see what happens.
Thanks for everyone help so far.