350SD, burning oil SECOND STAGE ENGINE - PeachParts Mercedes-Benz Forum

DslBnz · #1 08-29-2003, 10:15 PM

It started burning a quart every 2,000 miles

then every 1,200

now it's burning a quart every 500 miles right now.

Could it be valve seals? Darn well better be something minor;
Second-Stage engine by MB, here!

What other possibilities could it be? A lot of people are unfamiliar with these 3.5 engines and their different mechanical characteristics from the 3.0.

psfred · #2 08-29-2003, 10:24 PM

Burning or dripping?

Blue smoke means a bad turbo, nothing wrong with the engine (yet, all the oil ain't good for the combustion chambers).

Bent rods make that horrible clanking, so if you are just using oil, you need to find out why before assuming the engine is toast.

Bad turbo seals will also dump large quantites of oil in the exhaust, hence the blue smoke. Not unheard of here on the forum.

You can run a lot of oil down bad valve guides, but I'm not sure you can get a quart in 500 miles down there.

Check for excessive blowby, too -- this would mean rings or bent rods (ouch!).

Peter

DslBnz · #3 08-29-2003, 11:17 PM

No blue smoke. Just carbon.

EGR has been giving me trouble, lately.

I haven't seen ANY blue smoke, starting up, or going down the highway. I have seen the 350 from the tail recently, when following it, and just a light amount of carbon, consistently comes out of the exhaust. Unless that's not carbon.

sixto · #4 08-30-2003, 01:38 AM

What's a second stage engine? Did you jettison the first stage engine after launch? Just kidding.

Are you sure you don't have a leak? The encapsulation panels will hold a lot of oil.

A quart in 500 miles sounds more like a bad valve guide than valve seal.

Has fuel consumption changed?

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

DslBnz · #5 09-02-2003, 07:35 PM

Some more recent symptoms:

This car knocks loudly at idle, now. When it IS idleing, it might shake a lot, but no smoke comes out of the back, at idle, or even when you lay on the pedal.

I will keep driving and monitoring the oil.

My EGR is still connected, but the car is used on the highway everyday 75 mph up to 115 (not everyday, really

)mph. I don't think there's enough crap in the EGR to cause that rough idle. Unless the EGR failed. But then, what is consuming the oil?

The oil is not leaking out, it is fairly dry underneath and throughout engine.

I mentioned this before, this engine is the 'newly designed rods and pistons 350', that replaced the first one. If my engine goes down, you can mark that in the MB technical history books, since most of you have never heard of them dying. But I damn well hope that is not the case.

FUEL CONSUMPTION IS NORMAL ABOUT 27 + MPG.

Thanks for your advice,

sixto · #6 09-02-2003, 08:01 PM

Things to check for noise:

- delivery valve seals and washers. When these get stiff and/or leak, there's a nasty knocking most obvious at idle. Did you get a new IP with the new engine?

- hydraulic valve lash adjusters. Can be noisy in a 603. Mobil 1 sometimes quiets them. New lash adjusters are as flaky as old lash adjusters.

Things to check for oil consumption:

- turbo seal leaks into intake manifold. Did you get a new turbo with the new engine?

- uhh... can't think of anything else right now.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

mr. Goodwrench · #7 09-02-2003, 10:36 PM

To DslBnz: I am particularly interested in your engine problem. I have a really good running engine in my wife's '93 300SD. I bought the car in '95 with 32,000 mi. on it. It has the 3.5 engine. However it has been using a lot of oil lately. It started to use oil at about 50,000 mi. It's oil consumption increased rapidly to the point that it uses 1 Qt. every 400 miles! The car has only 64,000 mi. on it!. The engine is smooth, quiet and powerful. It starts instantly in single digit weather. It has not lost any coolant. It doesn't have any external oil leaks.

I have never seen any postings of failed valve guides or seals on these engines on any forum. I have seen many postings of catastrophic engine failures. If you look at the postings on the following link you will be amazed. You will have to check out the 300 SD as well as the 350SD or 350SDL models to get the full picture. Most engine failures are noted in the 300SD section.

http://www.mercedesproblems.com/index.htm

DslBnz · #8 09-02-2003, 10:53 PM

Thanks for the great link.

I noticed that the symptoms are very similar to what my car is doing. That's what worries me.

However, you only have 64K miles on your car. Is that the original engine? I would strongly suggest that the dealer fix your car for NOTHING. In fact, the LABOR SHOULD BE FREE! I hate MB for not standing behind these cars and it makes me wonder who's in charge of this company. Oh wait, I know. It's Daimler-Chrysler, now. Not Daimler-Benz. MB stood behind MY 300SDL when it was 10 years old (trap oxidizer).

I don't see why they should spit all over 350 owners just because the cars are 'old'. MB certainly never made many 350's, and because of that they should call each one of them back.

DslBnz · #9 09-03-2003, 07:36 AM

UPDATE.

After working on the car, early this morning. And checking oil (I left it down a qt before to check for similar symptoms of valve seals), I concluded that the cause of the shaking, rocking and rolling, was the EGR. After another 130 or so miles total, the oil is hasn't dropped an ounce. Looks like my 350 engine might be in the clear after all, with new valve seals and a new EGR (or I'll just rip it off).

Thanks for all your suggestions, but I think I'm all set, now.

gsxr · #10 09-03-2003, 12:16 PM

Valve seals often shows up as blue smoke after extended idle. At least that's what I had on my car with a dislodged valve seal - let it idle for 30+ seconds and rev the engine, and you get a BIG cloud of blue smoke. Oil consumption was up to about a quart per 3000 or 4000 miles, where it had been a quart per 7000 or 8000. A tight OM603 engine should definitely be in the 4-5kmi per quart range or better, never 1-2kmi!! If you get the valve seals done, ONLY buy the OE dealer valve seal kit, don't get the aftermarket seals. They are very different, as I found out the hard way.

Oh, if you can disable the EGR and the car still runs well, just kill the silly thing. On some engines (like the 90-93 2.5 turbo) you can't just unplug it, as the computer knows what you did and punishes you by killing turbo boost. Hopefully your 603 computer is not as unkind.

Good luck,

grease lightnig · #11 09-03-2003, 12:24 PM

I just sold my 1993 300 sd for this reason. At 210,00 miles Iwas putting two quarts of oil in every 250-300 miles.

I changed turbo and the turbo shop said "It did not look that bad it is purfect now"

I lost the glow plugs so I took the head of see how I had the intake maniford off--I know crazy ratinal. The machine shop said The head looked real good you would never know it had that many miles I don't think oil was getting by.

My compression was 400 in every cylinder no cylinder off by more than 10 points.

Someone told me it was a warped piston and it would pull yhe oil in onhe bottom of the stroke.

gsxr · #12 09-03-2003, 01:11 PM

Grease, the rods bend, making the cylinders oval shaped. The cure is a new short block, or new sleeves with new pistons and rods. All very expensive. Probably a good thing you sold the car, although I feel sorry for the person who bought it...!

grease lightnig · #13 09-03-2003, 11:32 PM

Actually it was a diesel mech in Vir, he knew this and he was happy when it purchased it for so low a price and that I had already done the head and turbo and a/c evaporator. (24 labor hours) He was ok pulling the engine, he just did not want to pull the a/c out of the dash.

I actually sold it because the trans-cooler started leaking antifreeze into the trans and vis versa. It started shifting real bad so I drained the fuild and changed the filter put new stuff in and it work for a day then the water light came on and I realize the antifreeze was pink not orange. So I drained the trans and radiator and purchased an aftermarket trans cooler and installed it. That can not be good for it. That was the final piss me off thing.

That bring me to the reason I am on this sight. I need another diesel. My wife say don't get a mercedes look at all the problems you had.

psfred · #14 09-03-2003, 11:54 PM

Don't try to keep the oil up to the top mark on the dipstick! Most of the 603 engines (and many of the M116/117/119 engines) will burn oil terribly above the midpoint between the high and low marks. Top mark is absolute maximum oil capacity, and the midpoint is down one quart or so.

See what happens if you don't keep it completely full, you may in fact not have an oil consumption problem!

Peter

DslBnz · #15 09-04-2003, 06:08 PM

Quote:

Originally posted by grease lightnig
That bring me to the reason I am on this sight. I need another diesel.

Get a well pampered, wonderfully maintained, with full books and records, W126 body.

I know guys that have owned W140's and gone back to '82 300SD's due to the 'complexity' assosciated with the W140.

I'd recommend an '86 or '87 300SDL, or an '81 - '85 model 300SD.

The '86 + models have a longer wheelbase(121.1"), and thus more rear seat space. They have exactly 5.5 inches more of backseat space than the older SD.

These two models you could drive forever. The absolute epitome of MB design, I'd say. Just make sure the head is okay in the SDL; if you decide to buy one.

Bottom line: Find a clean one and be happy