Sudden oil consumption part 2 - PeachParts Mercedes-Benz Forum

#1 11-05-2002, 12:15 AM

Tonight I looked at the turbo and I could spin it freely, but it would only do maybe one rotation when I spun it and let go. Also, as I was spinning the shaft once every 10 or so seconds it would bind ever so slightly and I would have to grab a rotor to get it going again. I don't know if this is normal or not. I could not feel any play in/out or side to side.

My intake manifold was dipped and completely cleaned at ~270K miles. Though there is no crusted soot inside, but it is very oily. There is a good amount of oil from where the crankcase tube vents into the turbo inlet to the turbo as well.

I checked the underside of my car very well tonight and I can't detect and serious oil loss. My oil light came on again today while idiling for about a half hour, but when I checked the oil, it was still over 1/2 full on the dipstick, and I added 1qt 600 miles ago. It also came on intermittantly on the drive home. Maybe my sensor is on it's way out.

I also replaced my passenger side motor mount tonight, but in the process of all this made a hariline crack in the nipple of my coolant overflow tank and broke the crankcase vent tube connection on the valve cover.

I have added 2qts of oil in 2800 miles, and it is about 1/8" below on the dipstick right now when I filled it originally.

#2 11-05-2002, 10:22 AM

Turbodiesel,
I wouldn't say that two quarts of oil in 2800 miles is excessive - yet. Based on the described diagnosis to date I'd check out the sending unit, especially if it seems intermittent.

#3 11-05-2002, 02:00 PM

But what's funny is that I went from using zero oil in 4000 miles to using a qt every ~1400 rather quickly. I know something isn't right and I don't think it has to do with the engine internals. I have absolutely zero blowby from the oil cap.

gsxr · #4 11-05-2002, 02:58 PM

1- The turbo behavior sounds more or less normal. If the bearings were shot, you would have a lot of play in the shaft. It's harder to tell if the oil seals are shot though.

2- A film of oil in the intake is normal, even with a good/new turbo. There's even a MB service bulletin that states this is normal and that MB will not do warranty work to attempt to "cure" what isn't a problem. A small amount may be present from the crankcase vent tube, at the intake elbow, but you shouldn't have big puddles or anything in there. If so... I dunno, either the pressure valve in the valve cover is stuck open, or you have an internal failure (not likely.)

3- The oil light can be misleading. There is a timer circuit in the dash that is supposed to delay the light turning on for 60 seconds after the sender trips it. After 15 years, the capacitors in the circuit dry up, resulting in false signals. You can test it by grounding the sender and timing how long it takes for the dash light to come on... I bet it's way less than 60 seconds.

4- If your coolant tank was original, it's just as well it broke... the plastic gets brittle from the heat. On the W124 models, there is a new tank with a silica gel pack inside to control corrosion due to the aluminum head & radiator. I assume the same is true for your W126.

5- 1400 miles per quart is a little high. My one car was getting 7500 miles per quart (before the new head), my other car is at something like 4000-5000 miles per quart (both with Delvac-1). Tip: DO NOT add to the "Full" mark. That is a maximum level, NOT a recommended level! The optimum for low oil consumption is between the two marks. Don't add until it actually reaches the "add" mark on the dipstick, as measured in the morning after sitting overnight (especially if you use synthetic, which actually does take hours to fully drain back to the pan).

6- I'd suspect possibly your turbo internal oil seals, especially if you have the Garrett turbo (with the rubber hose to the wastegate). Mine leaks externally pretty bad. Otherwise... maybe valve guide seals? It's hard to tell w/o more symptoms (any blue smoke at any time... under load, after a long time idling, etc?)

7- My car with the new head, that used to get 7500 miles per quart, suddenly started ingesting oil with the new head. I am REALLY ticked off about that. I suspect either the valve seals are installed backwards (intake on exh & vice-versa), or the machine shop screwed up the valve guides when they assembled it. Now it sucks oil past the guides at idle, and after idling for 30+ seconds, it blows a blue cloud when you accellerate. Oil consumption dropped to something like 4000 miles per quart (not sure exactly). I plan to yank the cam & inspect the (new!) seals, if they are OK, the head has to come off AGAIN! Aaaagh!

Best regards,

#5 11-05-2002, 03:07 PM

No blue smoke, maybe a small whaft when you start it in the morning cold, but's been doing that ever since i've owned it. I occasionally idle the car for over an hour at a time, and there is no blue smoke at any time.

Is there a seal kit for the turbo? I think I do have the garrett because of the rubber hose to the wastegate on the pass side of the turbo.

#6 11-05-2002, 03:12 PM

About 10,000 miles ago my car too used absolutely zero oil in 4,000 miles (the most I let it go). It was at the same spot on the dipstick as when I changed the oil. Ever since I had my timing chain and tensioner changed, it's been using oil.

Also, I notice my turbo isn't giving me as much power as it did maybe 20-30K miles ago. It kind of grunts at around 3000RPM right after the initial surge at 2750. Occassionally on the highway it will all of the sudden pep up and go like a bat out of hell, then it will die again, and grunt.

My "banjo" fitting is clean as well as the line.

gsxr · #7 11-05-2002, 03:25 PM

1- Yep, there's a seal kit, but it's a lot of work to R&R the turbo and then rebuild it. I'd look elsewhere first.

2- It's VERY odd that it started after the new timing chain. A stretched chain can cause excess oil consumption, but if you have a new one, which should cure that! Wouldn't hurt to check the chain stretch for grins, and also the IP timing.

3- If you have odd power loss and/or surging, check ALL the plastic & rubber tubing in the engine compartment. I bought new stuff from MB (probably only $20 in parts) and rebuilt EVERYTHING, it was amazing how much was brittle or broken. If you have a leak, or slightly plugged port at the intake or switchover valve, that could cause what you describe. If all that is OK, test your turbo output, it should be 12+ psi at full load (if not, your turbo is suspect.) Finally test the ALDA with a MityVac, it should hold pressure... if it leaks as fast as you can pump, this MAY be the cause of the surging.

HTH,

md21722 · #8 11-05-2002, 03:53 PM

Yes, as Dave says test the ALDA to see if it holds pressure by direct connection to the ALDA and then test the lines by connecting to hose that goes to intake manifold. i have one car that loses pressure as fast as I can pump and it surges, the other car (parts car) holds pressure better. I have a bunch of oil in my intake, but no visible oil leaking from the turbo. I've also had a few intermittant plumes of black smoke - 7 in all, 3 with full power, 4 without, not while cruising down the freeway at speed, but rather around town or lightly accelerating on the freeway in traffic. I have not had time for diagnostics yet as I'm rebuilding my suspension.

-brian

psfred · #9 11-05-2002, 07:50 PM

Turbodiesel:

If you started using oil after the chain/tensioner change, check for leaks at the front cover and tensioner. Both are known for leaks.

A broken blowby tube is VERY common if you try to take it off -- broke mine the first week I had the car, so just put a bit of heater hose over the two ends. Will replace it when I do something else that requires removing the valve cover, and will replace the grommet at the same time -- rock hard.

Variable and unpredictable boost is most likely in the boost control circuit. Check it all for leaks first, and replace the ALDA if it leaks (you can swap the one off the parts car, at worst it will be out of adjustment a bit, no more). On the 603, it's not mechanically tied in, just pushes against an operating rod in the pump -- captive nut at the bottom, hold ALDA with a wrench and use another to unscrew the captive nut, remove, install the other.

Don't forget the wastegate controller hoses!

If the boost regulation system is good, the turbo is sticking. Usually worse cold, and eventually will stop altogether.

ANY binding of the turbo means the bearings are shot. You may or may not have play -- if the problem is coked oil in the bearings from not cooling it off properly after highway runs, you have NO clearance! Seals can go bad without the bearings going, too -- and until you are using considerable oil, no blue smoke!

Turbo rebuild will vary from $400 or so to $750 or so at a reputable diesel shop. New bearings/balance will be around $400, a cartridge will be $750. This will be with a years warrenty -- be prepared to change oil supply and drain lines.

Peter

william rogers · #10 11-05-2002, 10:22 PM

not saying that you don't have a bad seal or bearings in your turbo or some other oil problem but if you look at the factory manual it allows for quiet a bit of oil usage as normal and that's on engines with a lot less miles.........
William Rogers.........

JimSmith · #11 11-05-2002, 11:50 PM

turbodiesel,

Given the abrupt change in oil consumption I would agree that while the rate may be within the range of what is considered "normal" it is not normal for your car.

I second psfred's assessment that the turbo bearings are shot. Like he said, anything other than smooth motion is a sign the bearings are no longer doing their job. If the rotating member is unstable as it spins, the likelihood that the seals have been damaged is high. I am not familiar with the internal lubricating oil plumbing and so I can't suggest how the oil is getting into your engine from the turbo bearing area. I would expect a quart in under 1,000 miles going through the intake and out the exhaust to be visually noticeable or at least as a change in exhaust odor.

That is about the consumption rate I had with my 1991 350SD after the engine rebuild that was diagnosed as a bad turbo bearing seal. Evidence of leaking oil was visually apparently in the inlet piping, which led to the diagnosis. The oil consumption was clearly going out the tailpipe - no mystery.

A refurbished turbocharger for that vehicle was close to $800 and not that readily available. Getting the old one out and the new one in looked like a real nightmare. Oddly, my 1998 E300 Turbodiesel turbocharger is much more accessible, althought the engine is more powerful and one would think the engine compartment of the car should be smaller and more cluttered, all of which would lead to the expectation that accessibility would be worse.

No leaks means you must be pumping oil out the tailpipe though.

Good luck, Jim

william rogers · #12 11-06-2002, 01:00 AM

I dought that you can smell or see oil usage at one quart per trousand, perhaps an emission tester could pick it up.......
William Rogers......