Ok guys. I was hoping that I had found my answer with the AC/power loss discussion earlier this week, but the AC doesn't seem to by my problem. I am having major power loss on steep, long grades that I wasn't having before. I've only had this SD for a little over a month, but didn't experience this until a few days ago. Both the fuel filter and the prefilter have been recently replaced. The only thing that has changed is that I finally got down to the point of putting in new fuel and refilled at a station near the interstate, hoping that that would mean fresh diesel. I put in fuel system cleaner and fuel enhancer (provided by my mechanic) when I filled up. Could the cleaner have loosened some gunk that is clogging something? Once I am on flatter ground or crest the grade, the speed comes right back and no problem. I couldn't make it up a hill today and had to back down and find a less hilly route back to the office...no small feat in Bham.... ....

Even then, I had to catch on on-ramp and almost didn't make it up the hill. Took the next exit doing 25MPH. Then it was fine. Turning the AC on or off doesn't really seem to matter. What am I missing here? I did find out that my aux fan isn't coming on in the middle of all this....HELP!

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TClanton
1980 450SL 90K
1980 300SD 112K

Sounds like the line(s) that run from the banjo bolt to the switchover valve, then down to the ALDA may be plugged/restricted. When this occurs, the proper boost signal is not delivered to the ALDA there is not an increase in fuel enrichment, thus, the vehicle is effectively operating as a non-turbo powered vessel.

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Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold

Yes, it is possible for injector cleaner to lift crud in the tank and cause fuel starvation.

How much smoke do you make? If you are leaving a huge black cloud with strange noises from the engine and no power, your EGR may be sticking open, or you have crap fuel.

Fuel quality makes a big difference, but truck diesel is usually OK. Not always, though -- try a different station next time.

If you have no smoke, you have a fuel delivery problem, either no boost signal (plugged or broken line, bad overboost protection switch or switchover valve) or plugged filters or lines, or a serious fuel line leak.

You may have also gotten a tank full of dirty fuel, although I doubt that from a truck stop.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

If I had a fuel delivery problem, wouldn't it be sluggish all the time? I'm not seeing alot of smoke except at takeoff from stop, but I don't think it's more than expected. I'm inclined to question the booster, but the car is really peppy except for on an incline....I definitely don't think I'm losing fuel because I almost never got down to empty to refill.....I averaged about 25MPG on my initial tank. I also need some instruction, since this is my first diesel. What is the ALDA/banjo bolt/switchover? I've got some manuals on order, but they aren't here yet....

Hopefully I'll get up to speed.....I really like this car, I'm just not familiar with diesel technology at all. Think I'll drive the 450 tomorrow......:p

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TClanton
1980 450SL 90K
1980 300SD 112K

Thanks for the tips!

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TClanton
1980 450SL 90K
1980 300SD 112K

TClanton:

ALDA = altitude adjuster = fuel regulator for increased boost. As the pressure in the intake goes up, the ALDA causes the IP to deliver more fuel.

The banjo bolt is a hollow bolt that holds a fitting shaped a little like a banjo, also hollow, to which is attached the hard plastic line that connects the intake manifold to the ALDA.

MB has an overboost protection device consisting of a pressure switch on the manifold and an electrically operated valve (the switchover valve) connected to the boost line between the intake and the ALDA. If there is too much pressure in the manifold (if, for instance, the wastegate in the turbo sticks closed), the switch will close, and that opens the switchover valve, venting the boost and reducing the fuel delivered so the engine won't blow up.

If the banjo bolt is clogged, which happens fairly often with age, the swithover valve (rectangular box, usually on the firewall) is bad and always vents the boost (typical failure mode), or the lines are leaking at the little rubber ends or are broken, you will have very low horsepower since no extra fuel is added.

Ditto if the turbo is bad (another long description -- check the boost lines first).

Hope this helps -- diesels are very different than gasoline engines -- not hard to work on or figure out, just different!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

Thanks for clocking in on this thread and my questions on the AC thread. At least I won't feel totally inept when I take her in for service. I'm definitely going to ask him to check the boost pressure right off the bat.

On another note, I'm a little upset that my aux fan will be so loud when it works, though (been following that thread, too)....I like the clacking at the red lights, but AC is a must in AL in the summer.

Terry

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TClanton
1980 450SL 90K
1980 300SD 112K

Terry:

You've got two things going there -- the aux fan and maybe the engine fan locking up. They are loud -- this is a german car -- function will come before aesthetics sometimes.

At least your AC works -- the 300TE leaked down again over the winter, will need to get ti recharged this weekend!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter

That new $1600 AC job last fall was a major reason I went with this car, along with the 112K....what do you mean about the engine fan locking up? Is that common?

TC

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TClanton
1980 450SL 90K
1980 300SD 112K

I'm assuming they went with a belt-driven fan clutch setup, as in most RWD vehicles. "Lock-up" is the clutch engaging and making the fan turn at the same speed as the rest of the engine, instead of windmilling along. If it gets warm, it's a common occurence.

On my F-250, it'll start locking up when I get into traffic on a warm day, as an example. It also sound scomparable to a jet airliner taking off To me, it's a sound, but I'm a weirdo.

DEFINITELY get the boost checked out. On flat highways going at a constant speed, a turbo's typically putting only 1 or 2 psi (sometimes even less) out into the engine. It's on hills and whatnot where they really start providing boost and assisting the engine on a climb. So, a boost problem is quite feasible. As has been mentioned before, bad fuel can make an engine do funny things, but if it's continued through more than one fill-up, I'd guess the fuel's okay (or at least not a direct part of the problem). One other thought might be to pull a fuel line and make sure there isn't any wildlife in there...algae growing in diesel fuel systems, particularly on older low mileage (i.e. having sat quite a bit) vehicles, can be a serious problem (there's another thread on that on this board).

Just some thoughts..good luck! And, a sa personal opinion, if you don't mind the look of aftermarket gauges, it might be a good idea to install an EGT and a turbo boost gauge on teh dash. That way you'll know for sure how much your turbo's putting out and how hard your engine's working...

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2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999

Some GOOD news.....was taking a little old lady home today and pulled in her garage, got out to open the door for her and heard my aux fan running! Don't know if I just hadn't reached high enough pressure to kick it in before or what. Any reason it would only work sporadically? Loose wire? Relay going haywire?

The consensus definitely seems to be my booster, so I'm trading the appointment I made for the fan to have it checked. Gotta be at a conference for the next few days, but headed in after that. Will update when I get back...wonder why MB didnt put a boost gauge on these puppies originally?

Thanks for all the help...

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TClanton
1980 450SL 90K
1980 300SD 112K

UPDATE!!!!!

Took her in this morning and told my guy what was going on ie:, sluggish on grades, etc....turned out that the screen in the fuel tank was almost completely blocked. They couldn't believe I was moving at all....the poor thing was thirsting to death! Guess the fuel cleaner loosened a bunch of crud and stopped things up. They went ahead and replaced the prefilter/filter as well. Also added something for algae growth as a precaution? All's I know is that it sure ran great on the way home.....I may end up liking this car better than the 450...

Thanks again for the help....

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TClanton
1980 450SL 90K
1980 300SD 112K

I have been following this thread for sometime now and would like to say that I am continually amazed at the information I get from this froum. I have posted a couple of times concerning poor performance and lousy fuel economy. Tried everything from filters to ALDA adjustments. Then I read with great interest Peters comment about the sticking EGR valve. He had discribed my symptoms perfectly, so I decided what the heck and blocked the thing off. WOW, power is smooth and consistant, and the fuel milage has gone back to near normal. That little tiddbit of information has saved me at least $400.00 by not haveing to have the injectors rebuilt. Thanks again to all those who contribute to this great forum.

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Keith Schuster
2006 E350 98K miles
2013 Ford Explorer 15K miles

I have not looked at how the 300 is set up over my old 200d as far as fuel intake and return but a quick (kinda quick) fix on the 200 for a dirty screen was to switch the intake and return lines on the fuel system and add a clear inline generic filter in front of the stock filters. The crud was blown off the screen and picked up by the return line, then filtered out. Went through about 5 filters @ 1.99 each over about a month. Also made sure not to go below a 1/4 tank to keep from running out of fuel and it worked great! When I switched back I never had another problem, and the problem before was so bad the car would stall from no fuel.

Rebootit: I will be monitoring the filters pretty closely over the next few weeks and may get some more details from you if I keep having problems....so far, so good.

Keith: You are exactly right about this forum...not having owned a diesel before, it has been invaluable to me getting familiar with things and learning about the difference in mechanics between these and gas enignes. I knew I loved my 450SL, but this forum is making me more comfortable with the 300SD every day...not regretting my purchase at all! In fact, I go out in the garage every night before bed and just look at 'em...:p

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TClanton
1980 450SL 90K
1980 300SD 112K