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  #1  
Old 06-11-2005, 11:45 AM
sikbrik's Avatar
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No smoke but no power!

Hi everyone,

This is my first post regarding anything "diesel" but I just picked up an '83 300TD for cheap. Needs a water pump (leaking) but not overheated. Anyway, I'll admit to being an extreme newbie here and I just wondered where to start.

The car glows and starts perfectly. There are some vacuum leaks, I'm sure, because not all of the door locks work, the blower doesn't work, and I have to actually lock the drivers door or use the "stop" lever to turn the engine off! Good brakes and everything, though.

The main problem I'm finding is low-end power. When climbing a steep hill it just seems to bog and go about 15mph with no apparent acceleration. If I really mash the pedal, I get to the top (eventually)! Anyway, off the line acceleration is about as dismal. From 20mph on up, it's a great runner. Does great on the highway. The thing is, it doesn't blow any smoke...ever! I know smoke is a bad thing but I figured that, while slugging my way up the hills, it would belch something out the tailpipe. A loaded tractor trailer is a good drag-race for me from a stoplight and chances are he'll win!!! That just doesn't seem right.

Having dealt with only gasoline engines, obviously I figure I'll need to change the fuel filter, air filter, etc. Someone mentioned injectors to me. I imagine I should put a boost gauge on and see where I'm at with that, too, as well as a compression check. Is there anything glaringly obvious that a newbie might miss and could be an obvious place to start?


Last edited by sikbrik; 08-03-2005 at 03:21 PM.
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  #2  
Old 06-11-2005, 11:47 AM
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not getting enough fuel...either from fuel strained clogged with fungus or algea, clogged filters or an air leak on the fuel system...
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1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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  #3  
Old 06-11-2005, 11:51 AM
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Quote:
Originally Posted by boneheaddoctor
not getting enough fuel...either from fuel strained clogged with fungus or algea, clogged filters or an air leak on the fuel system...
.........careful........he mentions that it "does great on the highway".



Can you please elaborate more about "great on the highway".

Can you get it to go 80-85 mph without any problem?

If so, it's not an issue of clogged filters.
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  #4  
Old 06-11-2005, 11:54 AM
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Do a search here for Banjo Bolt. It has a plastic line comming off, located on the back of the intake manifold and gets plugged with carbon. When this gets plugged there is no extra fuel supplied when the boost increases.
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  #5  
Old 06-11-2005, 11:58 AM
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Location: Holland, MI
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Steady cruising at highway speed does not require much turbo, but accelerating to speed or climbing a hill, does require more power.

The ALDA needs to sense pressure to boost fuel flow to make more power.

If you can, measure the amount of boost in the line right at the ALDA.

If it is low, check/clean the line from the ALDA, through the switchover valves and banjo fitting to the manifold. Clean out any blockages, make sure the valves are open when they are supposed to. Fix any leaks, too.

Best Regards,
Jim
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  #6  
Old 06-11-2005, 11:58 AM
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Quote:
Originally Posted by rg2098
Do a search here for Banjo Bolt. It has a plastic line comming off, located on the back of the intake manifold and gets plugged with carbon. When this gets plugged there is no extra fuel supplied when the boost increases.
His problem is from 0-20 mph. There is no boost in this operating range.
Probably should check this line anyway, but, it's not likely to be the issue he is addressing.
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  #7  
Old 06-11-2005, 12:00 PM
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Oops, forgot one thing. Check the linkage, be sure that 'full throttle' moves the IP lever ALL THE WAY.
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  #8  
Old 06-11-2005, 12:59 PM
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Great places to start, thanks!

To be a little more specific, once I get the RPM up to what I would guess is about 2500 (tach doesn't work either), it runs great. Chirps the tires shifting second gear if I keep my foot in it. Gets to over 85mph no problem on the highway. Really, once I'm moving a little bit, it's really nice. The problem is off the line acceleration or heading up a hill from a dead stop (stop sign, etc.)

Thanks to everyone for being so helpful! I didn't expect this kind of response! Great board!
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  #9  
Old 06-11-2005, 02:59 PM
Brandon314159
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Sounds like a routine boost check/bajo bolt cleaning is in order (just cause...) and the ALDA could use a little tweaking...it reminds me of my car before I worked on it.

A plugged boost sense line on the 617 will make it REAL sluggish everywhere however when mine was plugged (when I got it)...it would do about 55-60MPH on flat ground tops. Hills meant 25MPH however takeoff was not too bad. I could bark the tires in second gear as well.

It sounds like his ALDA could use some tweaking...and just do the good old regular car checkups (air cleaner, fuel filters, check boost, etc).

He got it for cheap...its worth putting the small investment of filters in.

Also do some searches regarding your vac. system not working...you will find a wealth of info.

Brandon
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  #10  
Old 06-11-2005, 04:16 PM
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I agree that the banjo fitting and the line to the overboost valve should be checked to be sure they are clear. But, the fact that the vehicle does 85 mph and, apparently, has boost at 2500 rpm and above, leads me to believe that this is not the main issue.

Since the vehicle is new to you, it would be recommended to start with the basics:

1) check the valves. (just cause). Make sure all valves are set to proper specs. This is normally overlooked by most owners. It can cause "issues" if they are way off.

2) Check the timing chain for stretch. There are posts in the archives on how to do this accurately using the #1 intake valve. If the chain is stretched too far, the valve timing is late and the injection timing is likely late as well. This will impact all performance, but, you will really notice it at low speeds.

Be interesting for you to connect a boost gauge to the line to the ALDA on the IP. Drive the vehicle with the boost gauge attached and see what it reads at various operating points. Be aware that it won't do much below 2000 rpm.
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  #11  
Old 06-11-2005, 06:42 PM
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Quote:
Originally Posted by Brian Carlton
.........careful........he mentions that it "does great on the highway".



Can you please elaborate more about "great on the highway".

Can you get it to go 80-85 mph without any problem?

If so, it's not an issue of clogged filters.
Good point....but what is his definition of good....I barely need any pedal travel to maintain 80 on the level....will it run 80 if its floored?
It takes a lot more to get up a hill than to maintain 80 on the level.
__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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  #12  
Old 06-11-2005, 08:50 PM
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Quote:
Originally Posted by boneheaddoctor
Good point....but what is his definition of good....I barely need any pedal travel to maintain 80 on the level....will it run 80 if its floored?
It takes a lot more to get up a hill than to maintain 80 on the level.
OK, say 85 mph.

You need a decent amount of pedal for 85 mph. Maybe 1/3 pedal, at least.
I would expect the boost to be over 5 psi at 85 mph. But, it's just a guess.

Top speed is about 105 mph. 85 mph is getting up there.
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Old 06-11-2005, 09:24 PM
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Quote:
Originally Posted by Brian Carlton
OK, say 85 mph.

You need a decent amount of pedal for 85 mph. Maybe 1/3 pedal, at least.
I would expect the boost to be over 5 psi at 85 mph. But, it's just a guess.

Top speed is about 105 mph. 85 mph is getting up there.
Well he should really be at 8-10 pounds of boost shortly after 2,500 rpm under acceleration..definately by 3,000 rp, .if he feels a surge in power between 2,500 -3,000 rpm then odds are he's getting the boost and the Alda is seeing it. But you are right its a good idea to make sure the banjo bolt is clear of crud. I'm curious what his pedal travel is at highway speeds and merging acceleration....if those are fine compaired to what others find is normal. Now for someone new to the diesel benz the off idle power before the boost kicks in may seem strange or unusual...

As far as pedal travel at 85mph.....it may be around 1/3 with 2/3 left to go, Mine is actually less, but it will pick up from 80-90 fairly quickly...however if he is struggling to get to 80 or maintain it...he has a problem, mine gets to 80 effortlessly and fairly quick...no I don't have stopwatch times to compare to. I've never had ny W123 past 90 and the W116 Has only been once over a year ago. Pickup was definately slow above 95 BUT its now running far better than it was then for power....and I am in no rush to prove how fast it will go. Its more than I am willing to drive and am happy with that.

Timing chain stretch is a good idea abouve 150K as if oilchanges were sporatic in its life it could be due....if its low its had frequent changes...

Valve adjustmets too, just so you will know when it was done and what they are. Again its possible they are due...

What was the average 0-60 mph times on these?...if he can provide what his is that will as an idicator tell us a lot.
__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Last edited by boneheaddoctor; 06-11-2005 at 09:34 PM.
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  #14  
Old 06-11-2005, 10:10 PM
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Quote:
Originally Posted by boneheaddoctor
What was the average 0-60 mph times on these?...if he can provide what his is that will as an idicator tell us a lot.
14 seconds is a good number.

Definitely should make a 0-60 run and report back. You are correct in that folks who are new to diesels don't realize the relatively mild performance below the point where boost kicks in.

Let's see what he gets.
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  #15  
Old 06-11-2005, 11:12 PM
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Will run a 0-60 tomorrow around 5pm EST

Thanks for all the info! This discussion is great...I'm learning so much. It never occurred to me that, while not 100% normal, this might be normal for a car that needs routine maintenance. I've been driving turbo volvo's all my life...gas engine+small turbo=great acceleration. 0-60 is rated under 8.5 on those things. Perhaps I'm expecting too much!

Regarding where the pedal is at 85mph, I'd say 1/3 of the way down. Accelerates to 90+ quite easily from 85 with about 2/3 throttle and feels as though it would do well over 100 if I mashed the pedal and held it.

Got the tach working again and boost is definitely noticeable from just over 2000rpm. This all sounds like good stuff based on what you guys said. I'll try to tee in a boost gauge asap and I'll take the advice that closest to the ALDA is best (until this afternoon, I had no idea what an ALDA was!)

My biggest concern is still that steep hill in my neighborhood but I'll have to reproduce it now that the tach is working and hopefully a boost gauge is installed in the car (thankfully I yanked one from my Volvo before it went bye-bye) before I jump to conclusions. It just REALLY bothered me that it wouldn't accelerate AT ALL over the entire course of the hill climb (usually about 4 seconds, in this car was about 30!)

Thanks again for bearing with me on this. Your advice is invaluable!

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