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77 300d low power and little rattle

2K views 17 replies 5 participants last post by  cooljjay 
#1 ·
Howdy All,
I bought this car a while ago and have been working through the "normal" problems. It has little power (compared to my buddy's 300d) and is really quiet. I bumped the IP timing a little and it made only a minor change. Mileage is about 20mpg. I doesn't seem to blow much out the oil cap and smokes little. It is showing 143k, but, I have no idea of the true mileage. It idles a bit rough like missing on one cylinder. Typically I'd be thinking low compression, but, with the low smoke I don't know.
Ideas would be appreciated.
Thank you,
Chas
 
#2 ·
Seems all right on the track to me. Milage is a bit low, I get about 24...27 was the best. Slow, yes veryyyyyyy slow special up here at altitude and throw a hill in front and your down to 55...if your buddies 300d is a 1980s model it will be notably faster, if it is a turbo it will for sure be faster.....if it has a type m pump, euro import....it will have 10-15 extra horses. Your car on a good day is 77hp!

Now to get a few more horses and to get s few extra miles, start the following..

Valve adjustment
New injectors
New fuel filters
Clean the fuel tank screen, clean tank if need be

Set the IP timing back to factory

Make sure you have the new black primer pump also

Sometime a transmission fluid change and rear differential fluid change can add extra horses

Have you replace your evil servo yet?
 
#3 ·
Howdy,
I'm not sure what the "evil servo" is....the one in the trans? I've done the valves, fuel filters, purge, and black pump. The oddest thing is the lack of rattle. Would a funky IP cause this? I know at least one cyl/injector is not working well. My buddies has huge mileage, smokes, is very tired yet still rattles like a "normal" diesel.
Thanks for your help,
Chas
 
#6 ·
The evil servo is what controls your climate control.

You never mentioned cleaning the tank screen or replacing the injectors....two services that need to be done.

Remember you messed with the injection pump...big no no....if you didn't have it set at 24 before top dead center....and you didn't drip test the IP, you may have messed up the timing.

Also please stop comparing this 300d with your buddies 300d. The 1980s 300ds are completely different beasts. You need to compare this to a 240d...if its a bit faster its running fine.

Also agreed on the valve adjustment. If the valves were tight, you need to recheck them.

Also have you upgraded your glow plugs yet?
 
#4 · (Edited)
If the Valve were adjusted and they were found to be really off; People sat to do it again after a few 100 Miles. The reason; after the first Valve adjustment where the Valves clearances were found to be really tight the new adjustment beats of the residue of the Valve Face and Seat and they tighten up a little.

Sway the suspected Bad Injector with one you believe is good. If the problem follows the suspected Bad Injector is the Injector at fault.
If the problem stays on the say Cylinder you have an issue inside of that Cylinder or extremely rare the Fuel Injection Pump.

If it is smoking at the Exhaust Tail Pipe what color is the smoke and when is the smoke happening?
Does the smoke decrease or go away after the Engine is completely warmed up?

When I first got My Car it was scary slow when first accelerating from a stop. After it was moving good it drove normally.
What was wrong is My Linkages between the Accelerator Pedal and the Fuel Injection Pump Throttle Arm was extremely Sloppy.
The various rods on the Linkages have specific lengths they are supposed to be. And, in My own case there was a Bolt and Kidney Slot that was adjustable to remove some of the slop. However, their is more than several Linkage arrangements.

On My Car I have a Automatic Transmission and it seems to run through the gears from 1-4 too fast and at a lower RPM then I would like. I have one with a Turbo so Mine is shifting into the Highest gear slightly after the Turbo has kicked in. So this is not a big issue as far as the Car actually moving.

On Yours if Your Automatic Transmission is shifting into the higher gears too soon it would cause you to compensate by giving it more Fuel and decrease the mileage.

One of our Members Stretch knows a lot about the adjustment on the older Transmissions if you think what I mentioned is part of your issue PM Him on the adjustment.
 
#5 ·
...

Sway the suspected Bad Injector with one you believe is good. If the problem follows the suspected Bad Injector is the Injector at fault.
If the problem stays on the say Cylinder you have an issue inside of that Cylinder or extremely rare the Fuel Injection Pump.

If it is smoking at the Exhaust Tail Pipe what color is the smoke and when is the smoke happening?
Does the smoke decrease or go away after the Engine is completely warmed up?

When I first got My Car it was scary slow when first accelerating from a stop. After it was moving good it drove normally.
What was wrong is My Linkages between the Accelerator Pedal and the Fuel Injection Pump Throttle Arm was extremely Sloppy.
The various rods on the Linkages have specific lengths they are supposed to be. And, in My own case there was a Bolt and Kidney Slot that was adjustable to remove some of the slop. However, their is more than several Linkage arrangements.
I think he means swap ..

I agree with the linkages. My 300SD had very tight linkages that prevented the fuel rack from opening fully. Once they were adjusted I must have gotten about 1/4 more movement from the rack.
I think you can also adjust the ADA (equivalent to the ALDA on a turbo) The ADA limits the amount of fuel to prevent black smoke. Taking the off the turbo engines is a huge improvement. I am not so sure if it is going to be so noticeable in the N/A engine. You can also turn up the fuel delivery in the pump but it might not help without getting more air into the engine.
 
#8 ·
I had a '77 300D

for a couple of years. Religious valve adjustments every 12000 miles until one could not be adjusted any longer. It manifested as a miss as you describe. Found a wiped cam lobe and was told that year range had "soft" camshafts and the only cure was a replacement.

It was my first Benz and although I thought it was a great car, I couldn't make myself spend the $4k estimate from the dealer. That was then and this is now. If I had that car today, I would change out the cam myself and call it good.

BTW, at it's best it was a dog performance-wise but I loved it still. Replaced it with an '84 300D (turbo) and now have an '83 300CD. Still miss the W115.

Bottom line; check your camshaft
 
#9 ·
Thanks All,
The valves were way out and I will run them again. The cam looked to be in great shape. This 300d (non-turbo) is much slower than my 240d, both have autos. It is also much quieter...like half or less rattly....new term. I'm not sure what an "ADA" is nor what vacuum line is connected or capped. The tranny seems to be very happy about shifting when I think it should....not too quick or hold too long.

I tried to do the drip test and must admit it didn't respond as I thought it would. I've done the drip test on my Mog and it went and acted as expected (per instructions). The PO had many issue with the car before I purchased it and I changed out the glow plugs first. I bypassed the "evil servo" with a ball-valve and am happy with having heat when needed.

Thanks again for all of your inputs,
Chas
 
#10 ·
So today I did another valve adjustment. A couple of the exhausts were tight again. One was way tight and may have been the "miss". I went after the drip test to put it right. I found the reason it didn't act "right" the first time I did it was that it was so far retarded. Even after I bumped it a while ago and got a little better response it still wasn't right and the drip still poured.... I figure that even after my "bump" it was still 4-6 degress retarded today. It is now working well and sounds more like a 617. I'll know more after the next fill up, but, it feels much better.
Thanks All,
Chas
 
#11 ·
I have given it awhile and still am getting about 20-21 MPG. It starts hard and is really a dog for starting when under 40 degrees F. When first starting, especially cold, I can floor it and it will take 10-20 seconds for the RPMs to rise like something in the IP is thick and not happy. Is that normal for a NA? Others that have these seem to rev right up.
Thank you,
Chas
 
#15 ·
Long Fuel Pressure Relief Valve/Overflow Valve Thread
Fuel pressure relief valve adjustment - PeachParts Mercedes ShopForum

This is not the complete drip method but what I have found makes it easier is if you scribe a Mark a cross the block and IP Flange so that you can return it to were you started if you end up having a problem.

You want to count the drips at the highest pressure. That means counting them while your are pumping on the Hand Primer.
If it is not dripping right; nudge the Pump just a bit and tighten down one of the Nuts so it does not move when you start pumping with the Hand Primer Again.

So the way I do it you are never moving the IP while you are counting the drips.

In order to move the IP in tiny increments I remove all of the Fuel Injection Lines so the IP is easy to turn.

Somewhere in the below links is how to rebuild the Fuel Supply/Lift Pump; not to mention a whole bunch of other repairs.
Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82

http://www.peachparts.com/Wikka/DoItYourSelf
 
#13 ·
The ADA is not capped and I have the timing set properly. It does run the best since I've owned it. At a stoplight it also has a little smoke that passes me.....always nice for the greenies at the university I work at. I have very little oil around the oil cap and not much blow-by. I've been wanting to wait on the injectors to see if the car is worth it. When I do them I'll do a compression test. I didn't know if the not revving when cold was a clue as to something in the IP.
Thanks,
Chas
 
#16 ·
What color is the Smoke?

White is Coolant or atomized unburned Fuel; you can smell it.

Black is poor combustion. Bunch of things can cause that.

Bluish Black is Oil and it will smell like Oil burning. Piston Rings/Cylinder issues or the Valve Stems/Guides/Seals are passing Oil.

Gray smoke is a version of the poor combustion. I had that on My Volvo Diesel from the Car sitting one Year and when I got it running I did not realize that My Coolant Thermostat was opening too soon.
6 months of driving later when Summer arrived I realized there was a problem with the Thermostat.
However, I must have had sticking Piston Rings. I soaked the Cylinders in Marvel Mystery Oil for one full week and again for another 3 Days.

Change the Oil and took it for a hard ride on the Freeway. Over the course of 3 days the gray smoke cleared up.
Note; I was actually skeptical that the MMO would work. But, it was cheap and I felt it was worth a try.

Others say switching to Synthetic Oil will also free up sticking Piston Rings but it takes 200-300 miles of driving.

Also in My case the Injectors had been rebuilt with New Nozzles.
 
#14 ·
I remember reading in a thread, that there is governer that allows the car not to reeve when cold....I can't remember the specifics though.....again I would check and adjust all your linkages to the FSM specs.....you won't know if the car is worth the new injectors until you replace them....the smoke most likely means the injectors are peeing instead of misting.....which will give poor power, bad mpg and melted pistons....
 
#17 ·
Howdy Dman,
I just read the whole 30 pages of the link. Interesting for sure.

My smoke is white/grey, warm or cold. I'm thinking about just changing the injectors since they look to be original and they are a service item. I may go ahead and check my spring too.

Thanks for the links,
Chas
 
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