1979 300sd w116 with 117k miles

Pressure washed the engine compartment yesterday and now I'm experiencing some type of hesitation or fuel restriction which is affecting the transmission shifting.

Took precautions by covering the alternator, covering the starter, covering the brake master cylinder with the reservoir, covered the turbo inlet (covered due to removing the air filter assembly) and disconnected the battery.

I was careful where ever I saw vacuum lines or anything that looked like it could brake off.

I did something wrong and I must have pressure washed something fragile or somehow got water into something thats affecting the way the car runs.

Symptoms:

Car will go into gear and drive well if you don't slam on the accelerator. It seems to shift fine for the first part of the drive, again, drives fine up until you hit the accelerator.

The car gets bogged down when trying to speed up. The engine will shift into gear when accelerating but it seems to not want to drive any faster.

Its like fuel is being restricted. It reminds me of this one time when the linkage to the RED STOP lever (linkage sits above and next to the valve cover) broke off at the rubber joint (piece of rubber where the linkage joins with other linkage arms).

I did pressure wash the injection pump so I was thinking that maybe I broke something off near there. I don't know.

Any suggestions are greatly appreciated

Please advise

I'd start by inspecting the ALDA line. If that was fragile and got broken off, you'd have no turbo boost since the IP would be restricting fuel. Worth checking...

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Going to check the line

I checked the plastic clear line that runs along the firewall and it looks fine.
I also checked the other banjo clear plastic line that runs from that little device that sits by the firewall to the ALDA itself and that one also looks fine. I had 2 brand new lines in my cabinet so i went ahead and replaced them anyway.

The injector rubber fuel lines appear to be leaking but not sure if this would cause the car do bogg down at acceleration.

It's almost like the linkage is the the problem.

Can't seem to pin point the issue

You should be able to check the linkage easily enough. Have someone push the throttle pedal to the floor (or put something heavy on it) and see if it moves the linkage to full fuel position.

The rubber injector lines shouldn't cause a bogging down situation, but they could possibly contribute to air ingress. Besides they make a mess when leaking so definitely worth changing out.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Checked linkage today and it looks to be working correctly.

Checked tranny fluid level and it also looks good.

Went for a test drive again and it seems to hesitate as you accelerate when trying to ggain speed. Now there is an obvious gain in speed then boggs down. This symptom repeats itself over and over within seconds. The car gains speed and all of a sudden it loses power then as fast as it lost power it begins to accelerate quickly then again losing the acceleration. Feels very much like when you have a bad park plug wire on a petrol engine. Hesitation is very obvious. Not sure what to check next

Sounds like air ingress into the fuel lines.

Cleaning the fuel line junctions may have removed the gunk that was preventing air ingress in an otherwise poor connection.

Check your clear lines for air bubbles when the car is running, there shuld be no air in the clear lines at any time.
If they are old and brown, backlight them with a small flashlight.

Temporarily attach a clear vinyl line in place of the cigar hose, as recommended by funola.
No air bubbles should accumulate there while running or sitting for extended periods, if your fuel system is properly sealed.


Edit: Intermittent activation of the overboost switchover valve is another possibility that could cause your symptoms.
Try unplugging the connector at the overboost switchover valve on the bulkhead.

__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Will replace the leaky rubber braided fuel hoses and then check the overboost switch over valve. Thanks

Out of curiosity which primer handle do you have on your injection pump? If it's the old style, they're very prone to leaking. It stands to reason that when you blasted off the injection pump that it could have easily caused the already fragile primer handle to start leaking air.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

First replaced all of the leaky braided injector fuel hoses with Genuine braided hoses(grey with orange lines) and that did not solve the hesitation and lack of engine power.

Then went to bypass the overboost switcher over valve and took the car for a spin....Problem solved

Thanks Alec300sd and Diesel 300 for staying with me...

What happens when you rev the engine in PARK or you rev the engine with your hand using the linkage under the hood?

__________________
'80 300SD - '83 240D - '00 E55 AMG - '02 G500