A few years ago, I had a REAL problem going up the mountains of VA/ W. VA. I was going up at 40 mph, with trucks coming up behind me at 70 mph.

We originally thought it was bad fuel, but that wasn't it. I later found out there's a THIRD fuel filter, the strainer in the fuel tank. That was clogged with algae, we cleaned it, and that fixed the problem pretty well.

I'm now having a bit of a problem climbing hills again so I thought the sludge on the fuel tank strainer was back. I had the entire fuel tank taken out to be cleaned, but .....the fuel filter wasn't clogged. The other 2 fuel filters are new.

The only clue I have this time is that the car stutters a bit on the first start up of the day, then after a few seconds it runs normally. If I get to a big hill, it starts losing speed. I wonder if there could be an injector that's messed up? I had them cleaned last year but they were not pop tested.

1991 300d, 205k

If it were a 617 with that mileage I'd look for a cracked vac hose on the device that provides more fuel when the engine and turbo spool up. I'm not sure how it works on the newer engine but it may be similar.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

it's a 602, not a 617, but the problem is similar. The most likely problem is a clogged turbo boost sense line. It's very easy to fix. On the left side of the intake manifold, there is a large brass sensor. Directly below this sensor, there is a small rubber hose connecting to a fitting in the manifold. Remove this hose, and undo the fitting. What you will almost certainly find is that the fitting is filled with crud. Clean it thoroughly in solvent, put it back together, and you will find your lost mojo.

If that doesn't do it, follow the hose and plastic line to the firewall. It will go to a vacuum switchover relay. The relay may be clogged, or not working. Remove, clean, test, replace.

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If its original, high probability the metal fuel line under the car has a rusty pinhole, sucking air. Replace the cigar hose with a temporary clear PVC hose, rig up your phone camera to shoot a video of it as you climb the hill, make sure you turn the flash on. If the video shows foaming fuel you found the problem.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

There's no cigar hose on a 602. If there was a pinhole in the fuel line, it would be sweating fuel and the problem could be located by eyeballing the entire length of the fuel system.

Have someone help you by sitting in the driver seat and working the go pedal. Check around all the linkages and connections. Look see if there's any cracked ball ends on any of the linkages. Make sure that all that is moving full range.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Then replace the return to tank hose with clear. It is possible for the pinhole to be so small it will not drip fuel but will suck air. Seen it on 2 cars with my own eyes. That lift pump really sucks. The pinhole is usually under a clamp.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Big clue which points to air in fuel. Stuttering on startup cannot be associated with the turbo or throttle linkages.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Loosing power going up a hill could be turbo not kicking in.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

If turbo was not kicking in, starting from dead stop would be excruciatingly slow. Was that condition reported?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

This is a 602. It will have reasonable power off the line without the turbo. The problem is the boost sense line.

The car stutters on start up just for a few seconds. The stuttering could or could not be related to the power loss problem. I don't know.

As to the fuel lines sucking in air but not leaking, the one reply said he's seen it before so that's a possibility. I've had no fuel leaks.

The turbo is kicking in. No problems there.

I like Mxfrank's suggestion about that clogged fitting. I will definitely hop on that first.

jeff

I cleaned the relay and it was clogged, but that whole area inside the intake manifold is caked with crud too. It won't take it much time to get re-clogged.

It's a common problem, especially on turbos. The crud is a combination of soot from the EGR and oil from the crankcase breather. Every couple hundred thousand miles, it's a good idea to take off the manifold and clean it out...the worst maintenance job on these cars. Believe it or not, there's not much impact on performance until the passages are nearly closed. I bet the sense port was completely plugged. How is it running?

The car runs great as usual, but I haven't been driving in the mountains yet. That's where the rubber really meets the road.

Though that part you mentioned was clogged and I cleaned it, with all the crud in the manifold I'm sure it will become clogged again in the next 10k miles or so. Too bad there' no way to suck out all the crud in there through that sensor opening. Short of that, I have to take off the crossover tube which is a hassle.