Greazer makes and sells a replacement overflow valve spring. I have ~1000 miles on mine, does well.

Because I struggle to do 40mph in 3rd gear up a 8% grade every time I take the truck to work. In this sense its been "Italian tuneup"ed dozens of times. (It's no garage queen) I'm doing everything I can to find the problem and the lift pump is certainly a place to look. The old fuel tank and lines had rust in them which probably caused havoc on that pump. (The pre-filter can only catch so much)

The fuel tank is brand new, are are the fuel lines along with rebuilt fuel injectors.

Good to know! I'll be reaching out to him soon :cool:

I hate to bust it to you, but this is normal. My 78 struggles to keep 45 on grades with altitude 5-7k.

My euro, which has the same engine as this and injection pump will make the same hill at 55 in 3rd. Yes it is a stick shift.

I don't know what else is on your wagon if there is an ac compressor that can drag the engine.

Also with out an ALDA you will experience tons of black smoke if you attempt to floor it to make it up a grade. Slowly n steady wins the race :P

Was you wagon ordered for the states or was in imported in the day?

I ask because they fashioned some crude egr stuff to help with pollution in the day. This can/could case a clogged intake, not enough oxygen to turn into energy etc.

Reading another thread that has a photo of your injection pump. I suppose you have never replaced the o rings on the M pump? Nor the copper washers? Also ever timed the thing as I see it appears to have never had a valve removed.

http://i185.photobucket.com/albums/x...nisch/mrsf.jpg

2 is an o ring and 5 is a copper crush washer. These being bad or the valve not being torqued correctly can also cause power issues. I replaced all my o rings with ones found in the assortment you can buy, I also bought the correct socket and torqued them down correctly. They all had bad o rings and were not tight. So I opted not to replace the crush washers.

It is also wise to learn about air density, the shortest answer is that when temps are cold there is less oxygen in the air thus it means less oxygen for a car to burn for power. Diesels really heavily on the correct amount of fuel and air aka oxygen to preform their bests.

USATODAY.com

I need to shower and coffee now :P Post pics of your engine, and closes ups....it may be easy for us who have worked on those engines to point out things that they less trained eye can see or doesn't know what it is.

I hate to toot my own horn, but owning a euro w123 has taught me a HUGE amount about how the euros differ from the us. Also my 78 being a us version...I have both examples to prob :P

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no 2 is the ring, if no leakage no use of changing copper washer or ring either
no 4 on the other hand is delivery/performance related and if worn must be replaced....

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Really where does this professional information come from?

All of my orings where hard, square and torn. These can leak internally and never be known, they can also suck air and not be know...

I suppose this goes along with the starter being maybe of fairy dust and unicorn horns and thus never needing to be replaced. :rolleyes:

Oh I knew I had PROOF, Judge Judy here I come :P

Old vers new.....with no leaks!

https://lh5.googleusercontent.com/-U...524_143111.jpg

Actually it isn't. As mentioned at the beginning of the thread I drove another 300GD a few years back that was in great shape and the power just blew my mind. The owner of that truck drove up the same hill that I struggle up and he did it in 4th gear. When I try to climb this (Or any large hill) the pedal is absolutely floored and there is no smoke whatsoever coming out the back.

Only ancillaries are the power steering pump and the alternator.

No way an 80s G-Class was ordered, it was imported privately but you are right in that they did bodge together an EGR system (It was the very first thing that I ripped out) Now that you mention this, i've never taken the intake manifold off but I do remember what my 603 intake looked like when I did my glow plugs a few months back. The 300GD air intake tube does have a pneumatic "sensor" which will tell you if the air filter is blocked but I'm don't think a clogged manifold would trip it. Hmm, that could be worth looking into when I have some time this week.

Going to back out of this now, and unsubscribe....comparing your vehicle with anothers vehicle is like comparing an orange and a lemon yes they are the same but they are completely different. There are so many variables between ones ride and anothers ride...its impossible to compare the two...

The OM617 did see a revision where it gained a few horse power. My 78 and my 82 all though both n/a's have a horse power difference of 17 horsepower and that is FACTORY. I may have a bigger difference as I am not positive on the compression numbers. Its not the auto that makes it slower its the engine and possible the rear end combo thus it is impossible to judge two "euro" imported Mercedes.

Power loss can come from anything from old grease in the rear to a power steering belt to tight...

That is the issue here, "NO ONE" will be able to diagnose your issue or if there is any. All we can do is shoot out ideas, and hope they are followed...instead they are turned down and me personal I feel like, Why should I even bother giving help?

Comparing his orange to my lemon has helped to point me in the right direction on the fact that I do have an issue that I originally didn't even know about. We went through and checked everything, both trucks have identical drive trains and they are an 80 and 82 respectively. By doing the comparison and slowly working towards finding the answer I have troubleshooted and learned quite a bit about my engine and how various components interact and work. A few weeks ago I was nearly stranded when a hose clamp on a fuel line came loose. Had it happened before I went on this quest I would have called a tow truck cause I would not have had an idea about what to do. However because of my fiddling I knew exactly what the problem was and how to fix it. Summed up, if things didn't break I would probably never figure out how to fix them.

Since learning about the issue in the first place I have done jobs that I have never done before and learned a lot in the process. I have rebuilt my injectors, replaced the entire fuel tank and the lines, did my first valve adjustment, and compression test and plenty of other smaller jobs along the way.

All of the above have yielded small albeit positive results but I still have a ways to go. A comparative analysis was the entire reason that I pulled the lift pump in the first place. If one pump performed considerably different then the other I would know that i'm on to something. If there was no change I would know that I would need to look elsewhere. Timing will probably be my next big project (And FYI any project I do I have to do alone with absolutely no help as there is no one to help me.)

Time is my #1 most limited resource and I don't have a garage big enough to work on the truck so unless I have the rare combination of free time with good weather then I can only go at the problems one small step at a time. This will continue to be a slow project.

I have followed most if not all of the ideas presented in this thread including yours.

I know at least two other people have asked you to check the throttle linkage to make sure when the accelerator pedal is pushed to the floor, the injection pump lever hard against the stop. You replied in the affirmative both times. However, given that you have no smoke at full throttle, your engine is just not getting enough fuel. Throttle linkage wear and/or maladjustment is very common on 123 and 126 cars with the same engine, so worth considering.

You've already focused on the lift pump, which is also a very good candidate. Rebuild kits are available. The pressure relief valve spring is in the same camp, I'd highly recommend new from Greazzer.

Has the injection pump timing ever been tested / set?