Also if you have no ideal when the valve clearances where checked add this to your list. You do not have to adjust them right now just make sure they all have some clearance and are not tight. The proccedure is in the archives. Should be done before a compression check anyways.

I got it running! There is some hackjob wiring going into the glow plug relay that as of yet I'm not sure whether is safe to remove and the added wiring keeps the lid from sitting snugly, so the glow plug wire plug worked itself loose. I didn't think to test voltage to all the plugs since they were all working before, but when I removed the injectors I looked down into the holes to see only one glow plug getting hot.

It was a good thing I pulled the injectors though - I have a bench testing tool and threw them on there to see what they looked like and OH MY, they were the worst injectors I have ever seen. They didn't pop at a particular pressure, a steady stream would just start spraying out at anything over around 1100-1200psi until the psi was allowed to just remain at that level. I don't have a vice anymore since I moved so I couldn't rebuild them with Monarks, so I just put in a set of junkyard pulls from a W126 300SD that tested to spec. Also the engine was previously staying quite cold and the heater wasn't very effective. I replaced the thermostat and now it's nice and toasty. Lastly, I topped of the diesel tank with 5 gallons of kerosene.

It felt slow as dirt after driving the 450SEL around for weeks, but when I got onto the interstate there is a bit of a decline and it was running over 100mph! I've never managed to get it over 92 before. Granted once the incline reversed it dropped down to 80 pretty quick despite my best efforts. Engine's quieter now too. Shakes and rattles rather a lot at that speed, so will have to look into what's up with the suspension. Rides comfortably at 70-80 so it's not too big of a deal.

I'll do a valve check at some point soon - I've done those before, and have a new valve cover seal to install that it looks like it's in need of. I also want to rebuild the injectors with new Monark nozzles.

Good to hear you got it going , skipping the valve adjust isn't wise as it's the # 1 cause of hard starting .

A W-126 should easily go 130 + MPH so you still have work to do , after the valve adjust consider doing a Diesel Purge with a bit NAPA / WIX # 3001 micronic filter in the feed line as you're purging , you'll be amazed at how much crud cleans out & lands in the purge jug ~ I use a glass one gallon jug and I purge until the return is 100 % clean , after you do this , it's a once a year thing .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Yep, going to do it soon - it took a couple tries to start in below-freezing weather this morning after sitting outside overnight.

No, that's way too generic of a statement. A chassis does not determine maximum speed, besides this is a W123, not W126. The engine is only a 2.0L non-turbo diesel, even the 3.0L OM617 would only get up to a little over 100 in an S-class chassis anyways.

According to the specs for this car (http://et.mercedes-benz-clubs.com/mediawiki/index.php/W123-200D-Getriebe/en):

Maximum speed: 135 km/h. So it should only get up to 84mph on level ground.

I did this already but only had one can of diesel purge available. Will probably order more and do again once I replace the injector nozzles and adjust the valves.

As I thought it was a W-126 and , you're DEAD WRONG about the chassis as the W-126 chassis is *so* much better aerodynamically , it raises the fuel economy bar by at least 5 MPG's and also the top speed due to the reduced drag coefficient .

My old '78 NA W-123 300CD easily went 85 , as the engine was totally clapped out it couldn't really overcome the wind resistance beyond that but 80 ~ 85 is do able in any 5 cylinder Mercedes Diesel if it runs passably .

My '85 300CD with it's turbo charger , had no troubles getting up to 125 MPH with the bad engine (scored # 5 piston & cyl. from canola oil etc.) before I chickened out .

SWMBO's '82 240D will do 80 @ full tilt boogie , it too runs out of power against the aerodynamics .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Okay, fine. I guess I don't know how many cylinders my car has, and must be wrong that 2.0 liters is less powerful than 2.4 let alone 3.0 with a turbo. I must also be completely ignorant to the fact that W126's came with not only OM617's but also the newer inline 6-cylinder engines. Oh well, ignorance is bliss!

In any case, I really don't care to argue about cars that I don't even own let alone am trying to discuss in this thread.