Date registered: Sep 2011
Vehicle: 1994 S350
Location: Sonoma County, CA - USA
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Greetings from Sonoma County, CA
Just signed up for the forums, have a lot to learn about Diesel MB. Since I was a kid I've been following motorsports. Trained to be a mechanic at one point and have a good general knowledge of automotive systems.
I've always wanted a diesel benz. I found one 3 months ago. It was a S350 with under 58k on the odo. Beautiful shape except the engine. Major smoking. A good look at the exhaust pipe indicated heavy oil burning. Had a feeling it needed a motor. Made an offer and took it home. It's still not running right, most of the story is below.
Any of you diesel guru's out there have any helpful advise on the story, I'd welcome your input. We are scratching our heads on this.
Story of the rebuild to date.
After performing all of the easy diagnostics for oil consumption (turbo, flushed the fuel system, intake, etc) we Pulled the motor. Found lots of oil residue in the exhaust ports of the head and some glazing. Exhaust valves were coated really thick. Cylinder walls had some sort of 'glaze' from something as well as the top of the combustion chamber.
The good news is the cylinder circumference measures were to spec, no out of round holes and factory honing was still noticeable with no score marks.
Pistons were coated with the glaze too. Interesting, what the heck would 'glaze' the inside of a combustion chamber?
Measured all the bottom end components at the machine shop, everything checked out. Cleaned and honed the block and put it back together. Replaced timing chain and H2O pump also.
Found nightmare stuff with the EDC. Waste gate was wired closed by some previous hatchet man, never allowing it to open. Several sensors were replaced and or bypassed. We have managed to clear all the codes in the EDS. We have the car running pretty well.
The Injection Pump is being sent out next week, issues remain...
Throttle response is very good cold and at normal operating temp just a little less responsive. You do notice exhaust smoke at times using very little throttle.
When temperature reaches the high end of normal (gauge just past 80) engine torque drops massively. If it cools down just a little some of the torque returns but not to the levels during warm up.
Engine is not heavily loaded as temperature climbs. Minor inclines at freeway speeds that require a bit of throttle to maintain speed causes increase engine temps.
H2O pump, thermostat and coolant were replaced.
I'm thinking the EDS is dialing back the fuel due to engine temp causing the severe torque loss. What's causing the temp rise?
I'm thinking the engine is heating up too quickly, possible high EGT's due to a injection pump malfunction. The other possibility is a plugged radiator.
Back to the shop on Monday.