260,000 miles and counting ?????

It may be that the glow plugs are not working. Have your repair shop check the glow plug relay's fuse a/k/a fuseable link.

Hard shifts are usually due to a vacuum leak - the task is for the repair shop to find it. Could be very easy, or not.

The engines that run for 400K miles are the ones whose oil is changed every 2,000 or 3,000 miles, all filters are regularly replaced etc. They're owned by very fastidious people.

The more typical lifespan is about 275K miles +/- 10%. Your car is about there.

The internal condition of any diesel engine can be determined via a compression test. That will tell you whether it's time to settle in for a few more years of dieseling or to start car shopping.

I've owned a '80 300SD since new and still appreciate its charms.

I have the same problem, 83 300SD 170K miles. Is there a way to check the glow plugs while still connected? They are energized from a relay so when power is off can you do a resistance check to ground? I removed

1 glow plug (#3) and bench tested OK. After re-installing it measures the same while connected or disconnected, about 8 ohms.

I believe the lady's glow plug relay fuse has melted and her engine's glow plugs are therefore not receiving any power. The glow plug relay has a cover which slides UP to reveal the fuse or fusable link. A replacement link costs about $1. Imagine, buying a M-B part for $1!

As to checking a glow plug, They should have some resistance BUT if they do that doesn't prove that they're working, in my experience. I've removed them and tested each with jumper wires from the battery - and each quickly boiled water BUT one was still weak and had to be found by elimination - install a new GP in #2 try it, no change, put old #2 into #3 etc until the misfire problem was fixed.

First check the link.

pull 5 prong plug put meter in plug and ground the other end to check for ohms.

the case, minus a few cans!

I agree with TG and Pool Man... very simple fix. All related to glow plug and its related parts.

If you replace one glow plug, replace them all. They are all the same age, right? If one is bad, the rest are getting there quickly. Not worth the hassle of dealing with the same problem over and over.

But the easiest problem to fix is the fuse-link. Check that first. And, Yea, it is only a buck.

Larry In the back yard, five-at-a-time under the oak.

When I removed the #3 glow plug and tested I did this with 12 volts and the plug glowed cherry red in a few seconds indicating that it was working fine. The reason I wanted to know if there was a way to check while still in the circuit was because I can hardly get to the connections and when I do the black plastic sleeve covering the wire cracks and disintegrates. The hardest one to get to is the #5 plug as it is stuffed back behind the oil filter and a b**tch to get to. I have not checked the wiring diagram (don't have one) to see how these are wired but they appear to be in parallel as there is an individual wire running to each one from the same source. If parallel then 1 plug could be bad without affecting the rest, can anyone confirm this? If they were series connected then you could check for continuity from the first to the last and then determine which one was your problem. My guess is the relay and fuse must be OK as I get 12v to every glow plug. I have an infrared thermometer on order to try and determone if the plugs are working without removal, anyone have experience with these and do you think my plan might work to test without disconnecting. Currently the glow sequence starts and runs until the glow light turns off and then continues for about 15 more seconds before shutting off and the engine just turns over without firing. Could this be valve related? Car runs like a scalded cat after I get it started, well maybe not scalded but the turbo runs full time and will actually put down rubber if I brake stall it. I can't get back to this problem until after Jan 2 but will post my findings; until then, have a Happy New Year everyone and thanks for the insight and input. Doug in Sacramento

if once started it runs good the motor is i would guess ok.

bad compression shows up slowly unless you forgot to put oil in it.

also glow plugs die one at a time so check the fuse. if its ok i would bite the bullet & get a relay for it.

now i did have one have the 5 prong plug not proper contact once. it needed to be firmly pushed in once cleaned .

the case, minus a few cans!

I suggest you focus on the car's glow plug relay rather than individual glow plugs. A bad relay will kill ALL the glow plugs which seems to be your complaint.

An individual glow plug's failure would allow the engine to start but it would do so with a single cylinder misfire for a few seconds after which all would be normal.