I must say that I have been very impressed over the years reading and reviewing the many posts of priceless information on this forum. I typically search and search until I find a solution to whatever seems to be ailing my '87 300 SDL, but I seem to be having some difficulties this time around.

The engine has always been rough whenever it is first started. Doesn't matter if it's 25 deg outside or 80. It's never been a problem though, and it's always smoothed out after no more than 30 seconds in either case. Then it purrs like a kitten.

For the last few weeks, I've had an issue when it's cold outside and I'm trying to get up to speed. In any gear, it appears that the engine has a hard time getting over 2500 rpm. It stumbles and almost feels as if someone is randomly pumping the brakes on me! After reading through several posts, I decided that I would try removing the ALDA unit off the IP. I was astounded by how quickly the car accelerated off idle, but it still didn't fix my problem.

This morning I went out and fired up the car (20 degree morning) and for the first time ever it died about 10-15 seconds after starting. I immediately initiated a second glow cycle and fired it back up. When I finally took off (let it run for a few minutes) it had a great deal of trouble getting going. It was stumbling all over the place and I noticed a good mount of bluish smoke coming out the back. This was the first time I've noticed this. After only a mile or two, and never getting over 45 mph, I finally turned back to the house and got my backup truck to get me to work (12mpg, by the way). Also unusual this time was the fact that the car started stumbling around 2000 rpm, lower than before.

Just for additional info, the car does use a bit of coolant. It's got a model 14 head (yes i know this is bad) but I had an SDL before this one that made it to 400k miles before this became a problem. Also, the car runs much better after it gets all warmed up, but it still stumbles before it gets ready to change gears. I assumed the tranny might be trying to give up the ghost, as I am expecting this any time- but it doesn't make sense to only have this issue around a certain rpm range. Another bit of confusion is that when the car is in park, it will easily rev up beyond the 2000 rpm, so it's obviously only an issue under load. Plus when I'm reving the engine in idle I can tell that the turbo appears to be functioning.

Anyone dealt with this before? Could it be something small like a fuel delivery issue, clogging filter, faulty injector?

Additional Info:

I've had the car for about 2.5 years
326,000 miles
Transmission was flushed at 287k miles.
Turbo was replaced (under oxidation catalyst recall) at 287k miles.
Always run Diesel Kleen through it after every 3k mile oil change (use Mobil Delvac)
Engine has the newer style vaccum pump which is working fine according to my mity vac. I went through the steps of checking to see if I had a transmission shifting issue due to vacuum, but everything appears to check out ok.
K&N air filter

I also forgot to mention that my fuel economy is not what I would expect from this car. It's typically in the low 20s, around 21-23 to be exact.

I would test the glow plugs per diesel giant website. Also have you changed the fuel filters?

__________________
81 300D Turbo 190K sold
83 300sd 319K best $500 I ever spent-daily driverw/ 2 tank WVO set up

may be worth a read..............
OxyCat

When it's fully warm........how does it perform? This might be difficult to quantify unless you're familiar with a properly running 603.

You might want to do a 0-60 time with it and post it and we'll see if the problem is present under all conditions.

At first glance, it sounds like an intake or an exhaust restriction of some type.

Glow plugs, always both fuel filters. If continues like it is, confirm fuel flow, and if not good enough, clean tank filter or replace. Also the quality of the fuel and most importantly, the air filter must be clean.....that maybe simply what is wrong...the air filter is clogged.

I've got a replacement set of filters (primary and secondary) that I picked up from diesel giant so I'll get those installed and take a look at the air filter as well. Seems like a logical place to start. Let me get this done and I'll get back to you guys in a few days. I've got to head up to Columbus, OH for the rest of the week. Luckily I'm flying and not having to drive!

Thanks again, I will update this thread upon my return.

You say you loose coolant. My guess is that the "rough running until warm" issue id due to coolant leaking into the piston bore(s). This is why you see it no matter the ambient temperature.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

I have same car with 233k on it, the milage is about the same right now.
Back during the summer I was getting closer to 25-26. I am hoping it is being caused by the winter fuel blends
My .02

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86 300SDL. 250,xxx on #14 Head. One eye always on temp gauge.. Cruising towards 300K

X2 and the cold just magnifies the problem. A compression test is in order to verify. You could test the glow plugs at the same time.

__________________
Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

Ok so I removed the plug on the exhaust manifold closest to the front of the car. I initiated two glow cycles and fired up the car. The temp this morning is 29 deg F.

It only stumbled for a second or so and started idling fine. After letting it run a few minutes, the temp needle started to climb so I took it for a spin. Still running terrible. With the addition of the new exhaust leak things just sounded bad. It just starts almost spitting and sputtering after getting up to 2k rpm. Makes changing even from first to second almost impossible- the car can't even get out of it's own way.

Next step is to remove/clean/replace the air filter. I haven't checked the glow plugs, but I suspect that I have one or more out of spec. I am not 100% concerned about this at the moment, as cold starting is useless if I can't drive the car.

Here's something else I noticed:

The turbo isn't really ever noticeable (as far as sound), but when I removed the plug it was the first time I was ever able to hear the turbo spool up. odd?

Even more odd, when I rev'd it up, I heard it spool the first couple of times, and then nothing. I did this again and again and the turbo never seemed to spin up so I could hear it. Is this normal? I would think that you would be able to hear the thing at all times. The turbo is only about three years old, it can't be giving me trouble now can it? It's an OEM German unit.

I will keep everyone posted.

You won't normally hear the turbo spool on these cars. If you do, over the diesel clatter, then the turbo has a problem.

Since the trap ox was changed so late in the game for this car, I wonder if compression is suffering badly?

Pull all your injectors and have them pop tested. I bet you have some pissers and low poppers in there. This will cause bad stumbling.

__________________
Cheers!
Scott McPhee

1987 300D

Yeah, I fear checking the compression. I don't even have the tools to do this- can you pick these up at a local auto parts store or do I need to order something custom with custom adapters?

As a general update, I removed my air filter and it was moderately dirty. I ran the car (very briefly) without an air filter and it appeared to improve slightly (very slightly at that). I feel like the more important factor here is that the engine was beginning to warm up. The warmer it gets the better it runs and after you've put several miles on it, it almost gets to the point where the stumbling isn't noticeable.

I think the next step here is replacing both fuel filters and then having the injectors tested. Still lots to do.

Well I think I fixed the stumbling problem. Seems I have neglected some maintenance on my car! About a year ago I ordered two new primary and secondary fuel filters. Despite my records, these filters never actually got installed. It appears that my secondary filter was pretty stopped up, so I can imagine that my primary filter wasn't much better.

After replacing these both, the car runs great! No more stumbling and when I first took off, it let out a huge puff of black smoke. It was beautiful.

I will report back hopefully tomorrow morning once the car has rested through another cold night to see if it takes 20 minutes of run time to get back to this level of performance- but I think everything is ok for now.

I am very appreciative of everyone's suggestions. I think I will still go ahead and check my compression at some point (probably once it gets warmer here in NC) and I still need to work on my glow plugs. I think I'm going to go ahead and start looking at those now. I downloaded the how-to from diesel giant so this should go pretty smoothly.

Thats it. Always change those two filters before winter. If you want to keep spending money, just keep fooling around with your car like you describe. Would be great for you to put the anti algae additive in your fuel, too. Drive, now, in peace and love that diesel.