Hard start and smokey. Where to start?
 

First off, it's important to know that Betsie (my '84 W123 300D) is not a daily driver. I live in Alaska, and she spends the whole winter (October through mid-April) in my garage. During the summer months I only drive her when it doesn't rain. I drive her maybe 2000 miles a year, if that.

Last year I started noticing that towards the end of summer, she was very slowly getting just a little bit harder to start on cold mornings. This just sloooowly crept up. She also started smoking just a little more each week, it seemed.

I did adjust the valves then, so they should be good (might be a tad loose, I found it difficult to hold the adjustment nut perfectly still, so I erred on the side of a little too loose, rather than too tight).
I also did two diesel purges last year.
I also did try to check the timing stretch, but when I made a topic it was pointed out to me that using the marks on the cam-tower is useless, so take that result for what it's worth I suppose.

Fast forward 7 months, and I just got Betsie out of storage. I had to do a quick 'n dirty fix on the transmisison line before I could start driving her, but now that I got her out on the road I noticed that she is reluctant to start, and when she does she smokes quite a lot.

Here is a video I made of a cold start (yes, I noticed in the video I have a brake light out...:rolleyes:):
https://youtu.be/vCe7JBBIXEU

The full tank of diesel she currently has is from early October, and has an anti-gel agent added to it. That fuel should be fine enough to run on, right?

Before the video starts I had already glowed twice, so the failed first attempt was after two glow cycles. She catches the third time, but as you can see smokes quite a bunch.

Once she runs, to me it doesn't sound like the idle is all that crappy. To my untrained ear it sounds fine. However, as you see in the video when I put her in gear the RPM's drop quite a lot and she starts to stumble. I'm going from reverse to drive and back to neutral a few times. You can tell when she's in neutral as the brake lights are off then.

This smoking and stumbling in gear will only last for about 2 minutes or so. After she warms up just a little, both the smoke and the stumbling in gear will disappear completely.

I don't want to drive her in this condition though, but I am having a hard time figuring out where to start diagnosing. I did a bunch of googling and researching, and advise ranges from checking valves again, to checking the stretch with the 2mm method, to checking and adjusting the IP timing, to checking glow plugs, etc...

So guys:
If Betsie was yours, and she showed the symptoms as in the video; where would you start? And keep in mind, I'm an IT-dude and really not all that handy with cars. However, with good instructions I've tackled larger jobs before (thanks to all of you!) like flex discs and rear axle's and engine mounts, so I'm not too afraid of getting my hands dirty. I just don't know where to start.

Before getting carried away, maybe it just needs to be DRIVEN? Seriously, if it sits around all the time and you're only putting 2K on it a year, it's probably got a bunch of varnish, carbon, and other crap built up in the engine. Take it somewhere and get it nice and hot for a long drive, burn all the carbon out of the head and exhaust.

From the video, it appears that your smoke is black, not white like you'd expect with timing problems. It's possible that you have poor spray patterns on your injectors. If it's carbon buildup, a nice long hot drive can only do it some good. If you're running prehistoric injectors, it may be a good time to consider new nozzles.

Hi Diseasel300 (cool name)! I do like to point out that I get her on the highway and above 70mph whenever she drives. On the last trip of the season last year I went for a 2+ hour continuous 75mph run (got up to 90 in a few spots) to blow out the carbon before putting her away.

You are right, the smoke is black, not white. It's not blue either, so it isn't oil. The state of the injectors is unknown to be honest.
What I do know is that the guy I bought it from 3 years ago totally neglected the car, so lots of deferred maintenance.

I don't have a pop tester. I assume there is no other way to test this? Can you replace just the nozzles, or does the whole injector (x5) need to be replaced?

Can they be rebuild?

My main concern is the ****ty starting. I don't honestly think it's glow plugs. It would run like poop in the beginning if it was glow-plugs, right? Which it kinda does I suppose, but only when in gear for the first 2 minutes.

In your video you let go of the key right as the engine was about to catch. That first "failed" start was solely because you didn't hold the key long enough! Give it a chance to do something before you let go.

If you had bad glow plugs, you'd be expecting white or grey smoke and the starting performance would be dreadful, assuming it even started. When it did, it would be very loud and raspy and likely missing out for a few seconds on one or more cylinders.

Generally black smoke is due to over-fuelling. If the injectors are in sad shape (or original to the car :eek: ) you could have a "squirt gun" effect going on instead of a nice spray. Until the head gets hot enough to vaporize that fuel, you'd be burning drops of fuel instead of a vapor and can certainly cause black smoke when cold or under acceleration.

The injectors can be rebuilt with new nozzles, in fact this is the preferred way to do it since the new Bosch injectors come from India and the quality is lower than whale crap on the bottom of the ocean. I made the mistake of buying new injector bodies for my SDL. 3 of them cracked where the hard lines attach and the nozzles are dreadful. You've been warned.

You might reach out to forum member Greazzer, he rebuilds injectors and has a very good reputation around here for turning out good work for not a lot of money. If your injectors are old or you suspect that's the problem, it can certainly be worth your time and dough.

It used to be that a flick of the key after glowing was all that was needed to start. Now I do indeed have to hold the key for a bit. The first attempt she did catch, then died right away. The second time I was holding the key for another second after it caught, otherwise it would have died again. It doesn't start as easy as it used to.

Thanks for the advice. I will sent Greazzer a PM.

I'll join in with you.

My car isn't hard to start, but has a shakey start up, and burns oil for 1 to 2 min.

I'm guessing valve seals and guides are worn because it only does it at start up.
Then the smoke goes away.

I think you just need to drive it for a while. Put some miles on it and let us know how it runs then. I bet it will be significantly better.

Have you checked the glow plugs?

If you have the original #14 head, you could be really surprised how worn the valve guides are. When I had the valves done on mine, the valve guides were replaced. The OEM guides are iron and wear quickly compared to bronze which are more common. Mine were worn to the point of being "wiggly". The machine shop was shocked it ran. Don't waste your time doing valve guide seals unless you're going to do the valve guides as well.

The shaky startup can be injectors or glow plugs. You could also have air ingress into the fuel system. I've dealt with all 3 on my car and they can make for some pretty embarrassing cold starts, especially if air is the culprit.

Thanks.


looks like another battle I'll have to fight.

Welcome to life with a 300SDL! They require a lot of patience at times. Great cars, but they are maintenance intensive, especially if they've been "deferred". For some "light" bedtime reading, you can see the "Diseasel" thread linked in my signature line. It's gotten quite long-winded, but that thread will probably be going on for years as I slowly redo that car.

Okay, put a couple of hundred miles on her the past month. Starting is still not nearly as good as it once was.

Here's a new vid:
https://www.youtube.com/watch?v=89NH5WykiYo

At 00:26 I put her in gear and she just sputters and dies.

The thing is this only happens with an ice cold engine. If I give her a about 1 minute of idling, she has no issues going into gear. If I drive her to work and start her up again within 4 hours or so, she runs like she always did. If she sits for 8+ hours, she doesn't start with authority and has a tendency to just kinda sputter and die. She has the same amount of power she always had, and I can keep up with traffic just fine and cruise at 85mph all day long.

I am more than willing to start throwing parts at it, but like I mentioned before; I don't really know where to start.

I don't think it's glow plugs, as she seems to run on all cylinders just fine when she fires up. But maybe it could be glow plugs?
Could this be an injector issue? Should I have those rebuild? I already sent some PM's to Greazzer, and he's willing to do it.

Could this potentially be a timing issue?

Not visible on the video is the haze of smoke I'm getting when she runs cold. She's always smoked a bit when cold, but now there is quite a haze. Weirdly, it's not visible on the video when I get out of the car though.

For reference: It was 45f out.

Idle speed is certainly low. I'd get the Tach fixed and get the idle dialed in where it should be. Low idle + cold engine = unhappy results.

I'd suspect you also probably have air in the fuel system. Check the usual suspects - primer handle, leaky hoses, lift pump, etc. Seems to help a lot of people diagnose problems by replacing the return line with clear PVC and looking for bubbles.

How many miles on the engine? That sounds like you could dump some Startron in and run the engine hard, fill up, change fuel filters and see what you have. I once dropped the drive shaft and towed the SD 300 mi home because I had no internet connection and didn't know how easily filters get stopped up.


Old fuel, sitting for months, not necessarily in great shape when parked point to getting the very basics known to be good. .

What color is the smoke? Timing is an unlikely issue if you describe you have good power. If retarded timing was an issue, you'd notice an increase in white smoke upon moderate to heavy acceleration and lack of power as well. Stretch is worth checking at your mileage though.

Check the glow plugs with an OHM meter and see what your resistance is. Acceptable resistance is between 0.1-4ohms.

Also, diesel purge, italian tuneup and filters should do the trick as well.. Diesels don't like to sit around, especailly these cars.. Drive the hell out of them. That's what they're made for.

When I had a 123, I'd always begin by setting the valves.

I'm not sure what sort of controls they had in '84, but if the car has an OVP relay, then a bad OVP would explain both the malfunctioning tach and the slow idle.

The idle solenoid that controls the OM603 engines wasn't present on the OM617's. They used a different injection pump. OVP can prevent the tach from working, but the other dash "idiot" lights usually don't work either. In his video, it seemed only the tach was dead.

Thanks for all the responses, guys. Certainly food for thought. I'm happy nobody said "omg, ur car is dying!!1!, buy something else", so that makes me feel better.

To address the dead tach; my Federal '84 has no tach amp, nor does it have the OVP. '84 federals apparently are oddballs.
Apparently, all cars before '84 have the tach amp. Californian cars '84 and '85 have the OVP. Federal '85's have the OVP too, with 84 Federal's having the signal go straight to the cluster.
I did try to fix my tach, but was unable to and have kind of given up on it for the time being. I think the problem is the actual cluster, not sure. The tachometer is very low on the priority list. It doesn't bother me at all that it doesn't work, but you are right in that I don't know the actual idle speed right now. That's a down side.

The odometer works fine, and I have no reason to believe that it's not correct, so it appears there are 270K miles on the engine. I have no documentation with the car though, so that mileage number might be useless if the instrument cluster has been replaced in the past. However, the car and especially the interior looks like it has 270K on it, so I am assuming that to be correct...:rolleyes:

The smoke is black. It's definitely not blue, nor is it white. You are right, I do really need to check the stretch following the 2mm method. I need to get a dial indicator and educate myself a bit more on how exactly to measure stretch. I did do it last time I did the valves by lining up the marks on the cam tower. That pointed to 2 degrees of stretch, but it was pointed out to me that measuring it like that is useless, so I guess that number means nothing.
I adjusted the valves about 4000 miles ago. They were fairly good when I checked them. None were much too tight. This was my first time adjusting them and I found it quite frustrating to keep everything exactly right while tightening everything back up. For that reason I erred on the side of a little too loose, rather than a little too tight.

I get no visible smoke when the engine is warm and I stomp on it. I've never seen anything in the rear view mirror, so I am definitely not "rolling coal", but with an ice cold engine there certainly is a haze of smoke visible in the drive way when I idle for a bit. This disappears after a few minutes when the engine is lukewarm.

I have an ohm meter, so I could check my plugs. I don't yet know how to do that. I am assuming I need to remove the plugs. I'll do some searching on how to check resistance, and will report back with the numbers once I figure out how to.:)

Thanks! I'll go and double check everything. I like the idea of replacing the return line with clear PVC. Does anyone know out of the top of their head what size tube I need?

If not I'm sure Google can tell me.

Thanks guys, really appreciate it.

There's enough people on this forum that fix "dying" cars that I doubt you'd hear anyone say yours was dying. Some of us are gluttons for punishment even.

You could have bad capacitors in your tach, or it could be the EGR system failing (there's another recent thread on that in this forum). Either way, there's ways around it. My suggestion for fixing the tach was to set the idle speed. It seemed way low in your video. A low idle will certainly result in excess smoke and very poor power when the engine is cold. Not enough heat to readily vaporize the fuel.

I wish I could take credit for the clear fuel line idea, but I can't. I've seen it mentioned by several other people, including some who really seem to know what they're talking about. All things being equal, you should have NO air in the return line if your fuel system is sound.

Air in the fuel lines can cause smoke (I've seen it), but your description tells me it has something to do with the injectors. What's the history on the injectors? Any idea when they were last tested and balanced?

Whoever told you aligning the cam tower and checking stretch thru that method was inaccurate was an idiot. There's no reason for that to not be accurate and unnecessary to use a dial indicator.

You also shouldn't let this car "Warm up" too long anyway. It's not good to idle diesels, it produces a lot of carbon inside the motor and intake.. Give it two minutes and drive it easy. Not above 2500rpms.

I really think you should dieselpurge it...

I know it's been months and this thread kinda died, but as a final post:

The hard starting seems to be pretty much entirely over. I've filled up with fresh diesel a few times, and have started using a diesel additive that is supposed to provide the lubrication that the ultra low sulfur diesel isn't.

I've also started accelerating more aggressively (only when the engine is hot). I'm somewhat less gentle with her. And she actually seems to enjoy that.

She's started like a champ lately. There sometimes is a dip/stumble in idle speed, the first time I put her in gear right after she fires up, but there has been no more stalling.

She doesn't smoke (only a little when cold) and has plenty of power. I was making a 120 mile round trip yesterday, 100 miles of which were highway with the cruise control set at 85. At no point did it feel taxing. It was quite comfy actually.

I'm planning on some engine overhauling this winter (timing chain, injectors etc), but I've been planning that for the past two winters as well and nothing ever came off it. The timing chain makes me nervous, but I guess I just have to get it over with. I don't want it to break; Betsie might not be the prettiest Benz around, but she's mine and I'd like to keep her for a while.

Don't replace the timing chain unless you've already done the 2mm method and you find that the results warrant it.

I don't know if this was mentioned but you can check your injectors at a Bosch shop or purchase or make a pop tester kit and see how it sprays.

I completely disagree with those that poo-poo the timing chain check using the marks on the camshafts. It is more than accurate enough to tell you when you need to change your chain (readings of 5 degrees or more). If you've measured 2 degrees, DO NOT change the timing chain unless you are simply looking for something to do. If you pull the valve cover again, take a look to see if the camshaft tower marks are repeated on all the towers. On the OM60x engines the marks repeat, so I lay a metal ruler along them with the end right over the camshaft shoulder, and use just one eye to eliminate parallax, and the reading is plenty accurate for your purpose. If you were measuring to insert an offset key to fix the camshaft timing, then use the 2mm lift method. If you simply want to know if it is time to replace the chain, use the ruler / mark method.

Back to your original problem. Sounds like you have it under control now, keep "driving like you stole it" after the engine is fully warmed up, that will keep the carbon burned out.

You do need to learn how to check your glow plugs. They will need to be changed eventually. One or two bad glow plugs would cause the problem you had.

Instead of spending money on a timing chain, buy a pop tester and test your injectors yourself. They are generally good for about 100k miles before they need service.