Black smoke after roadtrip

[mulrik]

Here is a story for all of you. If you want to skip it the questions are in the bottom.

Me friend and I who has been fixing up the car over the winter went on a roadtrip together. We wanted to see the 24 hour Le Mans Race in France and headed of from Denmark (a 1600 km trip). We got there safe and sound, no problems with the car, doing about 6.5 to 7 km/liter, 95 unleaded at 100-110 km/h. We even drove around in central Paris with it, which was both a dream and a nightmare if you know what I mean.

After the Le Mans race we wanted to go down south to Nice (800 km), but around 200 south of Le Mans we took a small break and when we started the car it spun the engine for a short while and then it just gave a little "clonk" everytime we tried to hit the starter.

Thinking it was the starter which was stuck we hit it a few times with a hammer and after an hour it started again, unfortunately as it later turned out!!! Well after driving about 10 km the car went dead down a hill. Having no brake vacuum when the car doesn't idle, we put it in gear and let go of the clutch and the car started again. Immidiately after going up a hill the car started to overheat and we pulled aside.

At this time the hour was 12 midnitht and we were stuck with the car that couldn't start after cooling down. Remember, an hour earlier the car was running like a dream. There was no way around it we were picked up by a truck and the guy, (only speaking French) tried to drop us of at a Renault mechanic. After arguing (neither of us speaks French) for a while he gave up, went inside the Renault garage (aha, it was his garage) picked up something and drove us to a Mercedes garage half an hour away.

There we could see for ourselves that the ignition, crankshaft and camshaft were totally out of sync with one another, nightmare!!! We tried to catch some sleep and a couple of hours later the Mercedes garage opened and off course they only spoke French. Nevermind they seemed nice and would take care of the car, as we understood it they claimed to have one guy who knew this type of car.

We hired a car to go down to Nice and came back 5 days later to pick up the car. It had been fixed and even been washed!! Well, partially fixed and washed... Now the car sounded like an old beetle, but at least it drove. They showed us that the woodruf offset key had broken and they had fixed that and realligned the cam, crank and ignition.

We couldn't figure out why the car sounded like a beetle then, but acceleration was ok and we took off towards Nice. It was only about 200 km from Nice that we found out the car was smoking black heavily on acceleration....  Nevertheless, the car was driveable and after another week driving only small distances around Nice we got the car on the train and back to Denmark.

Now here comes the question:
We are very sure the Mercedes guys did not align the fuel injection pump with the rest of the engine and therefore put unburned fuel out the exhaust causing black smoke on acceleration?? Another answer could be that the valves had been damaged when everything got out of sync. Therefore can black smoke be caused by wrong timing of fuel injection or can it be caused by damaged valves? Or can it be both???

Hope you enjoyed the story and learned from it. Today we think the problems were caused by the fact that we were not aware that the chain tensioner has to be filled with oil to work tight enough! What do you think??

The very best from
Ulrik


'67 250 SL Papyrus White 113043-10-000023

[knirk]

My first thought is that the engine timing went out of sync when the woodruf key broke. In the process of repearing this the mechanic may easily have let the chain jump out of sync with any of the sprockets. I would first check the ignition timing. then the alignment of the camshaft versus the TDC. Then remove the injection pump and check the alignment marks. Good luck!

Per G. Birkeland
69 280 sl aut 834
Norway

[ja17]

Hello Ulrik,
I take it this was a different 113 and a different time? Sounds like the timing gears seized, shearing the key on the chain sprocket. I think you are correct the injection pump was left very badly out of time.

If the valves were damaged (bent) the car would have lost compression and it would have run terribly.

A running  engine will keep the oil pocket for the chain tensioner full of oil. You should always pump up or prime the tensioner after these kind of repairs.

Joe Alexander
Blacklick, Ohio

[mulrik]

Well, I did check the cam and the crank with the ignition and after the repair. They were fine, behind by 10-15 degrees. And to you Joe, this was actually the very same 113 as mentioned in a previous post (Can't turn engine). This story was the beginning of trouble. I take to note what you say about damaged valves.

I actually did a compression test on the engine and all cylinders were around 105-110 PSI. I know its very low but the camshaft was also behind by ~10-15 degrees (on the crank) which offers an explaination to the very low compression.

This has been fixed now, but not by Mercedes in France...but by my friend and I. However, I need the answer to one question, that is, do you think (or know if) black smoke on acceleration can be caused by bad fuel injection timing??

'67 250 SL Papyrus White 113043-10-000023