Author Topic: Timing Marks (Read 21182 times)

mdsalemi · « **on:** May 05, 2005, 09:23:34 »

Does this make any sense?

Last year when my car was at Dr. Benz's he was not able to time it conventionally with a timing light; the distributor indexing was off as he said. He did it the old fashioned way (advance till pinging, then back off) and with some test runs got the car running correctly--neglecting the fuel issue but that's another topic.

So, for the fuel issue the car went into Karl-Heinz yesterday; he is a local mechanic who apprenticed in--you got it--Sindelfingen (on the 113 line), and who owns a 230SL.

I told him about the "distributor indexing" problem and the first thing he asked me was "Was the engine ever apart"? to which I said, yes, it was rebuilt by Metric. A smile comes to his face, he pulls out a pad and paper and makes a drawing. This is where "Does this make any sense?" comes in.

He explained verbally and with pictures that the piece with the timing marks on it can go on correctly, or 180 degrees out of phase. If it is installed 180 out, you won't see the timing marks when stroboscopically timing with #1 cylinder. HOWEVER, knowing that the 0 degree mark means TDC for #1 piston, if you are 180 degrees out on that timing mark plate, you will see TDC for the 4th piston in the firing order, or #6. Each 60 degrees of crankshaft rotation brings the next piston into TDC. So:

0 degrees, #1
60 degrees, #5
120 degrees, #3
180 degrees, #6
240 degrees, #2
300 degrees, #4
360 degrees = 0 degrees = #1

He said the bottom line is on my engine, you [probably] time with the #6 cylinder. He has not done it yet, but was very quick to come to this conclusion as he says he's seen this before on rebuilt engines.

I'm wanting to know to those who may have seen this or done it whether this makes any sense.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

jeffc280sl · « **Reply #1 on:** May 05, 2005, 12:14:45 »

I've never seen this myself. What he says makes some sense to me. If you look at the crank shaft piston 1 and 6 are 180 degrees apart. You mention this in your degree chart. So if the crank were 180 degrees out piston 6 would be at TDC and piston 1 would be all the way down. You would then adjust timing on the strobe for piston 6 where the timing mark would align with the timing scale on the crank.

Jeff C.
1970 280SL 4-speed

Mike Hughes · « **Reply #2 on:** May 05, 2005, 12:42:07 »

Makes perfect sense. Just hook up your timing light to the #6 spark plug lead (instead of #1) to check your timing.

- Mike Hughes -ô¿ô-
1966 230SL Auto P/S
Havanna Brown (408)
Light Beige (181)
Cream M-B Tex (121)

Tom230sl · « **Reply #3 on:** May 05, 2005, 15:21:48 »

So to fix this, would you just need to loosen the dist, pull it out a little and spin it 180? or is there more involved?

Benz Dr. · « **Reply #4 on:** May 05, 2005, 18:06:19 »

I tried all those things. Believe me, it wouldn't line up. I tried moving the distributor drive gear in every position but it was always out.
I've seen this on a number of engines but really can't explain it. I will though........

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org

Benz Dr. · « **Reply #5 on:** May 05, 2005, 18:08:04 »

So, did HE figure out your fuel poblem?

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org

mdsalemi · « **Reply #6 on:** May 05, 2005, 18:59:49 »

quote:
Originally posted by Benz Dr.

So, did HE figure out your fuel poblem?

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org

No, he has not actually done anything yet, I just dropped the car off yesterday in mid-afternoon. The "theory" on the timing was just one of discussion for something he had done before; something I wanted him to look at. I'm sure something was assembled wrong in the engine rebuild, but what and can it be corrected w/o tearing everything apart? And, two other mechanics timed the engine previously and none reported any issues--was I duped?

He seemed to have ideas on the fuel thing though, since he has said he has seen this problem before. Right now, the car goes about 20 miles and starts to sputter. Stop, turn off, turn on, and you are good for another few miles...and on it goes.

We shall see. I shall report back immediately. It would sure be nice to drive more then 20 miles, cause when she's running, she's running fine.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

TheEngineer · « **Reply #7 on:** May 05, 2005, 22:54:40 »

I had the damper off when I replaced the front seal. (That's the thingy which has the timing marks on it) It is indexed with a key. No way can it be 180° off. Timing the engine until it pings is the old way and it works well because it also takes the octane rating of the fuel into account. Strobe timing lights are relatively new and for people who don't know better. And you can't just pull the distributor and re insert it 180°. The drive dog is offset. When the car runs only 20 miles and then quits, it's probably because it doesn't get fuel. Loosen the gas cap and see if that works. If it does, the vent hose is plugged.

Naj ✝︎ · « **Reply #8 on:** May 06, 2005, 04:06:28 »

Mike,

I believe this quote should read 60 degrees CAMshaft rotation.

quote:
Each 60 degrees of crankshaft rotation brings the next piston into TDC.

Throws on the crankshaft are spaced at 120 degrees. In fact, Pistons #1 and #6 are mates. They go up and down together and both are on TDC at the same time, only one is on its compression stroke while the other is on its exhaust stroke. This is decided by the camshaft which rotates at 1/2 crankshaft speed.

Similary pistons #2 and #5 120 degrees behind and again #3 and #4 another 120 degrees).

Even if your distributor is 180 degrees out, as long as #6 is receiving its spark on its compression stroke, the engine will still run right and the strobe will indicate TDC regardless of whether its connected to #1 or #6 plug lead.

naj
65 230SL
68 280SL

ja17 · « **Reply #9 on:** May 06, 2005, 04:42:21 »

Hello Michael,
The vibration dampner is pinned with two steel dowels onto the crankshaft. Like the cog in the distributor, the two indexing points are slightly off-set. It would be unlikely and difficult to install it incorrectly, but possible, but the pins would have to be damaged during the incorrect installation process. This is not the kind of mistake an experienced engine rebuilder like Metric would make.

Now indexing the distributor incorrectly is a little more easy. This can be resolved easily without engine teardown.

Joe Alexander
Blacklick, Ohio

Vince Canepa · « **Reply #10 on:** May 06, 2005, 06:00:55 »

As Joe states, the two dowel holes are offset. From my experience, getting these old two dowel counterweights lined up properly is a pain in the kazoo when you are properly "indexed". To get the pins in the holes with the counterweight lined up 180 degrees out - I think it would require some heavy damage to the pins.

Also, the part with the timing marks is actually the external counterweight for the crankshaft. The big disc mounted in front of it is a harmonic balancer. So if the external counterweight is mounted 180 degrees out, would that not have dire consequences?

I'm always careful with "old German experts". They are no more universally brilliant than the rest of the world.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

mdsalemi · « **Reply #11 on:** May 06, 2005, 06:08:43 »

Vince, JA, Naj, etc.

This is all good information. If Karl Heinz can't fix it there's a reward for those who can.

Pete, the vent lines etc. are the easiest thing to check and that we did. Fuel cap on or off does not change things, sadly enough.

Without a strobe Dan has the engine purring--perfect 700 RPM idle, smooth acceleration, etc., but it would be nice to know that it can be timed with a strobe if need be. If something is assembled wrong I'm one for making it right.

The fuel issue is a mystery and I hope he can solve it. Last I heard from two people is disintegration of the fuel tank internals. I'm really in a bind not being able to really drive it for more then 20 miles. Limits my service options.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

norton · « **Reply #12 on:** May 06, 2005, 06:48:51 »

Mike I don't know if this will help or not, but on US cars it is possible for the outer ring of a balancer to spin on the inner ring, I'v seen this on Chevys and Pontiac's. I'm away from home again, so I can't go out and look at my car to see if this is can happen on a 113, hopefully Joe, Dan or one of the guy with 113 expertises will weigh in on this. It also seems to me even if the distributor is installed 180 out, all that would change is where the plug wires are installed in the cap, and that TDC is TDC and no matter where the distributor is, #1 cylinder should be firing some where near top center, and if the car is running good, it most likely is. So my guess is that there is something wrong with the balancer. Good luck

Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe

A Dalton · « **Reply #13 on:** May 06, 2005, 08:02:03 »

quote:
Originally posted by naj

Mike,

I believe this quote should read 60 degrees CAMshaft rotation.

quote:
Each 60 degrees of crankshaft rotation brings the next piston into TDC.

Throws on the crankshaft are spaced at 120 degrees. In fact, Pistons #1 and #6 are mates. They go up and down together and both are on TDC at the same time, only one is on its compression stroke while the other is on its exhaust stroke. This is decided by the camshaft which rotates at 1/2 crankshaft speed.

Similary pistons #2 and #5 120 degrees behind and again #3 and #4 another 120 degrees).

Even if your distributor is 180 degrees out, as long as #6 is receiving its spark on its compression stroke, the engine will still run right and the strobe will indicate TDC regardless of whether its connected to #1 or #6 plug lead.

naj
65 230SL
68 280SL

Naj has correct info here .
Being a 4 cycle engine , there are only 3 firing cylinders per revolution, not 6. And they are 120 degrees spaced, not 60..
Each piston has to do 2 complete revs for a single power stroke.
The three index marks that have to align to be spec are TDC on crank,
index mark on cam, and index mark on top of distributor housing aligned with the rotor tip. This will result in TDC of compression stroke , # 1 cylinder..
After reading all post,if #6 is on compression at TDC and the index of dist is correct, I suspect the cam timing to be 180 out.
Simply check the 3 Indexs when TDC of #1 is on compression stroke.
If the cam index lines up correctly, the problem is dist indexing is off.

Mark in KS · « **Reply #14 on:** May 06, 2005, 08:56:17 »

This is just a wild try at this subject, but here goes. If the car goes 20 miles and dies, then I sure think it's a fuel issue, too. What about the valve diaphram thingie that regulates fuel? If it's going bad, could it be a contributor to the problem?

I recall that this car looks immaculate. I assume that all the rubber hoses are new and without swelling. Just 2 cents from a rookie owner (2+ years).

TheEngineer · « **Reply #15 on:** May 06, 2005, 10:28:06 »

I had a Datsun Wagon once. It would sometimes just sputter, loose power and quit. Found money in the fuel tank. Must have been plugging the outlet at times.

mdsalemi · « **Reply #16 on:** May 06, 2005, 13:46:29 »

Thanks for all the tips, guys...Dr. Benz is reading this now and saying, "did this, did that..."

My greatest fear is that there isn't one problem here, no smoking gun, thus no magic bullet, but rather a group of perhaps peculiar little issues that add up to something big.

My saving grace is that after the restoration, there were several issues whose symptoms could have indicated big-buck repairs but were simple wiring issues.

Pete Lesler has suggested that the MID RANGE fuel mixture is off--running too lean in the mid range. All I can do is pass it on to Herr Karl-Heinz.

Will keep you posted. I just barely got to Karl Heinz the other day and it started misfiring/stumbling about 1/2 mile away...

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

J. Huber · « **Reply #17 on:** May 06, 2005, 14:00:16 »

If I didn't know Dan had given it the once over, I'd also suspect crud or air bubbles in the fuel system.

James
63 230SL

glennard · « **Reply #18 on:** May 07, 2005, 05:53:08 »

Harmony, synchronism, in tune. The MB straight six, overhead cam, non hydraulic valves, mechanically fuel injected, coil/point ignition engine is a purr-fect sounding machine - when everything is right. Mercedes engineers left open the possibility for we re-engineering types to reassemble the distributor in the wrong way, the injector pump off anything but 20 degrees, the cam shaft sprocket out of sync with the crank, the points opening with the valves open, vacuum -yada, yada, yada... Remember, it is a vacuum pump--. Put it back together the way MB built it.

norton · « **Reply #19 on:** May 07, 2005, 10:58:44 »

Mike I see a big out pouring of love here for the sick Pagoda, I'm sure she'll pull thru.

Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe

glennard · « **Reply #20 on:** May 07, 2005, 11:46:58 »

Mike, If it idles ok, but starts sputtering after a few miles under load I would suspect fuel problems(if everything else is OK). Rust and crud in the tank, fuel pump inlet strainer, fuel filter maybe? Disconnect the hose from the fuel tank to the pump inlet at the pump inlet into a big bucket. (Take safety precautions of open gasoline at all times.) Gas should flow full stream forever( until tank is empty). I had a tank of crud once that after a minute or two the stream fell to a trickle. The internal baffle, shroud, etc. of the tank traps the crud and restricts the flow(see old posts with the Aussie guy)to the pump. Another safer way is to disconnect the pump outlet hose, connect a clear plastic hose long enough to reach the tank filler pipe. Turn the key to run and watch the flow. Put the hose in a bucket at first for timed minute. Measure volume. Put hose in filler for five or ten minutes. Measure volume for a minute and compare. The suction of the pump tends to pull and compact the crud to block the flow. Bump the tank a little to help the crud move to block the line. If crud is the problem, Happy tank cleaning!

rwmastel · « **Reply #21 on:** May 07, 2005, 22:33:10 »

quote:
Originally posted by mdsalemi

The fuel issue is a mystery and I hope he can solve it. Last I heard from two people is disintegration of the fuel tank internals.

Did you not get a new fuel tank during the restoration?

quote:
Originally posted by Mark in KS

This is just a wild try at this subject, but here goes. If the car goes 20 miles and dies, then I sure think it's a fuel issue, too. What about the valve diaphram thingie that regulates fuel?

What part is this?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420

Benz Dr. · « **Reply #22 on:** May 08, 2005, 00:31:37 »

You see........ I moved the distributor timing by changing the idex - I know how to do this. It's not out 180 degrees, it's out maybe 40 degrees? It didn't matter which way I moved it, I couldn't get the timming light to strobe on the marks. It works on other cars but not this one. Maybe my timming light is screwy...

So I set it by test driving and moving it until I got the best possible performance. This car does pull very well - at least while it's running ~)
At any rate, this has nothing to do with why the engine stops running. There seems to be a fuel problem and the tank will pressure up.Then it will sputter whith the fuel cap removed. I think it's haunted.
All the vauum and vent lines appeared to be open so it's a bit of a head scratcher.

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org

Vince Canepa · « **Reply #23 on:** May 09, 2005, 06:02:03 »

Could there be a problem with the "flower pot" inside the tank? I had a weird problem of a similar nature on my 300TE and the return eductor at the "flower pot" (what is the official name for the thing, anyway) was plugged causing the car to die aat weird times. Just a thought.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

George Davis · « **Reply #24 on:** May 09, 2005, 08:24:29 »

Mike, this is a bit of a long shot, but check the fuel outlet fitting on the injection pump. This fitting is a valve, the early version has a small hole through it to allow vapors through even when the valve is closed; the later version doesn't have the hole. The later version of this valve needs to be used with a vapor by-pass hose from the fuel pump to a t-fitting in the fuel return line. If by chance you have the no-hole outlet valve and also don't have the bypass hose at the pump, then it could be vapor-locking. The change was made some time during the 280 SL production run.

Mark and Rodd, I'm guessing the "valve diaphram thingie" is the round thing near the injection pump. That thing is the fuel dampener, it's a diaphram in a chamber, but no valve. It's there to dampen out noise in the fuel system.

George Davis
'69 280 SL Euro manual

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Author Topic: Timing Marks (Read 21182 times)

jeffc280sl

Tom230sl

Vince Canepa

norton

A Dalton

Mark in KS

glennard

norton

glennard

Vince Canepa

George Davis