Timing adjustment - PeachParts Mercedes-Benz Forum

OMEGAMAN · #1 01-07-2006, 05:50 PM

The other day i replaced the front crank seal on my car and since I already had access to the crank bolt I thought might as well check injection pump timing. It was way off it was about 18 deg before zero. I could get the pump to adjust to about 23 deg. Man what a difference car runs better cold and has a lot more power. I'm not surprised that 5 deg made that much of a diffrence but that the car ran so well in the first place. It has always started well cold and produced good power at about 23 mpg. If you ever wondered about the pump timing on your car have a look it does not take long and what a difference. I'll post later with the gas mileage figures.

black280ce · #2 01-07-2006, 10:44 PM

Do you have to use the drip tube?

OMEGAMAN · #3 01-08-2006, 09:41 AM

I didnt use the drip tube method I used this one
http://diymbrepair.com/easley/iptiming.htm
I also tried the method from the guy a **************.com. His did'nt make a whole lot of sence to me be cause he wanted to remove the delivery valve but both methods produced the same results.

Brian Carlton · #4 01-08-2006, 10:06 AM

That's a good job and the procedure appears to be very straightforward.

Many folks that are new to these engines would be well advised to check and adjust the IP timing.

I had to advance the SD by a few degrees to meet specs. I'm rewarded with much better driveability. The fuel economy is running close to 27.5 on winter fuel. It might even be possible that the SD catches the SDL for fuel economy, once the winter fuel is terminated.

larry perkins · #5 01-08-2006, 11:48 AM

good job on the ip pump.
wouldnt you want to go a little futher and look at the valve timing ? i suppose the pump could have been set wrong in the past but i would bet that the chain wear has caused the pump error and if so you would need to replace the chain or use an off-set key to correct the valve timing.
larry perkins
85 old cars

biopete · #6 01-08-2006, 02:43 PM

I have 81 300D with drip tube still attached and find timing set dead on at 23* . Searched and read lots here on how to drip method but in process I now have a question. Haynes says range is 23-25 BTDC for my 615.912 Non Turbo(NA) engine. I am having trouble starting below 35F . Have to crank and crank through 2 batteries to get going. (I just dont start it those days rather than make starter worse.)

So in this case would setting it to high end at 25 help start in cold maybe ? (Setting it to 25 is "advancing timing " ringht?)

Also, I really should have checked chain stretch first but did not. I will do that. Im thinkning chain stretches would retard timing. Is that right. In which case I may just be better off adding woodruff key. Also, if you don't mind could someone point me to a link on checking Cam timing and chain stretch . Found some discussing it but none telling how to do it. Is it in Haynes ? I have that .

Thanks.

Hit Man X · #7 01-08-2006, 02:51 PM

I'm curious about the install of a Woodruff Key also before setting my IP timing...

Brian Carlton · #8 01-08-2006, 03:18 PM

Quote:

Originally Posted by biopete

I have 81 300D with drip tube still attached and find timing set dead on at 23* . Searched and read lots here on how to drip method but in process I now have a question. Haynes says range is 23-25 BTDC for my 615.912 Non Turbo(NA) engine. I am having trouble starting below 35F . Have to crank and crank through 2 batteries to get going. (I just dont start it those days rather than make starter worse.)

So in this case would setting it to high end at 25 help start in cold maybe ? (Setting it to 25 is "advancing timing " ringht?)

Also, I really should have checked chain stretch first but did not. I will do that. Im thinkning chain stretches would retard timing. Is that right. In which case I may just be better off adding woodruff key. Also, if you don't mind could someone point me to a link on checking Cam timing and chain stretch . Found some discussing it but none telling how to do it. Is it in Haynes ? I have that .

Thanks.

An interesting side note:

We had an impulse timing device at the NJ GTG last fall. Dieselnut14 measured six different 617 and 616 engines. The results ran from 6° BTDC to
12° BTDC. However, we had no reference to the M/B spec of 24° BTDC because a different method was utilized. The impulse device clamps to the #1 injector hard line and senses the change in pressure in the line when the injector opens.

So, in the process of rebuilding the SD, I set the timing with the RIV tool to the precise spec of 15° ATDC. This is a different method and the number is different, but, it provides a factory setting with an accuracy of better than 1/2°. The chain stretch was 2.5°, however, I did not take this into account when setting the 15°. So, in reality, I'm probably 1.5° late due to chain stretch.

Now, today, I brought the SD to have it checked with the impulse device. It measured 13° BTDC. The SD is currently more advanced than any of the vehicles at the GTG, and, even it is a bit late.

So, you can be quite confident that one or two or three or four degrees won't make any noticeable difference. That being said, I've got the suspicion that many of the 617's are running quite a bit later than they should be for maximum fuel economy and performance.

To check cam timing, you need to align two marks. One mark is on the rotating thrust washer at the front of the cam. The second mark is on the tower, right adjacent to the thrust washer. When these two marks are dead on each other (actually they are notches), then look down and read the crankshaft damper. The degree reading is the amount of stretch. Ideally, the crank will be at TDC, but, nobody is going to have zero stretch.

If the amount of stretch is 4° or more, you can consider a Woodruff key on the camshaft to bring it back.

biopete · #9 01-08-2006, 04:03 PM

Quote:

Originally Posted by Brian Carlton

An interesting side note:

We had an impulse timing device at the NJ GTG last fall. Dieselnut14 measured six different 617 and 616 engines. The results ran from 6° BTDC to
12° BTDC. However, we had no reference to the M/B spec of 24° BTDC because a different method was utilized. The impulse device clamps to the #1 injector hard line and senses the change in pressure in the line when the injector opens.

So, in the process of rebuilding the SD, I set the timing with the RIV tool to the precise spec of 15° ATDC. This is a different method and the number is different, but, it provides a factory setting with an accuracy of better than 1/2°. The chain stretch was 2.5°, however, I did not take this into account when setting the 15°. So, in reality, I'm probably 1.5° late due to chain stretch.

Now, today, I brought the SD to have it checked with the impulse device. It measured 13° BTDC. The SD is currently more advanced than any of the vehicles at the GTG, and, even it is a bit late.

So, you can be quite confident that one or two or three or four degrees won't make any noticeable difference. That being said, I've got the suspicion that many of the 617's are running quite a bit later than they should be for maximum fuel economy and performance.

To check cam timing, you need to align two marks. One mark is on the rotating thrust washer at the front of the cam. The second mark is on the tower, right adjacent to the thrust washer. When these two marks are dead on each other (actually they are notches), then look down and read the crankshaft damper. The degree reading is the amount of stretch. Ideally, the crank will be at TDC, but, nobody is going to have zero stretch.

If the amount of stretch is 4° or more, you can consider a Woodruff key on the camshaft to bring it back.

Thanks brian. Nice story. Very informative. That is what I needed. All thsoe NJ folks runnig BioD and have the timing retarded for NOx emmission concerns

Or mayb e not. BiodieselNow.com forum started by NJ people and now has a better part of a million members and there they speak of this method to reduce NOx. (Not really sure if it was specific to a any particular car.)

Anyway, Good news on my timing chain. Since I was at 23 BTDC on #1 cylander from the IP start of delivery check, I rotated around 23 Deg. to see the notches on the Camshaft washer and bearing housing line up perfect. !11 That is I read 0 on crankshaft damper and notches aligned on Camshaft Tower ( +- 1 Deg max.) Hang on for some pics. Does it matter that # cylander is up or should it always be the same reading on crankshaft damper when campshaft marks align as you said ? Be right back.

P.S. In chapter 2A of Haynes it talks about checking these marks but the manual never mention timing chain stretch check that i can find. It is in Camshaft R and R (removal and replacement). Not idiot proof though.

OMEGAMAN · #10 01-08-2006, 04:32 PM

Quote:

Originally Posted by larry perkins

good job on the ip pump.
wouldnt you want to go a little futher and look at the valve timing ? i suppose the pump could have been set wrong in the past but i would bet that the chain wear has caused the pump error and if so you would need to replace the chain or use an off-set key to correct the valve timing.
larry perkins
85 old cars

Cam timing is next I just have not had the time. If that is off too I can't imagine how well she'll run when I fix that

Brian Carlton · #11 01-08-2006, 08:55 PM

Quote:

Originally Posted by biopete

Anyway, Good news on my timing chain. Since I was at 23 BTDC on #1 cylander from the IP start of delivery check, I rotated around 23 Deg. to see the notches on the Camshaft washer and bearing housing line up perfect. !11 That is I read 0 on crankshaft damper and notches aligned on Camshaft Tower ( +- 1 Deg max.) Hang on for some pics. Does it matter that # cylander is up or should it always be the same reading on crankshaft damper when campshaft marks align as you said ? Be right back.

If you have the two marks aligned, precisely, the crankshaft damper will always be at or near zero degrees. Look carefully at the crankshaft, however. It's very easy to lose a couple of degrees and not realize it. The first real mark is at five degrees.

boneheaddoctor · #12 01-08-2006, 09:53 PM

Your cam reference point is not the mark but the valve at a certain lift...the specs of which I do not have handy.....the mark on the cam and head are assembly cues and not the precise point the cam is referenced at.

Brian Carlton · #13 01-08-2006, 10:00 PM

Quote:

Originally Posted by boneheaddoctor

Your cam reference point is not the mark but the valve at a certain lift...the specs of which I do not have handy.....the mark on the cam and head are assembly cues and not the precise point the cam is referenced at.

Although I agree with you Bone, I think those marks are close enough for use by most of us. Only if the marks show greater than 5 degrees would I consider bothering with the valve lift measurement. I'd probably use the valve lift measurement before I decided to insert a new key, however.

boneheaddoctor · #14 01-08-2006, 10:04 PM

Quote:

Originally Posted by Brian Carlton

Although I agree with you Bone, I think those marks are close enough for use by most of us. Only if the marks show greater than 5 degrees would I consider bothering with the valve lift measurement. I'd probably use the valve lift measurement before I decided to insert a new key, however.

no problem with that as a quick and dirty type reading...just didn't want someone doing this the first time to think that mark was a precise point of reference.

dannym · #15 01-09-2006, 08:56 AM

Here are a couple of good timing chain threads.
The specs for timing chain are in all the online manuals.

http://www.peachparts.com/shopforum/showthread.php?t=96572

Q on timing chain stretch...

I have used the 2mm valve lift method and the cam mark method and see any difference in the measurement.

I just eyeballed the cam marks this weekend and the timing was off by about 3 deg. I installed a 4deg woodruff key last year so it's getting to the point where I need to replace the chain. Maybe I should start using synthetic oil.

Danny