Is there a way to be sure my timing chain didnt skip a tooth - PeachParts Mercedes-Benz Forum

konstan · #1 09-08-2010, 09:00 PM

Ok so most of you know I am putting the motor back together.

I think the timing chain is in the right position (I kept a zip tie around it and the camshaft sprocket and I had it marked with paint to the crank sprocket.

What I am not 100% sure about is that it didn't skip a tooth or two on the timing device. I mean, I am reasonably sure that it didn't... but is there a way to verify?

Diesel911 · #2 09-08-2010, 09:21 PM

Yes.
Rotate the Enigine in the direction of normal rotation; line up the Camshaft Gear Timing Mark on the rear of the Gear exactly with the one on the front Chamshaft Bearing.
Look down at the degree marks on the Crankshaft Damper. It sould be on or extremely close to Zero which is Top Dead Center.

jt20 · #3 09-08-2010, 09:23 PM

it can not slip on the TD unless you removed the vacuum pump and the pressed in pins around the circumference of the device.

konstan · #4 09-08-2010, 09:31 PM

well I did remove the vacuum pump, and at one point I did have the TD out...

konstan · #5 09-08-2010, 09:32 PM

Quote:

Originally Posted by Diesel911

Yes. Rotate the Enigine in the direction of normal rotation; line up the Camshaft Gear Timing Mark on the rear of the Gear exactly with the one on the front Chamshaft Bearing.Look down at the degree marks on the Crankshaft Damper. It sould be on or extremely close to Zero which is Top Dead Center.

Thanks gonna go check it

jt20 · #6 09-08-2010, 09:34 PM

Quote:

Originally Posted by Diesel911

Yes.
Rotate the Enigine in the direction of normal rotation; line up the Camshaft Gear Timing Mark on the rear of the Gear exactly with the one on the front Chamshaft Bearing.
Look down at the degree marks on the Crankshaft Damper. It sould be on or extremely close to Zero which is Top Dead Center.

that will only tell you if the cam is in phase with the crank...

not the injection timing.

konstan · #7 09-08-2010, 10:17 PM

Quote:

Originally Posted by jt20

that will only tell you if the cam is in phase with the crank...not the injection timing.

Raaight... the cam I am 100% sure is in phase...

jt20 · #8 09-08-2010, 10:25 PM

sooooo...

it sounds like you will have to time your pump if you have any doubts about your installation.

vstech · #9 09-08-2010, 10:42 PM

only way to know if the pump gear skipped a tooth is to be sure you did not remove the pin and take out the gear. the chain cannot rise above a tooth in it's place.

Diesel911 · #10 09-09-2010, 12:45 AM

I am going to barrow a quote from vstech since it applies to me also.

"take my posts with a grain of salt... I skip over reading sometimes..."

Somewhere In our DIY section there is IP timing and what to do if you removed the IP to retime it.
DIY Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82

http://www.peachparts.com/Wikka/DoItYourSelf

jt20 · #11 09-09-2010, 02:03 AM

Quote:

Originally Posted by Diesel911

I am going to barrow a quote from vstech since it applies to me also.

"take my posts with a grain of salt... I skip over reading sometimes..."

me three.

Sev · #12 09-09-2010, 03:10 AM

NEVER take my posts with a grain of salt. simply pretend that my posts constitute the thoughts/opinions/views of Chuck Norris.

NEVER take Chuck Norris with a grain of salt, or Chuck Norris will take you out with a roundhouse kick

Stretch · #13 09-09-2010, 03:44 AM

The best way of checking you have got TDC on number 1 cylinder is to measure it with a DTI. When the head is in place you can do this by removing the front rocker arm set (on a OM617) and removing the valve spring, nuts, and washers so that the first valve rests on the top of the piston. You can then mount a DTI and turn the crankshaft until the dial stops moving - that's TDC.

Warning:- make sure the piston is very close to the top of the cylinder otherwise the valve could drop in - then you need to take the head off again.

konstan · #14 09-09-2010, 10:30 AM

Looks like will be easy enough with the engine still on the stand.

konstan · #15 09-09-2010, 08:44 PM

Ok so I did this. The only difference with the engine off the stand is that I have to plug the cigar (return) hose and the injector return hose so the pressure does not escape from them.

Using the drip method, the beginning of delivery (1 sec drop) is definitely between 20 and 21 BTDC... The FSM says should be 23-25. Now, the question is, if the chain skipped one tooth on the timing device, what would the discrepancy be???