Patient Name- Mr. Timing Chain Duplex
Age- 20Years Sex- Male or female –you decide
Address- W-126, V 8, 5.6L
560 sel MB 1988
Reason for visit- 100,000 miles checkup.

Chief complaints- None. Current mileage- 220,000 miles

Present History.- Never checked myself before. Running fine just like new.
Past History- I don’t know. Single owner before, Now second owner. No major break down. All the previous record available but no mention about myself.
Review of systems questionnaires-

1- Do you take 4-5 crank attempt to start the engine?—No
2- Hard starting?- No
3- Do you make flapping sound for few seconds soon after engine start.?--No
4- Are you making flapping sound all the time when engine running? No

Physical Examination- Not done- Need surgery to check ( Removal of valve cover to check chain stretch)

Diagnosis- Suspected timing chain stretch to a point that it can break. Needs to be confirm by Timing chain stretch test.

Management- Heart Attack ( Broken timing chain, bent valves damage pistons) can happen without sign and symptoms. We’ll do following surgery and replace following organs ( Organ transplant- cloned in lab- New? or From another person- Junk yard.?)

1- Timing chain
2- Camshaft gears
3- Upper timing chain guide
4- Tiiming chain tensioner and gasket
5- You fill in rest.

Operation theater- DIY

Surgery scheduled-

Timing chain and chain guide/rail replacement.

1- Remove both air cleaner hoses, air cleaner intake snorkel.
2- Drain radiator, remove upper and lower radiator hoses, transmission lines to radiator and remove fan shroud and radiator
3- Remove Fan and fan clutch from water pump.
4- Remove all the drive belts.
5- Remove alternator and alternator bracket.
6- Remove steering pump and set aside, don’t remove it completely.
7- Remove steering pump bracket.
8- Remove distributor, spark plug wires and spark plugs.
9- Remove both side valve covers.
10- Rotate the crank shaft clockwise to match the mark of camshaft gear with the mark of the camshaft tower. And check the mark on the camshaft mark to confirm the timing chain stretch, If timing chain needs to be replaced. Proceed with following.
11- Remove upper chain guides/rails on both side. Remove chain tensioner and tensioner rail. Install tensioner with new gasket and install all the upper new chain guides. These steps should be done before reeling in new timing chain.
12- Reel in new timing chain. There are more then one method of reeling in timing chain. Three Vice grips method or using special tool for timing chain installation.
13- Rest of the reinstallation is in reverse order.

Precautions-

1- Mark the distributor and engine housing to reinstall the distributor at the same position.
2- Timing marks on the camshaft, camshaft towers and crankshaft should be in alignment with their respective marks.
3- Cylinder # 1 should be at TDC.
4- Rotate crankshaft only in clockwise direction.
5- Distributor rotor should be in alignment with the # 1 sparkplug wire contact point of the distributor.

Potential complications

1- Jumping 1 or 2 teeth of camshaft gear or crankshaft gear.
2- Dropping chain inside the engine.
3- Timing chain stuck inside and crankshaft can not be rotated.
You can recover from these mistakes but it is more complicated and time consuming..

AFTER LEARING ALL OF THESE, I HAVE SECOND THOUGHT.

SECOND OPINION FROM ANOTTHER SURGEON.

1- Why not remove the Timing chain cover from the front of the engine to get the full view of the all the gears, all timing chain guides and rails including chain tensioner and everything else. Once I get to that point I may not have deal with above potential complications and some of those precautions since everything is in front of me. It is my feeling that once everything is open to me the timing chain job should be easy to do.
2- Why I feel that way-
a. I recently replaced the timing belt from V-6 engine of Isuzu Rodeo. After taking upper and lower timing belt cover off from front of the engine. Whole timing belt job was very easy. But it was timing belt not timing chain. And it was non interference engine.

CONFUSIONS-

1- I have searched many forums but could not find detail information about removal and installation of the timing chain cover to do the timing chain job.
2- I have w126 service cds and WIS dvds software on my computer and I consulted them too. The descriptions are not in detail and sometimes not clear to me.

CASE IS REFFERED TO SPACIALIST( Dr. You Guys)

MY QUESTIONS ARE-

1- Why most of us do not go that rout and do the timing chain job after removing the front timing chain cover?
2- How many of you have done timing chain job after removing front timing chain cover.? And what is your experience and recommendations?

3- Please fill in—

a. Expected number of hrs. to complete the job?
b. Minimum tools required for DIY?
c. What parts and gaskets are needed to complete the job?
d. Can I do it alone?
e. List of other jobs “while you are there”? Although I don’t like these jobs unless something is broken.


So, How should we treat this Patient.