Proper IP timing with chain stretch

[homepagz]

Anyone know the proper way to time the IP with chain stretch? My '92 300D has 3 deg's of chain stretch - so does this mean you still time the IP at 14.5 deg's? Or do I adjust the 14.5 up or down 3 deg's? (17.5 or 11.5 deg's?)

Thanks,

-John

[whunter]

Originally Posted by homepagz

Anyone know the proper way to time the IP with chain stretch? My '92 300D has 3 deg's of chain stretch - so does this mean you still time the IP at 14.5 deg's? Or do I adjust the 14.5 up or down 3 deg's? (17.5 or 11.5 deg's?)

Thanks,

-John

IMO the only way to correct the issue is rolling in a new timing chain, the existing one is wearing the (expensive) sprockets due to elongation.

Timing Chains Don't Last Forever

Diesel Timing Chain Thread

.

[homepagz]

Is 3 deg's considered "time" to replace the timing chain?

[whunter]

Originally Posted by homepagz

Is 3 deg's considered "time" to replace the timing chain?

Many examples of what a bad chain can do to any sprocket, from bicycles to stationary equipment or mega machines.
worn out chain sprocket - Google Search

.

This was written in response to the owner of a 300SD, but is generic to all roller chains.


Timing chain stretch does not exist = it is wear on the pins and bushings = Wear Elongation Measurement.


Chain elongation/wear is not corrected by an offset Woodruff key..

I have stopped checking timing chain elongation/wear on any engine over 250,000 miles, the labor/time is identical to replace the chain.
The cost of a chain is cheap insurance, and generally improves performance.

My rule of thumb is 200-250K miles I replace the timing chain = don't waste money/time checking it..

If the timing has not been changed since new = replacing the timing chain will bring the timing back where it belongs.

IMO: If the chain has measurable elongation/wear = Replace it regardless of mileage!!!

A worn chain is damaging the sprockets.

What is running a damaged - worn out timing chain going to cost ?

At least (by the labor time guide) 4.7 hrs labor + all of these parts....

1992 300D 2.5 Turbo

Injection pump timing device
MB# 6010702645
+ MB# 6019902440

master link, chain
MB# 0009972898

timing chain
MB# 0039975594

Crankshaft gear
MB# 6060520003

Camshaft gear
MB# 6010520001

Sliding rail
MB# 6010500816

Sliding rail
MB# 6010520516

Sliding rail
MB# 6010520316

tensioner
MB# 6010500711

gasket
MB# 6020160221




If you have not replaced your vacuum pump, this link shows what you are risking...
1992 300D 2.5 vacuum pump "FAILURE" ball bearings fell into timing chain

vacuum pump
MB# 0002303565

gasket
MB# 6012380780

gasket
MB# 6030140722


Usually these are failed, and need immediate replacement.

lever
MB# 6012001773

shock absorber
MB# 6042000214


.

[whunter]

Roller chain
Roller chain - Wikipedia, the free encyclopedia

Roller Chain Wear Life
Diamond Chain | Roller Chain Wear Life

DESIGN FORMULAS FOR ASA ROLLER CHAIN SPROCKETS
OmniGear & Machine Corp.

Mechanical Design Handbook: Standard roller chain drive design

The Complete Guide to Chain
The Complete Guide to Chain

[Simpler=Better]

When you time the IP you're basing your timing on the crank. So set the crank to the desired degree, and then time the IP.

With chain stretch the cam will still be 3* out though.

[homepagz]

Will chain stretch also cause valve noise?

What are the symptoms of chain stretch?

[sixto]

If the W124 FSM is to be believed (http://www.startekinfo.com/StarTek/outside/12264/Program/Engine/602_603/05-6015hw.pdf), if a difference of more than 4*CRA exists, replace the timing chain. The FSM reference for a 602.962 is 12* ATDC at 2mm intake valve lift. Eyeballing the cam tower marks should be representative if the chain is not elastic.

Sixto
87 300D