2003 300m special timing belt

Does a 300m special have a timing belt or chain? if belt at what mileage
does it need to be changed im at 138000km

 

The North American 300M has the 3.5 liter engine - timing *belt* -
change interval is 102k miles for the 2003 (water pump is driven by that
belt, so should be changed at the same time as well as the tensioner
pulley). Some Eureopean M's have the 2.7 liter engine, which has a
timing chain (no prescribed change interval for the chain, however, the
water pump is driven by the chain). Both engines are interference
(non-free-wheeling).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

You should only use the manufacturer's mileage recommendations on
a timing belt as the absolute longest amount of time before changing
the belt. What your supposed to be doing is a -visual- check on the
-condition- of the timing belt at least once a year. ANY cracking AT
ALL even very fine "spidering" cracking on the back of the belt should
result in an immediate scheduling of the car in to have the belt changed.

Ted

 

But we both know that 99.9% of people don't check them, and some lesser
percentage of people that even know about the subject to this level will
check before the prescribed change interval. I don't know about you,
but I don't. It comes under the category of not enough hours in the day
(to be that way - anal - about everything) and willing to take the
chance - especially if you have to pay someone to check it, i.e., over a
lifetime, the cost of having it checked weighed against the risk of
losing an engine due to a prematurely failed belt will probably cost
more, or at least I'm still willing to take the chance and eat the
difference if I lose the bet. If it was more accessible for inspection
- i.e., you raise the hood and look at it like you would an accessory
belt, that would be a different story.

Also, a timing belt's potential for failure is more dependent on the
condition of it's internal fibers/cords, which you have no way of
assessing, and is completely independent of any external appearance.
Also, many timing belts also drive water pumps, which in some cases turn
out to be the weakest link.

Also, if you don't do the checking yourself, chances are, for 90+% of
the public, eventually some shop will fraudulently tell them it needs
replacing when it doesn't, so they will end up replacing it when it
doesn't need it even under the inspection criteria you gave (that same
90+% would not know they could have the old parts returned for
verification of the old belt's condition, or not know that they were
given some other car's belt instead). IOW - your odds are better taking
your chances that it will go the distance - especially if you are
dependent for a repair shop to check it for you and you, for whatever
reason, are not able to check behind them (again - for 90+% of the
public that is probably the case).

IMO...

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')