In particular, how far people have driven before the valves wore to the point where thicker shims were required. The Duratec23NS from 2001 onwards does not have hydraulic lifters for some mysterious reason. Does something else pointing toward a rebuild announce itself first?

Another thread answered the general question of longevity for pre-2001 engines. (someone got ~373km out his '94 when it died)

(I mistakenly posted this question in the general forum and am reposting here)

All the best,
Andre.

 

the duratec is mazda engine

it uses a overhead camshaft

 

Chees_man, you are correct. My last truck had overhead cams and hydraulic lifters though, so I'm a little lazy in my wording.

In this case the proper term is "Direct Acting Mechanical Bucket (DAMB)". These are supposed to last at least 150000miles and first appeared in 2001. I figure by now the truth about how long they really last may be apparent. These buckets come in thickness ranging between 3mm - 3.75mm. My motorcycle's overhead cam design requires routine shim adjustment but at least it is not hard to work on. It bothers me a little that there is no hydraulic automatic adjustment here. My last truck (V6) went 360000km and ran fine when I sold it.

SVT passes torch to DURATEC 2.3 - Page 9 - Focus Fanatics
"Bucket-and-shim valve actuation eliminates the need to move the mass of a rocker arm, and therefore allows relatively higher RPM running

http://www.rallyrace.net/docs/duratec.txt
Decribes the design and mentions the 150000mile target life.

 

i want the longest life out of my engine
that is why i add duralube to my engine every oil change

i had it added to my manual tranny fluid ( dealer did it )
i never had any hard shifting problems after that

 

I've used only synthetic since 1981 and PTFE/teflon can't hurt. I was poised to install a bypass filter but there is just no space and I fear a hose failure also. A fixed shim rather than a hydraulic lifter struck me as a cheap step backward but hopefully I am wrong. I think this fixed shim will be unforgiving in its requirement for clean oil.

shifting is another interesting question. I have noticed that on this and other trucks that double clutching makes a difference in fall and winter when the trans oil is cold and has not yet warmed up. I researched it and concluded that thick oil causes the idler gear to spin down too quickly and double clutching spins it up again to allow the synchro cone require less friction to match the gear I select for it to mate with. I have some trans duralube on a shelf and may throw it in to duplicate your experiment.

 

right when i bought my reg cab std tranny ranger

i had phil the head mechanic take the truck back in and pour in the duralube in the tranny

it cost me an extra 25.00 dollars , but it is well worth the extra cost -it means extended internal component life

i could shift gears with my baby pinkie, that is how effective duralube is in the tranny

my engine ran so smooth- i could hardly ever feel it running