Re: [DML] Re: PRV Timing Chain Tensioners - Oil Problems

["Bruce Benson" <delornut@xxxxxxxxxxxx>]

One of the things that can cause lubrication problems with the timing chains
is the plastic screens covering the oil passages to the tensioners. If the
engine has a dramatic overheat they can melt or deform to restrict oil flow.
The tensioners maintain tension by oil pressure. If the flow is obstructed
the timing chains can slacken.  It's not a real common occurrence but if you
ever disassemble the timing chain cover and chain tensioners. I'd recommend
checking them.

Bruce Benson

> PRV timing chain tensioners are loaded by engine oil (passes through
> them on the way to the camshafts). If the chains wear too badly the
> tensioner pistons will extend so far that oil runs past them back to
> the pan, leaving the camshafts dry. This is one of the sources of "PRV
> oil problems", endemic to B28 as well as B27 (timing chain tensioners
> are identical).
>
> Bill Robertson
> #5939
>
> >--- In dmcnews@xxxxxxxxxxxxxxx, Nathan Robinson <nathanrobinson@xxxx>
> wrote:
> >
> > The PRV-6 engine had problems with oil delivery, and consequently, the
> > cam chains wore like a mofo. Also, the cam chain tensioners are hard
> > to check, making the engine (you guessed it) develop problems 'later
> > on' in life. The blowing up bit I can only imagine is what happened to
> > me.
> >
> > The cam chains wore considerably and broke prematurely. A borked chain
> > thrashing around at the front of the engine cover is quite a chore to
> > fix. And expensive. The 'new' cam tensioners and my dad's modification
> > to the front of the timing cover (and also scoring depth marks on the
> > tensioners as well - so we can tell how worn the chains are) makes
> > checking up on those little beasts a whole lot easier.
> >
> > When those chains break, it's generally cheaper to just find another
> engine.
> >
> > Nathan Robinson
> >
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