MC with valve cover off...

Bernard Littau bernardl at
Thu Nov 15 13:22:48 EST 2001

> > >> Can I run an MC I5 with the valve cover off, at low rpms, without
> > too
> > >> much of a mess?  Any BTDT advice?
> >
> > >No.  It won't run... just like taking the oil filler cap off when the
> > >is running stalls it.
> 1. you could block off the fume scavenging hoses to quell the vacuum
> leak.
> 2. then I think your camshaft oil jets might make a rather interesting
> mess, along with oil "thrown" by the cam.

I'm the one who originally posted the question.  Thank you to all who
replied, both on list and off.  Really I mean that :-)  This is a great
resource and education.

Just to summarize, not a single person claimed to have BTDT at low rpms (I
was thinking idle, should have said so...)

I had not thought about the vacuum line problem, but I believe it would have
been apparent, as my plan was to re-assemble the car, run it warm, then take
the valve cover off again and look-see what was going on with the
distributor gear.  I was planning on plugging the hoses going into the valve
cover, though it sounds like that might not be enough to get the engine to
run well.

I know from my old '73 BMW 3.0 I6 that it could be run at idle without too
much oil being sprayed.  That was how the valves were adjusted, the old
feeler gauge and move the eccentric valve adjuster with BMW tool 3453 (I
used an old sardine can key with a 45 degree bend in it instead :-).  You
could do the valves with the engine running at idle with pretty much no
mess.  Blipping the throttle meant instant mess (why do I know that?).

On my old Ford 351W, the valve covers were to keep dust off the cam, I am
sure.  It never sprayed any oil at idle or beyond.  Had several 'merican
cars like that.

I assume some of you 4k I5 people have non-hydraulic lifter valve trains,
and need to adjust them with the engine running.  What does a solid lifter
I5 spray during valve adjustment? Anyone actually tried a 5ktq at idle and
seen what it kind of mess it really makes?

At this point I am curious enough to go ahead and try running the car at
idle without the valve cover.  I'll report back.  Don't hold your breath, as
I have to work Friday, race Saturday (sailboats, 7 MPH is considered
fast...) and will get to re-assembling the 5ktq on Sunday afternoon.  Might
not get the car running until after Thanksgiving at the rate I am going :-(


Bernard Littau
Woodinville, WA
'88 5ktq

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