Miata Mailing List: April 1994, Message #47
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   From: Mark O'Connor 
Subject: Re: Valve Chatter (fwd)
   Date: Mon, 4 Apr 1994 11:21:43 -0400



Forwarded message...

________________________________________________________________________

Tom,

I'm a little confused.  I had the same problem with my 93 last summer and
I changed to 20/50.  The theory being that when warm, the oil tended to
thin out and drain to lower sections of the engine quickly.  It would take
a minute or two after restart for the valves to stop chattering (with 10/40). 
After installing an oil that remains slightly thicker at warm temperatures
(20/50), the problem went away.

I believe 5/40 would have either no or negative impact on the problem,
since this oil gets even thinner at high temperatures.  I've read
an article that suggests 20/50 not 5/40.  Unfortunately I tossed the
article and cannot forward it.  I think it was in last fall's issue of Miata
Magazine.

If you hear any comments that contradict my understanding of this problem,
I would appreciate feedback.


-Mark


On Sat, 2 Apr 1994, Tom Manson wrote:

> Good Day Miateers,
> For some time now I have been reading the communications regarding valve
> chatter on starter.  My Miata has seldom experienced this condition,
> although I will admit that I changed to 5W40 some time ago in order to
> avoid such chatter (as warned by the MCA and some of you on the net).
> However, the other day I was enjoying myself with the RPMs the other
> day, stopped (turned off the engine) and went into a shop for only a few
> minutes.  When I came back out a few minutes later and started the car,
> the chatter occurred.  This was the first time that I had heard it for
> any length of time (normal start-up chatter is usually to short to time
> or even to make sure that I recognize).
> 
> I was obviously concerned since I knew the car to be warm and the oil to
> be fully circulated (not laying in the sump after a night's rest).
> 
> Milton Horst mentioned this and I felt a little reassured since it had
> happened to someone else, and then Andy discussed it.  Apparently this
> (post-autoxing start-up clatter) is not critical.  Does anyone mind
> concurring with this?  Are there other autoxers out there that have
> experienced this post-autox start-up chatter?  Or anyone else for that
> matter!
> Tom
> Manson@fsd.com
> Tom.Manson@pobox.com
> 
> 
>