Original Message
Crankcase pressure
By Tom - 07/22/2002 3:55:39 PM; IP 204.87.61.254
I am puzzled that the stock 390 engine in my 1963 Thunderbird has a slight positive crankcase pressure (based on a home made manometer that I rigged up). I checked into this, because it was spitting a little oil mist out of the breather filter (as well as a little smoke).

The manifold vacuum is 21 at idle in neutral and 17 at idle in drive. I did a compression check on each cylinder and they are all within 160 to 165. I put a new stock PCV valve on it and completely cleaned out the PCV system. I even removed the adapter at the back of the intake manifold that the PCV hooks onto and cleaned all the gunk out of it. I also removed the spacer underneath the carburetor to be sure the PCV passage is clear. I completely cleaned off all the old gasket material and was extra careful to use the right gasket and to be sure it was properly positioned so as not to choke off any of the PCV flow.

I am at my wits end. Is it possible the metal mesh filter in the intake manifold is so cruddy that I am not getting adequate flow from the crankcase? There is a reasonable amount of flow through there, but I have no way of knowing whether it is more restricted than it is supposed to be.

This was about the first PCV system Ford put on this engine. Is it possible that it was just inadequately engineered, so that it gets overwhelmed if the rings are only mildly worn?

Does anyone have any ideas?

Thanks.
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Collapse <b>Crankcase pressure</b>&nbsp;-- <font color=#0000ff>Tom, <i>07/22/2002</i></font>Crankcase pressure -- Tom, 07/22/2002
Collapse <a href=../ForumFE/reply.aspx?ID=13772&Reply=13761><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor13772" onclick="return false;">Corroded intake manifold?</a>&nbsp;-- <font color=#0000ff>Dave Shoe, <i>07/23/2002</i></font><script type="text/javascript">
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 Corroded intake manifold? -- Dave Shoe, 07/23/2002
 RE: Corroded intake manifold? -- Tom, 07/23/2002
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