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RE: generic question on compression checks

To: Bill Babcock <BillB@bnj.com>, fot@autox.team.net
Subject: RE: generic question on compression checks
From: "Brad Kahler" <brad.kahler@141.com>
Date: Wed, 16 Oct 2002 17:17:14 -0500
Hi Bill,

The air pump has long been removed from this engine.  It originally 
came with a catalytic converter but some PO removed that.  I forgot 
to mention its a 79 jeep 360 engine.

I didn't ask if he had done a leak down test or if he only did a 
compression check.  I'll ask him about that when I talk to him again.  
Thanks.

Brad

On 16 Oct 2002 at 15:04, Bill Babcock wrote:

> How old is this Jeep? 
> 
> First thing I would do is a leakdown test on all cylinders--compression
> testing doesn't tell you what going on unless it's gross failure. If they
> are all holding well, then my assumption would be that the emission
> control stuff was cattywumpus. On newer vehicles virtually every system
> that could emit vapor or stuff feeds back into the engine for burning and
> catalyzing into warm mothers milk plus CO2. It doesn't take much for all
> this stuff to stop working right, and when it does, you're screwed. In a
> simpler time I'd say check the PCV valve, but new motors hardly even have
> them. 
> 
> I consider myself a decent mechanic, which means I don't B.S, myself about
> my limitations--I don't touch anything under the hood of any engine newer
> than 1970. I don't even change the oil. A rebuilder will be clueless--they
> are machinists and parts switchers. Here in Portland we're lucky enough to
> have one garage owned by a guy who has all the equipment and understands
> all this stuff. I take everything that's off warranty except the Ferrari
> to him. 
> 
> Find a guy like him. 
> 
> -----Original Message-----
> From: Brad Kahler [mailto:brad.kahler@141.com] 
> Sent: Wednesday, October 16, 2002 2:04 PM
> To: fot@autox.team.net
> Subject: generic question on compression checks
> 
> 
> Amici,
> 
> This isn't really Triumph related (other than its a tow vehcile!) but I'm
> looking for guidance on an engine problem.
> 
> We had an engine rebuild in our Jeep last spring and over the 
> course of the next year we had over heating problems, lack of power 
> and apparent blow-by.
> 
> We took it back to the rebuilder multiple times to try and get the 
> problem(s) corrected.  Never did have much luck.  However, trying 
> to get past the state emissions test last month this almost new motor
> failed miserably.
> 
> Here are the apparent symptoms.  OIl in the air cleaner coming from 
> the valve cover.  Compression check shows approximately 140-145 
> across all 8 cylinders at first.  However on the 3rd revolution of each
> compression check (which is what the manual says to check for) the
> pressure drops to 115-120 but comes back up to 140-145 on the 5th
> revolution.  
> 
> This doesn't sound like a piston ring problem to me.  It would seem 
> to be more of a bad cam.  The cam shaft was replaced, the heads 
> were given valve jobs.  Basically it was a complete engine rebuild.
> 
> Any thoughts on what to look for?  Should he just pull the heads and cam
> on the assumption that the rings are probably ok?  Or does this sound like
> a ring problem AND a valve/cam problem? 
> 
> Any help on this would be greatly appreciated!
> 
> Thanks
> 
> Brad

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