DeTomaso Mailing List: April 2001, Message #195

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> From: Asa Jay Laughton <asajay@asajay.com>
> To: Multiple recipients of list <detomaso@realbig.com>
> Subject: Re: Engine problems
> 
> At 14:46 04/05/2001 -0400, Thomas Tornblom wrote:
> >Here's a picture of cylinder 8 - 5 (in that order) plugs:
> >http://www.detomaso.nu/~thomast/plugs.jpeg
> 
> Looks like 7 is running rich.
> 
> >Right after start it feels as if it doesn't run on all cylinders.
> >
> >I took a compression test:
> >
> >cyl	comp (bar)
> >5	8.0
> >6	7.8		
> >7	8.5
> >8	7.5
> 
> Was the compression test done cold or hot?

Cold.

> If cold, hmmmm.
> If hot, then it's possible your having a compression problem that is
> sealing the cylinder once it's warm.  Do both a hot and a cold compression
> test and let us know the results.
> 
> >This is what the head looked like when I replaced the gasket:
> >http://www.detomaso.nu/~thomast/efi/head-left.jpeg
> 
> Yup, same cylinder doing the same thing before.  Too rich, not getting
> clean burn, etc.
> 
> I'm beginning to suspect the lifters (why oh why didn't I replace them when I 
> >had the intake off...).
> 
> You can still check this with the engine assembled.  You just need a dial
> indicator and something to hold it solid to the valve or pushrod with.
> Just mount the dial indicator agains the valve or pushrod and rotate the
> engine watching the overall lift.  Compare to other cylinders.  This will
> generally let you know if a cam lobe is going bad, however, I tend to thing
> the problem would be "permanent" and not go away when warm.

Yes, that my line of thinking also.

> 
> The only other assumption might be that the piston has excessive clearance
> in the bore, causing lower compression when cold and better compression
> when warm.  I do find it odd though that number 7 appears to have the
> greatest compression.

As I did the test cold I don't think this is the problem.

> 
> Have you done a cylinder leak-down test?  That might provide some clues as
> well.

Not yet. I have planned to this.

I forgot to mention that the entire ignition system is relaced since last year, 
wires, dist, coil.

> 
> 
> >I pulled the left valve cover last night to verify that the rockers at least 
> >seems to move properly. I noticed that the oil deflectors in the rockers
> are not 
> >mounted the same way as in the service manual:
> >
> >See:
> >http://www.detomaso.nu/~thomast/deflector1.jpeg
> 
> I think you are correct, I think the deflectors are mounted backwards in
> that photo.  I'm not sure, as all mine are now roller rockers and don't use
> the deflectors.
> 
> Asa Jay
> 
> ----------------------------------------------------------------------------
> --------------------------------------------------
> Asa Jay Laughton
> Mobile Network Hardware Development
> [Engineering New Products]
> 
> Itron, Inc.
> 2818 N. Sullivan Rd.
> Spokane, WA  99216
> (509)891-3306			asajay.laughton@itron.com
> FAX(509)891-3355
> Visit our web site at http://www.itron.com
> 
> 
> 

Thomas

Real life:      Thomas Törnblom             Email:  Thomas.Tornblom@Hax.SE
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