Re: AMC I-6 Oil weapage / leakage / seepage

[Peter Marano <carmine@xxxxxxxxxxxxx>]

Oh Frank!

Stop!  The plastic valve cover was never any good! I take issue with
'Most didn't start to leak until 15-20 years old.'  The several that I
remember having to stop leaks on were less than five years old.  I 
wonder if anyone had a plastic cover stay dry for five years.  Adding to 
the woe was that a large portion of the plumbing and wiring was attached 
to or prevented access to the valve cover.

At one time AMC had a good valve cover sealing strategy.  A groove in 
the valve cover accepted a seal with a large cross section and the 
fasteners applied the pressure to the top center of the cover.  The 
original plastic valve covers had fasteners at the top, but the plastic 
cover was not stiff nor thermally stable enough.

When the 258 was redesigned for 1981 AMC would have done well to build 
the valve cover similar to the 250/287/327 and the 195.6.

Does the plastic valve cover even save any weight over the steel cover?
The kit that came with the revised plastic cover to stop the leaking (it 
didn't) may have weighed more than the steel valve cover!

Was any auto manufacturer successful with a plastic valve cover!? 
(Detroit Diesel had a plastic valve cover on the series 60 when introduced)

Peter Marano
slowly regaining his composure in Kenosha WI


> Date: Mon, 18 Oct 2004 18:46:39 -0400
> From: farna@xxxxxxx
> Subject: Re: AMC I-6 Oil weapage / leakage / seepage
> To: mail@xxxxxxxxxxxx
> Message-ID: <ADVANCES62ZbLAX3cf3000001cf@xxxxxxxxxxxxxxxxxxxxxxx>
>
> I wouldn't exactly call it a "design flaw", though I know the 

plastic valve cover is much hated. It will warp over time, but the

cars/engines were made to last around 10 years with few problems.

That being the general design criteria, I'd say they met that.

Most didn't start to leak until 15-20 years old. The last AMC car

made was the 88 Eagle, it's 14 years old (but doesn't it use an

aluminum valve cover?). A lot of the leaks are caused by people

reinstalling too. The plastic valve covers really need to be snugged

up but very little torque on the bolts. To much uneven pressure

around it and it will always warp. Surfaces need to be squeaky clean

before applying sealant too. It worked well, but I don't have an

inch-pound torque wrench, and most mechanics wouldn't take the time

on a valve cover unless they already knew it was a problem area.

SO I agree with you in one respect -- it wasn't the brightest idea in

the long run, but I wouldn't say it's a design flaw from an engineering

standpoint.
> On October 18, 2004 Brien Tourville wrote:
>
>
> > These engines ran a plastic valve cover that
> > was a failure the day it was installed.
> >
> > AMC removed using a few of the bolts - why
> > I'll never know - which allows the plastic to
> > 'bulge' - allowing the gasket to fail in areas.
> >
> > The aging plastic warps - adding to the number
> > of gasket failures.
> >
> > There have been a number of engine fires
> > due to these Design Flaws.

>