[AT] OT: Chevy Chevette (was Re: Yellow Farmall now cold starting

[Steve W.]

Ralph Goff wrote:
> On 1/3/2011 11:02 AM, Will Powell wrote:
>> 
>> And now with the 6 cylinder Chevy's around 1999. Every one of the
>> engines have weak intake manifold gaskets. I have replaced the
>> gaskets on my Fathers 1999 blazer and 1996 Monte Carlo. He also had
>> to replace the same gaskets on a buick le sabre he used to own. In
>> manufacturing there is no isolated incedence... If one fails, they
>> all fail. In my opinion that gasket should not fail. My father is
>> still loyal to GM... I don't know why... Maybe its because his 1999
>> blazer has brought us closer together? I repair something on it
>> practicly every weekend...
> So the GM 4.3 V6 had intake gasket problems? I'm touching wood here
> but my 97 Blazer at 140,000 km has never had engine problems of any
> kind. Just lucky? Cold climate? I don't know.
> 
> Ralph in Sask.
> 
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> 
>

The basic problem with the 4.3, 5.7 and the rest of the new design of
the V engines is the clamping area between the head and the intake. The
redesign of the head changed the angle that the intakes gasket gets
clamped and causes the gasket to tear. This coupled with the new gasket
material they used is the cause of the problem.

On the earlier engines the intake sat down in the V and the bolts went
through the flange at a 90 degree angle into the heads. This clamped the
gaskets evenly across the face BUT it also required much higher
precision machining and more labor on the part of the assembler to
install the bolts correctly.
The new design has the intake setting in the V but the bolts now set at
a 30 degree angle and clamp diagonally across the gasket into the head.
What this does is compress the gasket tightly on the top edges but less
at the bottom, it also means that when the heads and intake expand due
to heat the actually impose shear forces on the gaskets.
The end result is that 90% of the failures are from torn gaskets at the
lower front edges of the water jackets.

GM realized there was a problem with the gasket material used in this
application and came out with a second design for the gaskets. It
largely stopped the problem in the later engines. BUT they built a LOT
of them with the older gaskets.
When I encounter one needing repair I don't even bother with GM gaskets.
I go grab a set of the Fel-Pro problem solvers off the rack. These are a
better design with a stainless core and silicone/graphite material on
the facings.
I believe McCord and Hastings also have similar versions. GM does have a
very similar gasket out but I can get 3 sets from Fel-Pro for the price
of one through parts.

The heater outlet is a PIA and the main problem there is the pot metal
used. You can buy a nice machined brass replacement for them for
reasonable money. The easy way to remove the old one is to take a dremel
OR one of the multifunction tools, cut two cross slots down to the
intake and break out the pieces. Install the new one with some sealer
and call it a day.

I have done a bunch of them in the past few years.

I don't know of any brand that really has a corner on the "We roll crap
out the door every now and then" They have all had some real lemons come
down the pike. With all the new high tech crap though it is getting to
the point where you had better be REAL computer literate to even try
working on them.
A design friend of mine at FoMoCo was telling me the other day about the
latest item they have where the vehicle will act as a WiFi hotspot so
that you can use all your toys around it. Then he said it also has a
nice feature that the "dealer" can use to access the onboard system and
do diagnostics and read real time data...

I mentioned that it sounded a LOT like a good way for a Cop to be able
to write you tickets as well. Just think a Cop could be behind you, tap
into the system and see if you are using any wireless devices, if you
have the seat belt on, what the actual speed your own computer says you
are going is and if you applied the brake when you noticed the officer
behind you. OR even just run the VIN, and charge the tickets to the
owner of record without any involvement, just install a few WiFi
receivers along the road and grab it as you drive past...

-- 
Steve W.
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