| [GMCnet] Cad500 Remflex Mod [message #292896] |
Thu, 24 December 2015 19:19 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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On Tuesday, I replaced the leaking right exhaust pipe doughnut on the GMC.
Today, with the temperature nearly 80*F, I decided to replace the L.
exhaust manifold gasket, which I found leaking while checking the dough
nut
-- despite the 6" of rain we were getting today.
When I last installed manifolds on this engine, I installed high quality
studs, and dual brass nuts, to make future maintenance easy.
Unfortunately, I didn't really think far enough ahead: With studs in
place, the L. manifold cannot be removed without also removing the
transmission dipstick, along with the front extension I've added. It's
also necessary to disconnect the exhaust pipe, which has not been leaking
on that side. :-(
Since those complications promised to make a 5+ hour job out of a 2+ hour
one, I decided to cheat the system. Since I could slide the manifold away
from the head 1-1/2" or so, there was plenty of clean-up access, and with
the 4 independent exhaust ports, a multi-part gasket seemed to make sense,
if I could install them without having to slide them over the studs.
The photos at the link below show how I butchered a Remflex gasket to make
it fit. I had a used, partially destroyed, gasket (center of 1st photo) to
use for experimentation.
The 2nd and 3rd photos show the configurations I tried. The first two (on
the left in 3) worked well; the 3rd terribly. The 4th photo shows how I
cut up a brand new Remflex RF-14-001 gasket, and the 5th what I installed
on the engine.
https://goo.gl/photos/4Tm8qvZzUMMCkmBLA
As far as I can tell, everything went fine. I was extremely careful with
the hobby knife and straight edge: After scribing where I wanted to cut, I
always put the straight edge on the "keeper" side of the 6+ pass cut (1
pass could have been enough, but the carbon is so delicate that I didn't
want to risk it), and held it down very firmly. To minimize the chances of
damaging the "keepers", I made only necessary cuts, nothing fancy. I never
impinged on the surfaces which will make contact around the exhaust ports.
The "away sides" of the holes are missing, but I don't think that will
matter. The Cad's ports are all individual with a bolt on each side of
each of them, so they're well retained.
Since it's a delicate job putting the long Remflex gaskets on 8 studs (and
much harder to put the manifold on them), I think I prefer this method.
Certainly, I'll be tempted when I have to do it again to cut the gasket
into at least two, probably 4, sections. If the manifold is removed, I
won't have to violate the mounting holes but will run less risk of handling
damage to the gasket. There may be some slight sealing detriment in this
current iteration; if the holes aren't touched, I don't see how there could
be ANY.
Y'All keep your fingers crossed that this works -- I haven't run it more
than 1 minute yet.
Gotta close and order a set of spare Remflexes. :-)
Ken H.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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