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General ChatChat about all things Blazer (and related vehicles). Off-topic stuff should be in the lounge, and all mechanical problems should be posted in the proper forum.
The aggravating thing is that I just changed the gaskets maybe 20k miles ago... oh well...
At least I know what I'm getting into this time? lol
Yes, and youll likely be doing it again in another 20K because the surfaces are NOT clean and NOT ready for gaskets.
Just because it looks to the naked eye like the old gasket has been removed DOES NOT mean the surfaces are clean (they arent, they are rusted and dirty).
Those surfaces (cylinder heads and probably also manifold but I cant see it...) are not clean. If you can see the imprint of where the old gasket was, its NOT ready to reassemble.
There is a lot of force, heat and corrosion over the years that makes depressions and chemical changes in the materials. This causes little depressions, cracks and eroded spots in the material.
The surfaces are no longer FLAT either.
Those surfaces MUST be ground or sanded down till they are smooth and the traces of the old gaskets are gone. Thats a major PITA to remove the heads.
The dark areas around the ports that show where the old gasket was are LOW SPOTS that will tend to LEAK again.. A machinists parallel strip scraped across the surface will show it much better.
Ive done this job on that engine (4.3) without removing the heads. I used a piece of polished granite countertop about 6 inches long and sandpaper on the manifold and head surfaces, after taking steps to keep the debris (old gasket, material from the head/manifold and sanding grit) from getting in the engine. If it gets in the manifold, it doesnt matter, its removed and easy to clean. The surfaces looked about as clean as if they had been on a surface grinder.
IT is a mistake to "look at the old gaskets to try to see where they failed" . You know what the failure was. The gasket is irrelevant.
The old gaskets are not being reused, so they are irrelevant.
BTW the picture does not show a gasket blown "out", it shows a gasket that was torn IN-wards when the manifold was removed.
Gasket sealing in modern times, for faster assembly, are done with 'fancy plastic gaskets."
In the old days, it was done with a can of Monkey S___t (yes, thats what it was called...."Indian Head"..gasket shellack) that made a horrible mess, especially when trying to replace an old gasket.
Gasket sealing is NOT just mechanical, its also CHEMICAL. The surfaces MUST be chemically clean.
This is not 40 years ago when the surfaces had gasket glop smeared all over them with a flat paper gasket. These new gaskets seal on selected areas (the rings around the ports) and those areas MUST be nice and clean and flat.
Yes, and youll likely be doing it again in another 20K because the surfaces are NOT clean and NOT ready for gaskets.
Just because it looks to the naked eye like the old gasket has been removed DOES NOT mean the surfaces are clean (they arent, they are rusted and dirty).
Those surfaces (cylinder heads and probably also manifold but I cant see it...) are not clean. If you can see the imprint of where the old gasket was, its NOT ready to reassemble.
There is a lot of force, heat and corrosion over the years that makes depressions and chemical changes in the materials. This causes little depressions, cracks and eroded spots in the material.
The surfaces are no longer FLAT either.
Those surfaces MUST be ground or sanded down till they are smooth and the traces of the old gaskets are gone. Thats a major PITA to remove the heads.
The dark areas around the ports that show where the old gasket was are LOW SPOTS that will tend to LEAK again.. A machinists parallel strip scraped across the surface will show it much better.
Ive done this job on that engine (4.3) without removing the heads. I used a piece of polished granite countertop about 6 inches long and sandpaper on the manifold and head surfaces, after taking steps to keep the debris (old gasket, material from the head/manifold and sanding grit) from getting in the engine. If it gets in the manifold, it doesnt matter, its removed and easy to clean. The surfaces looked about as clean as if they had been on a surface grinder.
IT is a mistake to "look at the old gaskets to try to see where they failed" . You know what the failure was. The gasket is irrelevant.
The old gaskets are not being reused, so they are irrelevant.
BTW the picture does not show a gasket blown "out", it shows a gasket that was torn IN-wards when the manifold was removed.
Gasket sealing in modern times, for faster assembly, are done with 'fancy plastic gaskets."
In the old days, it was done with a can of Monkey S___t (yes, thats what it was called...."Indian Head"..gasket shellack) that made a horrible mess, especially when trying to replace an old gasket.
Gasket sealing is NOT just mechanical, its also CHEMICAL. The surfaces MUST be chemically clean.
This is not 40 years ago when the surfaces had gasket glop smeared all over them with a flat paper gasket. These new gaskets seal on selected areas (the rings around the ports) and those areas MUST be nice and clean and flat.
Salvaged the front passenger side airbag discriminating sensor, today. The electronics box had separated from the mounting bracket and was hanging by its wires atop the aluminum skid plate. Ground its rivets off, tested it, cleaned it up and glued it back together (backed up by steel cable ties) threaded the rivet holes on the radiator mount and installed it with bolts. Bolts are nice, couldn't get my rivet gun up there to do it that way anyway.
Also received my Greywerks rear differential cover APT-111102 today from Zoro (the supplier/shipper). Very solid pressing good thick powder coat with terrific gasket. Pleased and it was super fast. The lubricant in there now might have all 215,000 miles on it!
Still on the hunt for a replacement lower intake...
THOUGHT I got lucky, nabbed one off a 2010 4.3 out of a Silverado. The series where they did away with the distributor and went with a coil pack and an electric throttle body, otherwise it looks identical. Turns out, they're NOT identical... The first giveaway was the fact that the throttle body was a 4 bolt mount instead of a 3 bolt. No problem I though, I'll just reuse my old upper plenum. Then I noticed that there's a bolt hole missing, where the fuel line mounts to the rear of the intake. Figured if that was the only difference, I could have fabbed up some sort of short bracket to mount with another bolt and give me a new mount hole there where it needs to be to hold to the fuel line.
As it turns out, in order to fit that 4 bolt throttle body, the very front two plenum mounting bolts are spaced out a little further than the ones in our 4.3's with the 3 bolt throttle bodies...
So, no go...
That being said, at work today we got in another 04 Blazer. Has the intake on it that I need, but I can't pull it off since it's a complete engine... So hopefully it'll sell locally next week and the core will come back to us with a good intake on it that I can grab lol. I WILL be getting the new AC compressor off of it for my spare parts shelf
It’s good had to replace a wheel bearing. Got the big 3 wiring done just waiting for a socket to come so I can pull a plug from the head and install a temp sensor for the intrepid fans I got everything is ready and wire to be installed
08-26-2020, 06:58 AM
