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#196
07-12-2019, 10:32 PM
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New tank went in...
...more problems came out. :/ When the fuel sending unit was removed and put in a safe place until the new tank came in, even though I was extremely gentle with it I discovered that something has shifted. These senders have two metal end stops for the full and empty states and in between you get a resistance between 30 and 230 or so. An empty tank will cause a high resistance but for some reason it now sticks at 160 ohms for an empty tank, which is about 1/4 tank on the needle. Curiously the full resistance has dropped to 3 ohms, so a full tank swings the needle past the F and pegs it. It's almost as if internally the slider has moved on its pivot rod, but neither AMC nor the internet implies this is adjustable. Well the tank's full now. I'll have to take a look once the tank is pretty much emptied out again. For those also asking about just buying a new one, there are none. 
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#200
09-23-2019, 09:24 PM
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It turned out the plastic grommet in the sender assembly is cracked. It must of gotten nudged.
 The good news is that even though it split the pickup is still snug enough to be nudged back and then recalibrated (with a few frustrating misadjustments before getting it perfect), so I've been happily running with a happy tank and sender for the remainder of the summer. In the meantime the headliner was dropped to begin with reupholstry, the console was reinstalled and the prewiring began for all the funky accessories. The final thing that was performed before summer officially ended was to adjust the mixture screws. The carb rebuild left a lean running condition and we verified that all adjustments are still matching to the Carter spec, so now that we know the engine, exhaust, electrical, intake and the carburetor are in good order we can perform the adjustment and not need to worry about external variables. The problem is that AMC's own documentation does not describe how to do the adjustment on an electronic feedback carburetor. In fact, it's as if the half a page of mixture screw adjustment procedures are not intended specifically for this car at all... The internet is awash with different ways to do it (by vacuum, by ear....these people are crazy), but me and my mechanic determined the easiest way was: -Turn the computer on while telling it the engine is cold. This centers the stepper motor and the metering pins. We don't want them trying to correct the mix while adjusting or you will be stuck rubberbanding your adjustments, so sticking them in the middle means we can make the adjustment and not have to bias too lean or rich to compensate. -Turn the computer off and unplug the stepper motor -Attach tachometer -Start the car and let it come up to temp. -Set the curb idle to spec -Perform the mixture adjustment, as per spec. You will need two screwdrivers with marks drawn on them to ensure you are turning both screws at the same time and to the same positions. -Complete adjustment by turning off engine, removing tachometer and reconnecting the stepper motor. It will re-initialize the next time you turn the car on -Verify adjustment by installing plastic air cleaner cover (the how-to is in the book but it's basically a piece of plexiglass over the top of the air cleaner), starting the car, letting the car enter closed loop and ensure the metering pins oscillate back and fourth within their range -Optional: Probe the signal wire for the O2 sensor and attach either a Digital Multimeter or an oscilloscope. If the mixture adjustment is correct the voltage should swing between 0.8 and 0.1v with no prolonged time on either end of the waveform (due to still running still too lean or too rich) The great thing about the electronic feedback is that precise mixture screw adjustment isn't necessary. Just get it in the ballpark and it will do the rest. So everything under the hood is now done after a year of work, it's getting 24 highway and 17 city in 2WD and the interior is coming together. Next year is gonna be all about suspension and bushings and it badly needs all of that.
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#203
10-07-2019, 11:58 PM
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The coolant switch failed again. I noticed as the mercury dropped the car would stall at a rolling stop or idling at a light.
I ended up purchasing one of the official AMC testers for the feedback systems. It's nothing special other than it reduces an hour or two of testing down to about a minute. I really don't need it but I couldn't resist the bragging rights.  It immediately hung up waiting for the car to warm up. I waited until the engine was clearly hot enough to open the thermostat and then checked the CTS from the diagnostic port. It was open and forcing the car to stay open-loop. When I went to disconnect the harness to test at the switch itself it separated into two pieces. When I rebuilt it back in June I used JB Weld. While it should be able to handle the heat of a wet manifold it was now a brown color and crumbled. I reached out to a connection and bought another one that was used, but supposedly good from a junked rust bucket. Unfortunately it to seems to have an internal corrosion issue. I'll swap them out for now and rebuild the rebuilt one again but use a high temperature rated epoxy.
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#205
10-08-2019, 09:01 AM
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Ya know it would be funny if your thread got more traffic than the eagles nest because your doing a better job than them...
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#206
10-08-2019, 09:33 AM
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I did the writeup on rebuilding this exact switch there, only to discover you can't see it unless you are a registered member, so it won't get cached and indexed by Google.
Videokarma, thank you for the most part for not hiding chunks of your forum behind a registration wall.
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#207
10-08-2019, 09:49 AM
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Quote:
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#208
10-22-2019, 07:04 PM
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People sure were not wrong when they said the 258's valve cover is impossible to keep oiltight. It started weeping through at the back last spring but then three weeks ago I started noticing oil dripping down from the skidplate. An inspection found the valve cover was leaking towards the front and today I noticed that the gasket split above spark plug #1.
 From there I can't tell if it's related or unrelated but oil is starting to appear around the harmonic balancer. If a new valve cover gasket makes that stop then I'll ignore it until I degrease the engine again but it it stays I'll have to pull the balancer off and service the front oil seal, the timing chain cover and what the hell, lets also replace the timing chain as well since we are 265000km into its life probably. On the inside I finally got around to fabricating the mount for the Car Phone. The metal frame under the dash and above the ashtray already has a bolthole so I grabbed the most rigid piece of steel I could find and bent that into shape with a bolt welded to the end. 
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#209
10-22-2019, 10:42 PM
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Is that a cork gasket on the valve cover? Cork gaskets are shit. Buy a FelPro rubber gasket, like one of the nice ones. I forget what they call them. It's like a problem solver or something like that. Molded rubber, not just die cut. PermaDry! That's what they're called.
https://www.rockauto.com/en/parts/fe...r+gasket,10710 Not 100% sure that'll fit. Says 86+
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#210
10-23-2019, 10:28 PM
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Rubber gaskets seem to be discontinued according to Lordco, plus they are not recommended if you have the plastic valve cover still. (but I don't have that, so we're all good!
 )There's a bunch of different methods to seal the valve cover and most use a lot of RTV. I could only imagine how much nicer it would be if there was an aftermarket silicone compression gasket. My Fel-Pro gasket is the VS 50244 and it's about $40. It's different from the one you suggested in that one side of the cover only uses three bolts and less ribbing.
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