My first FSJ pickup - questions

[tgreese]

Yes, the '79 cluster has the PWM voltage "regulator." It turns on and off, to average about 5V over time.

If the cluster loses ground, the "regulator" will stop cycling in the "on" condition. This will over-voltage your gauges and I presume they will peg to the top of their range. Prolonged loss of ground is said to ruin the gauges. The "regulator" is inside the temperature gauge.

The immediate fix is to make sure the ground to the cluster is good. The cluster grounds through the screws around its perimeter, as well as through a wire in the long connector (not the round connector). This is shown in the TSM. The later manuals show this better - suggest you look at section 1L of the '82 manual on the Tom COllins site. In particular, look at page 1L-46. Pin 4 on the long connector is ground, and you see that it continues through the circuit board to the screws that hold the cluster to the dash.

You can replace the regulator with a 7805 or 7806 IC. This is an excellent upgrade that works well, is a sturdy and inexpensive chip, and will protect your gauges if you lose the ground connection.

https://www.mouser.com/c/semiconductors ... ugh%20Hole

[Country Jeep]

Does anyone know the bolt size for where the seats mount to the floor pan? Got some new rails, but my truck is missing all the seat bolts, and we could only find the torque rating in the TSM, not the diameter or length.

[tgreese]

IIRC 5/16"-18. Maybe 1.5" long?

There's no published info like that, AFAIK. The parts book will give you part numbers for hardware, but it does not tell you what size or length. Suggest you start a collection of bolts and nuts. With experience you can look at them and know the size. You can buy a size gauge if needed https://www.amazon.com/s?k=bolt+size+gauge

[Srdayflyer]

flushing the engine, autozone, napa, oreillies, use to carry a radiator flushing kit made by prestone that you installed a tee fitting in 1 of the heater hoses and a garden hose adapter was included along with a radiator filler neck elbow , hook up the hose start the engine and turn on the hose, there was also a flush chemical that you could run in the engine and radiator to clean the system,prior to flushing after the chem flush just run the garden hose till you get clean water out of the radiator elbow , then drain the system and then add new antifreeze just and fyi

[Srdayflyer]

just checked amazon they still sell the kit $4.00 best way to ensure a clean system

[letank]

Does anyone know the bolt size for where the seats mount to the floor pan? Got some new rails, but my truck is missing all the seat bolts, and we could only find the torque rating in the TSM, not the diameter or length.

3/8 x16 and 3" length for the bolt, but you need 3 studs as per OEM installation which are 3/8 x 16 on the base and 3/8 x 24 for the other side, which are suspect are NLA.

Check this pict for the placement, from Theodore,

viewtopic.php?p=222866#p222866

[Country Jeep]

Some meaningful progress has been made - photos here, most recent ones in the After folder.

Completed so far:

Body
- Front cross-beam of bed cut out, new segment of steel welded, painted
- Several sections of the bed patched, welded, siliconed, painted
- Bed bushings replaced with some rubber lying around
- Cab floor patched, welded, exposed metal painted
- Seats replaced with Corbeau frames and some no-name seats that fit the frames
Fuel
- Original gas tank kept, cleaned out
- Replaced sending unit
- Replaced all rubber hoses
- Replaced main and return fuel hardlines from tank to engine
- Rewired and rerouted fuel level sensor ground
Brakes
- Front drums rebuilt
- Brake fluid flushed
- Brake booster vacuum line reattached
Drivetrain
- 1x oil change: Wix 51258, 5qt 15W40 Rotella, 11oz ZDDP
- Replaced distributor cap & wires
- Replaced v-belts
- Replaced radiator
- Replaced fan clutch
- Replaced water pump
- Replaced thermostat (180*F)
- Replaced coolant hoses
- Engine block flushed of coolant post-radiator install not once... not twice... nay, not even thrice... but 7x times total - you better believe the water coming out at the end of the day was potable
- Adjusted timing
- Adjusted idle
- Driver-side exhaust pipe reconfigured to appropriately distance from gas tank
- Front and rear (confirmed open) axles drained, refilled with Fram 80W-90
- Transmission fluid topped off after radiator replacement (already very clean)
Electrical
- Rewired rear taillights (rat's nest from a prior tow kit removed)
- Replaced voltage regulator
- Replaced starter solenoid
- Rewired everything from the battery to the starter solenoid and alternator, plus respective grounds and ground straps
- Finagled the ground to the gauge cluster... sort of (dash no longer making good contact with firewall, several unknown black wires under dash cut by someone prior)

Truck made it the 150mi trip from parents back to home with no known issues and estimated 13mpg. Driven an additional 100+ miles over the course of the week and allowed to idle in one pizza drive-thru for 20mins with no known issues.

Stock gauges now read consistent figures most of the time, but every once in a blue moon, they will all max out at once, but can be brought back to normal with a couple love taps on the front housing. Per consistent readings,
- Oil pressure when warm and idling in gear is stable around 20, and while driving reads around 45
- Fuel level reads accurately and consistently now
- Temperature suggests it never overheats now, but rather is not staying warm while driving; will reach the expected part of the gauge between 1/3 and 1/2 when idling in park over time, but drops down beneath the first line above C after a minute on the road and hovers in the black space
- Amp gauge missing needle Meter read at the battery is around 13.6v when running at idle

Parking it again for a bit. What I plan to do next, unless anyone has any suggestions:
- Replace all brake lines, including full length of hardlines
- Replace oil pan (it's been years since I messed with an old-school oil pan, and yours truly stripped the drain plug the very first time I went to tighten it)
- Have anything and everything that could potentially be a safety concern in terms of a bolt, etc. not being tightened to spec inspected and tightened appropriately
- Have transfer case and axles inspected to determine if Mile Marker part-time kit is already installed
- Have all vacuum lines pertaining to the transfer case replaced
- Replace driveshaft u-joints, or the entire driveshafts if for some reason that were needed?
- Replace the power steering box; it's leaking fairly bad

[Country Jeep]

Got a fair few things done and have it on the road regularly now, but got a new issue.

After getting the gauges sorted out, I finally got around to replacing the light switch, cleaning up the cigarette lighter, getting some wires coated in some 303 Aero to keep them from splitting, etc. Earlier on, I had replaced the ground cable that comes from the housing around the alternator to the battery, the small wire that goes from the battery to the fender, and the lower one from the engine block to the body. But recently as I’ve been driving it more and sometimes at night with the headlights on, the small wire that goes between the negative terminal and the fender has started melting. I haven’t observed it when it was hot enough to melt, so I’m not sure when it’s been at its hottest, or if this has just been slowly over the course of the past few months.

Should I look into anything in particular? Is this just a matter of needing a higher gauge cable or strap to run from the battery to the fender?

Before melting: https://i.imgur.com/CWkorCK.jpeg

After melting: https://i.imgur.com/qhKTz4R.jpeg

[tgreese]

This is bad. Unless you are running a winch, or big big lights, or similar, that small wire should be fine to return all the normal running current back to the battery. Lights and ignition is not enough current to melt a wire like that.

From your picture, it looks like you have a winch. The winch motor has to be grounded through at least as large a cable as the positive cable to the winch. How is the winch grounded? If the ground goes through the frame, you need a heavy cable from the frame to the engine to the battery. Normally there is a braided cable that bridges from the frame to the engine.

Same issue with the lights. If your lights are enough to melt that wire, you need a ground wire of equal or larger size returning to the engine block and ground. That 14 ga wire from the sheet metal to the battery terminal could be a bottleneck, if the sheet metal is isolated from the engine.

[Country Jeep]

This is bad. Unless you are running a winch, or big big lights, or similar, that small wire should be fine to return all the normal running current back to the battery. Lights and ignition is not enough current to melt a wire like that.

From your picture, it looks like you have a winch. The winch motor has to be grounded through at least as large a cable as the positive cable to the winch. How is the winch grounded? If the ground goes through the frame, you need a heavy cable from the frame to the engine to the battery. Normally there is a braided cable that bridges from the frame to the engine.

Same issue with the lights. If your lights are enough to melt that wire, you need a ground wire of equal or larger size returning to the engine block and ground. That 14 ga wire from the sheet metal to the battery terminal could be a bottleneck, if the sheet metal is isolated from the engine.

Winch is n/a; dead and not wired. Rather than a braided cable, there is a standard ground cable running from the engine block to the body. I’ll take photos and a video tomorrow to help with assessment.

Also, I saw the original reply before the edit, and I believe the large ground cable going direct from the negative terminal is bolted up somewhere around the A/C compressor like you had suggested, rather than the alternator; I’ll confirm as much tomorrow as well. It was one of the first things I replaced in 2022, and I remember having a tough time getting a wrench in where the nut or bolt head was located.

[Country Jeep]

Photos and video of ground cables here

[tgreese]

Yeah, sorry my original post was not very focused. I was distracted at the time and edited it some.

If you have no winch and the factory lights, seems like the wire damage would have to be from a bad ground to the starter motor. After starting, all the dash and lights power comes to the dash through the original 10 ga wire that originates at the alternator, loops up to the dash to the ammeter, and returns to connect to the battery at the starter solenoid. The wire from the body steel to the battery cable ground post is both short and maybe a 12 ga wire. Not much different. That will handle your usual running/driving current; you only need the big cable to the engine when the starter motor is running.

You have a fault in the ground cable connection somewhere. You have a bolted connection at both ends of the ground cable, a bolt at the engine block and a bolt at the cable clamp, either of which could be a bad connection. Possible you have corrosion at the bolts, or inside the crimped lug at either end. I would punt and replace it all. You can buy a cable with the small extra wire to the sheet metal and both connections molded into the battery end.

https://www.rockauto.com/en/moreinfo.ph ... 00&jsn=424

The original cable connects to the engine up at the bracket bolts, as you previously pointed out. The connection down on the engine block may intuitively seem better, but I'd guess it's either the same or worse than connecting to a nearby bolt on the engine block. The engine block is a huge conductor, with any location for the connection being identical within measurable limits. Most of the resistance is coming from the battery cable, I'd predict... shorter and/or larger diameter will be better.

[Country Jeep]

Yeah, sorry my original post was not very focused. I was distracted at the time and edited it some.

If you have no winch and the factory lights, seems like the wire damage would have to be from a bad ground to the starter motor. After starting, all the dash and lights power comes to the dash through the original 10 ga wire that originates at the alternator, loops up to the dash to the ammeter, and returns to connect to the battery at the starter solenoid. The wire from the body steel to the battery cable ground post is both short and maybe a 12 ga wire. Not much different. That will handle your usual running/driving current; you only need the big cable to the engine when the starter motor is running.

You have a fault in the ground cable connection somewhere. You have a bolted connection at both ends of the ground cable, a bolt at the engine block and a bolt at the cable clamp, either of which could be a bad connection. Possible you have corrosion at the bolts, or inside the crimped lug at either end. I would punt and replace it all. You can buy a cable with the small extra wire to the sheet metal and both connections molded into the battery end.

https://www.rockauto.com/en/moreinfo.ph ... 00&jsn=424

The original cable connects to the engine up at the bracket bolts, as you previously pointed out. The connection down on the engine block may intuitively seem better, but I'd guess it's either the same or worse than connecting to a nearby bolt on the engine block. The engine block is a huge conductor, with any location for the connection being identical within measurable limits. Most of the resistance is coming from the battery cable, I'd predict... shorter and/or larger diameter will be better.

Thanks for the help. Removed both ends of both large ground cables to check for corrosion; didn’t find any, so I sanded / wire brushed the mating surfaces and remounted. Temporarily replaced the smaller wire coming from the negative terminal with a red 12ga wire and new crimp ends. I’m going to follow your suggestion and order the combination cable since it’s built-in and significantly shorter than both upper and lower ground cables, each of which look to be around 5’ or 6’ in length.

IMG_3545.jpeg

I only found out the wire was melted because I was doing another flush of the coolant system a couple days ago. I was dreading taking the drain plug out because I had to source one from the hardware store since the radiator came without one, and I had the hardest time getting it to seal. I used Permatex the first time around and managed to get a good seal after a third try, but no luck this time around. What would be the best way to address this?

IMG_3546.jpeg

[tgreese]

Don't aluminum radiators come with a plastic petcock for a drain?
https://www.amazon.com/Dorman-61136-HEL ... 000C5G7TG/

If not this specific one, you could look at the Dorman Products site for something compatible. Dunno, a local radiator repair shop might have one too.

Also, the extra wire on my J20 connects to the core support, not the inner fender. Probably won't matter.

[Country Jeep]

Don't aluminum radiators come with a plastic petcock for a drain?
https://www.amazon.com/Dorman-61136-HEL ... 000C5G7TG/

If not this specific one, you could look at the Dorman Products site for something compatible. Dunno, a local radiator repair shop might have one too.

Also, the extra wire on my J20 connects to the core support, not the inner fender. Probably won't matter.

It was supposed to come with one; contacted the seller and they confirmed as such, but were not willing to ship out a replacement despite mine missing unless I shipped the radiator back. Thanks for the link, I’ll definitely look into getting one of those instead and make sure it’s the right size!

Noted on core support connection. Will see how the current arrangement goes for now until I get the combo cable in.

[tgreese]

Don't aluminum radiators come with a plastic petcock for a drain?
https://www.amazon.com/Dorman-61136-HEL ... 000C5G7TG/

If not this specific one, you could look at the Dorman Products site for something compatible. Dunno, a local radiator repair shop might have one too.

Also, the extra wire on my J20 connects to the core support, not the inner fender. Probably won't matter.

It was supposed to come with one; contacted the seller and they confirmed as such, but were not willing to ship out a replacement despite mine missing unless I shipped the radiator back. Thanks for the link, I’ll definitely look into getting one of those instead and make sure it’s the right size!

Noted on core support connection. Will see how the current arrangement goes for now until I get the combo cable in.

Huh. Did you use your credit card to pay for the radiator? The card company might have helped with that.

Good luck with the Dorman part. Your local independent parts store can get Dorman items same or next day from the local warehouse. The store should help you if you're a regular customer.

[Yeller]

Use an oil pan drain plug gasket, should seal it right up.

[Country Jeep]

Current plug for the radiator finally sealed up, so I’ll put the new plug on when it comes in whenever I do another drain or flush.

Finally getting around to inspecting the transfer case - something I should’ve done much earlier on. No major issues getting the fill or drain plug off. Can anyone tell me what this fluid is though? I was expecting to find ATF since I have front locking hubs and have been suspecting I already had the part-time kit installed, but now I’m not sure - seems a lot like the QuadraTrac specific oil, for someone whose only ever seen it online.

IMG_3634.jpeg

IMG_3633.jpeg

IMG_3632.jpeg

[tgreese]

Milky is water contamination.

The Quadratrac uses a special fluid that's 30W ND motor oil plus friction modifier. As you pointed out, ATF is the wrong fluid for a Quadratrac, unless it's been converted to part-time by removal of the internal limited slip differential. This does look too dark for ATF, but maybe not for motor oil.

Have you tested that the center differential locks or spins freely in response to the e-drive control? You can do the torque bias test in the TSM, though you won't need a torque wrench if it's converted to part-time. If converted, maybe this is some DSPO action?

[Country Jeep]

Milky is water contamination.

The Quadratrac uses a special fluid that's 30W ND motor oil plus friction modifier. As you pointed out, ATF is the wrong fluid for a Quadratrac, unless it's been converted to part-time by removal of the internal limited slip differential. This does look too dark for ATF, but maybe not for motor oil.

Have you tested that the center differential locks or spins freely in response to the e-drive control? You can do the torque bias test in the TSM, though you won't need a torque wrench if it's converted to part-time. If converted, maybe this is some DSPO action?

Have not tested yet. The vacuum hoses from the 4WD selector on through and beyond the firewall have been rotted out for many years per PO, and I haven’t replaced them yet. They’re 1/8” diameter, and assuming the tc diaphragm still works, I could get those replaced next and do testing now that I’ve got the old fluid back in thanks to a turkey baster. Truck has shown e-drive since PO had bought it, and it’s been how I’ve been driving it since purchase in 2022 as well. Which, if I’m read up correctly now, would be bad with or without the kit since the hubs have always been unlocked on dry pavement - am I understanding that correctly? There’s a lot of info on QuadraTrac, the MM kit, and all their intricacies online, but it’s hard to wrap my head around completely with all the threads I’ve sleuthed here and over at IFSJA. Either way, the fluid has that distinct burnt smell; it was extremely potent the moment I opened the fill plug.

EDIT: In the meantime, may not denote anything, but just in case, I confirmed the locking hubs are Warn and not MM.