ghetdjc320

Little teaser for my personal radio build

Technically you could also use a red light filter behind the lcd if you wanted to. That wouldn’t be a bulb filter though. It would be a red semi-transparent plastic filter material.

It took several times of flushing the core to get it clean. Lots of silt and crap stuck on the corners that would come loose. Multiple vinegar flushes worked though eventually. I had crystal clear water after a couple of flushes and then had completely chocolate brown silty water after doing the vinegar flush the next day. Radiator is the same story

Nope, it’s just on the bulb itself. You’d need a color filter for a t1 bulb. Or you could run an led

Try back flushing the heater core by itself. The small passages tend to be the first trap of loose scale and rust from the block. Vinegar works well. You can use the heater hoses connected and let it soak the core for a day then back flush multiple times. You can flush the block separately as well without the radiator

Excellent info. I'm going to compile all these suggestions together into the first thread at some point for quick reference. Id also like to discuss cooling system upgrades that don’t work or don’t work well. What tops my list is still high flow water pumps (unless you increase radiator capacity), thin multicore radiators, and triple e fans (with some exceptions)

Looking good! I’m in the middle of some interior work as well. Btw, @Dzimm makes some console replacement latches if you need them. Upgraded design over stock

So one last note on the signal flow I sure found interesting and this will probably be my final tech entry on these radios. In typical 80’s fashion, there is a lot of circuit back and forth reminiscent of the main wiring harness on the XJ/MJ. Here is a bit of signal flow logic that should prove extremely helpful for future mods: The tape input comes to the preamp board first for attentuation by two potentiometers (one for left and one for right channels) before leaving the preamp board and returning to the main board via the 7 pin connector between the preamp and main board. The main board is the one that selects the tape input or tuner input and typically mutes the other inputs automatically. Until the exact mechanism of switching can be determined along with some type of system hack, there is no point in trying to use the tape input as a selectable source. This may change if I get some spare time someday to create a work around. The main board then send the main L and R audio channels for the radio or casette over two pins that end up connecting to TP471 and TP371 which are where everyone inserts their aux input mod. The signal then goes to the treble tone control, the bass tone control then the volume control. At this point, the line level signal then exits the preamp over the 3 pin jacketed wire to the main board amp section. This is where it gets interesting. Contrary to popular opinion, the amplifier does not have 4 discreet channels, it is a 2 Chanel amplifier only. The amplified two channels now go to the power board where the main relay, main connector and other items are sitting vertically on their own board near the rear. From that board, there is a 6 pin connector that goes back up to the preamp near the volume control. Two of those 6 pins carry, you guessed it, the amplified L and R positive signals. Those two amplified channels then get fed to the balance and fader control which account for the remaining 4 pins on that ribbon connector: RR, FR, FL, RL. These go directly to the main connector speaker outputs. So that pretty much sums it up. With that info, you can mod away to your hearts content. There are so many different options here. It would be relatively simple to convert the internal amplifier to something more powerful and modern. DSP tuning, aux input, Bluetooth input, anything you can imagine is possible. And a note on the bulbs, there are two behind the display (pictured below) and 3 on neo-wedge bases for the front panel illumination. There is another that ilumanetes the tape door. They are all T1 bulbs. The 7219 bulb from VCC (available at Mouser) is a great quality replacement. If you’re changing them all, you’ll need 6 bulb. But I’d grab an extra one or two in case you break or misplace one as they are tiny. Swapping out the bulbs behind the display is a bit tedious but well worth it. Just don’t burn the ribbon cable with your soldering iron or that’s pretty much the end of your radio u less you are a micro-soldering master I also removed a good LCD display from the front panel as a spare.

Overall dimensions are 9w 8h and 6.25d giving .17 airspace with 1/2 birch. Driver displacement of .02 give us a final of .15 and right in the money. Added 40% polyfill to dampen the response a bit. Some update pics of the finished product:

Added the renix temp sensor issue to the list. I’ve been curious about the ported HO mod. I’ve heard two lines of thought on this, one is that the restriction assists in cooling by slowing the coolant flow a bit out of the block to aid in heat transfer. The other is that it’s for thermostat orientation as you mentioned. I know when I swapped to a high flow pump and the high flow housing with a still stock size radiator, I felt the water was moving to fast to effectively transfer the heat.

Very good info. I’ll add this to the list above under “Solutions that work” or something to that effect. I don’t run a mech fan at the moment but can definitely attest to how well they work. When it comes to cleaning/flushing, do either of you use any chemicals?

Agreed. A lot of LS swaps I see don’t properly address the fuel pump. They just think that if it can hit X psi at idle than it’s good to go. They don’t seem to understand fuel demands under load. Interestingly, on my YJ stroker I built back in 2016, I installed a Holley terminator tbi setup. It was definitely running rich. The interesting side effect is that I could not get my engine up to operating temp quickly. I had very little heat in the winter and always ran cool. Never went above thermostat temp and was very slow to even get to that point. On the other hand, a performance built 4.0 I had in my first MJ had lean running condition and every so called “upgrade” cooling component in the book did nothing to fix the issue. I ended up needing to wire in a fixed resistor into my CTS circuit to help the engine think it needed a richer mixture. After that, problem solved! Oddly enough, the hotter an engine gets, the leaner the ecu seems to adjust the fuel trim

I thought I’d start a thread on the frequently recurring topic of engine cooling. I’d love to see some club input on the various problems/solutions to this issue. Something we can reference going forward. Obviously, there are many factors that contribute to overheating but I wanted to touch on a few common ones along with some of the common fixes. All too often we see some new cooling system “upgrade” that touts some miraculous cure for overheating. But did it actually improve something or just fix something that was broken or that was already end of life? The ones that we see a lot of are (in no particular order): 1. High flow water pumps 2. Multi-Core radiator upgrades 3. Triple e-fans or a variation thereof 4. Water wetters and coolant additives 5. High flow thermostat housings 6. Hood vents 7. Heat shielding products 8. Low temp thermostats Anything else I’m missing on this list?? The underlying overheating issue we see (in no particular order) 1. Clogged or dirty radiator/coolant passages 2. Bad water pump 3. Coolant system leaks 4. Cracked block/head/blown head gasket 5. Lean running condition 6. Incorrect coolant fill 7. Bad thermostat 8. Failed Renix temp/fan switch Anything else I’m missing on this list?

I actually need some of these as well. Lmk if you find one that works.

Looking great! Were you planning to do any upgrades to the AX15?