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Half Pint - Z22 swapped 510 goon

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I guess no one has recently replaced those switches on their 510? I never got an answer... such it is. I'll likely order them soon. I think they are correct.


Went junkyarding today. Picked up a radiator, electric fans and an overflow, all from a 86 Prelude. It was half off day and I still feel like it cost too much for what I got. Man the yards around here have gone up in price. Enough crying.




I tested the fans on a battery. Both work fine. I guess I'm going electric earlier than I planned.


I sealed up and pressure tested the radiator. Seems like it holds pressure solidly. Did some clean up to it today, but there's more to be done.


I also started working on the exhaust manifold.




I had to cut the egr and air injection pipes off. They just rounded more and more no matter what I was doing. So now I just need to plug the openings.






Whilst at the junkyard, I also saw this demi roofrack on an 80s Tercel.




I was considering taking it for my wagon, but I think I would prefer a full size one. I'll find one eventually. I'm not actually looking very hard. Trying to focus on only what's necessary for running and driving first.

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Interesting how these work. The exhaust pulse is followed by a low pressure wave that sucks air from the filter down those pipes. To prevent pressure from pushing exhaust up the tubes a one way reed valve is at the air filter end. A continuous series of suction waves draws fresh air into the exhaust without the need for a pump.

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Soooo....yeahhh... that gigantic fan I bought with my radiator will never work. I'm not sure why I thought it would. I knew my clearances were small. That fan won't even clear block, not to mention the pulleys that happen to stick out the front of the motor. I could make the small one work if I choose to.


So I'm looking at other options.


94 Honda accord fan




Pretty low profile fan. They are about 2 5/8 inches tall. I have about 3 inches if space, so these should work. With only a small amount of simple modification, I can fit two of them, which has the added benefit of creating a nice looking full coverage fan shroud as well. I think I'm going back to the junkyard next week to pick up two of these.


I drew up a schematic for wiring these bad rides. It relies on ground switching, so design wise it matches Nissan/datsun as best I'm able.




I'm planning to use a dual temperature fan switch. It should actuate the primary fan at a regular temperature and then if it gets to too high a temperature, it will activate the second fan and run both. Additionally, the auxiliary fan will be directly controlled by the a/c controls, so when the a/c is on, that fan is on, like a modern car. This diagram may still need a little work, but I'm proud of the fact that I was even able to come up with this.

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Work progresses. I got some radiator hoses fitted. They are both a factory hose for something else. Both hoses are 1 1/8 inch on radiator side and 1 1/4 inch on engine side.


Top hose is a Gates p/n 22461. Originally found in an 86 Mercury Topaz with the 2.3L engine. Still need to trim it a bit more.






Lower is Gates p/n 21311. Originally found in an 82 Toyota Tercel. Limits alternator movement on the tensioner, so I may need to add in a piece to gain additional clearance.





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Here's some pics of basic fan fitment. I might be able to clear a non clutched water pump, but I will likely have to de-clutch this pump so as to maximize clearance to the fans. It's possible that the drivers side fan shroud will even need a small notch to properly clear the pump pulley. If you imagine the clutch not being there, then it should fit fine.








Here's the dual fan assembly. I cut a little off each fan shroud to fit them on the radiator. Now I just need to modify mounts to get them bolted on.




I also took the horns out. They made it a struggle to get the radiator in and out. I had to drill through the screw heads to remove them, but it worked. Rad slides in and out quite easily now. Different horns will be installed elsewhere eventually.



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The clutch fan can be unbolted and split apart, and the silicon oil removed. With careful use of an angle grinder, split the case off the bearing and you have loads of clearance.


Here's mine, you can see the inner bearing race. You could trim it even more but stay away from the press on pulley. It's fine just don't cut it off flush.



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Drew out the a/c schematic for the 720 wiring harness in my 510. I did this because I'm planning to tie my auxiliary fan in to the a/c on switch, as explained in previous posts.




I have had to edit my original wiring schematic for the fans. I realized that I was wrong about how the BMW fan switch works. At the low temperature it grounds one terminal. At the high temperature, it grounds the other terminal, and disconnects from the first one. Which means that my design won't give me all the features I want.


So I need a way to:

1. Run fan A on the low temp

2. Run fans A and B on high temp

3. Only turn on fan B with the a/c switch while leaving fan A free to be controlled by the temp switch.


Attempt 1:




This works actually. But it's incredibly cumbersome and not simple. So I kept looking for a better way.


Attempt 2:




Would a diode fix my problem? If I just wire A and B to the secondary terminal, and B is also wired to the a/c switch, both fans will turn on in every scenario. But what if I limit the direction of flow?


But here I'm pretty sure the a/c switch would still turn on both fans.


Attempt 3:




So here's where I've landed. A diode between A and B that would allow A and B both to ground at high temp, but the diode would prevent B from going to ground when the switch was at low temp, so only A would run.


Fan A would try to ground through the a/c switch when actuated. Another diode on the a/c switch would prevent A from grounding through that switch, but would still allow B to turn on, and also allow B to be operated by the high temp switch.


Anybody see any issues with this final draft? Anybody even understand what the hell I'm blathering on about?

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Diode is the answer. I like to use bridge rectifiers because they have a mounting hole and spade terminals. Wire each output to one of the ~ terminals and the fan relay to the - terminal. Break off the + terminal or tape it up.


You'll need a diode between the A/C switch and the fan B relay or else your compressor might come on if the temp goes high.

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Let me clarify that.


You would use 2 bridge rectifiers. One for each relay. Wire the -terminal of each rectifier to each relay. On the A rectifier, wire each output of the BMW switch to one of the ~ terminals. On the B rectifier wire the A/C switch to one of the ~ terminals and the hi output of the BMW switch to the other ~ terminal.


uxcell® 5 x Silver Tone Metal Case Single-Phase Bridge Rectifier 1KV 50Amp KBPC50-10 https://www.amazon.com/dp/B00CFSVB7G/

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Sweet. Thanks Engine Room. If I'm understanding your recommendations on rectifier placement, it matches my "Attempt 3" design. If that is not correct, would you mind taking another crack at explaining where to put a diode (or rectifier) on the a/c-fan high side?


Or are you suggesting a third diode, on the leg of wiring marked R/G right before the a/c switch?


(I have no qualms about someone submitting an improved schematic, should they feel rambunctious :) )


Thank you for the recommendation on what to use also. This elecrical project is stretching my abilities beyond their max, so some of what I'm doing is part logic and part blind guessing :thumbsup:.


While I was trying to figure out if diodes did the things I thought I diodes did, I came across these simple in line diodes.




BMW used them, at least in the 90s, in their auxiliary cooling fan wiring. Bmw forums seem to suggest that these are there for the exact purpose Engine Room suggests, to keep the compressor from kicking on when fan switch goes to high. I could score these at a junkyard, and I really liked how they are spade connected inline units.


I can find them for sale, but I can't find any actual technical data on them. Since they were already used in a cooling fan system, can I reasonably assume these are sufficient for my purposes? Especially since they are on the low load side of things?

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Duke, want to learn wiring? Put the wrong wiring harness in your car. Holy crap. My brain feels like an MMA fighter. It's getting the crap kicked out of it, but likes it and enjoys the fight and the victory.



Between converting from fusible links to jcas type slow burn fuses and needing fuses for a competely fabricated cooling fan assembly, it has occurred to me that I REALLY need a way to measure how many amps I have traveling through various circuits. I have zero idea what rating of fuses to use to replace the fusible links. If possible, I have even less (so...negative...?) idea what fuses to put in my fans.


Enter this thing.




Ammeter and shunt. Measures up to 200v and 200 amps. If I understand how to use this correctly, I can put the shunt in line "in place" of each of my new prospective fuses, turn on everything that is powered through the that fuse, and the meter, connected to the shunt correctly, will tell me how many amps are being drawn. Thus I will know what amperage fuse to install. I hope I'm right...


I am odd in the car world. I hate spending money on tools. I need this and I will use it, but money spent on tools is money not spent on the project. I hate buying consumables even more...


Luckily this is only $20. I'll winge about it, but it's not actually terrible. :)

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If you have the old fusible links they are color coded.


Pink   30 amp

Green   40 amps 0.50mm²

Red  50 amps 0.69mm²

Yellow   60 amps    

Black  (80)  80 amps 1.25mm²

Blue  (100)  100 amps

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Well that is definately helpful Mike. I haven't seen that chart before.


Now I guess that I will be verifying those draws, instead of just figuring them out. With the random changes I've made, I don't really know if I've changed enough to change the fuse needs.


And I have no idea what these fans need still.

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I modified my water pump as per Mike and Charlie's suggestion. I took a slightly different approach. I noticed when I had unscrewed and removed the front of the clutch that the whole back half is pressed on to the shaft, then the end of the shaft is flared out to hold everything in place snugly. I made a few relief cuts and then pressed the clutch off the shaft.




The tip of my puller was too big to press down through the center of the clutch, so I put a socket in under it. That worked fine.





In this one you can clearly see the relief cuts I cut into this, hoping it would allow the flare to collapse more easily. It worked out great. Little effort and not much time invested.




Then I cut off a large chunk of the shaft with a cut off wheel on my grinder and then finished the edges and top off some with my dremel and a sanding drum.








A little paint, and I will be ready to reinstall this. Then i can make some progress on the actual fan install.

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Painted and reinstalled my water pump today. Then test fit my fans.






Drivers side doesn't fit, but the clearance issues are exactly what I expected. I'm hoping I can cut the shroud and have the space I need.




I picked up the bmw fan switch today. Alas, I was unable to obtain the diodes. The generation of bmws at the yard did not have them.


But the bmw fan switch uses an m14 thread and the radiator uses a larger one (m18 I think). So I'm turning the old sender into an adapter. I broke the plastic off the top and then drilled it out some.






I just need to cut off the bottom, finish drilling and tap new threads.

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The harness I installed has 3 fusible links, which I have now replaced with PAL type fuses. I went and looked at the FSM for the 82 720 my wiring is pulled from, which showed the original fusible links to be 2 greens and a black. Using the chart Mike so kindly provided, those are 2 30 amp links and an 80 amp link.




My fuse block is currently setup with a 75 amp in place of the 80 amp link, and the others are already 30 amp fuses, so it looks like my fuse block is pretty much already setup. Sweet. Now just to figure out fan draw.

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I try to fuse as closely as possible over my required draws. So if draw was 32 amps, and the closest I can get is a 40 amp fuse, that's what I will use. I just have developed a minor obsession with actually measuring my amp needs. I could always fuse low and if it blows on startup, go one size bigger till it's ok, but I'm not a fan of that process.

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