bought a junker z, need help with just a few things

[daktah]

hey yall, i bought a $1000 junker 5 speed 86 zx with a few problems but with its drivetrain in good condition. most i already fixed but there are just a handful left i need help with.

---heat
this is the top priority for me as right now as its usually -10 to -20 outside. firstly i have auto climate and the ambient sensor is either dead or disconnected (amb temp is -56) but i have no idea where it is located so i cannot check (if someone has pictures of where to find it that would be awesome). second when i set it to defrost and hi the air coming from the windshield vent is pretty warm, not scorching but warm enough but the door window defroster vents are cold. when i set it to auto the floor air is the same pretty warm but the window and windshield vents are all cold. the coolant and reservoir are both topped off and im pretty sure there is no air in the system (if there is a bleed valve i have no idea where it is) and the car doesnt overheat and stays at 200-220 or whatever the center of the gauge is. the water valve doesnt seem to be working so i just zip tied to the arm up but it didnt seem to make too much of a heat difference (up is open correct?). also i tried the climate auto diagnosis (hold auto and off and turn car to on) but it does not do anything so i dont have an easy way of testing everything. i think the blend door motors are ok because swapping between defrost and auto (so it turns on floor air) works fine. i have no idea where to go from here.

---tacho
i have the digital dash and surprisingly everything works aside from the tach. i popped out the power supply and resoldered every point and did the troubleshooting guide in the fsm and it says to replace the cluster assembly, i ran the onboard test with the a+b buttons and none of the tach bars light up. i assume its a solid assumption the cluster itself is dead? if so is there any way to repair it myself? i dont want to spend 1/4 the value of the car on a new cluster just for the tach and i dont want to swap to analog gauges because it ruins the awesome 80s future aesthetic.

---odometer
sometimes it rolls, sometimes it doesnt. when it isnt i can hear a quiet consistent clicking from behind the dash. i assume the gears are stripped and occasionally engaging and rolling and occasionally skipping and clicking. are their rebuild kits available or am i going to have to harvest gears from another cluster?

---fuel
when i got the car the fuel gauge had 3 ticks and said it had 3 gallons left. i tried to top it off but it only took like a gallon before the filler clicked off. i thought maybe the filler tubes of 3 decades long past were smaller than nowadays and the fuel was flowing too fast and backing up so i tried to fill it manually about halfway but the fuel would keep bubbling up and got to the point where it was pooling up on top of the little flap, however the gauge still will only read 2-3 gallons so its likely the sender. is there any way to test the sender without removing it from the tank? i was looking up replacements and theyre pretty expensive at like $150, is there a way to fix it or a cheaper aftermarket replacement available?

[evildky]

Welcome to Nico!
That's a heck fo a first post, i'll do what i can to help or point you int he right direction.

Heat, your symptoms aren't the usual but i'll suggest you check the dashpots and vac lines anyhow. Usually cracked or broken vac hoses keep the blend and directional doors as well as the heat valve from working, in this case the heat valve, located on the firewall, in heater hose behind the engine defaults to open, meaning constant heat, usually through the defog vents. The lever on the valve is horizontal as i recal. The dashpots can be broken or just sticking a vac pump will usually free up stuck dashpots, more info here http://www.xenonzcar.com/z31/hotairfromac.html
and
http://www.xenonzcar.com/z31/HVACReconditioning.html

Tach, I'm not much help here, sounds like you worked your way through the tests so might want to watch ebay or scour the junkyards for another cluster.

Odometer, the 86 as I recall uses a cable to drive a sender in the engine bay. If the speedo works but the odometer doesn't then it's most likely the odometer itself, again a replacement cluster might be in your future.

Fuel, Sounds like you have a bad sender or gauge, the sender is the more likely issue, might just be seized or might need replaced, there is an access hole in the hatch floor to make replacement easier.

[daktah]

Thanks, I put a good amount of work into the car over the last week and the heat is mostly fixed (i wired in a 10k resistor across the amb circuit to give me control over the HVAC and all of the vacuum devices seem OK aside from the water valve itself which I'll just bypass and later convert it to an electric solenoid working the valve arm), the sender is definitely corroded (popped it out and did the FSM testing and it reads 2-5x more resistance that it should) and Im still trying to swallow spending $175 on a new one, and I'm getting a month off of work at the end of the week so I'll be able to get into the gauge cluster uninterrupted for the tach and odometer (and maybe post thread if I find something interesting or easily fixable) and I'll just roll it forward a few hundred miles because I'm sure it hasn't been working for a while. Those are really the last big issues with the car after that it's all cosmetics and little things like the headliner falling off (just needs regluing), the hi beams not working (going to clean the contacts in the stalk when I have the dash apart) and that I only have the right door speaker playing audio.

Since I can't seem to find the amb sensor or connector or wires I can only assume it got ripped off at some point and rather than spending $75 on a new one I'd rather just make my own equivalent thermistor, does anyone know it's resistance curve so I can get an equivalent device? Ie at 50 degrees it's 10k, 60 it's 15k, 90 it's 30k, etc

[evildky]

The ambient sensor is inside the dome light housing iirc

[daktah]

Are you sure? I know there is a head and foot sensor for the auto climate but it was my understanding that the amb reading was for the outside and some of the other posts I read about it state it is attached somewhere behind the bumper

[evildky]

oh, thought you meant the interior sensor, never had a digital car myself

[daktah]

well i ended up fixing all of these issues and more, now the car is much so much better than when i got it and ive only put in about a grand so far. now there are 3 more issues i need help with and likely these will be the last 3 before the car is as good as its going to get (knock on wood).

1: the timing marks are about 90 degrees to the right of the needle at full advance, at full retard they go somewhere under the pulley. obviously this isnt right, however the car runs and drives absolutely fine at idle or cruising speed or at redline. all of the plug wires are going to the correct cylinders too so its not like they gave it some crazy firing order to make it work. since i cant properly set the timing like this i just let the engine warm up and then just rotated the distributor until the engine would idle at its smoothest and fastest and tightened it down.

its kind of hard to tell because of the quality (i had to do 720p for 60fps to capture the timing light and fully zoomed in) but if you look on the right side you will see the marks at full advance, then they will scoot under the pulley when i turn the dizzy to full retard, then come back when i go back to full advance. see the picture for a better quality view of where the timing marks are at full advance.

2: the exhaust pops every few seconds at idle, except its not really pops but deep blubs. they tend to go away if i retard the timing and become more frequent if i advance the timing. i cant give exact degrees because of the above issue however. popping is more often while the engine is cold but it becomes less frequent as it warms up. it doesnt ever make a loud and/or fiery pop and i *think* it goes away when you go anywhere above idle, but im not sure if its just being masked by the engine note.

unfortunately its pretty hard to hear because its such a deep sound, you may have to turn up your volume or wear headphones. just listen for when the bass clips a little bit, its hard to describe but once you hear what i mean you will know what im trying to say,

3: there are 2 distinct noises coming from the front of the engine, a rhythmic scrapey kind of "chit chit chit... chit chit chit..." and a constant low pitch sort of warbling that goes "wahwahwah, wahwahwah" that transform into a whine when the engine speed picks up. both are rpm dependant and happen when cold or hot. the chit sound is loud enough to hear inside the cabin with the windows up and the radio off, the wah sound isnt but it still sounds like garbage from the outside. its not the water pump, alternator, or power steering because i took off both belts and ran it and both noises were still present.

at first the engine is idling normally, then i retarded the timing all the way to slow the engine speed, then i advanced it back to normal, then i revved up the engine a bit to show that both sounds occur at all speeds.

[evildky]

I'd take the front of the engine apart and find out. It's cheap insurance to do the timing belt, once you open it up it's a good time to doe the water pump. I'm guessing someone put the crank pulley on without the woodruff key and that's why your timing mark is out of whack, again opening it up will tell you for sure. The noises could be a bad idler, tensioner or a belt walking due to a missing slinger, I'd open it up and find out exactly what's going on inside the timing cover and if all the parts are there.

[daktah]

i was figuring it might be timing belt related because thats really the last place i havent looked. not really looking forward to draining the block again if i do need to replace the belt because i just did it 2 months ago to flush the system but if it will fix the noise then ill go for it. you wouldnt happen to know what size the woodruff key is would you? also what is a slinger?

[daktah]

so i went into it today and found out that the crank pulley is definitely keyed to the crank. when im using the timing light the pickup is for sure on cylinder one too. not exactly sure what the problem is.
as for the timing belt noise im just going to order a new belt and tensioner and just replace it. im not going to bother with the water pump because if all goes well it will have some form of sbc in it in the near future and if it doesnt pan out its easy to replace on its own if it comes to it.

[evildky]

When you did the belt did you replace the tensioner and or the idler? Did you inspect them at all? Kinda sounds like a bearing going but hard to tell on video. When you had the timing gun hooked up, you did have the sensor on the plug wire to cylinder #1 right? That's the front most plug on the passenger side. There are also numbers on the distributor cap, make sure none of them are crossed. Unlike most cars where the plugs hook to the cap in firing order the vg divides left bank form right and iirc the drivers side isn't even sequential.

[daktah]

i havent replaced the timing belt. yes the timing gun was hooked on #1. i just replaced the rotor cap and wires and made totally sure every cylinder was correctly hooked up. yeah i noticed it was like 1 3 5 4 6 2. hoping its just the tensioner bearing or something because im not about to replace a bearing inside the engine.

[8631z]

just a note on the timing marks. you can bolt the the pulley on the harmonic balancer 6 different ways. it may have been removed and put back on wrong. i have done that far to often.

[evildky]

You shouldn't be looking at the removable pulley, there should be a mark on the damper itself, which can only key on in one position

[8631z]

on mine the timing marks are on the dual set of pulleys. and there are 6 10 mm screws that hold that to the dampener. i had no keying for the pulley to dampener so it could go on 6 different ways.
as for the "wahwahwah, wahwahwah" sound. it sounds like the aiv and that's a normal sound. the other noise is bad.