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Thread: Electrical Questions
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mazdaorbust
Revvin Up
Posts: 82
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posted July 19, 2007 01:36 PM |
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Electrical Questions
Hello,
I recently started working on my 75 repu and have gotten far. The electrical needed some work but was able ro figure most of it out. There are 2 issues which I am working on right now. The first thing is the light which indicates that the exhaust is overheated will not shut off. The exhaust does not feel to hot to me but I do think that the cat might be clogged up. Wil this cause the light to come on? I would think so but I figured I would be ask the question just incase it could be something else. When I got the truck I found many loose wires in the motor compartment and I have been able to hook up most wires using the stock wiring diagram with success. I am not sure if there is a particular wire that would control this. The other question I have is how does the coolant resevoir for cold start work? The wiring is hooked up but I have no idea how it works. Is it manually activated or does it automaticly work? Even though I have had a few headaches I take pride in the fact that I have been able through trial and error fix most of the problems I have found. It just makes you appreciate the end results more.
Thanks in advance for your help.
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Klaus44
Redlining
Posts: 365
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posted July 19, 2007 02:37 PM |
 Edited By: Klaus44 on 19 Jul 2007 14:39 |
Are you running a completely stock exhaust?
Working air pump, etc., included? regardless, an unblocked, free flow through your exhaust system is crucial to both performance, as well as engine health.
Your light may or may not be the result of a faulty sensor/wiring/connection, as well. (?)
No need to worry about your sub-zero assist; I'm assuming you'll never need it, even if it should still function as intended. Personally, I'd delete it, unless, of course, you're looking for that factory-stock thing underhood...
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mazdaorbust
Revvin Up
Posts: 82
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posted July 19, 2007 03:26 PM |
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Electrical Problems
The truck has a complete stock exhaust which I know is not healthy for rotary. I am going to replace it sometime next week with a free flowing one. The motor does have all stock items but living in CT my truck is exempt from emisions so I was going to pull off the air pump and anything else that I dont need. I probably pull off the cold start bottle since my truck is put away for the winter anyway. I was just wondering how it worked. Thanks for the response. I know that there are a few wires still loose in the engine bay which I havn't found a home for. Maybe its one of these?
By the way do you know of a way to make the gage lights brighter? My lights are not working very well. Can I just change the lights for brighter ones or is the voltage going through the lights going to restrict them anyway?
Thanks
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mazdarx605
Redlining
Posts: 314
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posted July 19, 2007 03:49 PM |
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Hey Hector,
I am not sure what is causing your light to come on like others have said it could be a clogged cat,or wiring,but my bet would be the wiring. I would be more than happy to come down there,and help you out some weekend,but I have no idea when I can get down there.I am not an automitive electrical genius,but I am an electrician,and understand wiring pretty well. I can also help you with other things if you want.
Let me know if you want me to come down.
Chris
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mazdaorbust
Revvin Up
Posts: 82
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posted July 19, 2007 04:55 PM |
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Electrical Problems
Hey Chris,
I'd be great to have you come down. This weekend is going to be bad for me. Maybe next weekend? I figure between the both of us we should be able to fix it or make it worse! Just joking. I'll send you an e-mail early next week so that we can set it up.
Hector
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Klaus44
Redlining
Posts: 365
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posted July 19, 2007 05:40 PM |
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*If* your air pump is working...:
...make sure you leave it that way, until ready to install the RB header! Un-modified, (and perhaps modded, as well), the thermal reactor can get hot enough/hold enough heat to collapse or compromise apex seal springs, at least for whichever apex's end up stopped in the 'hot zone' when you shut 'er down... *if* the air pump is removed/non functional.
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mazdaorbust
Revvin Up
Posts: 82
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posted July 19, 2007 06:32 PM |
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Air Pump
Thanks alot for the info. I was actually going to take it off before installing the new exhaust. I guess that would have been a big mistake.
Thanks again.
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sparky
Redlining
Posts: 299
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posted July 19, 2007 06:47 PM |
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Regarding exhaust temp warning lite....
In the photo gallery of this site there are some scans of a wiring diagram for 74 REPU. Page 1 shows a sensor connected to the emmissions control unit for Heat Hazard. It looks like the emmissions control unit also turns on the indicator light. The sensor is located in cab under passenger seat above catalytic convertor. I had the same issue with a 74 REPU I used to own. I was running RB header and exhust. Not too worried about light being on. Anyhow, according to diagram the sensor has a normally open contact...ie) high temp condition closes contact and emmissions unit receives 12 volt signal. You should be able disconnect wiring on sensor under passenger seat and light will turn off. Sensor is round and flat. About 1" diameter. Good luck.
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RotaryRob
Revvin Up
Posts: 53
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posted July 19, 2007 07:11 PM |
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No "Cat"
These trucks never came with a "cat" .. catalytic converter. If it has the stock exhaust system it is equipped with a thermal reactor. This is just a big, heavy steel box that substitutes for a proper exhaust manifold and reburns the exhaust gases by adding oxygen via the air control valve and air pump. A malfunctioning air control valve can put too much air (oxygen) into the thermal reactor and cause it to get REEAL HOT!! The FIRST thing I'd do is disconnect the air pump. Or, if it really is getting too hot, you will be able to actually see it if you look under the hood after dark with the thing heated up. You will want to remove the air control valve and block off the opening when you install a header and freer-flowing exhaust system.
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Klaus44
Redlining
Posts: 365
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posted July 20, 2007 09:18 AM |
Edited By: Klaus44 on 20 Jul 2007 09:20
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Sage advice...
...about the function of the ACV, that is. Sounds like there's more than one way/more than one speed to destroy a stock engine (!) Only way I'd ever consider running a thermal reactor without working air pump *and* ACV, would be if I gutted it, first, and/or altered the insert that causes the rotors' exhaust pulses to aim *at each other*, (supposedly to help quiet matters...)--yet another source of increased heat/decreased flow.
Still, no substitute for a proper (RB) header, (and block-off plates)...
Regardless: If there's any doubt whatsoever as to whether or not your exhaust is internally blocked, (perhaps due to disintegration...?) -- only truly safe thing to do is not run it until it's fixed.
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mazdaorbust
Revvin Up
Posts: 82
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posted July 23, 2007 01:23 PM |
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Exhaust
I looked at my exhaust yesterday and cat actually looks stock. It even has a metal sheet below it blends in with the others. So if it didn't come with a cat someone did a real nice job making it seem so. Eitherway after the great response I have gotten so far I am going to wait to buy the RB header before eliminating anything. It seems like the right thing to do. I started the truck for a while and realized that the cat is clogged. I was going to take cat out and gut it out just so that it would breath a little better while I work on it. You can tell as soon as you give it throttle that it isn't right. I also bought a RB muffler for it which should make it sound even better. While working on it yesterday I also noticed that when I drove it down the street 3rd gear grinds a little. Do you know if the gears out of a newer transmision would work or do I have to fine another repu tranny? I have read that a tranny out of a 79-80 rx7 drops in with little modification. My truck needs a clutch kit so I was going to wait until I dropped it to check it out.
Once again thanks for the feed back.
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Klaus44
Redlining
Posts: 365
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posted July 24, 2007 08:02 AM |
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Try this:
Before giving up on the trans. that's in there now, try draining and refilling with AmsOil Synthetic Gear Lube. Believe it or not, that stuff can actually improve/restore function (to a degree) over time/with further use! That is, if it's not *too* far gone... When you drain, watch to see just how much metal does/does not come out.
If you have the original 'ribcase' trans., the parts have gotten hard to come by. Yes, the '79/'80 5-speed will drop right in, with minor crossmember bolt-hole relocation -- but, your ratios will be a bit different...
You may want to retain/re-use some of that stock heat shielding around the exhaust. If you won't be needing your stock exhaust, there's probably someone here who'd be interested in it, even if parts of it have seen better days...
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Brad
Rotorhead
Posts: 1672
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posted July 24, 2007 10:42 AM |
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I would definately keep all the exhaust shielding
Those pipes get hot and the heat transmits to the floor then u get hot. I ended up keeping the stock shielding under the cab, then added aluminum shielding under the stock shielding. And extended the aluminum shielding down and about an inch below the magnaflows I have under the cab. Made a real difference, heat and hot air get directed down and away.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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tom93r1
Redlining
Posts: 458
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posted July 24, 2007 10:52 AM |
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About the cold start assist... I believe it should be automatic. Either way I would eliminate it for sure. I had an 87 rx7, turboII with the system and one morning it decided to dump the entire contents of the bottle into the motor. The car was stuck at work for about a week until I could get it cleared out. Finally I had my friend push me around the parking lot in his car and it blew steam for about a mile down the road before clearing out and running right. I will never give that craptastic system a chance to strand me again!
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Klaus44
Redlining
Posts: 365
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posted July 25, 2007 08:08 AM |
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Nice new word there...
...'craptastic'... gotta love it, Lol!
"Dude! That's so... *bitter* !" ;)
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