1976 280Z Reliability Update

[sscanf]

Hi All,

I have been missing from these parts for a little while. Too much going on but my 1976 280Z has been my daily driver until this week (brake booster see below). Not much to report except that it starts every time and has (generally) been running great. Highligths:

1. About a month ago I took my buddy to see Pat Benetar at the Casino Ballroom in Hampton Beach, NH. A 130 mile round trip drive. I warned him that it was a much bigger drive than had been attempted before in the Z but he insisted that we take it. I loaded up with a complete tool kit (based on recommendations from here). Had the front wheels balanced. Doused all the wires with WD40 (thunderstorms were threatening) and we hit the road. Result: Not a single problem - had a great time. PB Rocks! Generally kept it around 70 on the highway Hit 90+ once or twice. Sure seems like a 5 speed would be nice.... Everybody loves these cars around here too - lots of comments. There aren't many Zs around these parts any more.

2. Shame on me for not testing the TPS but there is definitely something wrong with it. If I run with it connected I am getting about 18 MPG, with it disconnected I'm getting 21+ MPG. I suspect the WOT switch is to blame.

3. I had done the temp sensor mod before but have since replaced the 5K pot that I used with a fixed 500 Ohm resistor because the pot kept drifting and causing problems. I want to eventually replace it with a thumb wheel style 1K pot (with an an on/off switch as a theft deterrent) on the center console next to the hazard switch but 500 makes it run pretty nice.

4. I have a water leak somewhere in the back hatch that is driving me crazy. Bottom right side as you look at the back of the car. We have had some heavy thunderstorms and it is soaking the carpet when this happens.

5. Brake booster developed a leak this past weekend. I have a new one on order from Rock Auto ($105 + $40 core charge + $8 shipping). Looks like an easy job.

6. Some exhaust stink when the windows are open. I guess I need to check the seals around the tail lights (but maybe there is another seal somewhere else that is the problem and is also causing the water leak, see 4 above).

7. I think there is an old mouse carcass hidden somewhere in the back. I still have all of the trim taken out of the back and have shoved various cleaning implements into all of the Z's nether regions but I only found his nest, not his body. He still likes to put out a little bit of stink, especially after it rains (see 4 above). Does anybody know their way around the various tunnels and cracks and crevasses in the back? Any suggestions?

So, I have put about 2500 miles on it since April and, all in all, I am happy!

Dan

Edited July 29, 2014 by sscanf

[S30Driver]

Sounds like it was a nice trip to NH....

I assume you have the false floor out at the front of the deck area so that you can get to the open storage bins up there.

Inaccessible when the floor is still in.

I have the same slight rain water leak at the lower right of the hatch. I think it is where my fairly new seal goes past the hatch strut, had a hard time getting it to fit right there.

[Zed Head]

I also had a lower right hatch leak. It was actually coming through the window seal, but traveling a pretty good distance. What I determined was that the water was leaking in at the top of the rubber, between the metal and the seal along the top edge, running down the open channel between the metal and rubber and coming out inside. I sealed/glued the rubber to the hatch frame all around the seal, top and sides. A new seal probably would have done the job. It's working, in the meantime.

I had a similar leak at the windshield, but in-between the glass and rubber. The old rubber just gets stiff and doesn't conform anymore.

[S30Driver]

Thanks for window seal info Zed, I'll take a look at that.

[FastWoman]

Dan,

I think everyone buys control-type potentiometers from Radio Shack for the potentiometer modification, but those would be very fussy, imprecise, and prone to getting knocked out of alignment. I always recommend using a screw-adjust, 15 or 20 turn trim potentiometer instead, which can be adjusted very precisely and which will NOT get knocked out of alignment. Radio Shack apparently has this one in 1 kOhm:

https://www.radioshack.com/product/index.jsp?productId=2062307&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032230

You can also order these things off of ebay.

My recommendation is that you determine your target resistance (in your case 500 Ohms) and then find a potentiometer that's comfortably higher than that value, but no more than approx 2 times higher. (One reason your 5k pot is so fussy is that your adjustment is down in the very bottom of its range.) Happily, the 1k Radio Shack pot would be just right for you. I will note to OTHER people, though, that this is not necessarily the right value for YOUR car. For instance, my own car needs about 2.4 kOhm of compensation to run right, so I have a 5 kOhm potentiometer installed.

If you want a switch as a theft deterrent, you should not have it on your potentiometer, as you would lose your tune every time you engage the switch. Instead, have a switch that's separate from the potentiometer. I would suggest wiring it in series with the potentiometer, so that when you open it, the engine will dump massive amounts of fuel. I think it will run, but it will be belching black smoke out the tailpipe, and the plugs will probably foul after a minute or two. There are better places to install a theft deterrent switch, though. You can interrupt the fuel supply with a fuel pump shutoff switch. You can interrupt the sequencing of the ECU by interrupting the #1 wire to its big-hunkin' connector. You can interrupt the power or reluctor connection to the ignition module. You can interrupt the starter control wire.

I always thought a great theft deterrent would be to wire a single-pole, double-throw (SPDT) switch to the starter wire. Have the common connection wired to the key switch and the starter wired to one leg of the switch. Then wire the other leg of the switch to your horn (or horn relay?). In the theft deterrent position, the horn would blow when the thief turned the key. If you want to be a bit stealthier about it, you could power some sort of transmitter with that wire, so that you'd get an alarm signal inside your home.

There are many ways to design a theft deterrent system. I think making the engine run poorly is probably the least effective of these -- because it still runs, right?

Edited July 30, 2014 by FastWoman

[rossiz]

funny, i was visiting relatives in MA this summer and we went to see the go-gos at hampton beach casino - didn't drive the z from seattle, though it would have been a helluva reliability report to post!

i agree w/zed re: the hatch leak - check the rubber seal. i had the same thing. the PO installed louvers attached via thin strips of aluminum which slipped under the seal - when i removed it, the seal was deformed. my quick/cheap fix was to buy a tube of silicone and used a small screwdriver to pry back the seal around the glass and squeezed a bead in between the glass and rubber, working my way from the drivers side about 4" above the bottom, then down, across the hatch and up 4"on the passengers side. tedious job, but after i wiped off the excess it's invisible and completely stopped the leak - and we get rain over here...

[sscanf]

funny, i was visiting relatives in MA this summer and we went to see the go-gos at hampton beach casino - didn't drive the z from seattle, though it would have been a helluva reliability report to post!

Hampton Beach Casino is my favorite place to see a concert. The Gogo's would be great there.

I will check that seal again. Thanks.

I have a break booster story that I will post in a separate thread to make it easier to find.