[jade76]

I went to fire up my engine for the first time the other day and started noticing smoke coming from the back side of my engine. At first I thought I had a short in the harness, but come to find out my ground strap from the block to the firewall was extremely hot and was the source of the smoke.

So, I checked all my grounds and even added another ground from my block to the frame. This stopped the smoke I was originally getting, but the ground strap from the block to the firewall is still getting pretty warm to the touch. It's not nearly as bad before I added the extra ground, but I'm still concerned about it. I did paint the firewall and was thinking maybe that strap is got a weak ground, but I'd hate to mess up my pretty paint job if I don't have to.

Any ideas what may be causing this or what else I can do? I'm positive my battery and block now all have good grounds, so I'm needing a little help figuring this out.

 

[69gofast]

When I first tried starting my car, mine did the same thing, even burned my hand. The contact wasn't clean enough, the paint needed to be cleaned off more. I just run mine to the frame. It fixed it fine. If you have to crank along time it may heat up but you have other problems if the car cranks along time before it starts.

 

[71SS454]

Clean the paint off the firewall and the engine better AND run another ground strap directly to the frame. Your ground strap is getting hot because your putting too much of an electrical load on it. The heat you feel is wattage, which is bad in this circumstance. Also the wire going to to frame is a good idea, because without it your trying to out all that power thru sheet metal only and the frame creates a slightly shorter path back to the positive.

 

[Igosplut]

Loops. Frame-engine-body. Never assume that because the subframe is bolted to the body that it's well grounded.

 

[jade76]

Thanks guys for the input.

I think I have all the bases covered now, so I should be good to go. I just wanted to get some more input to make sure I didn't have something else going on. It still gets a little warm when cranking, but at least I can grab it without burning my hand. I may find another spot on the firewall to ground the strap from the block better, where it won't be as visible if I remove the paint.

Tony

 

[Custom Jim]

You need to have a main ground cable properly sized to go from the battery negative post directly to the engine. Ideally it needs to go to the starter housing but this cannot always happen easily. If this cable is bolted elsewhere on the block (and the starter is bolted to the block) there could be some voltage drop which at that point the starter could be trying to get a ground through your smaller wire between the engine and the body of the car.
You also need to have good, clean, and tight electrical connections on the cable and the surfaces.

I'm assuming this is on a 76 Nova ?. On my 77 Nova the batterys negative cable off of the battery goes to the alternator bracket. This connection off of the cable end to the alternator bracket then has to pass through the bolt and the star washer. The ground then continues through the bracket to the bolts that hold it to the motor. The ground then goes from the block to the starter's housing. All of these bolted together parts and connections may not be good electrically. Painted brackets on top of painted surfaces do not conduct electricity well. This is why ideally the battery negative cable should go to the starter housing.

I would also inspect the small wire from the battery negative terminal to the fender of the car. This wire is the ground for everything else on the car. I had a problem with my 77 a while back with the GEN light coming on now and then and this connection was bad. What was happening was the body of the car was trying to find a ground back to the battery and alternator through things like the shifter linkage and emergency brake cables. You definately need a good engine to battery ground connection for the starter. If it is poor then the starter will be trying to find a ground elsewhere. If you do not have a good electrical connections you could be like a buddy of mine and his main ground cable became poor and disconnected and he actually fried the shifter cable and was unable to get the shifter out of park.

If you are working on a 76 Nova I see no need to have a ground connection to the front subframe. The subframe is pretty much electrically isolated from the engine and the body of the car as it mounts to rubber isolators (body mounts). The only reason you may want to ground the frame is if other things are grounded to it.

Jim

 

[jade76]

Thanks Jim, there's some things to consider.

Yes it's on my 76. I mounted the battery in my trunk. The negative post from battery is actually connected to the rear subframe since I went by the instructions with the relocation kit I got from Summit, and it seemed rather expensive to buy a 20' cable to run to the engine compartment. I figure my ground is traveling through the rear subframe, subframe connectors, and to the front subframe which is grounded to the block both using 2 gauge battery wire, and the small wire from negative post is grounded to the body at the trunk latch as well as from the block to the firewall.

I'll have to look into it a little more, it's possible that it isn't grounding sufficiently that way, but at first I didn't have the front subframe grounded to the block and when I added that ground, it seemed to take care of it.

I'm definitely going to run a few more tests to make sure I don't fry my system.

Thanks for the input!

Tony

 

[Custom Jim]

Thanks Jim, there's some things to consider.

Yes it's on my 76. I mounted the battery in my trunk. The negative post from battery is actually connected to the rear subframe since I went by the instructions with the relocation kit I got from Summit, and it seemed rather expensive to buy a 20' cable to run to the engine compartment. I figure my ground is traveling through the rear subframe, subframe connectors, and to the front subframe which is grounded to the block both using 2 gauge battery wire, and the small wire from negative post is grounded to the body at the trunk latch as well as from the block to the firewall.

I'll have to look into it a little more, it's possible that it isn't grounding sufficiently that way, but at first I didn't have the front subframe grounded to the block and when I added that ground, it seemed to take care of it.

I'm definitely going to run a few more tests to make sure I don't fry my system.

Thanks for the input!

Tony

If you think cabling was expensive back when you bought it, price wire now. I've seen home wire jump from $30.00 a roll to $100.00 a roll and the coax and car wire I use on installations has also jumped considerably.

Anyway, with you giving more info as to how the car is with the trunk mounted battery then by having the battery grounded to the rear frame and then from the frame to the block this is fine (providing to the front and rear frames are welded together as well as the subframe connectors). I'm gonna assume you have these connections/terminals soldered to the wire and nut and bolted to things ?. If so that's good. I would also expose the bare metal where these bolted on connections are at for good contact and then maybe add some star washers to them so it digs in and then after making the connections, cover it with something like black silicone to slow down corrosion.

If you run a new longer negative cable I have used the tailshaft housing bolts and the bell housing bolts on my 73 before and it cranked over fine (but I also had some of that "cheap at the time" 1/0 wire for both positive and negative cabling runs). I have on some race cars wired it up using the roll cage by welding on a nut to a bar up front and in the rear to then connect my ring terminals off of my cabling to.

You could also double up with a ground on the other side of the engine to the frame and in the rear another one from the other frame rail to the battery.

Jim

 

[jade76]

Thanks Jim.

I'm assuming my grounds are good now, I noticed all my lights are now brighter than before, and I even have dash lights that didn't come on before. But I'm having an ignition problem that I thought was solved.

I think my fuse block has a bad connection. Sometimes my test light will read fine from the fuses, the next minute nothing. Sometimes one side of the fuse block will read fine and the other nothing. I wiggle it a little and reads fine again. The engine won't turn over from the key. The neutral safety switch has two plugs going to it, one with a red and green wire and the other with two purple wires, and when I cross the hot purple wire to the red wire it cranks over as it should. I've even tried two other neutral safety switches. The starter switch is brand new, so I'm kind of lost on this one too. I'm almost considering buying one of those new aftermarket harnesses, but I just have this feeling it's something simple that I'm overlooking.

One other thing is I have a large red (10-12 gauge) wire with a connector that isn't connected to anything. I believe it would normally go to a junction on the firewall, but I've also been told it should go to the starter. It stays hot even with the ignition off, and I've already got the hot wire with the fusible link hooked up to the starter. Could this be the source of my problem?

Thanks for your time and help!

Beyond testing for continuity, I'm electri-illiterate. lol

 

[Custom Jim]

I'm having an ignition problem that I thought was solved.

I think my fuse block has a bad connection. Sometimes my test light will read fine from the fuses, the next minute nothing. Sometimes one side of the fuse block will read fine and the other nothing. I wiggle it a little and reads fine again. The engine won't turn over from the key. The neutral safety switch has two plugs going to it, one with a red and green wire and the other with two purple wires, and when I cross the hot purple wire to the red wire it cranks over as it should. I've even tried two other neutral safety switches. The starter switch is brand new, so I'm kind of lost on this one too. I'm almost considering buying one of those new aftermarket harnesses, but I just have this feeling it's something simple that I'm overlooking.

One other thing is I have a large red (10-12 gauge) wire with a connector that isn't connected to anything. I believe it would normally go to a junction on the firewall, but I've also been told it should go to the starter. It stays hot even with the ignition off, and I've already got the hot wire with the fusible link hooked up to the starter. Could this be the source of my problem?

Thanks for your time and help!

Beyond testing for continuity, I'm electri-illiterate. lol

You could have a bad connection on the fuse block and/or with the bulkhead connector behind it. Most terminals in the fuse block are crimped onto the wire and offer a limited life span compared to them being soldered. By wiggling the fuse block you are also transmitting some of that motion to the bulkhead connector as they share the same mounting bolts and clips.

Try this, wiggle the wires on the bulkhead connector in the engine bay. Depending on how hard you do it or if you do groups of wires it too may transmit the motion to the interior fuse block side but maybe it's worth a shot.

The large red wire. Can you trace it down to see where it goes ?. It might have gone to the starter, it might have gone to a junction block, or it could have been the main feed out of the alternator. If you can get a general idea where it's at and where it goes I may be able to look at my 77. My 77 has factory air and is a V8 car and might be similiar to your year.

You can use your test light troubleshooting the bulkhead connector also. Some things you do need a good multi-meter but what you are tracing down and troubleshooting the light will work fine.

If I had to narrow a guess on your car, I'm going say a poor connection on the bulkhead connector unless your car has been exposed to a lot of moisture and rust and in that case maybe the connections behind the fuses.
I've seen a few bulkhead connectors apart and most have had discolored and poor connections inside of them.

Jim

 

[jade76]

Thanks, I'll check that out. I'm going to go ahead and pull the fuse block and bulkhead connector anyways to check the terminals and I'm sure I'll be able to get a better idea what's going on then. They're not the factory harnesses either, so maybe it's possible the terminals aren't connecting properly, but they did look pretty clean before I installed it.

I guess this is what happens when you get impatient and just want to get it going. It's now taking more time to figure out the problems.

Better to have the problems now rather than somewhere down the road while cruising. It's all a necessary learning experience. Next time if it happens again on my next project, I'll have somewhere to start thanks to your input.

 

[laser-red-nova]

One place a lot of people ignore when putting an engine together is where the motor mount brackets mount to the block. The paint should be sanded off the mounting bosses before installing the motor mount brackets, for a good ground. Just my $.02.

 

[jade76]

Thanks for all the help guys!

Traced everything down, and apparently just had some bad ignition wiring under the dash that wasn't connecting. I finally took a friends advice and by-passed the neutral safety switch and fired her up tonight for the first time.

Still concerned though, all grounds are tight and making good connections, even made sure all paint was removed at mounting points, but the ground strap from engine to firewall still getting warm and all the rest are staying cool to touch. It's not so bad that I can't grab ahold of it, but it's definitely drawing some current through it to get warm at all. Is that normal, or do I need to look into different grounding points?

 

[67pete]

Might try a grounding wire from the body to the front sub-frame....