Where's Your Engine Ground Connected ?

[Christian Van H]

Hi all! I'm rewiring an Nissan SD33 engine install, and cant find any info on where to connect the heavy ground wire to the block. I thought most diesel engines had their ground wire connected somewhere near the starter, but it seems you can hook the ground wire up almost anywhere...any thoughts? Thanks, Christian

[Ex-Calif]

Anywhere large enough that has a positive path between the starter secondary and the battery is fair game in my book. All other electrics connected to the engine must also have a clear path to the grounding location. It helps if it is not low on the engine where dirt grime and corrosion increase.

My engine has a lifting eye on the top of the head near the back. The negative terminal is attached here. Make sure the surface is not painted.

[Jesse]

Most of the electrical problems I have encountered have been ground related, both on my own boat and others I have worked on. It is very helpful to have the engine ground terminal located in plain view for easy access and maintenance. Near the starter is best.

[James S]

Originally Posted by Jesse

Most of the electrical problems I have encountered have been ground related, both on my own boat and others I have worked on. It is very helpful to have the engine ground terminal located in plain view for easy access and maintenance. Near the starter is best.

Agree....you'll want to be able to easily get to it...and as Ex-Calif says, be sure its a good clean unpainted surface....

Sounds like your making some good headway Christian

[Blue Stocking]

Christian,

This may open a can of worms among my respected friends here, but I believe, and have wired many installations so, that to connect grounds at various locations on a block, increases the risk of electolytic action in the various components thru which the current flows. I have observed IMO, increased consumption of the zincs, and blistering at the cylinder head to block interface, when multiple grounds are connected. Large starter motors, such as the Delco-Remy MT series, require dedicated grounds. One might argue that this has nothing to do with corrosion, but it does indicate the importance of current flows thru the engine. If the customer agrees, I always recommend a heavy buss bar close to the engine for multiple negative connections, with the engine as a dedicated connection.
Can't remember if ABYC says anything about this.
Just my $.02 cents

[Pete7]

Originally Posted by Blue Stocking

I always recommend a heavy buss bar close to the engine for multiple negative connections, with the engine as a dedicated connection. Can't remember if ABYC says anything about this. Just my $.02 cents

This has been one of our winter jobs. Didn't like the idea of half a dozen different negative wires all using a single engine mounting bolt when it should be holding an engine mounting. Replaced with a HD buz bar and single HD cable to the engine.

Pete

[Christian Van H]

Originally Posted by Blue Stocking

If the customer agrees, I always recommend a heavy buss bar close to the engine for multiple negative connections, with the engine as a dedicated connection.
Can't remember if ABYC says anything about this.
Just my $.02 cents

This is exactly what I have done, using a Blue Sea 600 amp., four bolt buss bar. Thank you all for your great replies! Great idea on mounting the wire up, out of the most corrosive conditions and somewhere close to the starter. I feel much better now!

[Fishman_Tx]

Originally Posted by Blue Stocking

Christian,

...to connect grounds at various locations on a block, increases the risk of electolytic action in the various components thru which the current flows. I have observed IMO, increased consumption of the zincs, and blistering at the cylinder head to block interface......

Yup, this is why my timing chain cover is like swiss cheese.

[David M]

At the starter motor. It does not matter where so long as the terminal has very minimal resistance.

[Ex-Calif]

Originally Posted by Christian Van H

Great idea on mounting the wire up, out of the most corrosive conditions and somewhere close to the starter.

...where you can get to it...

PITA to try and get to the back of an engine on some installs.

Not sure if I understand the suggestions but I would not vote for having the starter ground pass thorugh a negative bus bar. This introduces a minimum of 4 connections in the ground circuit for the starter. I agree that multiple grounds at different locations is not good and is also messy.

I could see a direct ground for the starter and a separate ground bus for the other electrics. However the ground bus could come straight off the battery bank.

Not much could be worse than in a storm at night, on a lee shore, hitting the happy button and hearing, "Click..."

[daddle]

Originally Posted by Ex-Calif

Not much could be worse than in a storm at night, on a lee shore, hitting the happy button and hearing, "Click..."

Spoken well-lah. Saw you guys racing a week ago as I sailed past Changi. Looked like many boats. Cool.

Yeah, thank moronic Detroit for the starter ground problem. Why did they want to put current in the starter case? Grounds should not carry load currents, but that cat is already out of the bag. Run as direct as you can from engine battery and switch to the starter. Put the cable on one of the starter to bell-housing bolts if you can. Another, possibly smaller 'house-sized' cable can bond this same engine bolt to the main 'house ground' terminal block somewhere central 'electrically'. The engine is not necessarily the main ground of the system. The keel, toerails, or rig may be closer to 'ground' at all frequencies. More than one ground bond on the engine, or anything, is asking for endless problems: like an inadvertent second ground thru the control panel.

[Blue Stocking]

If the starter is not built to require a separate ground, as my Westerbeke is not, I come off one of the starter mounting bolts, and take the return to the buss bar stud mounting the lead from the battery. Use heavy duty tinned lugs installed with a proper crimping tool.


Daddle--you were typing at the same time as me

[Christian Van H]

Originally Posted by Blue Stocking

I come off one of the starter mounting bolts, and take the return to the buss bar stud mounting the lead from the battery

Great! Now what do I do? Use the starter mounting bolt down low, or the clean, up out of the way bolt I can get to? I KNEW THIS WOULD GET CONFUSING! Me thinks that closer to the starter is better, but that makes it further from the glow plugs...

[chala]

I would not use any bolt that is structural like a starter motor holding bolt or nut and stud. For two main reasons: one ”intercalling” material will reduce the thread grip and two if the material “intercalled” is soft it will make a loose connection.

[Blue Stocking]

I agree,

I replaced the bolt with a piece of hard threaded rod with nut and washer to retain starter, then lug for ground with separate nut and washer.