Engine Grounds

[GNBeswick]

Does anybody have a diagram or photos of the grounds coming off the engine to the frame or firewall? I suspect I may be missing or have a misplaced ground, but I dont know for sure.

 

[TRICKSIXPA]

The ground on the fire wall goes onto the top left bolt of the bell housing of the transmission. Then there are the grounds connected to the harness as it runs along the firewall. They bolt onto the rear of the passangerside head. A lot of times they get ripped out because people forget about them and pull the engine out.

 

[GNVenom]

Four ground ring terminals, seven wires including a black 12 gage wire and a tan wire. Attached to the rear cylinder head, passenger side, and the transmission bell housing bolts. Sometimes they're all on the cylinder head, and sometimes split between the bell housing and the head. Either way, it's a proper place to see them.

EDIT: This applies to the 1986 and 1987 models. The 1985 grounds are on the front bracket, passenger side of the engine.

 

[GNRick]

If anybody tells you to ground the firewall to the top of the intake don't believe them.

 

[Red C5]

There was a GREAT thread about grounds a year or two ago on here. I'll try to dig it up.

 

[GNBeswick]

Thanks for the help guys. Attached are some pictures of what my grounds look like. Both the ones off the engine harness and firewall were "connected" to the intake manifold. Im now in the process of trying to get them on the head and bell housing.

 

[jpwalt1987]

If anybody tells you to ground the firewall to the top of the intake don't believe them.

Why? Whats the deal with that?

 

[GNRick]

Why? Whats the deal with that?

I tried it and car ran like crap (when it actually ran). I bought a heavy duty ground strap from CarQuest. Much bigger than stock. Don't know if it makes any difference but it looks cool.

 

[Nick Micale]

Since I did my first head gasket job many years ago, I have NEVER replaced the engine harness ground rings on back of the head, it is way too difficult.

Since GM installed these grounds on an intake studded bolt at the trans dipstick, I decided to follow their example.

Just exchange the bolt with a stud from the front of the intake where the factory lifting bracket is mounted as that bracket is expendable, and use that as your ground terminal!

 

[jpwalt1987]

I have always bolted them to the intake. I use a longer bolt on the ignition module bracket and an extension wire with a ring terminal. Never had any problems.

 

[GNVenom]

An engine ground is an engine ground, regardless of whether it's on the intake mounting bolt, engine block, cylinder head, or bell housing bolt. Every location is at exactly the same ground potential.

 

[charlief1]

Has anyone tried putting a ground between the motor mount and the frame? You can then do one from the frame to either the battery or the body and it should be better than the stock set up.

 

[Nick Micale]

From what I have learned about the electrical system on these cars, the frame should never be used for an electrical ground.

The main battery ground goes to the engine as everyone knows, and also there is a ground branch attached to the body. It is vitally important that any current path being supplied voltage MUST also have the same ability to return the to the battery.

Critical engine sensors have this direct path back to the battery, and other items like lights, take a path through the body to the battery.

The low carbon steel frame made up of many pieces bolted and welded together is a very poor conductor, and it gets worse with age and corrosion. Compared to a length of stranded copper wire, it is NOT a proper conductor in any electrical circuit.

Some owners may say that "the frame grounds work ok on my car", but when performance is increased, supplying AND returning the circuit to the battery, can and does, become critical, and can give un-wanted issues.

 

[GNVenom]

Yep, Nick is right. you GROUND the frame, but don't USE the frame for a ground.

 

[charlief1]

And that was why I asked. Thanks guys.

 

[RmvBfrFlght]

Have a quick question, is the frame actually tied to ground on these cars? I've looked and haven't found a ground that ties the frame to vehicle ground system.

RemoveBeforeFlight

 

[dennisL]

Its my understanding that the body is grounded, not the frame.

 

[CGASTON]

Have a quick question, is the frame actually tied to ground on these cars? I've looked and haven't found a ground that ties the frame to vehicle ground system.

RemoveBeforeFlight

Your gonna have to make your own ground...

 

[RmvBfrFlght]

dennisL and CGASTON, thanks for the info. I've seen multiple threads referring to the frame as being used, or correctly, not to be used as a ground path. Was thinking that maybe a/the frame ground cable was left off this car someplace along the line.

Nick, I've read many of your posts. Even ran a 8 AWG wire from the engine block to the gas tank, thanks for your insight.

Also, I did the same as Nick posted above with the intake bolt/stud for a ground location. Real easy to get to them when an R&R is required. A little anti-seize on the lugs/threads helps in conductivity and negating corrosion.

RemoveBeforeFlight

 

[TurboBuRick]

Here is a simple question for Mr.Micale and Mr.Spina. Forget about it being a Turbo Buick. Say you are welding some frame braces or reinforcements on the rear frame of the car. The welder is in front of the car. Do you clamp the ground on the body of the frame of the car????

Sorry for the hijack but i promise it will be relevant.