MGB & GT Forum

This past weekend I was trying to start the wife's B, I managed to get it started and it idled for about 5-10 seconds then quit abruptly. I tried several times to get it running but it would not start so I checked the spark, of which there was none. While the wife was turning the engine over to check for spark I could smell something starting to burn and I noticed the wiring going to a small round black electrical relay or solenoid was starting to melt so I had her shut the B down asap. While looking over the relay I found one of the terminals was broken on the inside and the terminal that the wire was attached to was very loose. I've tried to figure out exactly what this relay thing is but haven't had any luck so I thought asking the experts on here might be my best route. This relay is located on the passenger side fender under the hood, it has a square connector going to it with some white wires connected to it. I suspect that something gave out on the relay and caused it to short. Any help is greatly appreciated.

You should have two round black relays (resembling a Kodak film canister) mounted on the passenger fender. The one closest to the front of the car is the ignition relay, and the one close to the windshield washer fluid container is the starter relay. Here's a link to very useful wiring diagrams: http://www.advanceautowire.com/mgb.pdf. Look at page 26 for your '79 MG.

---

'80 MGB, de-smogged, Factory OD, Schlemmerized 25D distributor, HIF4's, Bell Stainless exhaust, VTO wheels from Hap, Bits4Brits relay kit, Classic Auto LED's, Speedhut tach & speedometer



Edited 1 time(s). Last edit at 2015-10-07 11:52 AM by thadman.

Excellent, thanks so much for the info thadman!!!

Something else I should mention and it's probably related with this issue. Since we've owned the B, there are times when we turn the key and all it does is click, if I keep turning the key off then on it will eventually start. Would this be the ignition relay or start ( I suspect the start relay)? I might go ahead and change both anyways.

You can use new modern style relays if you'd like. MUCH cheaper than OE style ones. You'll have to ask for the wire setup though. Or, I can try to remember to post it when I get home later today.

Might as well go ahead and replace both - simple to do. The start problem could be any number of things, even corrosion between the battery cables and battery post, although the new relays might do the trick. Start checking/replacing the easy stuff first!

---

'80 MGB, de-smogged, Factory OD, Schlemmerized 25D distributor, HIF4's, Bell Stainless exhaust, VTO wheels from Hap, Bits4Brits relay kit, Classic Auto LED's, Speedhut tach & speedometer

Thanks again for that info, the wire harness setup seems like the way to go, would make a good project for me once I get my shop built. Since we don't drive it in the winter I may just temp fix it with the NAPA relays and connectors to get it into the garage so I get it up on dollies and out of the way.