No start when hot - starter won't engage

OldnDecrepit

A few weeks back my 1990 740 GLE (B234 motor) wouldn't re-start after I stopped to pick up some parts in Southport. The car had been driving fine up to that point. All the lights would come on when the ignition was turned but the starter wouldn't engage.

After the mechanic "bridged the starter" the car did start and run perfectly. Been running fine for the last few weeks too. Yesterday after arriving home and, after having the car sit for 5-10 mins, I tried to start it and discovered the same problem. Lights come on fine but no engaging of starter. Wait 5 minutes and then car starts perfectly again.

The battery and alternator are fine. So do I have a bad ignition switch or bad starter or some other problem?

Vee_Que

its a common fault, what needs to be done is a relay fitted from the ignition switch signal that is currently on the starter, and wired to just signal a relay with fused battery voltage, basically the wiring is old and weak.

familyman

I had a similar problem years ago. Drove over 100km distance - in a heatwave - much of it at over 100km/hr. Turned engine off. Couple minutes later went to start it again. But starter motor wouldn't even click. Gave it a whack with a large shifter - still nothing. A mechanic I knew happened to walk by. He said, "Wait 20 minutes." So I did, tried again, it worked fine - and never did it again - including on the return drive home in/at the same heat/speed!? (I tested it after the return drive.)

That was a 1976 244 though (so B18 engine I think) - so maybe/probably not the same thing!?

jamesinc

I had this exact issue on my 740 Turbo. I replaced the starter with a good used one and the problem went away.

Vee_Que

76 244 is not a b18.... B18 was last used in a 122 in 1966!

egads (she/her)

My 68 145 with a b18 disagrees, but yeah, still 60's. :-P

Do the 90's have the crumbly harness and jumpy engine mount problems that can kill the wiring around there that earlier 740's have?

Major Ledfoot

familyman;68728 wrote That was a 1976 244 though (so B18 engine I think) - so maybe/probably not the same thing!?

As others pointed out, the B18 wasn't standard on any 240s I know of. I don't know what years (if any) 240s overseas were fitted with B17 (around 1800cc) and B19 (1986cc) versions of the B21 OHC redblock engine.

However, as far as I know, (and please correct me if I'm wrong) starter motors will interchange between B18 / B20 / B30 pushrod engines and the later B21 family & B230 family redblock engines.

jamesinc

I put the starter from a B23 in the 740 Turbo, it worked fine. As an added bonus it sounds cooler. Has that old school cranking sound.