Volvo: Volvo starting/starter problem, negative battery cable, wagon one

Question
I have a 1990 Volvo 740T wagon. One day it wouldn't start, didn't turn over, just one loud 'click'. I took it to my local mechanic who installed a new starter and a new battery. One week later, it did the same exact thing again. It was towed back to my mechanic but by the time the car got there, about 2 hours later, it started right up normally. This intermittent problem has happen exactly the same way (one loud click - engine doesn't turn over) twice again in the last two weeks. It seems to happen once the car is warmed up awhile by driving. So far, I've been able to start it normally again after waiting (and probably, cooling off - the engine and me) for an hour to an hour and a half. My mechanic and most others say bring it in when it is not starting; they cannot fix intermittent problems. Besides the starter and the battery, are there any soleniods or relays I should replace (or any other part I'm not aware of)? One mechanic said I have to replace the wiring harness - is there anything to that?

Thank you,

B Metzger

Answer
i would check the negative battery cable where it's bolted to the engine to see that it's not loose or ready to break off. it sounds like the starter needs to be adjusted, some models have shims (thin pieces of metal) where the starter is bolted on to position it closer or farther away from the engine. not sure about your car or if this is the problem. hopefully you didn't get a defective starter put in.