Sorry, not Bronco related, but I trust you guys won't mind a quick question. My son was driving his 86 GMC Jimmy with a 350 engine down I-25 at speed when he heard a large bang and what he thought sounded like a metal grinding noise coming from the engine. He immediately pulled to the side of the road, turned the engine off and had it towed home. He thinks the engine is blown. I went out this morning and turned it over and it starts and runs but clearly there is something wrong. I can't tell if it is internal to the engine or one of the accessories. It is a loud noise, but to me it sounds more like a screech -- like there is a bad bearing in something. There is no oil loss and no hole in the side of a cylinder or anything. So the question is, if the engine is blown, would it still run or should I be looking for something else that went bad? Thoughts?

Check the oil pressure. If it has none - do not run it. If it does, and the engine itself seems to run smooth, I would investigate where the noise is coming from.

Not much help I know - but without oil - you will kill that engine in a hurry.

Nope, that is fine. I should have started there and I didn't even think to look at the gauge -- I just listened to the engine, checked the oil level and checked for obvious leaks. I'll have my son take a look! Thanks!

Son says that the engine is showing normal oil pressure at idle -- somewhere around 30psi -- but yesterday was running a little hot, like 195 degrees instead of 180 degrees before the big bang.

195 isn't bad for that engine, but of its running smooth, good oil pressure, then start checking the accessory drive, if you don't see any thing obvious there or around the fan, remove the belt and start it up and see if the noise goes away that'll tell I if it's accessory if it goes away, if it doesn't it's engine or transmission

Water pump perhaps? Just guessing here...

That is very much what I am hoping!

So just FYI, once my son got in there and started looking, one of the spark plugs had basically blown itself out of the cylinder. He had put these spacers in -- not exactly sure what they were -- to help with (somehow) oil use and plug fouling. They seem to have worked for him, but in this case what the spacer seems to have failed. Still not sure why it didn't just run rough. Instead, it sounded like it was going to blow up! Grrr...anyways, all is well that ends well.