85 Corolla Knocking Only When In Gear

[92seo]

I'm posting this for my brother. He's got the car up at a shop, but it is good to hear some input from others that have knowledge of these cars in particular. So, here's the deal:

He was driving his 85 Corolla and all of the sudden it started losing power, knocking loudly, and smelled of gas. So, he had it towed to a shop. The mechanics said that it runs great when in drive, but as soon as it is put in gear it starts knocking and wants to die.

Any guesses as to what might be the problem? The mechanic seems to think it might be an exhaust issue, but admitted to being somewhat stumped.

[dirty hands]

if knocking under load

it could be big end bearings if 1/2 the revs
or main bearing if knock for every revolution of the flywheel

how much pressure is coming out of the exhaust

next look at plugs

get a compression test done

[92seo]

Thanks for the recommendations.

The first mechanic, the one that he's used for years, had it for a couple of days because he thought it was the exhaust (catalytic converter specifically) and wanted to "make sure". Well, he determined it to be the exhaust, and had my brother's car towed to a shop for that. In the end, between a couple of tows, the diagnosis fee, and the brand new exhaust, my brother spent $600 or so.

Then he drove it away and the same thing happened, only worse, and it broke down and had to be towed yet again. He had it towed to another shop, which quickly did a few tests and diagnosed it as running on only 2 of 4 cylinders because there were cracks in the engine somewhere. I think he said something to do with the valves or valve guides or something. I don't remember, and my brother wasn't real clear because he said that he was so mad he kind of spaced out when the mechanic told him, especially because the mechanic couldn't believe that the other one didn't notice the obvious.

So, his car is shot. The engine is toast, and he just put a brand new exhaust on a worthless car. He had just recently put new CV joints on, a new timing belt, plugs, wires, etc. He's kind of devastated, because he doesn't have money to throw away like that and now has no vehicle to boot.

So long, Toyota Corolla.