aaron26889

i just bought a 97 cobra with the 4.6 in it and it is making a knocking noise. my friend told me he thinks it is the main bearing going bad. i was wondering how difficult it would be to replace or how much it may cost.

uberstang1

Replacing a Main bearing is COSTLY. I'm sure there some backyarders that can do it with the motor still in the car but most shops are going to pull the engine. The proper way to do it would be to remove the engine, remove all the serpentine belt accessories, remove the timing cover, remove the clutch assembly and flywheel, remove the chain tensioners, remove the oil pan, remove all the rod caps and main caps and removed the crank shaft and check for abnormalities that may call for the crank to be cut or replaced, then replace the bearings and re-assemble, im sure theres a few things that need to be removed that I missed but you get the idea. But anyway when does the motor knock? When a main is bad it usually will knock on start up and be more of a wrapping while the engine is running. If it knocks under accelaration more rapidly and pretty much all the time I would lean towards a rod bearing. Unfortuantly either one is pretty much the same repair procedure. Basically if you cannot complete this task you're self It will probably be cheaper to find a used engine and drop it in.

kugzgt

where are you located in pa? uber said he dont mind getting his hands dirty, he'll take care of ya ;-)

uberstang1

Lol I'll be more than happy to swap a motor for ya if you're paying.