We have a 91rs 305 tbi with 100,000 + miles on it. In the last few days it has developed a load knocking noise, especially in gear. It sounds like something hitting the inside of the oil pan. There is a dent in it that has been there since we bought it. Is it possible that the crank could be hitting it ?

 

If there is a dent in the pan, depending where, it is very possible that a part of the rotating assembly is getting smacked into it. Try taking a portion of heater hose and probing around. Stick one end in your ear, the other, just move it around. See if you can decipher exactly where it is coming from. All the gauges read normal I presume?

 

have you checked the flexplate? a friend of mine had a knock in his 89 rs and he thought it was the engine.so he let it go for a month.i decided to climb under the car and see what it was and to my surprise i could move the flexplate and converter back and forth. i would check that first.and as for your oil pan maybe you ran over something.just a suggestion.

 

have never read exactually right anyway. My 16 year old drives the car and I asked him if he remembers hitting anything, he shrugged his shoulders and said I don't think so. So he probably did. I it easy to replace the oil pan ?

 

Not really, no.
Remove the dist. cap, support the engine with a jack (not on the oil pan)and remove the engine mount bolts and the nut that holds the trans to the X member. Jack the engine (have someone watch the back of the engine so yo don't pinch anything or hit the dist on the firewall). Take all of the oil pan bolts/nuts off and drop the pan. You may have to rotate the engine by hand as you pull the pan aft so it will clear the crank throws.