Bearing knock

[tomg928]

OK, I bought my 86 GN a few months back. I was told from the priviuos owner a complete tune up and oil change was done. I seen new wires, distributor box, ect... The car has around 100,000 miles, stock. The oil was pretty clean and level was correct. I drove it 5 or 6 times since purchased. I Just put the correct 8.5 rear back in. I took it out the other night, around the nieborhood putting the rear to the test. The car ran extremely strong, fast. I had a from ear to ear. I went into the garage the next mornning and started her up. I heard a knock, sounded like it was comming from the bottom of the engine. She heated up and the knock was gone. I shut it down and drained the oil. Noticed the oil was black, but the color was more on the grey side. Would this happend if regular oil 10W30 or W40, was used. I'm not sure what kind of f@$king oil the previous owner used in the car. I threw up a post on what oil to use. Rotella seems like the way to go, but would it stop the knock..... I think I'm F@#ked Any thoughts:frown:

 

[getchasum]

Gray oil......Check to see if you are missing any coolant.

 

[tomg928]

Gray oil......Check to see if you are missing any coolant.

Would that cause a knock?

 

[Chuck Leeper]

Cut the filter open, and see WTF is there..DO NOT use a hacksaw to cut it..

 

[t-topflyer]

Has the engine been over-revved recently? If so, you might have a bearing clearance issue. Rotella is good, but it cannot compensate for that. If it is still running, you could likely save quite a bit of money and time by going ahead and having the bearings replaced. About a $500-$600 job, but worth saving $4000-$5000 in engine build expense if you catch it early. If you are capable of doing it yourself, you will save much more money.

Another area to check would be the torque on the flywheel bolts. Sometimes that can cause a knocking sound if they are loose. Carbon knock is another issue, but I doubt it would be in this case.

 

[tomg928]

Yeah, I figured that.....I'm gonna bring it to my uncle's shop, and let him check it out and do the job. I'm not experienced enough to start a project like that. Is there a special bearing I should buy? or just go with stock? I would like to see if I could purchase them from this forum. I'm pissed because the rear wasn't the original and blew apart and now the bearing issue. OH WELL....

Thanks for all the helpful info......Tom

 

[gnsrule]

Dont forget the balancer bolt too. If thats loose you'd swear you have a rod knock.
Good Luck
Craig