Knocking and a belt squealing

[atcvette]

I recently ran my 84 a little low on the fuel side of the house. It took roughly 18.4 gallons to fill her back up. Seems as though thats a bit much, I'm not sure of how large the tank really is though. However, after filling the tank and adding a bottle of STP Fuel System Cleaner. Within one mile my engine starting knocking. Then the very nexy day, I start it and I still have the knock, but now the belt is squealing too. The sound seems to be coming from the right side of the engine, lower portion. The squealing goes away with increased rpm's. But, the knocking just gets worse. I think the squealing could be my water pump, I have had some cooling issues in the past, but the knock I am not sure of its cause. Could it be a rod, lifters (no ticking though), or possible bad ignition timing. Referencing the latter, a few days prior it had died a few times after running for awhile then driving at slow speeds. When I would goto accelerate it would sputter, die or felt as though it was really bogged down. I hope so one may know the cause or atleast point me in the right direction. Thanks.

 

[vetteboy86]

I believe the fuel tanks in the C4's are about 20 gallons. I find it very hard to believe that running the car down some on gas would contribute to an engine knock. Could it be the bearings for the water pump pulley? A noise in a car is hard to track down. You can buy the mechanics stethoscope, that will give you a general direction. Not to mention it is very cool listening to the motor in this fashion. Go with the obvious first.

Good Luck,
Craig

 

[nyernga]

I'd approach it as two different issues. First, the squealing could be anything from the serpentine belt to that aforementioned bearing issue.

The bogging down when attempting to accelerate sounds like a clogged catalytic converter. Does your car have the original? And how many miles on her? I don't know if a clogged cat could contribute to the knocking sound so it could very well be 3 issues.

 

[lagasvd]

My first thought since it's on the right side of the engine is to check the idler pully and belt. (This would have nothing to do with running low on fuel). If the spring is bad or the bearing is bad and belt is old this could cause a "knocking noise" that could go away when you rev the engine and a bad belt could definetly cause the squeling noise. Check the belt tensionor indicator on the bottom of the idler pully arm. Even if you might not think this is the problem and it's been a while replacement of the bearing and belt is relatively cheap. Replace the bearing by pressing out the old one and buying a new one from NAPA, about $8 and buy a new belt. About 30 minutes work and it's done.

Gene

 

[atcvette]

I am not sure if it is the original cat, but I would bet it is. The car has 118,000 on her. I will look into the belt and pulley issue. I thought possible the fuel, because she had set for awhile before I got her. I thought possible some junk may have been sucked up into the fuel system. This is only the second tank of gas I have put in her. I orginally had an oil leak, it turned out to be nothing major. Some one, for some unknown reason removed the whole dip stick and tube from the crank case and just set it back in the hole. Thats was genius at work, I tell you. Now that that has been remedied, I am not smoking at all. I read a possible reason could be that the dip stick is actually hitting the cam shaft. They had that issue on the early 84s'. Mine was built in early 83. Could that possible be the cause too?

 

[Jeb]

I'm thinking bad cat also. That would explain the bogging down under a load.

The knocking is probably NOT the dipstick hitting the crankshaft (not the cam shaft) as that wouldn't generate enough noise to worry about...for long anyway. If you want to test, just withdraw the dip stick a few inches and see if the noise goes away.

Is it knocking all the time or only when under a load? If the latter, check your base timing. Do the 84's have knock sensors, etc.?