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Jerry, Master Mechanic
Category: Car
Satisfied Customers: 16839
Experience:  ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
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91 Buick Park Avenue: the timing chain and gears..rebuilt..knocking

Customer Question

re;laced the timing chain and gears, rebuilt the oil pump but the car is still knocking, this is for a 91 Buick Park Avenue, 3.8 liter motor, non turbo
Submitted: 8 years ago.
Category: Car
Expert:  Jerry replied 8 years ago.
That engine has a nylon timming gear on the camshaft originally. What happens is when it wears out, little peices of it go down into the oil pan and get sucked up into the oil sump screen.
It is recommended that you take off the oil pan and clean out the screen whenever you do a timming chain and/or gear.
Of course, there is always the posibility that a bearing could already be damaged if it has been run this way. Before you drive it I would recommend taking the oil pan off and see.

I hope this has helped you, Happy New Year!
Customer: replied 8 years ago.
ok the timing gear is metal on the camshaft. are you talking about the gear behind the timing gear?
Expert:  Jerry replied 8 years ago.
No, I meant the one that came on the engine when it was new.
I remember that some of them were nylon (which is supossed to run with less noise) and we always had to get the peices out of the oil pick up tube.

Does it sound like a lower end knock or more like a lifter noise?
Customer: replied 8 years ago.
sounds like a lower end knock
Expert:  Jerry replied 8 years ago.
It may have picked up some timming pieces and it got into a rod bearing or something. Either way you would have to take the oil pan off.
Customer: replied 8 years ago.
ok, also could the timing gear tensioner be causing the noise also?
Expert:  Jerry replied 8 years ago.
No. I don't remember that engine using a tensioner for the timming chain. As long as the knock is in the lower end I would say the oil pan has to come off.
Customer: replied 8 years ago.
ok, he has taken the oil pan off and he said there is alot of metal slivers in it, would that cause the noise
Expert:  Jerry replied 8 years ago.
Yes, that is probably small pieces of the bearings.If you look at the edges of the rod caps you may be able to see which one(s) they are from.

In any case, the best repair for that would be a reground crankshaft kit that comes with the bearings that match the size of the journals.

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