I have a 98 Toyota Camry. Recently while driving, it began to have a bad knock. Had just been on interstate.?

You shouldn't drive it until you isolate the problem to

know if it is serious. The first thing to do to begin is

to try to find the area from which the knock originates.

Listening while moving around the engine might get

you to the general area. Either that or just start out

using a mechanics stethoscope. The knocking can

be isolated very well with the stethoscope.

The main worry here with a knock is where in the

engine does it originate. Or does it originate in an

area at, or near the transmission. It even makes

a difference if it is a transaxle model, or rear wheel

drive transmission.

Determine if the knock is from the top, middle, or bottom,

the front, or the rear, or the area of it in the transmission.

If it is in the bottom of the engine it could still be a rod

knock due to the bearing, a bent rod, or a bolt that may

have come loose, or dropped into the pan where it is

being bounced into the crank, but not locked it yet.

If it is in the middle of the engine, about half way up

inside it could be a wrist pin or piston. The wrist pin

problem is usually defined to be more of a slap than a

knock, but can still be a problem. The piston could

also be slightly hitting a valve, or the head. This

sound might also be found at the top of the engine

just as pronounced. A bent pushrod can also be the

problem in this area. Hydraulic lifters that collapse

might cause the knock, but will also bend the pushrod.

At the top of the engine it could be a bad rocker arm,

or camshaft. It could also be a water pump problem.

The collapsing of the heater hose could also indicate

a knocking due to an air lock in the engine-to-radiator

system. Although, it could be expected then to have

some overheating. A crack in the head into the water

jacket of the engine where a vacuum could be

introduced into the heater could also be a problem.

On vehicles with a chain drive for the cam at the top

of the engine one of the pads that quiet the chain can

also be worn, broken, or badly out of adjustment. This

sound would be found at the front end of the engine,

but could be top, mid, or bottom.

In a conventional transmission vehicle the knock could

be a crack in the flywheel.

In any event here it is critical that you seek out the

problem as some can be very serious for you to try

driving anywhere. It is also most likely that you will

have to tear into the engine, or transmission to fix

the problem.

There are just many possibilities to be considered

until you can isolate the one. With any problem the

first thing you must do is to go through the checking

to find the area of the problem before you can

actually isolate the cause enough to make a move

to fix. You never want to merely use guesses.

im thinking it might be a pushrod. my car knocked to and it was the pushrods or the lifters i think. check it out before your engine gets messed up. i think if you keep driving it one might snap and itll go through your engine and youll have to buy a new one. i think that can happen anyways

bad lifter or rockarm loose