Toyota Nation Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
174 Posts
Discussion Starter #1
I have a corolla with a 4AF engine (carburator). there is a constant tapping noise at idle. When I rev the engine it dies down abit. What could this be???? i thought it was the lifters so i've changed intake side but the nosie is still there. someone had told me after that there speacial way of removing the cam and placing it back in. Please could someone help as it is fricking pissing me off? Thanks. :(
 

·
Resident asshole
Corolla
Joined
·
9,552 Posts
Might be the valve lifters out of spec... or a cracked exhaust manifold.

i thought it was the lifters so i've changed intake side but the nosie is still there
Uhm, did you measure the gap? You dont just change them into new ones you know, and you shoulda adjusted both, intake and exhaust at the same time.:rolleyes:
 

·
Registered
Joined
·
45 Posts
This problem is caused by your valve lifters being out of spec. Its easy to fix, you just need the proper specs. for that engine.
Remove the valve cover and measure the clearance between the cam lob and the "bucket. The specswill be different for intake and exhaust.
Then take your measurement and compare it with the specified clearance. Your parts store should carry shims that you put in after you have removed the the old ones.
One thing to note is that thereis a mathmatical formulathat you can follow to figure out whatsize shim you need. I don't know it off hand but I will tryand find it and post it asap.
 

·
Registered
Joined
·
59 Posts
Interesting enough

The tapping sound at idle also occurs in my 1991 corolla (electronic fuel-injector). My mechanic once adjusted the TBS (throttle position sensor), and everything turned fine -- no tapping sound, stable idle rev, less vibration at idle than what I felt before. However, my euphoria only lasted a few weeks. Weeks later everything became what they used to be. Now I can hear very clearly the tapping sound, so irritating, just like the car telling you "I'm getting older day by day."
 

·
Registered
Joined
·
33 Posts
when doing tappet cleanrances make sure you have the piston on the other side at tdc.

eg if you are doing the valves on cyl 1, make sure cyl 4 is at tdc, dosnt matter what stroke... well, as long as the valves in cyl 1 arnt open or half etc.

if you havnt done it before go ask a mechanic mate who has or something, you dont wanna screw them up and make it worse :p
 

·
Registered
Joined
·
1 Posts
look at the chain that connects the camshafts together and make sure that the chain doesn't have any slack. I'm having the same problem, except that I sucked water up in my intake by accident and it made the same noises w/ a dramatic loss of power. I took it to my mechanic and they opened the valve cover up, looked and saw that the valves looked fine, but the chain that drives my cams are loose and the oil pressure driven guides are all the way out (full tension). We think that one of the guides may be broken. Anyways, check and see if the chain is loose. I have a '98 'Rolla (16 valve EFI DOHC).
 
1 - 9 of 9 Posts
Top