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1990 4cyl engine knock when reving

1.4K views 4 replies 4 participants last post by  66conv6  
#1 · (Edited)
I have a 1990 G2 4cyl engine knock when revving.
as "The Camry Man" I repaired over 300 of these G4's and the one & only last knock was the water pump.
Already tried the following on this one;

  1. Listened to engine with long screw driver from ear, definitely a knock
  2. Pulled plug wire one at a time and found #4 when pulled = no knock
  3. SOUNDED LIKE THE TOP BUT GONNA PULL PAN ANYWAY
  4. Figured rod bearings so I pulled the pan on this G2 = EASY
  5. ALL bearing looked perfect , no slop ..:spy: hmmmm ???
  6. Pushed around on the pistons and wrist pins = all seem tight
  7. Brake cleaner the threads and rod nuts, applied red lock tight ,hand start & torqued to 36ft lbs final.
  8. inspected flex wheel bolts = tight
  9. Reinstall pan , added 5w30 full synthetic.. restart engine :drama:
  10. Still has same knock at rev unless I remove #4 wire ???
These NON- Interference ?? now thinking about valves on #4


Any help would be assisting ALL :thanks:
 
#2 ·
knock with detonation is
rod
wrist pin
piston slap

non interference, valves should make noise with or without ignition since cams keep turning with constant force.

i remember a while back a guy in hawaii had wrist pin knock where the pin was tight but the piston couldn't move as it had seized so under ignition it was slamming the piston against the rod and crank since it couldn't rotate well.

did the bearings look perfect or was there some wear? surprise you didn't throw bearings at it probably would have been around 60 for OEM bearings
 
#3 ·
Brake cleaner the threads and rod nuts, applied red lock tight ,hand start & torqued to 36ft lbs final.
Are you sure this is correct? All the Toyota engines I've worked with call for engine oil on the threads then torqued to spec no thread locker.
 
#4 ·
Rod bearing torque

Reason I did not put oil on threads is because I read that if you don't replace the rod bolts and nuts there is a chance of throwing a rod later.

Worried about threads stretch and coming loose without thread lock. I know I probably will not be able to get nuts back off now but it would be good to know. Gonna try it if I replace the motor anyway.


Also I didn't care about this engine if it didn't fix it then I will throw a used one I got on the shelf.
Just try it once because it was a rare symptom.
Don't want to rebuild engine for just a loaner car I use at the shop.

I will pull motor and save it for using later or for parts.
 
#5 ·
Ok. I gonna come out of left field here.

Is it an automatic trans? If so make sure torque convertor bolts are tight. If the bolt heads back out far enough they will strike/interfere. My car made the same noise (don't understand the #4 plug wire bit) diagnosed by a couple shops as rod knock. Third shop fixed it.