1996 Toyota Previa 1996 Toyota Previa SC knocking after hea

1996 TOYOTA PREVIA
135,000 MILES • 4 CYL • 2WD • AUTOMATIC
Avatar
MAUJOSH
  • MEMBER
  • 2 POSTS
1996 Toyota Previa SC knocking after head gasket job.
It did not not knock at all when it came in.
Had blown head gasket between 2 cylinders and ran well but had rough idle before changing head gasket.
Had a professional rebuild the head.
Put together and it runs smooth except loud knocking.
Bore-scoped and found no debris.
Power-balance test comes out even.
Checked rod bearings they were fine.
It runs and idles fine.
It only knocks while running not while being rotated without plugs.
Thanks for any help.
Jun 4, 2010 at 2:06 PM
Advertisement
Avatar
MHPAUTOS
  • CERTIFIED EXPERT
  • 31,937 POSTS
What are the oil pressure readings, cold idle, hot idle and hot 1200RPM?

mark (mhpautos)
Jun 4, 2010 at 7:26 PM
Avatar
MAUJOSH
  • MEMBER
  • 2 POSTS
I will test it and get back to you.
Jun 4, 2010 at 8:16 PM
Advertisement
Avatar
MHPAUTOS
  • CERTIFIED EXPERT
  • 31,937 POSTS
OK, thanks.

mark
Jun 4, 2010 at 8:40 PM
Avatar
GARAGETUNER
  • MEMBER
  • 1 POST
If everything is fine and the van runs normal, I guarantee the noise that you're hearing is from the cam sprockets. I believe you had skipped one important step in reinstalling the camshafts during your cyl. head job process.
On the exhaust cam, it has split gear, before you remove the cam, you must lock down the SPIT GEAR before removing it.

Solution:
1. you remove both cams (again) and everything everything else that's involve-you may need to one motor mount to get to the chain tensioner. You can just lose the intake cam and leave in the spot just enough to remove the exhaust cam.
2. remove the exhaust cam and lockdown the split gear by:
a)set the cam on a vise, turn the outside gear clockwise as until the hole are line up and lock it down with 10mm bolt.
3. Reinstall both cams, then remove the 10mm bolt from exhaust cam and put everything back.

This process should take about 1-5 to 2 hrs.

Good luck

Samay, the previa guy from Seattle.
Jul 21, 2011 at 3:49 PM
Avatar
RIVERMIKERAT
  • CERTIFIED EXPERT
  • 6,110 POSTS
maujosh, were you able to resolve this issue? If not, does the knocking speed up when you accelerate?
Sep 29, 2011 at 7:44 PM