Loud Engine Knock below 2,500 RPM

[claudiovarga]

1995.5 rodeo, runs fine, good power, etc.
Developed a rather loud engine knock at idle and up to 2,500 rpm.
The noise stops above 2,500 and everything sounds fine.
Sounds like a loud clicking sound, can't tell if it's the top or bottom.
One (none Isuzu) mechanic didn't know anything and just said the motor was dead, but I'm not buying it. miles are 99K
Any advice?

[trooperbc]

Originally Posted by claudiovarga

1995.5 rodeo, runs fine, good power, etc.
Developed a rather loud engine knock at idle and up to 2,500 rpm.
The noise stops above 2,500 and everything sounds fine.
Sounds like a loud clicking sound, can't tell if it's the top or bottom.
One (none Isuzu) mechanic didn't know anything and just said the motor was dead, but I'm not buying it. miles are 99K
Any advice?

yes this more than not misdiagnosed and you are right not to buy it.

this is the classic symptom for
the timing belt tensioner, which keeps the timing belt tensioned correctly and when it goes (it's a small selfcontained hydraulic dampner), whe it goes the timing belt tensioner pulley "paddle" starts slapping into that tensioner and *****causes the racket often misdiagnosed as a thrown rod. when the rpms get ~2500rpm +/- the belt calms down and the racket disappears.

the fix:
*replace timing belt
**replace timing belt tensioner
***replace water pump (it's driven by the timing belt and the belt work has to be done all over again to replace, probably sooner than later.
****replace timing belt tensioner *pulley* only after inspection turns up an iffy bearing

get the parts from isuzu. it's not worth the chance on ebay stuff for a job like this

this can be a doityourself project if you are up for it and have the correct info on how to do it. there's plenty of good writeups out there

and then there is the isuzu factory service manuals from www.helminc.com

//bc

[FL 3.2L]

Guessing the timing belt/tensioner/water pump haven't been done yet?

[claudiovarga]

I had the timing belt/water pump done 40K miles ago, not recently.
I will have Isuzu shop where I bought take a look.

Assuming the tensioner is the cause, is there any potential for MAJOR damage done by my driving it until I can get it in for service in the next few days?
Thanks!

[FL 3.2L]

Could skip timing and damage valves. I wouldn't drive it. Did they not change the tensioner?

[FL 3.2L]

http://www.automotiveforums.com/vbulletin/t325554.html

Again, I wouldn't drive it...

[claudiovarga]

Don't know if tensioner was changed with water pump, etc.
It was a long time ago at 65k miles.
I will only drive it straight to the Isuzu shop and have them look at it.
Thanks again.

[Ramblin Fever]

x3 timing belt tensioner...engine is FAR from dead, i have twice as many miles as you.

[trooperbc]

and PLZEEE no more of this stupid baiting about the isuzu 3.2L v6 being an interference engine. it is not. this has been worked over here and this constant misinformation just misleads those that don't know

here DA WORD: DA FINAL WORD >

ALL ISUZU V6 ENGS ARE NON INTERFERENCE ENGS FROM 92TROOPER ALL THE WAY TO 2002 AND THE RODEOS 93 THRU THE 2003 MODEL YEAR,

3.2 3.5 DOHC AND SOHC

2004 DI 3.5 IS AN INTERFERENCE ENG

NO EXCEPTIONS JERRY

http://forum.planetisuzoo.com/viewto...?p=98391#98391

this means it's non-interference period. this means valves will not be damaged by mis-timing. this means that the piston can not hit the valves, nor the valves hit the piston.

comeon....

//bc

[FL 3.2L]

So you'd have no problem driving it? I'd say not interfering while turning by hand is very different from a running situation. It'd be foolish not to treat almost any engine as if it were interference. There are posts on this forum about valve damage and timing belt breakage.

[amigo-2k]

[quote=FL 3.2L There are posts on this forum about valve damage and timing belt breakage.[/QUOTE]

On a 2.2L GM engine commonly in the Rodeo and Amigo, but I can't say I have ever remember anyone with valve damage on a 3.2/3.5L


I can remember a post from 2eye in which he said he had his timing belt off and tried to start the truck for the heck of it and it did no damage.

And I think there was recent post here from a guy with a 98 (3.2L) that his belt snapped at 205k and he replaced it and went on his way.

[FL 3.2L]

Just saying it is prudent not to drive it as is. Search threads by wildlysmiley and redbug.

[Ramblin Fever]

typing w/broken hand...sorry for mishaps.

i do remembr one 3.2l owner stating his belt had broke and he believed it damaged his valves, but don't remember if he ever finished his thread.

i can with experience say that my belt jumped a tooth, tb tensioner went out causing engine to sound horrible nough that i refused to even put it in gear to drive it. called for a flatbed to come get her, i wouldn't have dreamed driving it the 25 miles to the shop that fixed it...no long term damage was done, but you'd have sworn otherwise from the sound.

i will repeat that the alldata books do say otherwise on this engine, as i mentioned a few years back, but mine didn't suffer any issues, and i'm not surprized for written info to be incorrect on this engine.

now...does anyone know bout the 3.4L v6 toyota engine?? interference or no??...coming up on 70k on that baby already

[2000izusu]

Originally Posted by Ramblin Fever

now...does anyone know bout the 3.4L v6 toyota engine?? interference or no??...coming up on 70k on that baby already

same situation. "official" sources say it is . but everybodies experience says it is a free wheeling engine (non- interference).