Its a 98 Amigo, 3.2 V6 5spd with about 80,000 miles. It gets full synthetic every 3300 miles.

Last saturday it started with a diesel like knocking/clacking sound when I started it. At first it was worse around 2500 rpm +/- under light or no load. Under load such as accelerating the noise was much quieter, and often not present at all.

Reading up indicated that a timing belt tensioner could be a likely suspect. I replaced the timing belt and tensioner tonight and the noise persists. Unfortunately its also getting worse. It is now sometimes notceable at idle and through out the RPM range.

I added some sea foam tonight and I'll see if that helps at all tomorrow.

DO the 98 V6's have adjustable lifters? Would one suddenly be out of adjustment? Or might something have broken?

Any ideas of other things to check?

Any similiar problems?

Thanks,

Mike W
(still planning on Moab! )

What weight of syn oil do you use?

Well there goes my initial thought <img src="/forums/images/graemlins/confused.gif" alt="" />




IIRC, they do not.





Maybe your truck heard you were planning on lowering it and is retaliating <img src="/forums/images/graemlins/wink.gif" alt="" />

I'm interested to see how the Sea Foam works out for you before getting too far into this. Seems like if it was the lifters clogged up, it would gradually become apparent.... not just randomly be bad one day. Any other symptoms (odd colors/smell from the exhaust for example)? Not sure if this is relevant since it usually affects idle more than anything, but when was the last time you cleaned/replaced the EGR valve?

Good luck with it, Mike <img src="/forums/images/graemlins/patriot.gif" alt="" />

The trucks been running 5-30 for the last 50,000 miles.

It actually idles smoother with the new timing belt <img src="/forums/images/graemlins/smile.gif" alt="" />

The EGR was cleaned out about the same time I did the Intake Gasket which was either last January or February (about 1 or 2 monthes ago).

The Sea Foam did squat.

I have noticed the noise subsides slightly when the vehicle warms up. At idle it is a slight tick-tick like a lifter. Under load it is slightly louder but still sounds like out of adjustment lifters. However when the engine is free wheeling between 2000 and 3000 RPM it sounds like a bearing fell apart and is missing completely. Its a loud knocking sound.

EDIT: The valves most certainly ARE adjustable and not hydraulic. They don't use the adjusting screw type deal like on my old 2.6. Adjustemnt is with shims. Perhaps I'll start with a valve adjustment, and see where that leaves me.

-Mike

ps the thought of multiple causes hs crossed my mind and really scares me! <img src="/forums/images/graemlins/ignore.gif" alt="" />

I just bought a 91 Trooper 5 months ago, the guy I bought it off went and got a 3.2 1993 with 140KMS on it, he had complained to me about a knocking last week, I just saw him today and he has to replace his motor? the Crank has gone and he is looking at about $5000 to get his engine rebuilt. maybe check your crank?

I hope it's nothing in the bottom end (i have 2 isuzus in my shop right now '98 rodeo & '99 trooper, rodeo is knocking & has big shavings in the pan & the trooper has a cracked oil pan/block). Just to make sure it's nothing serious, drain the oil in some container & check for shavings (small or large).

Another thing that comes to mined is your water pump. Did you change it when you did the timing belt?

http://isuzufaq.ibctech.ca/#faq17

what about the idler tensor for the S-Belt?

If it turns out to be valve adjustment then you need to ask why. A sudden change in valve lash would suggest the possibility that a valve isn't closing all the way. Either that or something's changed in the geometry between the cam and the rocker.

Just my $.02

Serpentine idler tensioner (and serpentine related items) Nope, I pulled the serpentine belt today and ran the engine with out it, noise was still there. I checked all of the pulleys anyway and did find the alternator pulley to be some what loose, but any noise from that is minor. Atleast for now.

The water pump is fine, no leaks, no wobble, and no I didn't replace it. Now that I know what I'm doing I can have it replaced in an evening.

I also changed my oil tonight no signs of any shavings, looks like normal, except maybe a little thin (sea foam). No signs of any other contaminants. Pulled 4+ quarts out, so thats a good sign as well.

One thing to note, when I started up after the oil chage the lifters were extremely loud until the engine regained oil pressure after 1-2 seconds.



True, which is why I am digging into this. I AM concerned. One thing to keep in mind is the lifters are adjusted using shims rather than a screw type of mechanism. I've seen other types of shims break/fall out. Would it really be impossible for something like that to happen in this case? I would certainly like it simply need a valve adjustment ( which the more I listen to it is what it sounds like ). If its piston related, repairs are going to be a bit more $$ Even if I do them my self.

I may pull the rocker covers tomorrow and look around, I'm out of town next week and won't be able to do much until I get back anyway.

-Mike

Mike, forget about adjusting the valves. They are hydrolicaly adjusted by the oil pressure (who ever tells you otherwise dosn't know nothing about these engines).

What you may have is a stuck lifter. Try racing the engine (in park or neutral) to 3500 - 4000 rpm abruptly (i know it sounds bad, but if it's a stuck lifter it may just get it unstuck).

One more way to make sure it's not the bottom end, is putting real heavy oil like 20w50. If the noise quites down or goes away, bad news.