94 Passport 3.2 ticking/knock

[ralpht44]

I just changed my oil over the weekend. I used a bosch filter with Castrol synthetic 5w-40 oil. Today I noticed a knocking sound at low RPM's while stopped at a light. When I accelerated in to second gear ir sounded perfect. I have no loss of power just a loud tick/knock and i can't figure it out. Seems to be coming from the front of the engine by the fan. Engine has 112k on it and I am not 100% sure if the timing belt has been replaced. I am the second owner. Any sugestions?

[surferfletch]

Tensioner. Defer to Ramblin' for the long answer!

[Cat Fuzz]

Sounds like the timing belt tensioner.

[Ramblin Fever]

Could be timing belt tensioner; but, could also be bosch filter.

Is this your *first* time using this oil/filter combination??

FWIW - there's an Isuzu mechanic expert that very highly recommends using Rotella synthetic 5w-40 diesel oil in these engines for optimum cleaning/protecting.

My engine in particular does not like the Bosch filter, rather Napa gold or OEM Isuzu

[Ramblin Fever]

Originally Posted by surferfletch

Defer to Ramblin' for the long answer!

Just noticed this,

Guess I'm starting to get lazy

[ralpht44]

I just talked to a mechanic who is a friend of the family and he immediately stated it was the oil filter. he informed me to get an EOM or OEM filter asap and replace the Bosch so Ramblin you were dead on.

[surferfletch]

Originally Posted by Ramblin Fever

Just noticed this,

Guess I'm starting to get lazy

Hope it is just the filter.

[ralpht44]

Well, I replaced the oil filter with a NAPA gold and although the noise has diminished it is still there. Just weird that this occured right after I changed the oil. How long should I let it run assuming it is the filter? Thing I find weird is that it has no loss of power and sounds pefect when shifted out of first or when you step on the gas a bit. I am baffled and taking it to the shop tomorrow.

[Ramblin Fever]

Is this your first oil change WITH castrol oil??

Personally, I've been down your same road, these trucks run/sound great on Valvoline Maxlife & Napa gold filters - TRUST ME!

[trooperbc]

i'm going back to your first post. have you done anymore work on pinpointing where that noise is coming from. is it still from the front?

many mechanics (and customers too) can attest to any number of weird coinsidences. if the knock *is* from the front, then it has nothing to do with the oil change, the oil filter or the phase of the moon either.

and you are right back at the initial ideas of the timing belt tensioner. it is common for the knock to go away at higher rpms of ~2500 rpm. it's one of the ways you can discount it as a rod knock.

many mechanics of nonisuzu persuasion are not aware of this phenomonen. they attribute the noise to lots of things and even want to rebuild your engine. while you have a NON-interference engine (meaning you won't get valve and cylinder damage if your timing belt breaks) there are advantages to doing it before the belt tears up the timing belt covers, for example. you will do at the same time: timingbelt, timing belt tensioner and water pump. possibly also cam seals, and timing belt tensioner pulley if indicated upon inspection.

if you look up top in the FAQ there is the idea it could be something with the serpentine belt hardware (though i haven't heard that before for this kind of knock).

any new info ?

\\bc

[Ramblin Fever]

Originally Posted by trooperbc

if the knock *is* from the front, then it has nothing to do with the oil change, the oil filter or the phase of the moon either.

\\bc

I still disagree with you on this Trooperbc; I'm not doubting that his tensioner could be an issue as well, though. That is VERY possible too; just offly coincidental to start the VERY next day following an oil change.

But I myself wanted to retest my theory, as remember bout a year ago I had this same issue, it DID turn out to be timing belt tensioner/waterpump related, reared it's ugly head 6 mnths later - HOWEVER, I just recently wanted to see if that same noise would come back by using a $2 cheap filter; i.e. walmart brand on my 2nd to last oil change.

Sure enough, that close to same ugly noise came back within seconds of firing up the truck; switched back to a Napa filter 2 days later - no noise, quiet as a mouse.

I *truly* wanted to see if this noise would return simply by filter brand - for me, it did and many many other car owners of different makes/models notice differences in sounds of their engines with different filters as well; Isuzu is not the only one prone to this.

FWIW - my tensioner, waterpump, belt, etc etc only have 20k exact on them as we speak, and there is nothing wrong with my engine; trust me it's MUCH quieter then my sister's Trailblazer was when they owned it, and 10-times quieter then most other Isuzu's around here.

Wanna hear something funny ??....Sssshh, I have a Motorcraft (read: Ford) filter on my Toyota Tacoma, Napa was out of filters for it last time around.