Honda Odyssey engine rattle

[myf360f1]

Hi All,

The family bus namely a 1999 Honda Odyssey 2.3 V Tech with 114000Kms developed a sound (overnight) which is kinda hard to describe. So at idle the sound is not there but at about 2500rpm it starts and then goes away at higher revs regardless if the car is stationary or moving. Interestingly as the car gets up to full temperature the sound decreases but if you blip the throttle when the revs are falling you can just pick the sound up. If I had to describe the sound its kinda mechanical knocking which changes in loudness depending on the revs.

I checked for any loose components as well as any exhaust shrouds all were tight. I looked at belts and brackets, even removed the oil filler cap but the sound wasn't any different. There are no other noticeable symptoms, I mean it still drives fine, there is no temperature changes, its not using oil or water.

Im hoping someone may have come across something similar.

Any thoughts?

[admin]

No temperature change puts the "overheating knock" out of contention.

Its probably going to be one of those things that drives you nuts, I think your best bet is to try and find out, as best you can, exactly where its coming from.

If you can isolate the sound to a specific area, it will be easy to work out what it is (yeah, I know, easier said than done )

[myf360f1]

No temperature change puts the "overheating knock" out of contention.

Its probably going to be one of those things that drives you nuts, I think your best bet is to try and find out, as best you can, exactly where its coming from.

If you can isolate the sound to a specific area, it will be easy to work out what it is (yeah, I know, easier said than done )

LOL.... Thanks Admin. I have been googling heaps and the sound is a little like this

[gordon_s1942]

My limited knowledge of science is I believe that when things warm up, any 'sound' is reduced in resonance so if your satisfied its NOT in the engine itself, then it has to be where the heat is and the exhaust system is high on the list.
You could get a mechanics stethoscope or using a long screwdriver or rod over 18 inches long and holding at the top, VERY carefully place it onto various parts of the body, frame or engine.
If it touches what is making the noise, that should change its sound.
Do a COLD test first to see where you can put the rod so it wont touch anything it shouldnt like the spark leads as these bastards REALLY bite.

What I detest about rattles is that it rarely is coming from where you think it is or what could be causing it.

Get a good light to illuminate the engine bay and no loose clothing like unbuttoned sleeves etc.

[myf360f1]

Hi Gordon,

Yes tried the screwdriver process but the noise was apparent on every item with very little change. We thought it may have been the large resonator but the sound was the same, even through the catalytic convertor.

Your absolutely right about tracing the sound, depending on where you are around the car the sound appears to come from that point. I first thought it was in the valve train, but after removing the oil filler cap the noise remained the same. At the same time my brother was thinking it was in the bottom end like a bearing of some thought but when we got under the car the whole exhaust system had the same sound.... what a pain.

Coincidentally I checked my service records and it appears the car is due for a cam belt change, last one was done almost 5 years ago but the car has only travelled 18000kms. Im thinking of taking to my local Honda dealer and getting them to do the belt and look at the noise.

[gordon_s1942]

Hey, any chance this is a 'built In, I need to be changed' Belt noise ???
Could they have made the belt so that as it wears, it exposes a 'noise maker' like a strip or metalic thread that causes no harm but make it noisy?
Something like they do with some Disk Brake pads that show a warning light when their worn so far?
180 K over all or since the belt was changed but arent they supposed to be done every 100 k, if so you only 20K off doing so and everything (including your) on the engine is older now too.

[myf360f1]

No they don't have a warning on the timing belts unfortunately, I think this is purely coincidental. These motors require cam belt changes 100,000Km or every 5 years whichever comes first. Its just coming up to 5 years now but its only done 18,000Kms since the last change. Belts deteriorate with time not just use. Its possibly cam belt slap like in the video, so I might as well get the belt done anyway.

[Rick]

I'd be replacing the timing belt ASAP as well as the tensioner, just to do a quick test, remove the serpentine belt start the engine to see if the noise is gone

[gordon_s1942]

I have no idea what those timing belts run on, cogs,gears or pulleys but is it possible the 'noise' is from them caused by the newer stiffer belt as they (if origonal) have done over a 100K now havent they?

[myf360f1]

Thanks Rick, will have the cam belt done but I wont be doing it, those days have passed

@Gordon the inside of the belt has square cut teeth that run on the cam pulley and crankshaft pulley both with corresponding square cut slots, the backside of the belt(completely smooth) runs against a tensioner pulley which is known to fail with long term use. I feel that this sound is not that type of noise, but in any case the belt is due so while they are looking they can start there.

[Rick]

If the water pump is located in the same area I do recommend replacing that as well

[myf360f1]

@ Rick, yes it is and yes I am, will need to take a second mortage now

[Godzilla]

Walk into supercheap auto and buy yourself one of those mechanics stethoscopes, they are cheap and come with a long rod so you can point at any part and hear the noise level clearly.

If you cant tell the difference with one of those....well.....your going deaf.

I dont know who i managed for so long without one.

Hondas are a funny one, i just fixed a noise on a S2000 that had a few mechanics scratching their heads.

It had a timing chain, not a belt, and the tensioner is operated VIA oil pressure from the motor.

In a nut shell i recoed the tensioner with a sand blaster, when new they are slightly rough inside on the worm gears, when worn they get slippery and cant hold tension.

However having said all that, you cant predict what the noise is through a forum, you need to get it somewhere in case its serious.

For all you know, it could just be a cracked or loose heat shield.

If you need a mechanic who wont rape you, send me a PM, i have someone that ive known for years thats a professional workshop in Sunshine, they guys honest, in fact too honest, when ever im too busy i hand him my cars and all my customers cars because i can trust him.

Ive often stood over his shoulder while he has worked and watched him, i see the way he works, just like if i had the time to do it myself.......no short cuts, no bodge work.

[lsemmens]

If it sounds like the Audio from that link. I does sound mechanical, so the "stethoscope" trick should Identify it. I'd be disconnecting all pulleys first (i.e. serpentine cable that drives Air cond., water pump, alternator, etc). If the noise is still there, than you can, at least say that the noise is coming from inside the engine. (maybe timing belt, or bearings).

[myf360f1]

Thanks Godz, but unfortunately Sunshine is not practical for us southerners

@Isemmens like most modern cars today to access the belts require the skills of a magican the access is woeful. I also checked the tension on the alternator and AC belts and they are very tight and have no cracks or deformation, plus I ran the AC and it made no difference to the sound. If its under the cam cover (and Im not convinced it is) that I will leave to the pros to look at.

[VroomVroom]

i'd be suspecting the belt tensioner , they can rattle when you blip the revs or at odd times. let us know how you went

[gordon_s1942]

Many years I had a Toyota Crown with an external Belt Tensioner and one of the owner/mechanics of the dealership drilled a hole in the end of the casing and inserted a bolt with a lock nut in it as he said he didnt believe that when the Timing chain stretched as it got older, the hydraulic adjuster would be able to push the 'slider' against the timing chain properly.
His idea was if you just turned the bolt inwards a turn or 2, that took up the space created by the piston as it moved in as the belt stretched.

[Godzilla]

My son had a friend bring over a Astra with a rattle that changed pitch and frequency as it warmed up.

The owner had taken it to 3 workshops, all 3 said the head and front cover needs to come off to change the timing chain and tensioner (this model was chain not belt)

My son asked the owner to swing past for another opinion from me as i was gawking and making some crude remarks about how a car with less than 100,000Km could need a new timing chain.

Opened the bonnet, owner started it, moved my head to the drivers side where the chain was, moved to the right away from it and called my son and the owner over.

Noise got louder away from the chain.

Looked under the exhaust manifold and found a rod that operated the ERG valve rattling around in the hole it mounts into.......bent the rod where it goes into the hole to take up the slack, noise never returned again.

And there was the owner wondering which mechanic he was going to hand over the thousands to moment earlier........

[gordon_s1942]

AHHH Godzilla, this is where you werent working as the others were on the principle of 'here we have a Mug so lets fleece him', shame on you !!!

Although I have never seen it myself, I believe Page One, Chapter One has the instruction of when even if your aware of the problem but its obvious the Owner doesnt, pick the most plausible and expensive to do problem requires repair or replacement.

In this case, I think you can hint to your Son for a Bottle or carton of 'Whatever' from the owner as you deserve it, because no matter what it costs, its a hell of a lot less than what he thought he had to pay out for.

[myf360f1]

Ok Update time, so after doing the sums on replacing cam belt, balance belt with seals and as well as a major service and two new tyres and this is before getting to the core of the problem it was decided to move the old girl. The car's value is around 4K so rather than muck around we traded her in on another new Honda. We have been looking for a replacement for a while and have been delaying because of one reason or another so this tipped us over. Unfortunately we didn't get to the bottom of the issue but in this case we felt it was better for the long term.

Thank you to all for your assistance.