V6 engine noises...

[fivepints]

Howdy all. As the other half and I get accustomed to driving El Bongo our ears have become increasingly attuned to a high-ish pitched mettalic rattle (the missus calls it a grinding - but she also agrees that it could be a rattle) at about 2.5k revs+. It probably goes on as you get higher in the rev range but the sound of the beautiful V6 drowns it out.

Our bongo has done just over 57k miles so I'd be surprised if it's a major issue but BongoFury paranoia is upon me and I just wanted to check with other V6 owners to see if they've ever noticed anything similar? It's definitely rev related and it sounds like it's coming from under the passenger seat. It's never intrusive but it's all I can hear at the moment! Any useful advice appreciated!

[missfixit70]

Alternator bearings?

[fivepints]

I'll bear it in mind ( ) - sorry - for our next service - or until they go bang - but I have no idea

[missfixit70]

Use a long screwdriver or metal bar as a sound conductor, rest one end on the alternator where the bearings are(or whatever you suspect) maikng good solid contact, obviously being careful of moving parts (elf & safety & all) that then stick your ear on t'other end, you'll hear it if it is Vibration analysis, we used to have expensive machines & monitoring systems to do the same thing & measure the type of vibration so you could tell when machinery reached a point it needed seeing to before it actually went bang.

[fivepints]

Just went looking for a factsheet based on your advice and the alternator certainly looks like it's in the right place - will have a listen tomorrow. Presumably this is not a critical fix though? (We're off to Switzerland next week!).

[missfixit70]

No alternator - no go. Do you really want it exploding (worst case scenario) under your passy seat? then being stranded while you wait for a new one?
This happened recently to a very technically knowledgable member, got badly let down by the European breakdown they had, stranded in Spain for nearly a week, ended up, phoning Ian to send him out an alternator & belts & fixing it himself, ruined holiday, very stressed, long story, hundreds of pounds out of pocket (long story - but finally got reimbursement but no apology).
Personally if I had any suspicions mechanically I wouldn't be driving abroad.

[fivepints]

Hmm.... OK - fair point - will see how investigations go tomorrow - still under "warranty" from dealer so not worth the risk I guess.

[missfixit70]

Not an issued then - get it back to the dealer & sorted

[fivepints]

Aye - that said - alternator at only 57k miles? That's not exactly Mazda longevity there is it!

[missfixit70]

but how old is it? have the belts been overtightened, easy to get it wrong & being sat doing nowt can be as destructive than being used, that's if it is the alternator

[mister munkey]

Best to not just go on mileage.

It may be low miles but that often means long periods off the road. That can also be a bit of a hindrance in the longterm for bearings & the like depending on storage conditions.

[fivepints]

Ah the joys of Bongo ownership

[missfixit70]

Ah the joys of Bongo ownership

Or any car I had a couple of mk 1 Espaces, alternators failed for a pastime as would steering racks, the steering rack situation got so bad that most recon racks were actually re-reconditioned (or re-re-re... you get the picture ) nightmare to replace, last one I had done, failed after less than 100 miles, proper renauilt back street garage whoI spoke to afterwards said this was getting more common, only way to go was sumat like £800 for a new one car was only worth half that (I'd only paid £100 for it)

Keep us posted with how you get on, hopefully it's something minor

[cheffy34]

under passenger seat is the aircon compressor, easy to find out if it is that just take the belt off, water pump, steering pump and alt are run off the other belt these can be isolated by taking the tension out of the belt when the engine is running wether it the correct way i couldn't tell you but it worked , i have an intimate love affair with the front of my engine at the mo it is actually quite easy to strip down the front of it to get to the cam belt

[fivepints]

Right - engine examined - screwdriver applied to part which I'm pretty sure is the alternator (indicated with red arrow in pic). Part definitely vibrates more than the engine block but does not make a noise when rev'd hard in both park and neutral.



Seems that the noise only occurs when the vehicle is moving which suggests to me that, unless the alternator takes up more load when driving, the noise is coming from one of the parts which transfers energy from the engine to the wheels. This makes me slightly more nervous as a break there can surely not be a good thing! Any ideas what I should look at next? The cambelt/tensioner/water pump were replaced last week.

(Incidentally, I also have three empty bolt fixings on the engine block which I assume are not required - anybody know what should/should not/could potentially go there? Indicated with red circles).

As always - thanks in advance