Chain noise

[Jonty]

Hi all

Sorry another query. I’m noticing the main belt for the water pump etc sounds like if has chain noise. The noise is loudest around the bottom pulley. It very consistent and doesn’t sound like anything is grinding. It’s a brand new water pump so can’t it. Is this normal or potentially a bearing?

[CFI]

Hi all

Sorry another query. I’m noticing the main belt for the water pump etc sounds like if has chain noise. The noise is loudest around the bottom pulley. It very consistent and doesn’t sound like anything is grinding. It’s a brand new water pump so can’t it. Is this normal or potentially a bearing?

Perhaps you’re hearing the timing chain?

[Jonty]

Perhaps you’re hearing the timing chain?

Potentially I am but its very noticable (can easily hear it from the front of the car). When I have heard loose timing chains befroe those it is more of a rattle than a consistent sound of a chain. Shoudl I hear the Delorean timing chain?

[dmcnc]

Are you sure it's not your v-belt slipping? what does your voltage with the engine running look like?

[David T]

Possible it is one of the idler pulley bearings.

[Jonty]

Thanks voltage is fine. What I’ll do is see if my local mechanic can have a listen to see if it’s a familiar sound before I pull anything apart

[DMC-Ron]

You might try locating the source by elimination. Take off the belt driving the water pump and generator. Briefly run the engine to see if the noise changes. Obviously, you do not want to run the engine more than 30 seconds; just long enough to see what the noise does. You could also do a test with the belt driving the AC compressor removed. Seems doubtful that this would be the cause but you never know, there are a couple of idler pulleys on that belt.

Ron

[DMCMW Dave]

Just lift the A/C belt off the top pulley and spin the pulley. Very quick noise test. Obviously doesn't test the bottom one, but they tend to wear out at the same time. OR just remove the belt. I've heard pulley bearings that get as loud as the engine.

[Jonty]

All here is a vid of the noise
https://www.youtube.com/watch?v=P9pqYyh4yaI&app=desktop

[Jonty]

Just lift the A/C belt off the top pulley and spin the pulley. Very quick noise test. Obviously doesn't test the bottom one, but they tend to wear out at the same time. OR just remove the belt. I've heard pulley bearings that get as loud as the engine.

Thanks - I actually don't have an AC belt on at present.

[David T]

Well, then it can't be an idler pulley bearing! It is going to be a water pump bearing, an alternator bearing or (least likely) a problem in the chain drive for the cams. As previously suggested, run the motor for a minute without the water pump belt and see if you still have the noise. Look at the underside of the neck for the water pump up at the weep hole. If you see moisture or staining you probably need a water pump.

[Jonty]

Well, then it can't be an idler pulley bearing! It is going to be a water pump bearing, an alternator bearing or (least likely) a problem in the chain drive for the cams. As previously suggested, run the motor for a minute without the water pump belt and see if you still have the noise. Look at the underside of the neck for the water pump up at the weep hole. If you see moisture or staining you probably need a water pump.

Thanks - it's a brand new water pump!

[dmcnc]

Thanks - it's a brand new water pump!

Just make sure you put a long screw driver on the webbing and put your ear on the handle to confirm it's the source. A mechanic stethoscope would be even better.

[Jonty]

Just make sure you put a long screw driver on the webbing and put your ear on the handle to confirm it's the source. A mechanic stethoscope would be even better.

Thanks - could it also be the crank pulley bearing? I did post a video of the sound on page 1.

[Jason]

Fan on the alternator hitting something?

[Jonty]

Fan on the alternator hitting something?

Hmm will check that out as well thanks

[David T]

Just because it is a new water pump doesn't mean it can't be bad. Overtightening the belt can cause the alternator or water pump bearings to fail prematurely.

[dmcnc]

Thanks - could it also be the crank pulley bearing? I did post a video of the sound on page 1.

It's difficult to pick the sound out from the video. I would also confirm the fan blade isn't hitting something as mentioned. (i.e. alternator tensioner)

[dn010]

Take the belt off the water pump and run the engine (cold) for a short duration, see what it sounds like. No change in sound = something internal like the chains. Sound goes away with no belt? Then it's either the water pump or alternator. I've had a brand new water pump fail before (Hervey pump). This pump failed after about 5 miles, I drove it home with no belt in the dead of winter by shutting the engine off while coasting down hills and the gauge stayed low thankfully.

[DMC-Ron]

Does the temperature sender sense actual engine temperature when there is no coolant flow? Just curious.
Ron

[FABombjoy]

It would sense whatever heat has convected to the top of the passenger side rear head.

[David T]

It would sense whatever heat has convected to the top of the passenger side rear head.

If you are very low on coolant you will not get a proper reading.

[FABombjoy]

I mean, if there's no fluid circulation you won't get any kind of proper reading.

The gauge is something of a courtesy anyway as the needle movement isn't particularly linear.

Either way, as a diagnostic, a cold engine would be safe to run for a few moments even with the WP belt removed.

[Jonty]

Hi all

I tested without any belts. Still there. Local mechanic was a bit baffled on a listen. Def somewhere internal around the timing chain. Here’s another vid

https://m.youtube.com/watch?v=kPr_RZUwFGM&feature=youtu.be

[David T]

It does sound noisy. When was the last time the oil was changed and what kind is in the motor? Is there any metal in it? Do you have good oil pressure? How many miles on the car?

[Jonty]

Not sure on when Oil changed as last owner did (had it 2 months). Oil is a good colour. Heaps of oil pressure. Only 33k miles on stock engine. Not sure on oil type as that was previous owner. Wonder if it’s worth an oil change?

[David T]

It's easier to do an oil change than dig inside for the chains. If it is not the right kind of oil that *could* be the problem. What I would do is an oil flush first. Buy a bottle of oil flush, and run the motor for a while according to the directions and then do the oil and filter change. Whenever I buy a used car and don't have good, recent service history, I change ALL of the fluids and filters right away. That way not only do I KNOW when it was last done, I know the correct fluid is in there. That includes the motor, the transmission, cooling system, and washer fluid. The car should also have a grease job on the front end and complete undercarriage inspection.

[dn010]

Hi all

I tested without any belts. Still there. Local mechanic was a bit baffled on a listen. Def somewhere internal around the timing chain. Here’s another vid

https://m.youtube.com/watch?v=kPr_RZUwFGM&feature=youtu.be

You post this video of the noise but there is still a belt installed in it....

[Jonty]

Thanks Dave.

Yes there is a belt in the video but I’d just put it back on. Trust me the sound is identical without the belt. Just didn’t want to be stuffing around videoing with no belt on in case it got hot!

[Jonty]

Just an update that a mechanic has put a scope on it and is still isolating but thinks it might be the oil pump. It’s holding correct pressure though. A failing oil pump would be quite rare wouldn’t it? Assume this is a PITA to replace.

[chris williams]

Just an update that a mechanic has put a scope on it and is still isolating but thinks it might be the oil pump. It’s holding correct pressure though. A failing oil pump would be quite rare wouldn’t it? Assume this is a PITA to replace.
Very unusual yes, But if memory is correct it can be replaced by just dropping the sump. However if it's holding the correct pressure then I would doubt it's failing. Is the oil pressure gauge showing the correct reading? If you have not done this already why not try doing an oil change with the correct oil? A lot of people are putting such as 5-30 synthetic oil in the engines now and this is wrong. May be something as simple as this and wouldn't hurt (as suggested) to put a flush through let it drain for 24 hours and re-fill with a new filter and correct oil.

[Jonty]

Thanks - yes I’ve had a look at the service manual and it’s not too bad to replace but a few things new to come off. I agree it would be odd for it to fail but hold pressure. The manual test pressure garage was showing correct pressure.