Help with noise from front of engine M113 5.0 V8

Mark Hart

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Hi guys,

Looking for some advise on where to start looking for an unusual noise coming from the front of the engine.

My car is a 2004 CLK500.

Background to this is about 6 months ago I did an overhaul of the cooling system as preventive maintenance (since the previous owner didn’t seem to prevent much), this included:
New thermostat
New water pump
New tensioner pulley
New idler pulley
New alternator voltage regulator (why not whilst in the area)
New auxiliary drive belt
Full new set off radiator hoses and clamps
New coolant.

I also tried topping up the ac whilst having access to the condenser etc but it turns out I have a leak somewhere in the system that’s probably been there a while.

Every time I’ve driven the car there’s a sound that’s nagging me that doesn’t sound right, I honestly can’t remember if it was there before this overhaul or not.

I’ve recorded a video of the sound but it’s too large to upload here. Essentially when the car starts cold there’s a groaning noise that goes off after about 15 seconds, then you can here a high pitched whinging noise that seems to be coming from the area around the alternator. Ironically with alternators sometimes being called generators it sounds like one of those industrial electrical generator they use for lifts etc.
When I took the alternator off the engine to replace the voltage regulator I checked the pulley for play and it felt tight. The old water pump and idler pulley has lots of play so I’m glad I replaced them.

Do you think now with a good water pump, pulleys and new belt that maybe there’s too much tension on one of the driven components like the alternator that could be causing this noise?

The other thing I’ve noticed is when driving you can hear a clicking/ticking noise from the front of the car very faintly when between 750-2000 rpm, it sounds like the aux belt slapping, if you apply a small bit of throttle to 2200rpm the sound goes until you let off the throttle.

Would you guys recommend loosening the aux belt and checking all of the pulleys again?
What would you investigate first?
 

LostKiwi

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I'd remove the aux belt and check each pulley in turn by spinning by hand.
 
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Mark Hart

Mark Hart

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I'd remove the aux belt and check each pulley in turn by spinning by hand.
Thanks LostKiwi I’ll give that a go tomorrow after my second road trip to see if my abs module holds up .

The more I think about it, it’s coming from the left side of the engine, going from left to right in terms of position you have:

Alternator, idler pulley, water pump, crank pulley, tensioner pulley, power steering pump, ac condenser.

With that in mind everything left of the power steering pump (barring crank) has been replaced with the exception of the alternator, I bet it’s that, bet they are not cheap either.

Let you know what I find tomorrow
 

Oldspanners

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Hi guys,

Looking for some advise on where to start looking for an unusual noise coming from the front of the engine.

My car is a 2004 CLK500.

Background to this is about 6 months ago I did an overhaul of the cooling system as preventive maintenance (since the previous owner didn’t seem to prevent much), this included:
New thermostat
New water pump
New tensioner pulley
New idler pulley
New alternator voltage regulator (why not whilst in the area)
New auxiliary drive belt
Full new set off radiator hoses and clamps
New coolant.

I also tried topping up the ac whilst having access to the condenser etc but it turns out I have a leak somewhere in the system that’s probably been there a while.

Every time I’ve driven the car there’s a sound that’s nagging me that doesn’t sound right, I honestly can’t remember if it was there before this overhaul or not.

I’ve recorded a video of the sound but it’s too large to upload here. Essentially when the car starts cold there’s a groaning noise that goes off after about 15 seconds, then you can here a high pitched whinging noise that seems to be coming from the area around the alternator. Ironically with alternators sometimes being called generators it sounds like one of those industrial electrical generator they use for lifts etc.
When I took the alternator off the engine to replace the voltage regulator I checked the pulley for play and it felt tight. The old water pump and idler pulley has lots of play so I’m glad I replaced them.

Do you think now with a good water pump, pulleys and new belt that maybe there’s too much tension on one of the driven components like the alternator that could be causing this noise?

The other thing I’ve noticed is when driving you can hear a clicking/ticking noise from the front of the car very faintly when between 750-2000 rpm, it sounds like the aux belt slapping, if you apply a small bit of throttle to 2200rpm the sound goes until you let off the throttle.

Would you guys recommend loosening the aux belt and checking all of the pulleys again?
What would you investigate first?
Try getting a long screwdriver or similar and setting one end on the component and the other end to your ear and listening to see if that's where the noise is coming from. The A/C would seem to be the first suspect after all you've changed.
 
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Mark Hart

Mark Hart

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Try getting a long screwdriver or similar and setting one end on the component and the other end to your ear and listening to see if that's where the noise is coming from. The A/C would seem to be the first suspect after all you've changed.

Thanks I’ll give that a try too. I’ve got a YouTube account I’ll see if I can upload the video there as I did a comparison from each side of the engine, sounds to me like it could be from the left side but I could be wrong
 
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Mark Hart

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Guys, should the ac condenser have any play on the pulley? I’m assuming because it has a clutch to engage it that it should have a little bit of play?
 

LostKiwi

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Play is ok as long as it's not noisy.
With the clutch disengaged it should spin freely.
 
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Mark Hart

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Hi guys,

I’ve just taken the belt off and I’m absolutely disheartened.

I checked the alternator, it’s fine sound freely with no noises.
Checked power steering pump, no play on the pulley, turns with no noises
Checked the ac, there’s a bit of play on the pulley but it turns with no noise.

Now we come to my two new pulleys.
Tensioner pulley, a lot of play, I mean a lot like you can rock it 2-3mm. This was a brand new pulley I fitted in November last year, it’s done less than 1000 miles.
Checked the idler pulley, there’s about 1mm of play here too! Again a brand new pulley I fitted in November.
Both of these pulleys were Febi Blisten I bought offline from AUTODOC.

I guess I’ll have to email AUTODOC and see what they say, can’t believe it.
 
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Mark Hart

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Hi Guys,

Got in touch with the supplier they said they’d refund the amount if I posted them back the part and they validated it’s a problem. So I’ve had to order another pulley from another supplier, this time went for viaco, when it arrived low and behold it has the same play on the pulley so this must be normal if two new parts have this play.

So I have a spare now I guess.

So to recap water pump, tensioner, idler pulley and belt are all new.
Alternator and power steering pump have no play on the pulleys and turn freely without any noise.
There is some play on the ac compressor but this could be the clutch not being engaged (I know I have an ac leak so the compressor won’t be running if the system is dry).

I’m thinking logically it’s eirher got to be the crank pulley or the ac compressor. I’ve been doing some more research and apparently the crankshaft pulley and harmonic balancer is known to start to come apart and we’re replaced under warranty through the early 2000s. My car has no record of recall and the pulley is very corroded and looks old so I’d imagine it’s original.

Does anyone have any experience changing the crankshaft pulley? Could this be the cause of the odd noise and the ticking belt noise I hear when driving?
I’ve watched a few videos on YouTube on the m112 v6 engine and it seems like a bit of a pain because the bolts are really on there, guy had to get it off with a breaker extended with a 5 foot pipe...
 

DaveE320CDI

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Hi Mark, Have you checked or changed the free wheel pulley on the Alternator? these can give similar symptoms
as you are getting cheers Dave,
 
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Mark Hart

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Hi Mark, Have you checked or changed the free wheel pulley on the Alternator? these can give similar symptoms
as you are getting cheers Dave,

Hi Dave,

I’ve checked the pulley that the belt runs over at the front of the alternator, this was tight and spins without noise. Is that the pulley your referring too?
If not how do you check it?
 

DaveE320CDI

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Hi Mark, Yes thats the one its a free wheel pulley that is when not driving the alternator! but its got a clutch in it thats what plays up and sometimes is noisy, they arent expensive to replace can get them from any bosch dealer,
sounds as though it is may be ok from your description, but after all that you have changed thats what id go for! cheers Dave
 
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Mark Hart

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Hi Mark, Yes thats the one its a free wheel pulley that is when not driving the alternator! but its got a clutch in it thats what plays up and sometimes is noisy, they arent expensive to replace can get them from any bosch dealer,
sounds as though it is may be ok from your description, but after all that you have changed thats what id go for! cheers Dave

Dave, holy moly I would have never thought of trying that. Watched another YouTube video, kinda my thing, and to test it people say stick a screwdriver against the cooling fin and turn the pulley, it should turn one way but not the other. Hope I’ve got this correct.

Mine - won’t turn either way, it’s rock solid, wouldn’t budge, I’m thinking this could be the culprit, I’ll order a repair kit and see what happens.

Thank you so much for the pointer!
 
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Mark Hart

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Dave, holy moly I would have never thought of trying that. Watched another YouTube video, kinda my thing, and to test it people say stick a screwdriver against the cooling fin and turn the pulley, it should turn one way but not the other. Hope I’ve got this correct.

Mine - won’t turn either way, it’s rock solid, wouldn’t budge, I’m thinking this could be the culprit, I’ll order a repair kit and see what happens.

Thank you so much for the pointer!

Just checked all the other pulleys again.

Turning my ac compressor pulley there’s a scraping sound so I think that’s shot as well but I knew that with the ac not working anyway.

Had a look at the crank pulley and some of the rubber insert has started to raise from the pulley at the front and it goes about half way round, the rest is flush to the surface. From what I’ve read that probably means that’s imbalanced and will be causing some noise too.
This poor car has not been looked after.

Going to order a repair kit for the alternator pulley and a new crank pulley with crankshaft oil seal.
Then I’ll have to have a think about what to do with the ac :’(
 

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Hi Mark, Hope that is the culprit? you will need a puller to get the old one off, you can get them off ebay its like a splined shaft that you screw into the old pulley, good luck youll get there in the end mate:)
 

LostKiwi

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Hi Mark, Have you checked or changed the free wheel pulley on the Alternator? these can give similar symptoms
as you are getting cheers Dave,
It's a V8 - no freewheel pulley as far as I know.

OP if the crank pulley is the problem you'll see it wobble while the engine is running. If the pulley runs true it's fine. It also won't make a noise.
Your best bet given you have no A/C is a failing bearing in the AC compressor.

To replace the crank pulley needs 2 people. One to lock off the crank (can be done using a bar through the access to the torque converter) and one to swing on a very long bar on the crank pulley bolt. The bolt is done up to a very high torque....
 
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Mark Hart

Mark Hart

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It's a V8 - no freewheel pulley as far as I know.

OP if the crank pulley is the problem you'll see it wobble while the engine is running. If the pulley runs true it's fine. It also won't make a noise.
Your best bet given you have no A/C is a failing bearing in the AC compressor.

To replace the crank pulley needs 2 people. One to lock off the crank (can be done using a bar through the access to the torque converter) and one to swing on a very long bar on the crank pulley bolt. The bolt is done up to a very high torque....

Thanks Kiwi, I’m going to replace the crank pulley as preventative maintenance, I don’t like the look of it good or not. According to wis a tolerance of 0.8mm is acceptable but the ridge I felt was easily 2mm IMO, a good thumbnail tip at least.
Struggling to find the counter holder tool for less than £100... tempted to take it to my mates garage but he probably won’t have the tool either and end up bodging it which is worse .

In terms of the freewheel pulley for the alternator, wis doesn’t give me anything in terms of the alternator for my car it just says for parts see 24/056 :s looking online at the parts stores AUTODOC, Amazon, eBay and a couple of American sites like fcpeuro all list freewheel clutches for the alternator on C209.375 with engine M113.968.
What makes you think the free wheel clutch is not on this model?
Have you tried changing one in the past?
 

LostKiwi

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May depend on alternator but not seen a freewheel clutch on any M112/M113 engine to date (and I've two at present as well as had two in the past).
Part number I found in WIS is A1121550215 which shows a solid pulley.

When Cole did my pulley he locked the crank using a bar to wedge the torque converter against the bell housing.
Historically I've used a piece of old ring gear cut to the size of the starter aperture then held in place by an assistant as I lean on a breaker bar.
 


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