Strange Squeal?

[maddogrc]

Hey all,

for some reason whenever i aggressively accelerate from around 2.5K onwards when driving or from 3K onwards when hard accelerating at a stand still, i get this weird noise.

i've checked around and cant seem to find the source. i once had a squeaky belt, but this is just different to the sound that made.

vid so you can listen:
Imageshack - mov02554

anyone got any idea what it is? exhaust? turbo? (hope not) and the turbo seems to be functioning fine from what i can tell. all the water pipes coming from the turbo are hot so its deffo flowing coolant into it.

cheers,
george

 

[Old.Tony]

It might be the clip, but the squeal seems to lag a little behind the indicated RPM, which implies turbo. Engine's right up in the region where the thing would be going its hardest too.

At a guess, I'd say it's the early signs of turbo bearing wear and it's something I'd take to a mechanic before it became "current signs of failure, where's a tow truck?".

Hope it is just a wobbly mirror though!

 

[maddogrc]

ok, just checked my phone which i recorded it on and i guess i'll change what i said earlier.

when revving at a stand still it seems to happen at around 3.2-3.5K

 

[Dion]

Judging solely by the video, I would stake my left one on it being an accessories belt slipping. It doesn't seem to be tied to an exact RPM, it just happens high up in the rev range, and when you rapidly increase the engine speed. The belt is slipping till it's brought to speed. The sound is right. But I'd need video of it happening while driving to stake my right one.

 

[maddogrc]

you want a vid of it driving while watching the revs?

i just went on youtube. in this clip at around 5-8 seconds sounds the same as what i'm hearing in the cabin.

YouTube - Boost leak? Listen for whistle sound.

result was a belt

 

[Dion]

Yeah that would help, or if there's limited background noise then just an audio recording would do.

 

[maddogrc]

Imageshack - mov02555

thats as good as i could get as i had to leave for family dinner night which i'm at now, lame...

 

[maddogrc]

damn it, for me when i watch it seems after 1min it is lagging and making the sound delayed. bugger

 

[Dion]

Sounds like a truck when it's at idle. Cool.

Well, that video throws a bit of confusion into the mix because it's not really matching the behaviour that it exhibits when stationary, but my first port of call would definitely be all the belts. It's the cheapest and simplest of all the possible problems to diagnose and fix.

 

[maddogrc]

today i was adding some extra coolant to compensate for the amount i lost the other day when pulling out the dump and i accidentally spilt some on the belt area.

is it possible the coolant is causing a slippage?

 

[Old.Tony]

If it were the turbo bearings they'd pitch in time with the boost. What I'm hearing in the vid is a reasonable constant pitch - and nowhere near as high in tone as I'd expect from the turbine shaft.

It also seems to only happen when it's under some load. How's the fuel pump, rail and injectors? How much slack is in the belts, and are there shiny spots on the pulley-face side of the belts? Got any dri-lube lying about? I used to put that on the belts on my Jag to shut it up, but mine squealed usually in response to steering (power steering belt was a tad polished!).

 

[maddogrc]

of the recent turbo/dump removal and reinstall i did the other day this exactly what i did. since then its been fine til now, after i put the tad bit of extra coolant in and spilt some on the belts area.

pull off the IC
remove the turbo to IC metal tube bit (the bit where the turbo blows into the intercooler from) and remove the gasket there
remove all the heat shields (3)
undo 3 bottom dump to exhaust bolts
undo the 2 dump pipe holder/brace bolts
undo and clamp off the 2 water hoses in front of the turbo
pull off the tube at the bottom of the turbo that connects to the engine (waste oil return or something?)
undo the 3 top manifold bolts that hold the turbo in place
let the turbo drop a bit and pull towards the side away from the manifold
remove the oil feed ontop of the turbo (has a Q on the bolt)
undo the water tube/pipe coming from the side of the engine (both the oil and thsi water tube have a hollow bolt and a hole horizontally near the top of the bolt)
pull out the whole unit

after doing the checks while i was at it (see if was any play in the turbo, just a tiny fraction)

put the whole unit back in
refit the water tube to the side of the engine
refit the oil tube to the top of the turbo (the Q aligned the same as when before i undid it)
move the turbo across and lift it back up
chuck on the 3 manifold nuts loosely
reinstalled the dump pipe holder/brace bolts
reinstalled the heatshields around the turbo (not the one ontop of the manifold yet)
reinstalled exhaust
tightened the 3 manifold/turbo nuts properly
installed the top heat shield
reconnected the bottom waste hose
reconnected and uncrimped both water pipes
refitted the turbo to IC tube and gasket
reinstalled IC and tightened all fittings

the only thing i can think of going wrong was refitting the water tube to the side of the engine. is it possible i may have under or over tightened it meaning that the hole isnt in line with the tube? if i did this i'm guessing the turbo would of cooked by now and it'd be doing that noise all the time plus the other hoses wouldnt be flowing which they are.

otherwise thats the only mechanical thing done, a few days a go, before this occured.

 

[maddogrc]

after more youtubing i've come to several conclusions:

belts (hope so)
boost leak (perhaps one hose is loose or something cracked?)

gonna check the belts tomorrow, put some anti squeak stuff or something on to see if makes a difference at all; thats if they arent loose...

apparently can make a cheapie diy tester by plugging one end of the IC and attaching a silicone tube with a pvc end cap on it with a air hose fitting, and fitting that to the other end of the IC while pressurising the system to around 17 psi and should be able to hear the leak

 

[bushyd22]

coolant is slippery so it is a possibility.

 

[maddogrc]

ok, today i:

check all around the oil and water lines, seem fine, but when i put my hand on the water line going to the wall there was a bit of green coolant on it. i went to try again but nothing was there so i'm solely presuming it was there because i didnt wipe it off which explains why no other liquid was to be found

i sprayed all the belts with an anti slipping compound and still the sound occured.

i made myself a little pressure leak tester to see if there was boost leak, heres the vid:
Imageshack - mov02556

so i've got a boost leak from the intercooler, but even after doubling the pressure it didnt make the noise i'm hearing.

so i went for another drive and this video worked: (had the windows up for this)
Imageshack - mov02557

i'm still clueless...

 

[Old.Tony]

First, I've really gotta say this is an interesting way of diagnosing the problem, not only for those of us involved in the discussion and scratching our heads, but for the onlookers as well, who are getting to see and hear this - it's revolutionary!

That squeal really should change in pitch if it's related to any sort of engine speed (exhaust gas or rotational, eg water pump, air con compressor etc). As far as I'm aware though, the fuel pump is driven independently of engine speed. I'd really like to put a stethoscope on the fuel pump body, or the fuel rail. Under load, the pump would deliver a higher rate of fuel by virtue of the pressure drop in the rail, but shouldn't actually run any faster - perhaps what you're hearing is related to that. There could be a blockage in the rail, perhaps? The injectors will probably make a sound that changes in pitch with the change in RPM, and since we aren't seeing that, I am discounting the injectors.

If you don't have a stethoscope, a long metal rod works - for my motorcycle, I used to use a long flat-bladed screwdriver, putting the blade against what I wanted to hear inside, and placing the handle against my ear. It's a little dangerous in a car engine bay - I really recommend the stethoscope.

 

[maddogrc]

took it to the local service station mechanic and he reckons its the belts. says they need tightening and that the anti slip spray makes it worse...so going to do that tomorrow and if it doesnt work then i'll be slightly annoyed.

also, i dont know if this is true or not, but i oddly had a dream about the car issue last night and the guy in my dream said that it is possible air is in the oil lines when i removed it from the car and that it needs to be bled out or the turbo will cook, LOL

 

[flashum1]

today i was adding some extra coolant to compensate for the amount i lost the other day when pulling out the dump and i accidentally spilt some on the belt area.

is it possible the coolant is causing a slippage?

can do, problem is, once a belt slips it is more than likley gonna keep doing it regardless of how tight you get it. i'd be taking them all off and cleaning all pulleys with a solvent such as brakleen and fitting new belts. as pronav stated its a pretty cheap fix in comparison to most so definatley one to try.

 

[maddogrc]

well this morning i went to the garage and the guy stopped work to check out my car.

he tightened all 4 belts (only 3 tightening points though) and i took it for a drive; still made the noise.

i came back and he tried some lube on it and i gave the engine a nice hard rev; still did it...

so i offered him a 10 as a thanks for trying to help but he said dont worry about it even though he spent a good while having a look.

i drove off to my mates to do some study and on the way it kept doing it. i drove to maca's during the study break to show him, kept doing it.

i then drove home after around 7 hours of study and just decided to floor it most of the way...and what do you know, its basically stopped doing it! i can have the revs high and not hear it, but if i floor it to past 3.5K when driving then i begin to hear a bit of it.

its deffo not the turbo as i can clearly hear the spool up and spool down when driving and i havent changed anything since.

conclusion for now is that it is the belts and that perhaps the coolant i spilt is slowly dissolving away from the heat/friction. also there seems to be a new smell from the engine bay, but i'm guessing thats either the coolant burning away or that sticky spray on anti belt slip stuff burning.

cheers for all the help guys and will let you know if anything happens like my car blows up, lol.

also i'll let you know how i go about getting a new intercooler from nissan since mine is suffering a boost leak.

 

[Kickars2]

ok, firstky when it noise happens it's because of a certain boost level.
a mate of mine had this kind of noise on his zd30, he had got one muffler taken out of the exhaust and it just caused the turbo to make the noise for some reason, as soon as he got rid of all the muffler's it was fine.
it could be the leak in the intercooler, cause as you said when you give it more throttle the car run's more boost which in turn put's more air through that hole which could be making the noise.

take it into nissan and say there is a leak in the intercooler and its making a weird noise, if they say anything suss tell them to take it off and pressure test it. and BAM new intercooler