Ongoing turbo noise

[apc01]

This issue has been bugging me for over 2 years now and continues even after a complete professional turbo rebuild/recondition and visual inspections by mechanics.

During colder weather especially as we approach winter the turbo is extremely loud when it hits turbo boost, so loud in fact that people walking along a street stop to see where the noise is coming from. Putting my foot down the noise is so loud that I am reluctant to do it at all. The noise is difficult to describe but is sort of a loud hissing, rasping noise that is definitely not mechanical.

Here is the really strange thing however - as the ambient air temperature outside gets warmer and warmer the turbo becomes quieter and quieter until when the air temperature outside reaches 74 degrees in the Summer it is almost completely silent as it should be. As we approach Winter and air temperature falls it is becoming extremely loud.

I can only surmise that there is a small hole somewhere that expands as the air temperature increases, thus sealing the leak. Engine temperature has no effect.

All comments, suggestions most welcome.

Thanks.

 

[clivehorridge]

I suppose you've checked/replaced all hoses and securing clips?

Are the hose joints sealed with a compound?

The hose clips vary in effectiveness from one type to the next, have you replaced them?

Others may be along with some more inspiring ideas.

I don't even own a turbo

 

[StarCruiser]

Is your air filter one of the original Toyota ones or an after market? My turbo noise increased when I fitted a K&N, so it's back on the shelf at the moment.

 

[apc01]

Thanks for the replies.

The hoses and clips have not been replaced yet - the mechanics where I take it say they cannot get the parts to do it. Any suggestions where they could get the parts are most welcome - not a Toyota dealer of course - costs way too much.

The air filter is original.

The most significant factor is that the turbo varies between almost silent when the outside air temperature is 74 degrees or above to screaming loud when it is cold outside as it is getting now.

 

[Animal Mother]

My bet would be a loose (or damaged) turbo downpipe.

For turbo clamps, look for Mikalor online. The like of Demon Tweeks has them.

 

[apc01]

Thanks for the advice.

Any idea where I could get the new hoses from - not sure how many are needed even.

The mechanics I use have not been able to visually find any leaks so far, but my guess is the leak must be very small, otherwise warm outside temperature would not seal it. The fact that engine temperature does not affect it would suggest the leak is far enough from the engine.

 

[Shayne]

Positive crankcase ventilation , a leak in that pipework will sound like severe turbo problems .

 

[apc01]

Positive crankcase ventilation , a leak in that pipework will sound like severe turbo problems .

Thanks for the suggestion Shayne. Are these far enough from the engine so as not to be affected by engine temperature as opposed to outside air temperature.

I guess the issue the mechanics have is that if the motor is revved when stationary there is not turbo noise at all, it is only when it is being driven when reaching turbo boost the loud noise happens, so difficult to identify in the mechanics workshop.

 

[Shayne]

I don't know your engine but i doubt anyone did all that work to your turbo without making sure its working correctly besides which its a simple thing to test the pipework for leaks when the turbo is out . The down pipe suggestion is a good one i reckon but that gets so hot saying heat might effect it just doesn't add up .

The crank vent though does nothing , or at least on my 3.0L its just a pipe that nobody would ever look at . It puts crank gas back into the intake pre turbo .
The heat question might be answered by the fact there should be no piston blowby unless the engine is under load , when accelerating the heat goes up and so does the blowby so the pcv pipework is pressurized opening the the hole and letting out a howl .

When my crank vent pipe split it sounded like a howl caused by vibrating metal . As i say i don't know your engine but on my truck replacing the pipe is a 5 minute DIY job and i think Toyota charged me about 40 quid for the pipe .

 

[SteveS]

Just some thoughts - apologies if they are sucking eggs....
1 - are you completely sure it is the turbo? I'm thinking in the cold/winter there is a very different electrical load on the engine
2 - the other thought I have is (and this is perhaps just a wild guess) is could this be caused by the cold air/density.....is there a sensor for that?
3 - have you considered running the engine with the car stationary - this way the components will heat up - and then seeing if your screeching noise still happens
4 - turbo on boost creates full torque - is the noise related to an indirect effect of the turbo putting load on cold items elsewhere - possibly on cold/thicker fluids, auto box, etc etc
5 - can you get your mechanic to use an 'engine-ear' to record the source of the noise as its sometimes difficult to be sure where a noise is coming from
6 - can you record the noise on your phone and post it here?

above may be stupid ideas but you never know; when all else fails.....

 

[StarCruiser]

Any leak in crank case vent or intake pipe work will be accompanied by oil leaching out. I would look for oily leaks around the intake pipework and intercooler if you have one. Everything between the turbo and the inlet manifold. While at idle, i.e. Off boost, there will be slight vacuum at any leakage point. You can use a gas lighter refill aerosol to puff gas around joints and see if the engine note changes (speeds up). Obviously do this in the open away from any sources of ignition and in small quantities. If yours has an intercooler, a split in that may open up in the cold but I would expect oil around any leak. Of course, being where it is it may not be obvious which is where the gas comes in.

 

[apc01]

Thanks both for your suggestions.

I finally, with the help of the mechanics I use located the cause - it is a leaking inlet manifold. What appears to have happened is the gasket shrunk and the bolts came loose. The bolts have now been tightened which has greatly reduced the noise, but there is still some noise that should not be there. The garage could not locate replacement gaskets so contacted a Toyota main dealer which quoted £32 each - they reckon two are required. That plus up to 3 hours labour makes it not inexpensive.

Any further suggestions welcome, in particular where to get sensible priced gaskets.

 

[StarCruiser]

Pleased for you that it's found.

Amayama for your gaskets or try Simon Holton on here (search) mine for my 80 12v were not expensive and I did the lot otherwise you're going to get problems with the manifold sitting partly on thicker new gaskets and partly on older compressed gaskets. I also managed to remove every stud and washer rather than just the nuts and slid the old gaskets out and the new ones in as they are metal with bonded rubber. It wasn't a bad job TBH, probably about an hour to 1 1/2 hours. The worst was dropping the damn studs!! I never did find one of them.

 

[fbnss]

Pleased for you that it's found.

Amayama for your gaskets or try Simon Holton on here (search) mine for my 80 12v were not expensive and I did the lot otherwise you're going to get problems with the manifold sitting partly on thicker new gaskets and partly on older compressed gaskets. I also managed to remove every stud and washer rather than just the nuts and slid the old gaskets out and the new ones in as they are metal with bonded rubber. It wasn't a bad job TBH, probably about an hour to 1 1/2 hours. The worst was dropping the damn studs!! I never did find one of them.

think you've just answered your engine vibration noise!

 

[StarCruiser]

think you've just answered your engine vibration noise!

Please explain, oh wise supplier of chicken pieces…

 

[fbnss]

The worst was dropping the damn studs!! I never did find one of them.

 

[StarCruiser]

Well, I did buy a new stud, rubber washer and nut and fit them. And the vibration was there before and after. It would have been great if that WAS it, but alas it persisted, I'm afraid.

I have, however, recently discovered a fuel problem that MAY have had some bearing on the vibration issue. It's early days so I'm not counting my chickens.

Chickens? We seem to have gone full circle