Whistling noise at 2500 RPM?

[sniperFM]

Hello, and a happy new year to you all!

Over the last day or so, my 1995 2.5td AFT has developed a strange whistle at 2500 RPM's? It anly occurs when driving, not when idle revving the engine. My friend suggested it may be the exhasut manifold becoming loose? Anyone got any info on what this may be? Is 2500 rpm's when the turbo kicks in and could it be this in some way at fault?

Any help greatly received.

Kev.

[MAZABON]

sounds like i could be the manifold, have read a few threads about warping of the manifold

also i have seen a few refering to the studs whistling, normally No1 stud

[sniperFM]

OK, great!, will have that checked out! hopefully not too much of a job?

[wonkanoby]

soapy water n cold engine then start should give a clue...ie bubbles

[Bob]

No 1 Exhaust manifold stud breaking isn't that unusual. I've an idea there is a Fact Sheet in the Member's Area.

It isn't all the world.

[Northern Bongolow]

turbo usually comes in below that,at about 1900rpm,sounds like a manifold stud.
take off the turbo tin heat sheild,then put a spanner on the manifold nuts,one or more could be gone but still sat there doing nothing. my no 1 went,and the manifold needed skimming,and no8 was about to go.
if replacing the studs,make sure you use exhaust side studs and nuts,not inlet side,these are heat treated.
land rover exhaust studs/nuts are the same,and a lot cheaper than the gen mazda ones.

i did a factsheet thingy/thread with pics,it will be buried in the archives somewhere?

[bigdaddycain]

But before you start any intrusive investigations... Have a quick check that the lid to the air filter is securely clamped down. The air filter can whistle a bit in harmony with the turbo if the air filter isn't seated securely, 2500rpm is low boost range, pretty much as the turbo has spooled up, i know i can hear my turbo most around the 2500rpm mark.

[sniperFM]

OK, got an update, the whistling noise is now more of a squeeling noise and it is now lower than the 2500. It only seems to occur when i accelerate....if i am just cruising at the same speed it does not happen. as soon as i accelerate, i hear the noise...Do you guys think this may now be the turbo? If so, how much ball-park is a new/or reconditioned one? are they hard to come by?

Thanks for your wisdom guys n gals!

[wonkanoby]

you sure its not a fan belt slipping

[francophile1947]

OK, got an update, the whistling noise is now more of a squeeling noise and it is now lower than the 2500. It only seems to occur when i accelerate....if i am just cruising at the same speed it does not happen. as soon as i accelerate, i hear the noise...Do you guys think this may now be the turbo? If so, how much ball-park is a new/or reconditioned one? are they hard to come by?

Thanks for your wisdom guys n gals!

Exactly the same symptoms as my number 1 manifold stud Have you checked it for tightness?

[sniperFM]

I am having it removed this weekend and will probably replace them all to see if that works! I drove around the block last night with the passenger seat up and my mechanic mate kneeling in the footwell! he thinks it sounded like it was possibly coming from the manifold, but was hard to tell. This weekend will tell i suppose

Thank you for your input!

[phoenixroxy]

hi there, if it happens approaching 2500rpm. this is when the turbo kicks in. same thing happened to me.

you could only hear it while driving. turned out to be wear in the turbo impeller bushes. i replaced the turbo with a used one off ebay and no noise ever since.

rule out any other possibilities of course cos changing the turbo was a pain in the ass lol

[sniperFM]

do you mind me asking, how much was the turbo?

thanks.

[phoenixroxy]

hi mate think i paid about 100 quid for the turbo. bit of a gamble though cos there is no way of knowing if it was in better condition than my own.

[bongonaut-evv]

Hi I have a similar problem and it is the exhaust manifold gasket blowing at number 1 stud (behind alternator) at first I thought it was a belt squeek. it wont make a noise on idle or when cruising (eased off accelerator) because there is not enough exhaust pressure to force it out.