Strange high pitch sound - Need HELP!

[Oliver]

For sometime now, my engine has been making a strange sound?.

My car is a 94 FD.
The sound is coming from under the pressure chamber and extension manifold. To best describe the sound. It\'s a high pitch squeak or squeal. Almost like a Morse code used in the military with long and short sounds.

The sound will only start after the water temp gauge reads between 93C - 95C. If I shut the motor off after a normal drive and the water temp is under 90C, there is no sound. If I let it sit for a few minute and restart the motor (motor starts to heat soak) the temps rise, the sound also starts. Again, anything over 95C the sound starts and once the temps cool to around 88C - 90C the sound will start to fade away :confused:

The sound is not a drive belt or the air pump (I have checked) and I don\'t believe it\'s a vacumn hose but possably a solenoid?? I have suspected the Air control valve because I have heard it can make this type of sound.

After using a plastic tube and placing it to my ear. The strongest sound seemed to be traveling through the large vac hose under the pressure chamber (*see photo below*)

Before I begin checking for bad check values and solenoids. I was thinking of removing my PFC and reinstall the stock ECU to run an error code and see if anything shows up?

If anyone has any suggestions or ideas of what may be causing this strange sound. I would greatly appreciate your help Thanks.......

Oliver

[clive]

Hi Oliver,

How about an air leak from the gasket where the main manifold comes up from the side of the engine and meets the bananas over the top ?

Have you got a boost gauge if not it maybe worth fitting one so you know your boost pattern even if only temporarily while you track this problem .

All the best Clive
clive@mazdarotaryclub.com
//www.mazdarotaryclub.com

[Oliver]

Thanks Clive

I replaced my vac hoses last year and when I re-installed the manifold I just used the old gasket. It looked to be in great condition at the time. I also used the plastic tube to my ear to try and find any air leaks around the manifold but as you know. It is very difficult because there are so many things in the way. Looks like it might be worth checking again  

I have a boost gauge along with the PFC. It has always read a steady pattern around 11.5-9-11.5. Sometimes hitting 12 on the primary on a cool morning with a intake, dp, exhaust, and smic mod\'s.

Again, thanks Clive. I hope I can figure it out soon, it\'s starting to drive me alittle crazy. It\'s just wierd to me that it only makes the sound while the motor is at a certain temp. If it was a boost leak, I would think it would happen at different rpm\'s or something??

I have alot of searching ahead

[Oliver]

I had a chance to drive my FD late tonight and while the car was warm and the sound was present. I moved the pressure chamber out of the way and sqeezed the large vac hose in the first photo I posted. While the sound was chirping/ sqealing..... After sqeezing the vac hose the sound stopped! !!
So, my next question. Can anyone explain to me, what the green and yellow colored vac hoses (photo below) do with relation to me cutting off the flow with my fingers??? I still do not believe there\'s a cut in the vac lines but maybe something to do with the Waste control and turbo control valves? I understand the function of the values but not why the sound starts after the water temp hits over 93c and stops after I sqeeze the hose??

Just thinking out loud hoping someone has a good word for me! I will test the flow and resistance of the valves on Sunday.

again any suggestions??

Thanks

[Oliver]

try again......... photo was to big .

[apexkw]

well it looks like the green lines that go into the block are the oil metering pump lines...otherwise known as omp lines.  these are a critical part for a rotary engine because they supply oil into the rotor housings.  by inserting oil into the rotor housings it lubricates the rotors.  i have seen people remove these lines before but they always run a mixture of oil and fuel when they fill up the gas tank.

[apexkw]

the other lines appear to read whether you have vacuum or not.  this would make the omp increase or decrease the flow of oil into the rototr chamber.  on my single turbo setup i have it so that the omp is constantly under vacuum.  i would think that you have a bad solenoid or vacuum line...and in the worst case a bad oil metering pump.

[Oliver]

Thanks Apexkw

I tested 2 solenoids and checked all the vac hose running out of the solenoids, plus the larger vac hose (yellow in the photo) ....they were all ok. Will have to pull the manifold off again to check the other 2 farther in

Thing is, if it\'s a bad vac hose....why does the sound begin around 95C and go away again when the water temp drop?? Never heard anyone discribe this type problem before. I don\'t see any boost problems with primary or secondary and the car is just as strong as the first day I bought it. wish I had a tuner near buy...I\'m sure it\'s something simple...just cant find it yet.

Thanks again

[Oliver]

UPDATE .......Problem Fixed


I purchased 2 new oil injectors and 2 (plastic) oil pipe lines. I have been driving my FD for almost a month and the sound is gone! Just wanted to post this incase someone runs into the same problem someday.

[Oliver]

Injector lines

[Oliver]

connections on top

[Oliver]

one more......

[Oliver]

And under the motor.........

[Glenn Butcher]

FANTASTIC THREAD OLIVER!!!

So it was the Oil Injectors themselves that were making the noise? or only one of them?

Or was it the vacuum connection to the oil injectors.

Well done mate!

[clive]

Well done Oliver for finding such an obscure strange fault and for sharing all your information and findings with us, as l realise this little noise must have taken many hours to sort !.

Many thanks,Clive
clive@mazdarotaryclub.com
//www.mazdarotaryclub.com
//www.mazdaRX-8club.com