Hello dear friends, I am sorry but once more I am seeking advice. Recently I have heard an unusual whistle from somewhere under the bonnet when driving. I have noticed that it can be made to start or stop by reducing or increasing the throttle. I must admit I first thought that it was coming from the air intake but I am not so sure now. Another fault I have may be related, the engine seems to misfire when cold. I have replaced the water temp sensor but it has made no difference. I am now wondering if I have an injector that my be faulty. I would really appreciate some advice.
Kindest regards, Danny.

 

The symptoms you describe are indicative of a vacuum leak. I'm going to assume that the whistle sound increases when you let off the throttle or you are at a steady cruising speed. The cold misfire could be caused by "false air" coming in to the engine from a leak that isn't being measured by the airflow meter and causing a lean condition that the cold start enrichment can't overcome..

I'd start with a visual inspection of all the hoses/tubes and connections of the vacuum system, the air intake tract downstream of the airflow meter and the vacuum line to the brake booster.

I've had some success locating leaks with a propane torch (unlit, of course) by introducing propane gas to potential leak locations and listen for the idle to smooth out as the propane replaces the 'false air'. If you can find it, a can of spray ether starting fluid will work too, but isn't nearly as controllable as the propane.

If a visual inspection and a little propane fail to show the leak, you might want to take it to a garage that has a smoke generator for finding leaks. They would introduce smoke (I think they use something akin to baby oil heated to make smoke) at a slight positive pressure into your intake (after plugging your exhaust and AFM) and look for the smoke escaping from the leak.

 

Thank you so much, I will start looking and report back. I appreciate your help.
Regards, Danny.

 

Ditto.

Vacum leak. Much like a wood wind musical instrument

 

Yes, like a clarinet! BTW the noise eases when I reduce the throttle, so I hope the earlier diagnosis still holds good?
Many thanks for your input.
Regards, Danny.

 

light up a big tobacco, disconnect a vacuum hose and blow the tobacco smoke through it.
it has to come out somewhere!

 

While I would expect that the noise would increase as the airflow through the leak increases (less throttle is more airflow through the leak) - it ain't necessarily so.

Noise is just something vibrating, and everything has a natural frequency.. Perhaps the leak's natural frequency occurs occurs at a lower flow rate of the leak (throttle open) than the higher one (throttle closed)

I'd keep looking for a vacuum leak.

If your car has a air pump like mine (not sure the UK models do) I'd also be looking there.for an air leak

 

I am most grateful for all the great advice, I now have a clue where to start. I will be back with my progress soon.
Kindest regards, Danny.

 

A streak of memory just hit me. You commented that the whistle is heard while driving and that throttle position effects it. !!!

Sounds are wonderful and mysterious things. One may think the origin is in one place and actually it is elsewhere.

Am I right in that the driver's window is down as you drive?

If so, the fnisher on the door is right there. The rubber plug at the top might be gone. A near perfect wind whistle. Speed effects it. The throttle effects speed.

Connect the dots, so to speak...

Carl

 

Thank you Carl for your thoughts. I get your drift and yes, the small tube without its plug may well cause a whistle. But no, the plug is firmly in place and the noise is definitely coming from under the bonnet. The more I think about it, the more I am sure I am going to find a leaky vacuum connection. I expect to be able to spend some time on it later today.
Kind regards., Danny.

 

Yes this is a superb way of finding vacuum leaks, basically simulating the workshop $1000+ smoke machine for just a few bucks

 

Brilliant! Thank you for finding that youtube video.
I haven't had a chance yet to investigate but I shall soon and be reporting back.
Regards, Danny.

 

You'll need to take Scotty Kilmer with a grain of salt. (the person in the video) A couple of pints beforehand wouldn't hurt either.

https://jalopnik.com/this-emmy-award...shi-1696524549

 

Hi,

I have been experiencing the same symptom. I have also observed the right side of the engine, where the noise is coming from, is running a bit lean. After spraying carb cleaner all around the right bank I noticed there is a vacuum leak on the throttle body spindle seal. Check that one out...

 

Many thanks for your input. The noise is definitely coming from the right side.
Your conclusion sounds very likely in my case.
Assuming that is my trouble, what would be the cure? A replacement throttle body or can it be repaired?
Many thanks, Danny.

 

I got hold of a pair of used spindle seals from another car. So I am gonna install them, re-adjust the throttle linkage, clearance etc. and try it out. I also saw you can buy new ones rather cheap from SNG BARRAT

 

My dear friends,
I am happy to say that I am very hopeful the cause was indeed the rubber butterfly shaft seals. I removed the throttle body and found that the seals were worn. I have also had to order two new shaft screws that secure the butterfly flap because once removed they cannot be re-used due the the fact that a slot is cut into the base of the screw to lock in place. I have also ordered a new throttle body gasket.
I am not sure if I should use a sealing compound when re-assembling?
One other point I was pondering, when I removed the throttle body I noticed there was a quantity of black oil sitting in the bottom of the inlet manifold. Bearing in mind that this is the first time the throttle body has been removed since 1984, I suspect it is nothing to worry about?
I would welcome any thoughts or comments.
Kindest regards, Danny.

 

Eureka, you found it. And the fix is available. Win-win !!!

Dirty intake manifold floor. No issue for daily driver. No angst needed there,

Kudos.


Side bar:

Charged the depleted battery in my "lump". About 6 hours on the Schumacher "Smartt" charger took it from 35 % to 100 %. Slick, it fired almost immediately, Fast idle at 800 rpm's and then dropped to normal at 500. rpm'. Bang the pedal and it responds, "lets go..."...

Carl