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Triumph TR6 - Whistling noise

So far, in my adventures as a new and ignorant TR6 owner, the people who post here have been very helpful. I kind of know what all the things under the hood are now!

My new question is about a whistling sound I hear when driving, usually when decelerating. It may be doing it on acceleration too, but the exhaust is loud enough that is difficult to tell. I presume it's a vacuum issue somewhere. What do you guys think it is and how do I start checking it out? Thanks as always, John.

Start with the carb connection to the carbon cannister - I had a nice whistle there once.
Brent B

I whistle all the time John.

BY THE BY...... When you going to join this erstwhile group? Hmmmmmmmm?

Vacuum leak, yep, yep, yep. Brent has seen it too.

When you are decelerating you are creating a TON of vacuum. Remember, if you will, that an internal combustion, reciprocating engine is a PUMP. It really is.

SO... when you decelerate and the engine isn't 'working' you'll hear the whistle more betterererer.

By the way, now that you've figured out what all that stuff is, would you please tell ME? I'd sure like to know too. <G>

Jim Deatsch

Brent, on a 71, there doesn't appear to be a vacuum from the carbs (Su's) to the cannister. But it has to be somewhere!

And Jim, how do I join this erstwhile group other than posting here? With as much help as I need, I will gladly join.

Thanks, John.


First of all, go to:

Then, on the right side of that screen you'll see "Membership Access". Select "Triumph".

The next screen will give you the option of 'logging in' or to "click here" if you would like to register.

Jim Deatsch

Okay, Jim, I am now officially registered! Will this make the whistling sound go away?
JL Bryan


You'll never have to worry about it again. THAT'S how the administrators goad people into registering. ><

Jim Deatsch

JohnB - Oh, SU's... What do you connect the valve cover breather to - just the carbon cannister?

Sounds like besides a potential manifold leak it could be the brake booster. If you have a whistle at idle disconnect the line to the booster and put your finger over the vacuum side. See if that stops the whistle.
Brent B

They keep changing my name! Brent, I will look when I get home, but I believe the valve cover breather is connected only to the air filter cover. Weird.
JL Bryan

that's perfectly fine depending on what intake manifold you have John.

Mine goes from the intake manifold to:

1. The brake booster.


2. from the PCV valve to the rocker cover.

My only concern with John's setup would be that ther is, apparently, not a PCV valve in the line.

Jim (just another opinion)
Jim Deatsch

My '71 has a dedicated hose from the intake manifold to the vacuum assist brake unit. Another set of hoses connect the charcoal canister, rocker cover and both carbs (ZS). No PCV valve or connection to the air filter cover.
EC Smith

Hi Charlie and good old whats his name :)

yep the newer 71 and 72 have just the lines but there are nylon restrictors in the hose ends for the canister and front carb. Reduces air intake and front lean out at throttle off and low. I don't pretend to understand it completely but thats whats there. The original T fittings openings are a lot smaller than the current stuff for 3/8 hose as well. I think 3/8 is whats on them?

Problem with intake from crankcase vent to air cleaner would be needle contamination from crank vent and carbs being fed hot gassy air full tilt. The carb vac intakes on the ZSs are behind the butterflys and quite small as well internal if I remember right..

Speaking of hot air don't listen to Jim! The only thing that will make your whistle go away permanent is purchasing a top Highland Single malt Scotch and immediate shipment to the address that will be provided. If you decide to fall for it, I mean agree to it. Hey where here for you whatever your name is. :)

RickC you might want to check for those restrictors as well if your still have that front lean deal? Restrictors only on front carb for some reason? Something I didn't really think about till this post.

CharlieB by the manual yours are reducers both front and back we seemed to get quite a response playing with the canister valve on yours?

Too much air intake manifold behind carb for mixture to compensate? Hope that made sense?


Bill Brayford


I think you may be confusing me with someone else as all I have done to this point on the carbs/vacuum line setup is to replace hoses.

When a host of other needs are addressed then I'll focus on ignition and then carbs. Just throwing 2 cents in where not needed!

Have Fun,
EC Smith

Thanks, Bill, Brent, Jim and everyone else. The SU's have what appears to be a vacuum fitting on the rear carb, with a hose to the distributor. At Jim's suggestion, I checked that a week or so ago with a vacuum gauge and there doesn't appear to be any vacuum, although I have no idea why there would be a line from it if it serves no function. The whole setup is totally different from the ZS-no pvc valve or anything. I was hoping that someone might have bought a set of these things from TRF or Moss or someone and still have any instructions on how to hook up the plumbing. If not, I'll just fake it, but it sure likes a bad idea to run the valve cover breather back into the air filter assembly. It almost seems like it would be better to have it just go out the bottom of the engine compartment or something.
JL Bryan

I tried routing the valve cover breather to the bottom of the engine compartment, but hated it. Had a bad oil smell while driving, and working on the carbs when idling was just plain nasty! Went back with a "high tech" separator to take the oil out of the stream, and routed the gases to the carb fittings. I collect about 1/2 qt of oil every 150 miles and pour it back in - the new baffle installed in the valve cover should hopefully reduce that further.

So really, since your SU's don't have the "pollution" fittings, it makes sense that the hose goes inside the air filter assembly so that junk is burned.

A hint of garlic in the exhaust
Brent B

Hi aimed at Charlie Ballard he doesn't post much but reads frequently. Sorry for confusion.

John you likely still have the original intake manifold theres usually 2 holes 1 for brake Vac and one other. Probably closed off? If there is one I would restrict it though so you don't have full vac.

Bill Brayford

This thread was discussed between 21/09/2003 and 24/09/2003

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