Noob needs help 91 X-cab V-6
 

Hey guys,
I have a 1991 x-cab SR5 pickup with the V-6 3VZE engine. A few months ago I had to replace the fuel pusation dampener on the back of the fuel rail due to a fuel leak. To do so the whole intake plenum had to be removed to access the dampener. I got everything back together with new gaskets ect. and everything has been working great. All of a sudden I have a strange wistle sound comeing from the engine while I drive in 2nd and 3rd gear.(only times I really notice it) The sound only occurs while I am steady on the gas peddle. If I accelerate or let off the gas the sound stops :think: I have replaced a few old looking vacuum lines to try to solve the problem with no such luck. I have also rechecked the torque settings on all the nuts and bolts removed during the plenum removal and everything is nice and tight. Was wondering what you guys thought and if any of you have had similar issues?? Thanks, any help would be much appreciated!

If you think its vacuum just get some carb cleaner or ether and spray it around different spots where it may be leaking and listen to the idle. It should go up if you spray it on a leak.

Probably only does it at certain RPMs because there has to be a certain amount of air/speed of air sucking in it.

Thanks I will have to give that a try. Its frustrating because it doesn't make the sound when its in neutral. If I try to make it whistle it wont unless i'm driving which doesn't really make sense for a vacuum line. That's just my best guess what it could be. You would think if it was actually a vacuum line it would do it all the time?? It only seems to happen when warm as well... Its got me confused.

Yeah just spray it in different spot individually so you know where the leak is (if there is one). Maybe it just has to be under the right load. and it should also idle weird if its leaking. and if its only when warm maybe its because of expansion and contraction of the metal intake. It may all expand/contract just right to make it leak a little?

It sounds appropriate, especially since you took the intake off and all. Its easy to miss all those lines. And id go buy about 20 feet of vacuum line and replace all of it. It takes an hour or so, but its worth it so that you dont have to worry about those ever again. But other than that just make sure its not leaking at the intake. maybe a crack in you intake tube?

What about a locked up fan clutch? That'd be more of a howl though. A belt slipping? A/C tensioner bearing? Idler bearing? But yeah, try the carb cleaner first.

I've noticed the same thing on my 97. Also a v6 but not the 3vze. I thought it might be the throttle body so I cleaned that and then used sea foam but no change.

On mine it is fairly quiet and only happens when going about 30 mph. That's a good suggestion on replacing all the vacuum lines.

So the carb cleaner worked. It was a vacuum hose after all. I still need to get 20 or so feet of hose as you mentioned and replace the rest of them. I only had about a foot or so laying around the garage. After replacing a fairly loose hose the whistle has quieted down substantially but there is still a faint noise. I think once I replace the rest of the hoses it will go away completely. Thanks again for the help and suggestions guys.

Thats good to hear about the vacuum hose. I tightened my throttle cable last saturday and I haven't noticed it since then either.