Making 3.1 MPFI V6 Smoother/Quieter

[CutlassSL91]

Is there any way to make a 1991 3.1 v6 smoother and/or quieter? Mine is really noisy upon accelaration, and i heard there is some part that the 1992 or 1993 3.1 had that made it a lot quieter, any ideas? The exhaust is not an issue, because it is all comming from up front, and the firewall seems to be sealed right up. There is nothing mechanically wrong with the engine or trans

[95oldsVan]

Are you sure the exhaust is tight?Check the seal at the back of the exhaust manifold to the main pipe.If theres any looseness or holes,its gonna get noisy.I know you said its not the exhaust but just wanted to make sure you had it all checked.All it takes is a small rust hole or loose joint seal and it can whine like crazy.

[THe_DeTAiL3R]

Things like waterpump, AC compressor, alternator can make noise up front.

 

Aside from that, I there isn't really much you can do. They are noisey pushrod engines...

 

You can try experimenting with different kinds of oil, you may get some sort of result, but nothing dramatic.

 

What kinda mufflers are you running, and do you have a resonator?

[CutlassSL91]

i bought the car with the original exhaust which was fairly quiet and a rotted out cat. I had a brand new cat put in and magaflows which i am soon about to replace because its too loud for being my daily driver, they will be put to better use later on. At idle (with the quiet exhaust) the engine was nice and quiet, sounded very good, but once you take off you can hear the raspiness and the rush of something (must be water pump?). I know the 3100 engines are so much smoother. Is there something to coat the manifolds with to seal them up?

[Supreme Cutlass]

Is there something to coat the manifolds with to seal them up?

 

 

Are you sure it's not just a bad intake gasket?? If it's running really rough that might be your problem. My 3.1 isn't all that rough compared to my mom's vtech (all things considered).

[CutlassSL91]

idk, maybe it is just supposed to run the way it does, it really isn't that its really rough, but i guess i am just to the newer quieter engines like the 3100, and 3800 V6. I had heard once on here that the later 3.1MPFI V6 engines had some rubber seal on something that made it smoother

[DaveFromColorado]

There might be an issue with the engine, I'd try to find that before anything else ...

 

well, there's some things you can do to make it a bit quieter ... for starters - if it's actually the drivetrain that's noisey, you can dynamat the transmission itself, on the case right near the firewall - some people do this to help get rid of a false knock signal.

 

the other thing you can do is get the "dyna-mat Hood Mat" stuff, and line your hood, front fenders and firewall with it - it's time consuming, and expensive, but it will make it a whole lot quieter (and heavier too ... I'm gonna do this to my Buick ... dynamat every surface I can get to)

 

an other thing you can do is cut the exhaust off right at the engine - I'll bet you don't hear any noise over the exhaust anymore.

 

or a loud stereo system ... every time you hear a new clunk, or clattering, just turn up the radio a bit more.

 

--Dave.

[CutlassSL91]

thanks for all the suggestions, i will have to try them out!

[cutlsp]

or a loud stereo system ... every time you hear a new clunk, or clattering, just turn up the radio a bit more.

 

--Dave.

i'm guilty of doing that....... :oops: and now look at my cutlass its dead as a door nail :?