OK, so I've done quite a few mods recently and I noticed that there is a hissing sound behind the dash. I have a K&N FIPK, but it sounds liek it's in the cab. I have teh FIPK on my 4Runner and it isn't nearly as loud.

I was wondering if there are any vacuum lines in the cab to look for?

The hiss goes away mostly in park and neutral and is loud in gear. Would this cause my truck to feel sluggish?

Just curious if anyone else has experienced this.

Thanks, Seth

 

does your heat and ac work if it is a vacuum leak i could only think it being vacuum control for the heat and stuff im not sure if our trucks have that or not but its a possibility

 

the hvac controls are all i can think of. If I remember correctly from my 94 dakota, they are on vacuum. everything works,but there is a significant delay when changing zones (defrost to feet or main vents,etc.)

im going to open the dash tomorrow and search for leaks.

im really curious if this kind of leak effects the engine or tranny.

 

I tore the dash apart today and checked out the HVAC controls. I couldn't seem to locate a leak there and everything seems good there.

I went under the hood and secured the hose onto the crankcase breather with a hose clamp, since it appeared loose. Didn't really do much, though.

I took the air filter off and ran the motor. at idle, it hisses by the IAC, but this is to be expected.

With the dash apart in the cab, I hear the hissing get more intense when it is put in gear or when I step on the brakes sometimes. I'm almost certain this is not the K&N as this doesn't really change the idle or throttle.

With the dash off the sound seems to be closer to the steering collumn than the center of the car. Is there anything in this vicinity to check?

 

i cant think of anything... its a weird problem what about the vacuum line to the brake booster ot the booster its self that is the only thig i could think of

 

Thanks for the reply Dodge8691

I'm really starting to miss my Toyota Forums, there are way more people willing to help on there. It's relatively inactive over here. It seems like a couple times now people are quick to use the "Check the FAQ thread", like I haven't been there a million times. LOL I'm beginning to think most people don't have any knowledge to share on here.

Are there any other good 1st Gen Dakota Forums you can recommend?

 

This is the best one that I have found.

Dakotas are no where near as popular as Toyotas and as such, you're going to have less of a following.

If you're patient, this place can provide plenty of insight. It seems like you're experiencing an uncommon problem (unidentified hissing behind the dash), which will make it harder for guys to give you help with.

I would recommend having a buddy help you locate the source of the hiss(if you haven't already). If it's near the column, the brake booster or clutch cylinders could be your problem.

I say if it's not affecting performance, let it go. Old trucks rattle while they roll.

 

Like he said this is the best one around all the others are usless if you are patient you will get some responce an no problem I do my best to help so when I need it hopefully others will help me out

 

Hey, if you havn't found that vacume leak behind your dash it's most likely the speed control. Check to see if there is a small vacume line running off the connector on the powerbrake booster where the larger vacume line is connected. This small line will run through the fire wall to the speed control if your truck is equiped with one.

 

Does the hissing sound change when the brakes are applied? Try undoing the vacuum line on the brake booster. Plug the line and then start the engine. Does the hissing continue? If not, I would bet money on a internal leak on the booster. If the hissing does persist, do a closer examination of the hvac controls, as those are the only other thing that is related to vacuum, as that is what the hissing sound sounds like to me.