86Rexguy

Hey guys,

My car makes a weird, loud humming noise at idle. Stops at about 1000 rpms. Doesn't sound like a vacuum leak.... much louder. Its always done it, at least the 2 years Ive owned it. Seems to be coming from the front of the motor, but cant really tell. Anyone have any ideas?


-George

HAILERS

Pull the exaust hose off your acv and see if its relieving air pressure at idle. It should not be doing so.

86Rexguy

I really hate to admit it- but, I have no idea what the ACV is. Help?

Im still a rotory idiot. I bought the car in Jan of 00' as a commuter car- and havent had enough problems to learn a lot about it. The only problems Ive had were the slave cylinder went out about 2 weeks after I bought it, and the front U-joint went out, thus needing to have the driveshaft custom worked to repair (still friggen vibrates though, has for 1 1/2 years). So, Im not sure what any of the anatomy on the rotory motor is yet. Its been a great car, so- it's left all my spare time to my 96 Trans Am.

HAILERS

The air control valve is on the right side of the engine. Its about in the middle of the side of the engine. It has a black one inch approx, hose that goes from the air pump to it. There is another black one inch hose located at the bottom of the acv. That hose goes fwd to the right hand fender where there is a silencer or muffler for it. I thought someone might have left the black one inch hoe off the bottom of the acv. Its also a possibility that the black hose that goes to the air filter is off, making a humming kind of noise. Or it could be some other thing.

HAILERS

Here's a jpg of the engine and I circled, not too successfully the acv. I painted in red the outlet that you should find a black, approx one inch hose on. I thought maybe this hose got left off. No air to speak of should come out of this hole at idle, if the car is warmed up.

Felix Wankel

Also check the air pump hoses. I think they will make that sound if one is off.

BTW, the driveshaft vibrates still, because the u-joints are non replaceable. Grab a good one fron the junkyard and the vibration will go away.

86Rexguy

Wow- are you the real Felix Wankel?? If so, Im honored! If not- Im an idiot for being gullible.

Anyhow, sorry guys, for not checking this forum for a couple days. I havent had a chance to check this out yet, and its getting dark outside here now. Im gonna run out after I post this to take a look at the hoses. Ill let y'all know what transpires.

As for the U-Joints, ya, unfortunatly, I know they're not replaceable. I found out the hard way two years ago. I had the front yolk replaced with a chevy yolk, and a new u-joint attached to it. It solved a majority of the problem, but it still shimmied still after I picked it up from my mechanic. He tried talking me into have bolt ends done, but I was on a tight budget, and only had the front done. Something tells me the rear is bad too. Its been doing it for 2 years now, and hasnt gotten any worse. Trips above 90 mph are brutal though. You dont even notice it till about 45 mph. When the front went bad, you couldnt do over 40 without the car seriously feeling like it was going to shake apart on the road. My shifter is loose as heck from that (I drove it a good 60 miles after it's faliure), and a good 10 cracks formed on the dash from it too.

So, Im thinking the rear needs replacing, but, I can't find an RX7 in a salvage yard, or parting out in the papers for the life of me. I found a couple, and they had 200K+ miles on them, and I didnt want to take the chance. Having the same custom work done is way too expensive for my blood too.... it was $400 to have the front yolk done back then. I dont particularily want to do it again... and frankly, couldnt if I wanted too.


-G

86Rexguy

Ok, update-

I ran out there, but it was a litle too dark to see the hoses, and if they had cracks in them or anything. I went to the passenger side of the motor, and it definatly seemed like it was coming from there. But, it was tough to tell. I ran back and forth from one side of the car to the other, and only came to the determination, that the sound is much louder from the DRIVER's side of the car. And as silly as it sounds- with it as loud as it was, it was very hard to tell where it was coming from. But the sound goes away almost completely if you give it a touch of throttle. I just can't tell. it doesnt seem to be causing any problems.... its been doing it forever. its just annoying as hell