I have a total newbie question. Over the past few days my 4WD wagon has started to sound like your basic Briggs and Straton riding mower . I recently replaced the entire exhaust (with a lot of help) and am thinking the bolts may have come loose...or maybe I knocked one of the vacuum hoses free noodling with the engine. I've also noticed that the idle seems to be going batty as well. It's idling up at around 2K. Perhaps a better description of the sound is that inside the car I hear it tapping.

 

The car seems to run okay and while it feels like it has less power it doesn't seem to be hugely different than before the lawnower sound. I did a forum search and I get everything from blown heads to broken timing belt (I'll run down and check the timing belt as soon as I post this).

 

Anyone have any suggestions?

 

Kevin

Sounds a lot like you blew out one of the Air Injection Valves, and melted the silencer material - the plastic from the silencer will get sucked into the carb, mess with your throttle plates and cause the high idle - the noise you hear is the failed melted silencer not silencing anymore - it's like a little mini-muffler for the AIS. You can block the AIS valve with a quarter at it's inlet pipe, and remove the silencer. Clean all the crap out of the carb and your idle should go back to normal. Probably won't have to rebuild the carb since it runs, but you never know.

 

.... or it could be an actual exhaust leak - check the y-pipe studs in the head - notorious for working loose, and stripping out. Tap them over to 7/16"x20 if they are stripped and use a bolt with a lock washer.

 

GD

I vote exhaust leak.. make sure you have OEM gaskets in there... the aftermarket ones go south quick!

Aren't the bolts only supposed to be somewhere around 12ft/lbs or something really light like that? I know if you torque them down too tight, it'll distort the flanges and cause the gaskets to burn.

If you have a EFI (not a carbie) model then it very well could be an exaust leak before the O2 sensor. This will make the car think it's mixture is wrong and try to make it right.. Which will make your idle go up and down and also can make it run very high.

Look at the exaust where it bolts to the engine. It is very easy to strip those bolts and if they are not done up tight enongh it will leak. I have had heaps of problems with stripping the studs, so good luck...

I Helicoiled my exhaust stud threads( M10 1.25 thread). Aluminum sucks for threads if you dismantle and reinstall too much. I believe the torque is 19-22 ft lbs (or 25 as Haynes says, but 22 works fine).

The car is a carbie 86 GL wagon w/4WD.

 

The first thing I thought of was those bolts where the exhaust bolts to the engine. After I worked on the initial engine tune (plugs, wires etc.) I forgot to reattach all the vaccum hoses and it sounded just like it does now (which leads me to think it might be an exhaust leak).

 

I just had two of the bolts on the driver's side wheel loosen up (of course I thought it was the CV joint). So, the idea of loose bolts seems...let's just say I wouldn't be at all surprised. I'll check it out.

 

Occam's Razor:

"entities should not be multiplied beyond necessity"

Kevin

My vote is the exhaust leak...loose bolts...My Loyale sounds the same way...started again in less then 2 weeks after the 2nd fix ( new exhaust gaskets too) I am just learning to live with it cause I dont care anymore..not putting any more time or money into mine..just trying to get the last 4000 miles out of it so it can be retired with 200,000 miles on it

Last time my car sounded like that was when I was having ignition problems and I was running on 3 cylinders. You might want to take another quick look at the ignition system.

Other then my car is a 86 with fuel injection mine sounds like a tank to... I am willing to bet that is is the exhaust cause that is were most the noise comes from that on mine. Mine is well "holey..." rotted through I will replace it one day when I have the money or access to the tools anyway something that really helped with the noise on mine was changing the oil and adding a new oil filter. Along with a new air filter mine purs except it is a little loud but thats just the exhaust.

 

Enjoy your subaru hell I was born in mine...