Hello all, its been a while since I posted here lately. In the last few months my '08 Prius' engine has gotten progressively louder. I have tried fuel injector cleaner, Techron to be specific and that doesn't seem to have helped much if at all. The car drives fine for the most part but on occasion when I ease up on the accelerator, such as when I'm approaching the top of a hill, I can feel what seems like a miss or stumble. I have no check engine light or error codes. The spark plugs were changed around 110K miles with the correct ones. Current mileage is nearing 130K. Oil level is about a 1/4" below the top mark and I have regularly used Castrol Syntec 5W-30, but on the last change I got Mobile1 5W-30 Synthetic but no change in the noise level there. I did have an issue several months ago where I had reduced power from the engine and the battery was compensating for, which seemed to have been caused by a fouled igniter and went away after I replaced it. I know the engine is typically loud in cold weather during cold starts but now it sounds loud almost all of the time unless the engine has been thoroughly warmed up. I don't notice any loss of power particularly. I have uploaded a short clip on YouTube of the sound here: The whooshing sound I am unable to hear in person, so it may be some distortion from an echo or just my phone's mic. The engine noise is somewhat amplified by my phone, but it is still very much noticeable when walking by if the engine is running compared to a co-worker's G2 which sounds nearly silent with the heat and engine on. Any suggestions on things to check or do before I head to a shop will be greatly appreciated!
At 60ish (gen2) I replace the exhaust donut ( between block and exhaust ) which had disentigrated, 90$ for the part, also the muffler and tail pipe, but the loud was the donut.
Hi Lucifer, was that causing a similar sound and behavior in your Prius? I'm really hoping it's something as simple as a DIY repair. Edited for autocorrect.
I'm no expert, but my first impression was exhaust noise too. Try a piece of heater hose as a stethoscope and see if you can get close to the exhaust manifold.
...wow that's a noisy video Cub, hope you find the prob. I might have suggested a special oil but does not sound like valve chatter
Yeah, for some reason the recording is louder than it actually is, but I'll take a look this weekend. Oddly enough I haven't had any noticeable drop in fuel economy since this started happening. Granted I do expect it to be lower in the winter any way. I'll see if I can get the car on a lift this weekend and probe around.
I hear what sounds like an intake air hissing sound like a air leak. Check the black air input hose on the left of the airbox that goes from the air cleaner box down into the silencer box. Where that big hose makes a right angle into the air cleaner box it goes from hard rubber to soft rubber and easy to get a tear there at the elbow. Feel the tube you'll see what I mean. Also if the air cleaner box has been off it may be the throat clamp under the air box was never re-tightened. That will be a post maf air leak and may make the engine stumble as there's then unmetered air in the throttle body.
Ok, checked the air input hose and all good there, same with the air cleaner box, it was tight and the clamp was securely fastened. I raised the ol' gal up on some rhino ramps and felt around. It was a little hard to tell but the doughnut gasket does look a little suspect, but I can't say for sure. Will probably replace that anyway. The exhaust manifold looks pretty rusty, but I need to get up on a proper lift before I start poking around there. I'll get some pics next time and report back.
Finally got some decent enough weather and no back issues to get under the car. I didn't let it cycle through it's warmup until I could get it on the ramps and get back underneath. Felt around with my hand and sure enough, where all the exhaust header pipes come together, I could feel hot exhaust blowing out. Seems like it rusted through enough in a joint where it eventually cracked. I'll look around for a replacement, possibly from a low mileage wreck, new gasket and bolts. This doesn't look like it will be a fun job to do but seems it won't be so expensive. Thanks everyone for the help! Attached is the photo I snapped from under the engine on the backside showing the rusted header.
wow that's interesting we have another Va. Prius wondering about exhaust leak in Staunton. Too my knowledge we've not heard too much of that.
Yeah, the only thing that I can think of is perhaps road salt playing a role in this although I'd have to say I'd expect to see more Prii with the issue, and I can't find any references to anyone having had to replace the exhaust manifold for a similar reason.
doesn't seem like the manifold is stainless like the rest of the pipe you'd need shaped explosives to penetrate it downstream of the manifold
