2008 Prius making a loud knocking noise when started

Is it any color other than the gold with the tan cloth interior the ugliest one they make Is it ragged out really bad? Generally a gen2 . Will be worth fixing to many now put a lot of constraints on that like really ragged out dents parked in the sun faded headlights backs of headrest cracking and faded etc etc etc lost trunk cover those things can all make or break whether this model is worth repairing or the other person that's going to take on the repair has all those parts ready to go on the car like me. So almost any Gen 2 as long as it's not that ugly gold color is ready for me to slap my parts on it and keep getting it If the noise is in the transmission related to MG1 or two or the transmission it's definitely worth it because you can get a transmission for these cars for near nothing $100 two maybe. If it's the engine the one NZ is very popular still used today and was plenty of them in the yaris. And they are plentiful from the Japan domestic market low mileage takeout circuit so it's definitely doable and very reasonably doable on top of that nothing like a Gen 3 so there's some decisions to be made obviously You need to find out where the knock really is If it was the engine blown up that generally doesn't happen overnight that takes a good minute of running hot running extremely low on oil not ever being checked changed all of that sometimes smoking occurs smells things get to happening on an engine with maintained oil changes and just general things like that usually the engine doesn't get taken out but the transmission with its electric motors extra bearings things like that have been known to go south but it's relatively inexpensive like I say you can buy the whole transmission pretty cheap If you look around you can find these cars in places with reasonably low mileage like just breaking a 130 well maintained got a den in it and the insurance company totaled it happens every day down here in the southeast parts are plentiful

 

any trouble lights on the dash

 

This is the 1st generation (2001-2003) forum. I think you would get more responses in the generation 2 forum for your 2008. hope this helps.

 

Have you checked the oil after your oil change, is there too much or not enough oil on the dipstick?

 

What brand coils? What "solenoids"? When were the spark plugs replaced last?

You MIGHT have a misfiring cylinder. Or maybe the damper between the ICE and trans is coming apart. There's lots of parts you can throw at the car. Or you can do some testing.

Scan the ECM for codes. Look at data to see if misfire counts are increasing for a single cylinder. See if the coil can produce spark. See if the injector is beings triggered. Perform a compression test. Etc, etc. The service manual has much information.

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"the motor was shot" could mean a lot of things.

Stupid question but is there any oil in the engine?

Also, I've heard of people forgetting to take the key out of the slot when changing the oil...the engine kicks in while the oil's being drained and, well you know the rest

 

gen one ended 2003. gen 2 was 2004-2009.

there is a fill plug and drain plug on the side of the tranny. you remove the fill plug and stick your pinky in and feel for fluid. if not, top it up until it seeps out.

if you want to change it, remove the fill plug, then the drain plug. replace the drain and fill until it seeps out. you really need a lift, it's all underneath

 

i would get the codes read at a dealer, or someone with a prius aware scanner.

but at a quarter million miles, idk how much you want to invest in diagnosis and repair

 

Generation 2 is generally mid 04 to '09 somewhere right in there The generation one was a little coupe had a trunk Gen 2 was a lift back The generation 3 2010 up is a lift back or five doors they call it. On your generation 2 is the 1 NZ engines. On the transmission which is on the driver side of the car in the front behind the engine there is a drain plug and there is a fill plug You want to take the fill plug out first and then get the drain plug out and have a pan ready to catch the nasty black fluid that's going to complying out It used to be red not to worry about that it's just the way it is. Then after you let it sit and drain about 15-20 minutes smoke a cigarette go have a cup of coffee whatever put the drain plug back in I usually get above the car standing above the engine and transmission and use a quarter inch piece of tubing and a little pump that goes on the 1 gallon container of Asian CVT fluid most here will tell you to go by the Toyota fluid I use the Asian CVT fluid that you can get it most part stores it's marked for CVTs for Toyota Nissan etc I use a little pump thing to pump that in to the fill hole until a little bit runs out then I pull the tube out put the fill hole piece back in. Drive

 

If you or someone you trust know a lot about the car, then certainly DIY is on the table. If not, it's best you find a shop that specializes in Hybrids. A general repair shop is most likely clueless irt a Gen 2 Prius and is much more likely to misdiagnose a problem.

 

G'day Traci,
I have had a couple of cars with the same engine (1NZFXE) and occasionally when they get over 150K-250K they start making this horrible noise that sounds like it is missing and about to die a horrible death. A few moments of warm up and the issue goes away. My 2000 Echo (same engine) started doing it around 160K miles and continued until 265K when it was hit and totaled in front of my house (broke my heart). Now my 2009 Prius does the same thing and I expect it will do it forever unless I figure it out.

If your car has the right amount of oil (Check via dipstick) in it and the sound goes away after it runs for a few minutes I would not worry about it.
I have seen some freeze frame data on my 2009 Prius that there are occasionally misfiring errors on cylinder 3 after first start up at beginning of drive cycle when engine is cold. I have changed the coil on 3 and the plugs all looked good when I changed them a while back. Compression test also seemed fine. (did that while I was changing plugs)
A coworker has the same issue on a 2008 ~200K miles on it. Again I found (using Tech stream) some codes for misfires on #3 on their car. But again it goes away quickly.

A mechanic I trust to actually work on my car said he thinks this happens when there is a bit too much oil in the engine. He has a fair bit of experience on Prius cars (in Pasadena Ca. Prius cars are as common as boogers in allergy season). I have to admit that when I change my oil I do just put 4 quarts in instead of the 3.91 quarts recommended. I change and check oil and filter regularly.
I think I notice it more in cold weather. Well, cold by So Cal standards. 40-60F

The sound is like a really bad knocking and rattling. Until you get used to it it is most disconcerting.

I sometimes wonder if the VVT (Variable Valve Timing) valve is not doing what it is supposed to until it gets full oil pressure for a few moments right after the initial start up.
Maybe you could post a recording of the sound?


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