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Discussion Starter #1 (Edited)
First post, V6 knock - SOLVED! - water pump

Hey everyone, first time posting here. I'm an active member on one of the Ford 7.3L PowerStroke diesel forums (my, or should I say, "our" truck). Though I fully expect, since this is a Toyota forum, not a Ford forum, and given Toyota's reputation, for there to be less activity over here.

A year ago, we purchased a 2008 RAV4 Limited with the V6 (80k miles) from our local dealer. They had the full records from the previous owner, which is one of the reasons we purchased it. The previous owner was anal to say the least - he'd bring it in for the most minute complaints. Needless to say, THAT'S the kind of guy I want to buy a car from.

The RAV4 has been great, but recently, it's developed a knock. When cold, at idle, is when it's most prevalent. The TSB work for the rubber oil line was performed quite some time ago. What are everyone's thoughts on that topic, or anything else to check out? Could it be something as simple as poor detonation from old spark plugs?

We've been running Mobil1 Extended Mileage synthetic, 5W-30 (IIRC, but don't quote me on that). I can gather any other details you all may want. The wife and I aren't afraid to dive in and work on this car; I've handled almost all of the major work on the big diesel (injectors, clutch, etc.).

Thanks and cheers!
 

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Welcome! Old spark plugs will only cause "knock" if they have carbon or other deposits on them which heat up, generally under severe operating conditions, so that they glow enough to cause the fuel/air mixture to ignite prematurely, and spark plugs in the neighborhood of 80k miles aren't yet needing to be replaced. From the description of the sound that is not the cause. It would help to diagnose the problem if it would be possible to post a sound recording of the noise. Causes could a noise in the valve train, or less likely piston slap from a worn engine (unlikely with the miles on your engine), or the coolant pump going bad which is more likely a possibility with a 2008 RAV V6, a bad alternator bearing, or another factor. Using a car stethoscope may help to pin down the location of the sound.
 

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Discussion Starter #3
Thanks Jim. I'll grab a recording of the sound once it cools down. The wife just picked me up and drove across town. At operating temp, zero noise/knocking.
 

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The 3.5l V-6 is quite sophisticated and is not prone to knock. Like Blogson I seem to think it is a knocking noise only and somehow associated with the cold start.
 

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Not sure if this will add much value to the discussion but I'll post it here anyways.

I do get a knock/rattling sound from my engine when starting. The rattling sound is comparable to when you're shaking a can of spray paint. That type of sound. Now this noise started to develop this past year as now my vehicle is parked on a sloped drive way. I back up onto that driveway (nose pointed down) and it is a bit on the steep side. If I add a bit more oil to the engine it seems to stop it. So, not sure if the oil has just shifted away due to the slope or what. I do not get this knock/rattling sound when the vehicle is parked on a flat surface. It only happens when I start the vehicle.

Not sure if your vehicle is parked in such a manner. My RAV4 is a 2007 Sport V6 with about 160,000KMS on it.
 

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How often did you change the oil? The cam phaser could be gummy, you could have piston slap from worn pistons/cylinder walls, a loose rod bearing or even a water pump rattling.
 

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Discussion Starter #8
Sorry for the delay all, been quite busy. The knock is definitely on the passenger side of the engine, up high. It is RPM-dependent, and it doesn't go away all of the time when the engine is up to temp, only some of the time. Water pump?
 

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Discussion Starter #9
After a bit more research, it sounds like the water pump is most likely the culprit. Stopping by a very reputable Toyota repair shop today for them to have a listen. If it's the water pump, they'll do the job for $630, new Toyota pump included. Apparently, they too know that the engine doesn't need to be pulled to replace it.

As for oil, yeah, we stay on top of it with synthetic 5W-30, about every 5k. If this is piston slap, Toyota can forget about me ever upgrading to a Tundra!
 

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Discussion Starter #10
Just some feedback for everyone - we replaced the water pump, and the knock is gone. Thanks to all who chimed in. Hopefully this one goes a bit further than the factory one.

Cheers!
 

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Congrats for getting the problem sorted out, and thanks for keeping us updated!
 
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