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Discussion Starter · #1 · (Edited)
Hello, new member here. I'm here looking for info about a valve cover problem I have.

I have a RAV4 with about 113,000 miles on it. I took it to the dealer to have the valve clearance checked. The tech said that I had a hole in the spark plug hole and I needed a new valve cover. He said that the spark plugs were installed improperly and that caused the hole or maybe the coil pack was arcing to the valve cover. It has only affected cylinders 1 and 4. The vehicle runs smooth, no miss fires.

Anyway, I pulled the plugs and there were some holes in the valve cover. I replaced the valve cover with one from a junk yard and all is good. I just want to know what caused this issue. I have only found one reference to this problem and it was on this forum by Ic80 on 3-20-2015.

Any ideas on the cause. I sent pictures to Toyota, they said they had never seen anything like it.

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2008 RAV4 Limited V6
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Yeah, that's pretty bizarre, I don't know if that was caused by arcing or not. Maybe the wrong spark plugs were used? That engine is picky about plugs, you should only use the OEM Denso plugs--stay away from Bosch. So you replaced the valve cover with one from the junkyard? I hope you put a new gasket, especially the ones around the spark plug holes. Oh, and don't tighten the cover too much or you will deform the gasket. That's what happened to me.
 

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Discussion Starter · #3 ·
Yes, a new gasket was installed and I used a Haynes manual for the torque specs. The replacement valve cover came from a 2005 Scion TC. The replacement valve cover did not have any erosion/corrosion or whatever.
 

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I also have same issue and oil leaked in to plugs.. Mt technician fixed the hole with mseal for the time being.... Part is not available in used part market. Hole found on 1 & 4 cylinders... Strange technical issue.. Vehicle model 2007, RAV4
 

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I also have same issue and oil leaked in to plugs.. Mt technician fixed the hole with mseal for the time being.... Part is not available in used part market. Hole found on 1 & 4 cylinders... Strange technical issue.. Vehicle model 2007, RAV4
Ebay sell new ones which are going for around $82. Here are a few examples:

https://www.ebay.ca/itm/Engine-Valve-Cover-For-Toyota-Camry-RAV4-Harrier-1AZ-2AZ-2-0L-2-4L-11201-28014/113535056752?fits=Model%3ARAV4%7CMake%3AToyota&hash=item1a6f377b70:g:1lYAAOSw~HFcNGFG#shpCntId

https://www.ebay.ca/itm/Engine-Valv...-2AZ/153317457301?fits=Make:Toyota|Model:RAV4


A lot cheaper than dealer prices that are 4 times more.
 

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I just want to bump this old thread. Same thing happened to my 2005 Rav4 with 82,000 miles on it. Cylinder 1 and 4 are most affected as well.
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I just want to bump this old thread. Same thing happened to my 2005 Rav4 with 82,000 miles on it.
:oops: With 82K miles! That's crazy. I'm replacing my valve cover gasket in a couple days, now I'm interested to see what these spark plug holes look like.

So we know that arcing is caused by electricity seeking the path of least resistance, unable to make the gap at the electrode, it releases the energy at the next easiest location. Sometimes cracking the ceramic, sometimes melting the cap, and other times when unable to even reach the spark plug it'll arc to something in the engine bay.

What typically causes a spark plug to not fire is a fowled electrode, due to water or oil for example. Coincidentally, incidences of both of these are known on the 2AZ-FE.

SolRayz, why did you have the valve cover off, was it to change a gasket? And did you find oil on the plugs or coil? Incase you hadn't, I'd recommend changing the plugs and coils too.
 

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So I think I'd add replacing the valve cover gasket for knew 4.2 buyers. I replaced mine tonight and it was completely wrecked. Due to the low mileage of my RAV, I think these should probably be replaced by so many years, maybe 10?

I had a 1/8" puddle of oil in the #1 cylinder and 1/16" in the #4. #2 and #3 were dry. Fortunately I didn't have any damage to the valve cover, but, it's my suspicion it's because I caught the gasket leak early. I thought something interesting to note was the #1 plug exhibited signs of wet fouling.

I changed all the plugs with NGK IFR6T11, wiped the coils clean and reinstalled with dialectic grease.
 

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Do you have a 2007, or a 2017 model as mentioned in the 4.3 mechanical thread? I didn't think the 2017s had the 2AZ-FE . . .

I received yesterday the 2nd RAV4.2 I have purchased, 120k miles. I'm planning to replace the valve cover gasket in a couple weeks. My hypothesis being it's in worse shape than my other RAV was at 70k miles. I'll allot more time to do this, previous was changed mostly under shop lights and flashlight, and I'll take photos for documentation purposes.
 

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Do you have a 2007, or a 2017 model as mentioned in the 4.3 mechanical thread? I didn't think the 2017s had the 2AZ-FE . . .

I received yesterday the 2nd RAV4.2 I have purchased, 120k miles. I'm planning to replace the valve cover gasket in a couple weeks. My hypothesis being it's in worse shape than my other RAV was at 70k miles. I'll allot more time to do this, previous was changed mostly under shop lights and flashlight, and I'll take photos for documentation purposes.
I had a typo in the 4.3 thread, it's a 2007.

Mine it's only 181,000 Km ( 113k miles), after looking closer to the damage it's clear it comes from the inside. The gasket failed and started eroding the material from the inside out. I ordered a used part since the new one was roughly 500 bugs, once received and inspected I will replace with a new gasket This is the first failure I've had in this car and the engine has not shown any signs of performance issues or deterioration. Hope you can share pictures, I'll do the same after replacing mine.

Héctor.
 

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. . . after looking closer to the damage it's clear it comes from the inside. The gasket failed and started eroding the material from the inside out.
This is my hypothesis as well, which is why I think it goes unchecked for so long. I suspect this is partly contributing to the chain of events that lead to overheating and head bolt failure. Further evidence to demonstrate this I believe is the fact my valve cover gasket let lose on the back of the cylinders, behind the air box, a difficult place to detect.
 
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