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Race to the speed limit
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Discussion Starter · #1 · (Edited)
My valve cover gasket appeared to be leaking so I brought it to my mechanic for a in-there-so-might-as-well valve adjustment and new gaskets/PCV valve/etc.
A few hours later I get a call saying I should swing by because I might need a new valve cover.

Lo and behold.


A closer look:

The hole was 1/4 of the pictured size since I poked through to feel how brittle the material was.

From the inside:


I did a bit of research and this is the only post I found on DA for this issue.
But I did find an Odyssey owner with a similar issue and 1 2 other Odyssey owners with melted coil packs.

My mechanic said it's likely due to the cast aluminum cover getting too hot from either a loose plug or electrolysis due to arcing from the coil (3 of my coils' upper rubber rings were essentially detached from the coil and very brittle).
My rear cover was still in decent shape.

Has anyone else dealt with this issue?

The tube seal seemed fine, so I wonder what issues this hole would cause?
 

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Holy shibby!
 

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port & polish everything
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Arcing seems more likely given how localized the damage is. The melting point of aluminum is over 1200F. Hopefully you already replaced the appropriate coils and plugs.
 

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Race to the speed limit
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Discussion Starter · #5 ·
Had the same problem on my 2010 odyssey. I had to replace the valve cover and cylinder #5 coil pack.
Strange how it's the same spot on the cases I've seen...


Arcing seems more likely given how localized the damage is. The melting point of aluminum is over 1200F. Hopefully you already replaced the appropriate coils and plugs.
Plugs were replaced a few thousand miles ago (hydrolock scare LOL) and new Hitachi coils were ordered by the mechanic.

That makes sense, I guess a loose plug could have heated up the coil insulator to the point where it could arc against the aluminum and eventually wear it away.

Some cite the heat from the pre-cat could have caused it, but that seems less likely.
 

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That middle cylinder on the exhaust port side is likely a hot spot, it's closest to the exit port and the precat. Exhaust gas from all 3 cylinders pass near that area. That doesn't cause the hole directly obviously since the exhaust manifold is watercooled and intact, but maybe hot enough to degrade the insulator on the coil over time, and then cause arcing.

 
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Runnin' in the 90s
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If your plugs were replaced recently, could this possibly have been the fault of the shop who replaced them? If they installed them incorrectly I mean.
 

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Please relieve me of my ignorance. What is all that discoloration. I have only changed a handful of valve covers but not seen that black/brown/orange discoloration on the inside? The plastic one I changed looked new inside though the tube seals were bad and were for some reason integrated in the valve cover...
 

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What is all that discoloration. I have only changed a handful of valve covers but not seen that black/brown/orange discoloration on the inside?
That's exactly what I thought...

To the OP,
Is there a zillion miles on this Accord??
I'm curious as to what your valve train looked like!
 

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Runnin' in the 90s
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Probably from the extreme heat being generated close by. That's my guess anyway.
 

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The brown crud inside is oil stain, most likely from using conventional oil or not changing oil frequent enough. Mine with 275k miles last year don't look like that inside. See picture.

Plus #5 is known to get loose on the 7th gen V6, but i wasn't aware of 8th V6 gen having the same issue. However, I think plug torque should still be checked once a year.
 

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My understanding for the discoloration is by how where the head gets air into it. On the 6GA v6 for example, the front cylinder head gets air directly from the air intake whereas the rear cylinder head gets its air from the intake manifold. It's hard to see, but the front cylinder head here in this picture of mine is seen to be stain free whereas the rear cylinder head has that orange stain to it. In my middle picture, you can see the hose (just behind the blue paper towel) that goes across the top of the lower intake manifold. That is the hose that plugs into the upper intake manifold on one end and into the rear cylinder head at the other end.

My understanding is this: Since the front cylinder head gets fresh air directly from the intake system, it's free of oil and therefore does not get stained. Since the rear cylinder head gets its air from the intake manifold, there is some oil contamination and that oil contamination gets into the cylinder head causing the discoloration.

https://photos.app.goo.gl/oEGyzpoc9cZrqUqeA

https://photos.app.goo.gl/6m3VLdR3to6Ld6a58

https://photos.app.goo.gl/fCVzUoh5E2MKmRSv9
 

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Guess it's probably too late for a Gen 8 to get this fixed under Honda's 5 yr/60k drive train warranty...but asking is free... :devil
 

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My understanding is this: Since the front cylinder head gets fresh air directly from the intake system, it's free of oil and therefore does not get stained. Since the rear cylinder head gets its air from the intake manifold, there is some oil contamination and that oil contamination gets into the cylinder head causing the discoloration.
CD-
I think that's his front cover though...according to what he posted.
he said:"my rear cover is still in decent shape"(sic)
You mean to tell me there's a good chance the rear once is even cruddier??
Yowsah.
I did my valve adjustment at about 160K and my cover(and valve train) was clean as a whistle.
 

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CD-
I think that's his front cover though...according to what he posted.
he said:"my rear cover is still in decent shape"(sic)
You mean to tell me there's a good chance the rear once is even cruddier??
Yowsah.
I did my valve adjustment at about 160K and my cover(and valve train) was clean as a whistle.
Missed the part about it being the front cover.

I'm not sure about configuration of a 6GA vs an 8GA to know these sorts of differences. It's plausible that Honda did the fresh air to rear cylinder head. It's plausible that it's stayed the same. I don't have an 8GA, let alone worked on one, to know this.
 

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Race to the speed limit
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Discussion Starter · #16 ·
That middle cylinder on the exhaust port side is likely a hot spot, it's closest to the exit port and the precat. Exhaust gas from all 3 cylinders pass near that area. That doesn't cause the hole directly obviously since the exhaust manifold is watercooled and intact, but maybe hot enough to degrade the insulator on the coil over time, and then cause arcing.
Picture brought some insight, thanks! What you say makes sense.

If your plugs were replaced recently, could this possibly have been the fault of the shop who replaced them? If they installed them incorrectly I mean.
Awkward... That shop would have been me :-( When I replaced them, I didn't have a proper 1/4" torque wrench so I was probably a little light on the torque. I've since bought one, and I'll be checking tightness as regular maintenance now.

Please relieve me of my ignorance. What is all that discoloration. I have only changed a handful of valve covers but not seen that black/brown/orange discoloration on the inside? The plastic one I changed looked new inside though the tube seals were bad and were for some reason integrated in the valve cover...
That's exactly what I thought...

To the OP,
Is there a zillion miles on this Accord??
I'm curious as to what your valve train looked like!
The brown crud inside is oil stain, most likely from using conventional oil or not changing oil frequent enough. Mine with 275k miles last year don't look like that inside. See picture.
CD-
I think that's his front cover though...according to what he posted.
he said:"my rear cover is still in decent shape"(sic)
You mean to tell me there's a good chance the rear once is even cruddier??
Yowsah.
I did my valve adjustment at about 160K and my cover(and valve train) was clean as a whistle.
I bought the Accord at ~140K miles and it's now ticking towards 170K with Pennzoil Platinum Full Synthetic every ~5k since I do wring out the engine often.
CarFax (ah, yes, all-knowing CarFax) showed decent maintenance in regards to oil changes from the previous owner, but I wasn't expecting that much varnishing.
Valve train is essentially golden now, but no sludge.
Rear looks just about the same :-/
Looking up "oil varnish valve train" now has me very self-conscious of the state of my engine lol.

Plus #5 is known to get loose on the 7th gen V6, but i wasn't aware of 8th V6 gen having the same issue. However, I think plug torque should still be checked once a year.
From 7th/8th Accords to Odysseys, maybe it's a "minor" flaw* on J series. ¯\_(ツ)_/¯
*When combined with a light touch on the wrench.

Guess it's probably too late for a Gen 8 to get this fixed under Honda's 5 yr/60k drive train warranty...but asking is free... :devil
And too late for that piston ring rebuild lol... I've tried.
 

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Good luck with your car. I checked out a "low" mileage car as a potential replacement earlier this year. The salesman made it sound like a gem. But I popped off the oil cap and looked inside the visible area looked like your valve cover though I couldn't actually see under the valve cover.

Funny part is once I did that he knew I wasn't going to buy the car, I could tell by his change in demeanor and he said he was "going to wait inside" lol. There are shady salesmen out there.

I think these cars are pretty stout though. I had the low oil pressure light come on twice in my 2003 k24 and it still ran great. Just burned oil. Never left me stranded to the day she died at almost 180k
 

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Good luck with your car. I checked out a "low" mileage car as a potential replacement earlier this year. The salesman made it sound like a gem. But I popped off the oil cap and looked inside the visible area looked like your valve cover though I couldn't actually see under the valve cover.

Funny part is once I did that he knew I wasn't going to buy the car, I could tell by his change in demeanor and he said he was "going to wait inside" lol. There are shady salesmen out there.

I think these cars are pretty stout though. I had the low oil pressure light come on twice in my 2003 k24 and it still ran great. Just burned oil. Never left me stranded to the day she died at almost 180k
How / what killed it at 180k?
 

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Attached was my rear bank of valve train at 275k miles/10.5 years, I have always used Mobil1 5w-20 full syn. It's nothing gold, but very clean. The front bank looks about the same. I have seen gold staining everywhere, on engines that mostly use conventional oil.

Air distribution is rather even if you've ever taken apart the intake manifold of a later J-series engine, and I got down to the valves last year. There is no more or less air to the front or rear. The front bank (cylinders 4, 5, 6) does handle air/fuel mixture a little different because of the PCV and EGR valves.

I do add and run 2oz of marvel mystery oil whenever oil life is down to about 30%.
 

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