Pilot sludge buildup front valve train only

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Aug 7, 2011
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Oregon
I replaced leaky valve cover gaskets on my wife's 2005 Honda Pilot a few days ago. Has 198K on the odometer. For several years I would use whatever synthetic was on sale at Walmart, but over the past few years almost exclusively Supertech synthetic 5w-20. We've owned the Pilot since new and it always gets an oil change around 5000 - 6000 miles.

To my surprise, the front valve train had sludge deposits (closest to the radiator), but the rear valve train was spotless (near the firewall). This vehicle is mostly driven short distances, and maybe once a week gets a 15-20 mile drive.

I thought changing the oil at 5K intervals and using synthetic would prevent sludge buildup, but looks like I was wrong. Today I filled it with Mobil 1 High Mileage 5w-20 hoping the claimed extra detergents will cleanup some of this. Do any of you experts know why sludge is only on the front valve train? Thanks for your help.

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Athens, GA
I replaced leaky valve cover gaskets on my wife's 2005 Honda Pilot a few days ago. Has 198K on the odometer. For several years I would use whatever synthetic was on sale at Walmart, but over the past few years almost exclusively Supertech synthetic 5w-20. We've owned the Pilot since new and it always gets an oil change around 5000 - 6000 miles.

To my surprise, the front valve train had sludge deposits (closest to the radiator), but the rear valve train was spotless (near the firewall). This vehicle is mostly driven short distances, and maybe once a week gets a 15-20 mile drive.

I thought changing the oil at 5K intervals and using synthetic would prevent sludge buildup, but looks like I was wrong. Today I filled it with Mobil 1 High Mileage 5w-20 hoping the claimed extra detergents will cleanup some of this. Do any of you experts know why sludge is only on the front valve train? Thanks for your help.
I wouldn't worry a ton about it. My 2008 TL looks about the same from the PO doing changes by the OLM. Keep the rest of the engine maintained and that little bit of buildup isn't going to hurt anything. Short changes really won't do anything for you either. I do 5K changes and it looks the same change after change. The PCV is on that side of the motor, so all of the vapors get pulled that direction.

A Non-VCM J Series will run pretty near forever so long as you take care of the timing belt and give it decent maintenance.
 
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I believe that this is more common with FWD V6(or I should say, FWD " V " engines) than people realize. However your engine still looks good for almost 200K miles even if one cylinder bank is more varnished than the other. Actually, I am surprised that the way the front & rear look isn't in reverse with the rear looking more varnished than the front. Maybe my thinking is wrong. :whistle:
 
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That's a lot of varnish! This looks like a really solid candidate for the @High Performance Lubricants engine cleaner, which uses esters to clean. Unfortunately, this is not the first Honda V6 we've seen on here that looks like this or worse. @Trav has previously posted pics of the VCM variant that was in even worse condition.
+1 And a new PCV valve.
OP If the valve cover is still off soak it in Gunk parts and carb cleaner (available in gallon cans) to flush out the PCV openings in the cover. This is a bad one from a VCM engine, yours may not be as bad but this little valve and those few holes are all that is removing gasses from the engine. Sorry for the poor picture quality but you get the idea.

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OVERKILL

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No way I'd use an engine cleaner/flush. You run the risk of wreaking the engine for basically no benefit.
The idea of using an ester-based product is that it slowly works the opposite way the deposits got there in the first place. The polarity and high solubility work to free the broken down hydrocarbons that have plated out and put them back into suspension. This isn't aggressive like a solvent where you risk loosening large chunks and plugging the oil pick-up.

It operates in a similar to manner to how Mobil claims their 0w-40 cleans (using the same mechanism), but with a higher ester treat rate.
 

Ken_K

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Oregon
Did you adjust the valves while you were in there? At 200k they need to be done if they haven't been.
@ctechbob , I wanted to adjust the valves while everything was off, but noticed lots of sludge baked onto the adjuster nuts. I only had part of a day to work on this, so my thinking was run high detergent oil for a couple of changes, and then adjust when I'll have more time this June. The most important thing at that time was keeping my wife happy. That burning oil smell on the exhaust manifold was driving her nuts.

Also, I'm going to purchase the High Performance Lubricants cleaner that @OVERKILL mentioned. I read through several thread about this stuff and it looks very promising.
 

Ken_K

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+1 And a new PCV valve.
OP If the valve cover is still off soak it in Gunk parts and carb cleaner (available in gallon cans) to flush out the PCV openings in the cover. This is a bad one from a VCM engine, yours may not be as bad but this little valve and those few holes are all that is removing gasses from the engine. Sorry for the poor picture quality but you get the idea.

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@Trav, that's one nasty valve cover! No, my valve cover wasn't nearly that bad, but it was ugly. It appeared to have enough flow for blow-by gasses, but I need to give it a good solvent bath when adjusting the valves in a few months.

And, yes, I did replace the PVC valve while doing this job. To be honest, I probably let it go too long.

Question for you regarding the plenum and intake manifold. They're both heavily coated with grime. Visually it looks like black 60-grit sandpaper minerals lining all the passageways. My concern is small pieces possibly flaking off into the cylinder, but maybe I'm worrying about nothing? Since I'll be working on this again, is it worth giving those a solvent bath as well, or don't lose sleep over it?
 
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