Holy Engine Oil Sludge!
 

Well I knew this was gonna happen. Short back story on this before I start taking heat for this truck. I bought this truck with about 195K on it and have been putting on a lot of miles since this is my daily driver and I drive a lot for work. I've been having a good oil leak somewhere and I think I traced it back to the valve cover gaskets and the cam plugs. Seeing how this truck is over 220K miles on it now when I bought it with 195K miles, I figured its those items probably have never been replaced.

So today I get working on it and I just took the driver side valve cover off and holy hell! talk about sludge! I had a feeling I was going to find sludge but damn that looks like a mess. Im not sure if these gaskets were ever changed, theyre a little hard but in need of replacing. Even the screws hold the covers on were loose, so Im pretty confused.

Anyways, since I have the covers off now, what is the best way to go about cleaning the stuff out? Some of it is hard and some of it is still gooey.

https://i.imgur.com/V5xYY9h.jpg

https://i.imgur.com/Nm8AOQ5.jpg

I would manually scrap off the sludge on the valve cover but be careful not to crack it or break it. You can try using some carb cleaner or other solvent to help scrub the sludge off the cover.

I would try doing 1500 mile oil changes with a healthy dose of marvel mystery oil in the oil. It will slowly break up the sludge without plugging up the oil pickup screen. You'll want to use a decent synthetic oil also, it will help to slowly scrub that crap away.

Look for some BG109 and do it every short oil change. MM works too it’s got a lot of mineral spirits in it But if you buy the BG product you won’t use MM again to desludge.


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Leaking VC gaskets is probably the most common issue and yeah loose screws just as common. Do as other said, slow and easy does it, top internals look pretty good though, considering the VC condition (pic of mine for comparison). Luck and enjoy the Runner. :cowboy:

Substitute 1 quart of oil for 1 quart MM oil and use some cheap oil, store brand is fine. It's generally super cheap so great for 500-1000 mile oil changes when doing something like this. Look at Amazon brand oil, it's actually said to be very high quality. Make sure you change the filter every time you drop the oil also. Once you're satisfied the engine is clean, it may not be a bad idea to drop the oil pan and see what's going on in there. Very likely it needs a good cleaning.

I know seafoam has a procedure on the bottle for putting it in the oil to clean things out. I’ve never done it, I have trouble with the idea of putting something like that in my oil, but my old mans done it without issue.

I’d use a diesel spec oil like Rotella to flush it out. Higher detergency will help scrape off the stuff.

Kano Labs Kreen might be an interesting product to try.

For the actual valve covers, since they are off the vehicle... an overnight bath in 50:50 pinesol:water will loosen the vast majority of that junk. Zero risk, water based, strong enough to eat varnish off the inside passes of carbs (was my go-to for cleaning motorcycle/atv carbs for several decades as it doesn't hurt rubber/plastic).

If that scares you, then you can try just soaking with diesel/kerosene to "soften".

Right...zero risk if cleaning the VCs off the vehicle.
You could try 'citrus cleaner', the stuff sold at the hardware mall for about $8 a gallon. Full strength I've seen it remove the anodizing from aluminum over a few days. You could also take it to an auto machine shop and ask how much to hot tank the VCs.
The valve area of your engine doesn't look sludged up at all. Looks like you got to it in time. Personally, I'd stay away from magical mystery miracle products that dilute the motor oil with solvents. Doesn't make sense to dilute the lubricating properties of the oil to me. YMMV, as always. Added photo of what a sludged up valve train looks like in the 3.4. There was a worse one, but I can't find that photo right now.

ok so I just got back in and pulled off the passenger side cover and it was basically the same or slightly worse. I scraped off some of the bigger clumps of oil from the internals and vacuumed it out. I went over it and got pretty much everything that's loose. I'm gonna put it back together tomorrow morning and try whats been suggested.

I haven't done it yet, obviously, but would using seafoam at this point just be a waste or would I risk missing up the motor using it?

You want to do it slow. Or use a product that you put in the engine after the oil gets up to temp and hold it at 2000 for 15 min and then dump the oil and change the filter.

I think the sea foam might break it up and clog the oil pump inlet screen.


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There's risk in anything you do at this point.... pieces can come free and get stuck in vital places (oil passages).

You have a few options. You can go heavy, apply solvents directly to the heads and scrub/scrape as much off/out as possible. I'd personally consider this myself (I'm about 2 weeks out from doing my valve cover gaskets). This will require an additional step of running the engine for a short time to flood and flush the solvents/crud into the oil, then changing the oil.

You can go lighter by adding large amounts of "cleaners" to the oil, running it for "some" time ("some" being subjective to your risk tolerance, 20 minutes for the oil to come to temp being the minimum) then draining the oil. Rinse and repeat as often as you desire.

And you can go very light by adding just Small quantities of "cleaners" to the oil, or using high-detergent oil. I actually ran diesel oil in my prior 5VZFE since I also had a diesel car and liked to only stock one oil, only put 170k miles on that engine but it was always clean and well running ~ Mobile 1 diesel truck or Shell Rotella T-5 were my 2 main choices. Haven't done the first oil change on this newest 4runner yet as it was changed immediately prior to my purchase and I've only done 1500 miles, but I suspect that's the route I'll take again.

There's no shortage of engine flush products. The best seller on Amazon is "Liqui Moly 2037 Pro-Line Engine Flush - 500 Milliliters". Might be worth a try at $15. Put it in, let it idle for 15 minutes, drain the oil and filter, fill with your choice of oil and filter. Done.

https://smile.amazon.com/s?k=Liqui+M...ref=nb_sb_noss

The Amazon Basics full synth high mileage 10w30 is $17. It's also a best seller. I find synth oil to be a good cleaner. Maybe do two back to back oil changes. One at 500 miles and one at 1000 miles (or whatever you think is best) after the engine flush or maybe do the engine flush just before the second oil change.

Someone brought up a good point about breaking chunks up and them clogging the oil pick up screen. I think that's a valid concern. How difficult is it to drop the oil pan on these rigs?

https://smile.amazon.com/AmazonBasic...NrPXRydWU&th=1

I would try and vacuum out as much as possible. Then run 1/3rd of a bottle of Marvel Mystery oil and a good oil, then dump after 500 miles and repeat. Pull the right VC after 2000 miles and see how much progress you have made.

Soak the valve covers in diesel. Recycle it at vatozone after.

Why is the sludge removal so urgent. Step back a second. It ran good before you cracked it open. Why are you making life harder? Clean to cover. Ensure the pcv baffles aren't clogged. Use only an OEM PCV. Fill with synthetic oil and keep driving it. The sludge will go away slowly and safely. There is a risk even with MMO. Try Pennzoil Platinum. It turns dark very quick compared to many oils (ex. Mobil 1) on sludged engines.

That sludge is honestly nothing.