Get valve lash checked. Have seen alot including mine where gap shrinks to the point of burning valves. Had .008 in spec for intake side but less on exhaust side. Not in spec. Head is now at machine shop. Many people seem to be going through this as am I ☹️

Have your valve lash checked. Sposed to be checked like every 30,000 miles allegedly. Heard light ticking in mine. Then misfire code. 1 intake valve burned on 2 cylinders. Showed up on a compression test. .008 in spec for all the intake valves but less than on all of the exhaust valves. Had to pull head. Awaiting news on the head from machine shop☹️

@@pitchforkpeasant6219 i did all that, approx 10k miles i took the head off and send it to the machine shop. So the top end is new, valves were adjusted

@@juniororejel894 excellent. I just did mine but not in time. Still waiting to see how much damage was done. Glad i did a compression test and didnt make things worse to the point of needing a brand new head. Hopefully

Yes I just ran a bead of rtv on the head gasket/timing cover joint. I just used the standard gasket on the timing cover to block joint. I try not to use rtv except where it might be strictly necessary.

I very carefully dremeld a 1/8' channel in top of the timing cover to hold a thin bead of grey rtv before assembling everything on mine in the next few days. It's what Toyota did in the rear main seal aluminum cover. i should take some photos since i don't have a wonderful videographer as you do. These 2rz/3rz engines are great engines once you can overcome the asain built-in or engineered in stumbling blocks @@wrenchwranglers

I just put some RTV along the top of the timing cover and slid it back in. It’s still sealed. The only thing I’d do differently is use some RTV on the half-moon seals that go on the front under the valve cover at the ends of the camshafts. I used the rubber replacement units that came with the kit and they definitely need some sealant. There’s some oil seepage. Other than that it sealed back up just fine.

This does sort of sound like a symptom of a timing chain going bad, but (and I don’t know if the two engines are exactly the same inside) this engine has a timing chain tensioner that is made to compensate for stretch. It’s more likely there are multiple factors at play, possibly the chain guides could be wearing. It’s not to hard to check out the timing chain condition. You can pull the valve cover and rotate the engine and see how much slop there is between the cams and the crankshaft, which will tell you if the chain is indeed causing issues. If everything is tight then your problem lies elsewhere.

Engine sludge can be created several ways, but in my experience it is generally a combination of factors. Letting oil age too long where the additives break down (not changing it enough), using oils low in detergents (cheaper oils), running engines too hot and not changing the oil (overheating kills oil quickly), short drives that don’t warm up the oil and burn out contamination like fuel, not using high enough quality filters, things like that. Generally I have found that although one of these factors alone can sludge an engine given enough time, usually it’s a bunch of them combined.

@@wrenchwranglers can’t believe how fast you were in responding to my question. That’s amazingly nice, so thanks. Your composite picture of how oil sludge forms is close to what I had learned from my research, but you put it in a neat synopsis that everyone should know. I hope many people can get to it. The Taco you did so much work on is a 1997, compared to my 2000, so three years older, yet when you found a penny inside the cover, the condition of that DOHC top of the head was sparklingly clean in comparison to what I found when I opened mine. I’ve always used Mobil 1 synthetic oil at oil changes. But, the way I would decide to do the next oil change was to keep looking at the color of the oil on the dipstick, so maybe some changes were far apart in time? I don’t know for sure. Guess I will start monitoring miles and shoot for 5,000? You got me on the short trips, and at times the truck would sit for a few weeks between trips, mostly to Home Depot for bags of dirt or mulch. That said, my question now narrows to this. Can you imagine some kind of engine operating condition that would sludge the engine? For example, might the piston oil rings have gotten stuck with burnt oil so they weren’t as effective at sweeping oil from the cylinder walls, and that may have let a great deal more “blow by” occur? I had heard that a bad PCV system might also cause sludging, but didn’t understand exactly how. Or maybe bad timing? You seem to be a natural mechanic who thinks his way through problems. Hey, you didn’t use a FSM, and I cannot even change the oil without one!!!

@@billcowhig5739 yes a bad PCV can cause sludge. The PCV allows positive pressure created by the piston action (basically compressed air) to vent from the engine, but not suck air back through the valve during vacuum situations in the crankcase. Basically a one-way valve. That vented air is sent back to the engine intake to be burned. If the crankcase gasses and pressure are not allowed to vent it can blow seals or allow contamination and hot gasses to build inside the engine. All those collected hot gasses and such can cook the oil faster. That’s the short answer. And of course oil gets pushed places it isn’t generally supposed to collect. And so forth.

Also yes blow-by contaminates oil. Any combustion products going down past the rings will shorten oil life. Timing can effect oil life if the result is a hotter combustion chamber.... heat breaks down oil. Just like a leaner mixture creates more heat and also breaks oil down faster.

@@wrenchwranglers thank you yet again. That explains something that I didn’t properly understand. I have the two camshafts and all the shims out, and have been busy using up a lot of blue oil paper towels digging out sludge from every nook and cranny. I did a first pass cleaning of the lifter buckets, but the undersides still have lots of crap on them. Don’t see anything obviously bad with the caps or journals, but plan on measuring them to make sure they are in spec. As to the PCV valve, the FSM provides two tests of that valve, blowing through the valve from each direction, and the illustrations show lots of air flowing into the valve cover, but hardly any in the other direction, just as you described, a one way valve (check valve). I also read in the Haynes manual that if you shake the valve back and forth, you should feel something inside moving back and forth. My PCV valve appears to be working, according to those suggested tests, however I ordered a new one because I don’t trust that valve, or feel that something in the hoses might have clogged, causing my problem. Plan to disconnect both hoses and see if there might be something blocking one of the passages. The way you described hot gasses “cooking” the oil appeals to me as a likely cause, given the extent of sludge accumulation, and seeing so many engines taken apart in KZfaq videos that don’t look nearly as bad as what was in my engine. Plus, I carefully watched my oil and changed it with Mobil 1 synthetic oil all along, so never expected my engine to be so bad. Lack of use for extended periods of time and short trips, rarely on the Interstate, especially during the pandemic, seems the most likely cause, but those conditions would not heat up the oil in the way you described, unless the PCV system was not functioning properly. In the colder running temps scenario, the oil degradation process must be quite different, maybe bringing moisture from the atmosphere into the oil to mix the oil with the water to generate a foamy sludge? Another KZfaqr set down four ways you can cause the oil to sludge, and he added one I hadn’t heard before, when the engine runs fuel heavy (consuming too much gas). Is there a way that I could send you two photos, under the cover itself, and where the camshafts were, as of when I first opened the valve cover? I’m thinking that you might be able to recognize something just by looking. The gasket was leaking because it had gotten so old that it had broken in a few places.

If it’s been on for a loooooong time, then the wheel will probably have rusted itself onto the brake drum. Basically you have to shock it loose by using a really big hammer, or going back and forth with an air hammer jostling it. You can use a sledgehammer and hit the tire top and bottom and side to side to try to budge it. Don’t hammer directly on the shell rim or you may bend it.

On this vehicle I pulled and replaced the timing cover carefully without removing the head. The truck went back to the customer and has been running fine ever since with no issues. As long as you make sure to go slowly and think about what you’re doing it will be fine.

@@wrenchwranglers ok thank you for the reply, This video has helped me a ton.

Hmm…. I would probably first verify the parts were correct. There’s always a chance they gave you the wrong parts.

No you won’t have to pull the a/c charge unless you plan on completely removing the compressor

@@wrenchwranglers Thank you!

@@wrenchwranglers so I did it over the weekend. Truck does not rattle anymore! It took me 16 hours total with all of the cleaning and prep work. The crank bolt was the biggest setback. I tried using multiple air impacts, the breaker bar on frame and using the starter method, I tried to wedge a pry bar on the flywheel and try to muscle the crank bolt loose. Nothing worked so I resorted to using an induction tool at my work and I held it onto the head of the crank bolt for 15 minutes until it was hot to the touch and I proceeded to hold the impact down until it gave way. Thank you for the tips and tricks. It is most definitely a big job but it is not that difficult. Just takes a lot of time. I started at 12:05 PM on Saturday December 17, 2022 and I finished at 4:30 AM the next morning. It was non stop wrenching except for a 45 minute dinner break.

@@jimrossabrena7955 of the 16 hours you expended, how much time got eaten by the crank bolt? And did you purchase a kit of some kind before starting?

I did pour oil over the top end, but I filled the oil pump with Vaseline to get it pulling oil faster. Vaseline is just jellied petroleum so it dissolves immediately when oil hits it. There’s really no other way to prime the pump since it’s a gear pump above the oil level.

@@wrenchwranglers the manufacturer instructions from my engine say not to lube with jellied petroleum, but to pour oil over the gears. Maybe you can give me a little insight I’m not incredibly experienced. I was going to put a coating of oil over the gears before putting the timing and oil cover on, as well as what you did and pour a little over the top. I also have to measure the oil pressure without the plugs on to make sure 20 psi of oil is calculated with 16 quarts of oil, which after primed, is drained down to 5-6.

@@isaiahscarborough1654 I don’t think I’ve ever bothered to read the manufacturer’s instructions for an oil pump 😂😂. I just do what I’ve found works best over the years. You can certainly just oil the gears like they say but it takes longer to prime sometimes. And that extra cranking with zero oil pressure is not something I like.

@@isaiahscarborough1654 it sounds like they want to prime the pump by basically submerging it in oil… which would work. Just seems wasteful to me. But it would certainly work for sure because the pump will be under oil at 4 gallons of it lol.

@@isaiahscarborough1654 I suspect they recommend the ‘submerge in oil until prime is reached’ method because it’s kind of idiot proof. You can’t mess it up by leaving air gaps in the Vasoline. If you do the Vasoline trick correctly it will work with no wasted oil you have to drain later. Just make sure to completely fill the pump and gears, otherwise it might not prime fast enough.

If I remember properly (which may not be the case), yes the crank timing mark points down when aligned with the chain marked link

I doubt it’s the timing belt itself…. Even if it stretches there is a built in auto-adjusting tensioner, and if the noise is caused by a stretched or failing belt it’s usual catastrophic and not just a tick (think pistons hitting valves). Ticking can be valvetrain or sometimes an exhaust leak that changes because of heat expansion cycles. Sometimes even loose internal tolerances like a loose wrist pin on a connecting rod (which is generally more of a clatter or knock). But generally for intermittent I wouldn’t look at the timing belt.

@@wrenchwranglers i've had a Honda tick after a rebuild and it ended up being a exhaust gasket, like you mention

Sounds like a valve issue, the valves on these engines need to be checked/adjusted at higher mileage

Some of the bolts required a universal joint and some creative use of socket extensions, but I must be used to it because I don’t remember any particularly hard bolts. Anytime I pull a pan it usually involves a great deal of patience and strange configurations of sockets/extensions/universal joints to work around everything.

There isn’t an official replacement interval, since it has an automatic tensioner that adjusts for stretch and wear it is supposedly a lifetime part. The main issue is the nylon guides and the fact that these engines are going 300-400k miles with no major issues. This one was replaced because the customer requested it, but it probably could have gone many more trouble-free miles.

@@wrenchwranglers Thanks for the reply. I'm on the fence about changing it, though I think I will because I'm removing the trans to do clutch also, and with everything that has to be removed to get the head off, plus the transmission, I may as well just pull motor and do it all.

@@mikevee9145 if you haven’t proceeded with the work yet, and would like another opinion, from your description, and if you have the lift and stand, I would suggest you pull the engine/transmission to do the work. Once out of the truck, it would be so easy to access anything you needed to get to. And from that ease, you would find more things you could easily do while the engine was out, so when you put it back, it’s kinda-sorta like new. Just my opinion.

Do you mean the marks on the gears never align, or the relationship between the chain and gears never re-align? If the gear timing marks do not align properly with where they should be once rotated two times back to TDC on the firing stroke then something is badly off.

If the sensor is new, and the mechanical timing is verified by checking the timing marks, the distributor position could be slightly off. You have to verify everything is aligned at Top Dead Center in cylinder number one on the firing stroke.

The PO336 diagnosis/resolution starts at 44:42. It was the distributor base position being off by one tooth. Placing the distributor correctly resolved the issue (if I recall correctly). 49:28 for the start of the final determination of the problem.

@@wrenchwranglers thanks for response 👍😁👍

200,000 plus.... I don’t remember it exactly but there is a later video on this truck where I did mention the mileage.... I think it’s closer to 230k or 240k

If it is an interference engine, I. E. one where valves and pistons overlap if valves are open and piston is at top dead center, then yes pistons will hit valves and damage will occur. Most engines these days are interference engines, and even mistiming by a significant amount can cause damage. The timing chain or belt keeps the valves times properly so that they are closing or closed by the time the piston reaches the top of the stroke, and so cannot hit. If the belt or chain breaks this connection is lost and the piston and valves are no longer synchronized and can hit each other.

@@wrenchwranglers I've got a 97 tacoma and was going to replace mine myself, but I'm old & tired and will probably go to the dealer and have them do it. 230,000 + miles. How much do you think they would charge to do it?

@@omnipotentdwarf571 honestly they will probably charge you more than it’s worth because they are a dealer.... dealerships make money on service, not selling cars. Frankly your best bet is to find a reputable private mechanic who specializes in engine work. Some dealers pay a flat rate to their mechanics based on each job, not by time spent, also encouraging corner cutting. But they still charge the customer as if the mechanic spent a long time doing the job. So long story short..... I’m not sure but it will vary depending on where you take it so honestly it’s hard to say for certain.

@@wrenchwranglers I don't think the timing chain is making this rattle. I pulled the valve cover. The chain is snug, the tension arms look intact. The spring tensioner looks extended far, but looks good. The fan belts and pully's are snug, but the rattle seems to be coming from the front. The fan shroud is tight. If you could give some thought as to what it might be, I'd appreciate it.

@@wrenchwranglers There's a fairly good mechanic in town I'll ask later today

This is the 2.4L 2RZ-FE engine

Is it the same on a 98

@@joeyfaulks 1995 to 2004 2.4L in the Tacoma should all be the same engine, if I remember correctly

@@wrenchwranglers ok thanks

@@wrenchwranglers this is the best videos on the 2.4 timing chain that I've seen. On the internet

Yes it is

Not near enough, lol.... I actually do not remember at this point, but because they brought it to me and it wasn’t ‘on-site’ repair it was less.

@@wrenchwranglers Seems like a ton of work and you even cut some out by not taking the head off! How many hours you think it took? Thanks!

@@thegolfdude it took about 14 hours total, of course that is not across one shot because there was some waiting for parts and things thrown in there. So it is spread out across a few days.

you know its a huge job when the Chilton repair manual says, the timing cover is a massive undertaking @@wrenchwranglers