375k miles 3.4L lifter knock.......

So after a recent 500 mile trip i got an engine knock from my tacos 3.4L. Specifically the passengers side rear of the head (closest to firewall). Only happens above 4,500-5,000 rpms and i'm dead sure it's a lifter knock and NOT rod/bottom end knock. Have bent my fair share of pushrods on american v8s to know what lifter knock sounds like. Engine/ truck sounds completly normal, has normal power and runs fine shifting where i normally do (3,000 - 3,500). Have put probably another 300 miles since the trip with no issues (obviously avoiding high rpms).

Anyhow since i had a leaky vcg and had already purchased the gaskets i pulled my passengers side vc to see if anything looked out of wack. Everything looked fine, no scoring on cams or anywhere else just what i would consider normal wear for an engine with it's millage. no metal glitter anywhere to be found. Hooked up a remote starter trigger, disconnected efi relay/ fuse and spun her a few times. Watched plenty of oil come up everywhere it should, cams rotate and valves open and close as they should. Again nothing jumped out at me. Checked a few of the valve clearances and some were in spec and some out again nothing way out of wack. (Last valve adj done by previous owner at 288k miles, according to service records included with truck). Put the vc back on and did a thorough compression check and lowest cylinder was 210psi, highest at 225psi.

Thinking I needed a full valve adjustment and since i don't have the space to break it down, leave it sitting waiting for shims to come in and so forth i called a few local import shops..... One shop mentioned he had another 3.4L come in a few months back with same knock same side and that it turned out to be the actual lifter bucket being worn out and not just out of spec valve lash/shims. Said after swapping out the bucket and adjusting valves engine was back to good order. (quoted me $1,500 if my truck needs the same work)

So my question is has anyone ran into this exact issue on high millage 3.4s ?

Thanks!

 

Subbd to find out

 

These dont have push rods or rockers.....just twin over cams with lobes.

I always knew you lose valve clearance as they seat and wear down.
Never occurred to me that in real high milage....the valve pins can start pitting the buckets that they're pushing against.
That's probably the noise your hearing.......you've won the lottery to get heads to last this long.

Worst scenario, some valves may not be closing all the way.

If your gonna do buckets.....I'd redo whole head, or reman one....

Toyota 3.4 V6 5VZE Assembled Cylinder Head | King Cylinder Heads

 

Checking clearance is really easy, its the shim removal/replace/down time to get shims that is the issue.

To measure the clearance, I had to get a angled feel gauge set because seemed like straight one always was tight because of angle.
The FSM seems way too complicated with that 240 degree nonsense, only requirement is that cam lobe not touching shim (pointing up). Just turn crank, no need to remove timing belt.
If clearances within spec, your not out any money (ok a few gaskets). If you are out of spec, my advice would be to take it in because of aforementioned issues and if you make a mistake you can screw up your head. Its really tedious removing/replacing shims, especially when the head is on the engine with a 4x4, your back will be hurting.

I'm not an expert I just checked mine on the bench after a valve job. All were in spec and the tech wrote specs on the head.

With regards to OP I dont understand how worn bucket would not have excess valve clearance - perhaps that's what mechanic meant is the worn bucket can't be brought back into spec with any existing shim.

I saw one post where they said the nipple on the bottom can wear out. So if nipple worn, valve clearance would be very large and probably no shim thick enough to bring back to spec. Just guessing though.

 

With that many miles.....everything has a lot of wear on it. Would not do a half way job, only have to return......
the valve seats, guides, ect.
Whether or not it uses oil is where or not I'd stop at the head.

If your not gonna keep it long, I'd just do the buckets and shims.....

 

Agreed, I would pull the heads and get a valve job done. Valve adjustment is included. Used to be that people got valve jobs done at 100k miles.
If that engine has not popped the HG before he owned it that's amazing.

The thing with these engines is that they are incredibly durable but the head is a SOB to work on. Pulling the heads requires 2 cam removals and 2 cam installs (if taking for valve job) with all the damn caps going in the original spots.

When I got my heads back from the shop, I was preparing to install and I tipped the head to clean the mating surface and some of the buckets fell out - luckily it was obvious where they came from but I was at my wits end. I really miss hydraulic lifters and being able to pull heads w/o removing camshafts. I guess that's why valve job on these trucks can run to $4000.

When I was a teenager I pulled heads on domestics all the time and didn't know jack %%^&*. We were lucky to have a Chiltons but still got it right pretty much every time. I even did a bottom end once but didn't know to prime the oil pump and that engine had low oil pressure but still ran for 1000's of miles.

 

So that's what the shop i had on the phone meant. Some part of the lifter/ bucket wears out enough where you can't get proper clearance no matter the shim. Weird to me that it only apears at high rpms.

 

i'm absolutley not pulling the heads for a $4k valve job. whats the point of fresh heads on a 375k bottom end?! at that point a low millage JDM or even rebuilt engine swap would make much more financial sense. I can swap that sucker in a day.

It uses less than half a quart in between 7k mile Mobil one synthetic 10w30 oil changes. Doesn't smoke, has good power and still at 200+ psi of compression. As far as i know heads have never been off and head gaskets are OE. I credit the original owner for Mobil 1 oil changes and sticking to a strict maintenance schedule for the longevity of this truck!

Either way would love to hear from someone who has actually gone through this exact scenario of worn lifter bucket.

Ideally i'd like to pass this truck on in good running condition in the next 50k miles to help fund a low millage 2nd gen. So i'm not looking to dump a ton into it.

 

You say you can swap the engine in a day but you can't fix the lifter?
The $4k valve job figure was obviously for having all work done, I did mine for about $700.

Just pull the cam and pull the bucket out - its easy.

 

thing is any work i do is on the street (no driveway) and i can't have a vehicle that doesn't move for more than a few days. Strict stupid local laws.

I have no issues with doing the work my self. I used to build and 1/4 mile race short block fords back in the day.

I'm leaning towards ordering a set of lifters and just opening her up twice for the shims. If the shim master/shop kit wasn't $400 i'd just get it but i gotta keep it affordable. Really hoping it's the exhaust side as i just did my timing belt 2k ago and would really rather not have to pull the intake cam.

 

You can remove/install the belt tensioner w/o removing balancer/lower timing cover right? I think I have seen people do it.
So if you don't have to remove the balancer/lower timing cover you are already most of the way there, with no belt tension you can remove cam - you have to follow the FSM procedure or you can damage the head. If you don't have FSM access search the Internet for instructions.

Basically before loosening cam caps can't have any lobes pressing on the valves and I think its the intake has the gear service bolt (can use valve cover bolt) that holds the gear spring. There are dots on the cam gears facing the rear for intake/exhaust alignment. You could try to find the bad bucket before removing cam by using a feeler gauge thicker than max spec I suppose.

If it was me I suppose I would buy a few cam buckets and hope that the existing shim is close. If you need a different shim maybe try a cyl head shop, mine seemed to have lots of shims otherwise its order OTC at Toyota or online.

Don't forget to remove the gear service bolt when reassembling- I almost tied a string onto it.

 

Also, I finally got a wobble extension to remove the tensioner w/o removing the AC unit. Almost impossible with straight extension or uni joint but wobble extension made it almost easy. Access is so tight you have to do it blind though.

 

yeah i did the timing belt my self and had no issue pulling the tensioner without pulling the a/c compressor. Though i don't think i can reuse the tensioner (pull pin deal). I'm wondering if i do end up having to pull an intake cam and taking off the timing belt if it might not just make sense to pull all the cams and replace all the lifters on both sides since i'm due for a valve adj. anyhow. I mean if this one bucket wore out now who's to say another won't reach the same point of wear in the next 30-50k. i'd hate to have to do this job again and it's only $100 or less for the full set. Or maybe the old if ain't broke don't fuck with it applies and i should just replace the worn one i can hear now?!

I can hear for a fact it's one of the 4 rear (closest to passengers firewall) though there is no way to know if it's intake or exhaust for sure without maybe running it at high rpms with the valve cover off with my face right up in it. I used to run my ford v8s without the valve covers to adj my valve lash but not sure if it's doable with this engine.

 

that is some nice miles hope it does 375k more.

 

I'm thinking that probably the bucket nipple broke rather than just worn because never heard of this and it must be hardened steel. But won't know till you pull it.

The real problem with replacing all buckets is the valve adjust. I think its too much work to run with valve covers off because of intakes etc. Try inserting a oversize feeler gauge between cam and bucket to find one that has a lot of clearance - I think it will be fairly obvious with that much noise. Might as well check all of them same time - that can be done in about 1/2 hr and I assume would identify any other suspect buckets. I had to use an angled feeler because it seemed like a straight one was always tight because of the angle - at first I thought all of my valves were tight.

Removing buckets is easy with a magnet but make sure you keep track of which hole they came from. I put mine in a tray but they got scrambled although head guy didn't seem to care, I suppose all the valves seat a bit more with valve job anyhow.

If you have a vice you can put the pin back in the tensioner, otherwise might have to by a new tensioner since it come with pin installed.
There is a device on Amazon to press the plunger in while on the truck using the water pump pulley but its pricey - https://www.amazon.com/gp/product/B000I1E92Q?ie=UTF8 EDIT - DONT USE THIS, I THINK YOU HAVE TO CUT BELT TO USE IT.

I understand your predicament with the time limit but what can you do? They are even trying to ban people from working on cars in their own driveway in some areas. I bought my truck new so I'm pretty careful on doing repair once and right but I also need it to make a living so have to balance that - if it were me I would just look for out of spec clearances and fix that. At least then you have some breathing room and can plan on what to do next if you have additional issues.

That $1500 quote from the mechanic does not sound all that bad but I'm the same way, if I have tools and knowledge why pay some one. I did bring my truck in for timing belt once and it was $1200 15 years ago. They advertise $350 but at that price all they do is the belt.

 

With that many miles, there's a decent chance its had a head job.....
....so might be worth rolling dice and doing just buckets and shims/adj...
really depends on condition of the rest of the engine, if oil consumption is low, I'd say go for it.....

However what if he gets in there and finds a burn or bent valve??
Should of gotten taken care of immediately, that head may be in steve jobs territory by now.....
Good thing its a Toyota.

 

Got a video of the noise? My fathers truck and my 2002 both have more clatter on the passenger side than my 2001 with 297k ever did. My fathers had since he bought it with 65k miles, now at 197k. These engines don’t have lifters. The spring is all that’s there and the cam pushes directly down on the valve through the bucket. Too loose of valves will make horrible clatter. Typical wear for these engines are the clearances getting tighter which leads to less noise..


Exhaust manifold tick can sound like a worn lifter, but very rare on the 3.4



for the record, my 2001s first valve adjustment was at 277k miles. 3 valves were too tight by a hair. All the others were in spec. I doubt you have any serious issues. But I would definitely get the adjustment done

 

What were the valve clearance measurements? Was one in fact 'loose'? Which one?

It's also very hard to wear a bucket or a shim. If there's wear it should be obvious. Like falling out of place obvious. Did engine run poorly?

A valve out of spec. this bad should chug pretty bad.

I'd put money on it being something else.

Not to say I don't make bad bets.

 

[QUOTE="hessian42, post: 27286526, member: 197193"

Either way would love to hear from someone who has actually gone through this exact scenario of worn lifter bucket.

.[/QUOTE]
Read entire thread now after just running through earlier.
My experience is on bikes, virtually all modern bikes use buckets now and I've never seen a broken bucket, If it had you would have seen all kinds of carnage as it would not last 10 seconds at 3K rpm.

Your valve clearance numbers and compression numbers do not reflect anything being wrong up top. Those high of numbers on compression means you prob. didn't hold throttle open when cranking. I can't imagine an engine that old still being so tight.

I'd really look elsewhere but if you still have off covers, adjust them all to spec. Mix up which ones are out and move them around. Many times you'll only need 2 or 3 new ones.