3.4 valve clearance

Are you guys checking the valve clearance on your 3.4s? If so, how often? Does anyone have experience with this?

 

I am wondering the same thing on the 4.7L. Trying to keep the DC hummin. Haynes manual says every 60,000 miles. FSM also mentions performing a valve clearance check, but I did not readily locate how often / how many miles. I'm at 264K and it has never been performed to my knowledge. I'm thinking of doing it at the same time I do the valve cover gaskets, though they are not leaking thankfully.

 

I've never check mine even when I had the valve covers off at 310k. https://www.tundras.com/threads/wha...-gen-tundra-today.2558/page-1913#post-3519185

 

Seeing as no one responded in over a year, I'd say two things: not many people here have the 3.4L, and also, these trucks don't need valve adjustments.

Sure I can see someone at some point needing one, but really...My 98 Tacoma had the 3.4. I sold it with 330,000 miles and not a single valve adjustment. Seems like the 4.7 is the same. Unlike the 20R/22R/RE, where I'd do it every 20k.

 

Suspect you are correct on both counts. Had it only been in the Haynes, probably wouldn't have asked. Will stick to my original plan. Thanks for confirmation....

 

Seems like they're worth checking while you're in there. I'll bet a lot of people with similar mileage, myself included at 235,000, would be interested to know if they're in spec!

But I wouldn't open up the engine just to inspect them.

 

Agreed.

 

1997 T-100 with the 3.4 V6. 277,000 miles. Owned it since new. Have never even considered checking the valves. Engine runs like the day it was new.

 

For the last year I owned my Tacoma with the 3.4, the gas mileage dropped from 19 to 17mpg, highway. At 300,000+ miles I wasn't too worried about it, but I was curious about the cause. Obviously at that mileage there could have been a lot of things. But...maybe finally time for a valve adjustment? Or low compression? Still had the original injectors, too.

Probably a mix of all those things and more, but I'd be curious if maybe at 330,000 it finally needed an adjustment. Guy I sold it to planned to drive it for a few months, then completely rebuild everything over this winter. I wonder what he found when he tore it apart. Last I heard from him was just a day after I sold it to him, a text saying a check engine light had come on and the oil was low. I told him to let me know what found when he hooked up a scanner but I never heard back.

Check engine light one day after the sale was just bad luck. But I mean...330,000 miles...you know? Low oil, if I had to point a finger, was his driving style, though I wasn't going to accuse him. Only time I ever had to add oil between changes was when I really pushed the truck while pulling the trailer. When I rode along with him on the test drive I noticed he was happy to cruise along at really high rpm without worrying about shifting. If he drove it that way all the way home (~120 miles of interstate), it wouldn't surprise me if the oil was low.

Really, really wish we had checked it while he was looking over the truck. Oh well. No idea if he felt sour about the sale, or just realized pestering me about a 20+ year old truck with 330,000 miles that he repeatedly told me "I'm just going to pull and rebuild the engine and transmission anyway" wasn't appropriate...Still, we got along and both felt great about the deal. Then I got that text. Definitely left me feeling bad.

Anyway. Tangent.

 

I'll throw my hat into this conversation from two perspectives. I own a 3.4 powered truck, I've parted out a few Toyota's and I was a Toyota dealer tech for the better part of 10 years.

On my own T100, I did the valve cover gaskets at 160k after owning the truck since 102k miles. I knew I was planning on eventually supercharging it, so while in there, I checked the valve clearances. Out of all 24 valves, I had an exhaust valve on each bank that was "iffy" meaning just on the edge of could be loose, could be tight, on the edge of spec. It was a judgement call either way. I didn't adjust, and the truck still runs flawless and quiet with 240k miles. I ended up falling on a supercharger 5k miles after checking the valve clearance, so it has been supercharged and beaten on for close to 80k miles, and I do mean beaten on. She regularly saw shifts at 5k to redline at full boost, and prior to buying my 5.7 Tundra in 2018, it was my DD and tow rig. I've hauled upwards of 7k total weight in scrap with that truck. It didn't like it, but it did it and the engine was the least of my concerns with that weight. I still own it but haven't driven it in close to 3 years as I'm in the process of solid axle swapping it. I also have parted out a few 3rd gen 4Runners with 3.4's, one of which broke its frame at the rear trailing arm mount on the frame at 340k. The engines buyer asked me to pop the passenger cover off to check for sludging and valve clearance. All valves on that side were perfectly fine, well within spec.

As a technician, the only time I've ever checked valve adjustment was at customer request, or if sludging/engine performance issues were involved. In my career, I've checked maybe 2 dozen engines valve clearance, and other than the old 20/22R 4 cylinders, I've never found one out of spec. But those engines service manuals call for inspection every 15k if memory serves correctly, and they are notorious for getting clicky and out of spec, but also don't use the shim and bucket adjusters that most late model Toyota engines use, the 3.4 and 4.7 included.

 

Right. Shims. The R-series engines it was just a lock bolt and screw. Loosen bolt, adjust screw. No parts necessary other than the valve cover gasket.

For a short time I had the 3.0 V6. Read up on the valve adjustment and thought "shims?" WTF? Huh? So I had the dealership do an adjustment (I was young and naive). Assuming an hour work. It was either $400 or $600, can't remember now. I was legitimately shocked. And this was somewhere around 2010. Back then it wasn't an automatic $500+ any time a mechanic touched your truck.

So...the fact that these engines don't seem to need adjustments is a really nice thing.

 

Add that to the list of things wrong with the 3.0

The old techs always had stories about those engines. The head gasket recall was a thing of unfortunate legend. And every Toyota tech I've known that worked for Toyota prior to about 2010 has a horror story about a 3.0. I owned one. I used to defend it. Then I totaled that truck, and really started my career, and realized how stupid I was to defend that junk.

The only Toyota shim engine I know other than the 3VZ-E 3.0's to have valve adjustment problems were the 2/3RZ 4 cylinders in the 1st gen Tacoma and 3rd gen 4Runners. Those engines had a mild reputation for the exhaust valves eating their valve seats and slowly receding into the head, making the adjustment tighter and tighter, to the point where they lose compression, or destroy the cam/shim bucket because there is no more slack to take up. I've seen probably 4-5 RZ 4 cylinders do this, but every time was over 200-250k and the customer declined the work to repair it and I never saw the truck again.