[fisher112]

Hi everyone,

I am just finishing up a valve clearance adjustment on my 99 3.4 auto, 126k miles. I did a lot of searching for information on the forum and elsewhere before I got started, and didn't find much information, so I thought I'd offer some insight (and pictures soon hopefully) on the procedure and results. I run Mobil 1, and have since break-in, which may or may not affect the rate of valve clearance change. But of the 24 valves, only 7 were out of spec. When I pulled the shims on these 7 valves (this engine is a shim & bucket design, fyi), they were remarkably unworn. Where the cam lobe rides the shim, you can still see some manufacturing markings! I don't know if this is common or not, but in my experience there is usually some visible wear on the cam - shim interface, so I was happy with what I saw. I did not use a shim removal tool either, so it's not required though it would make the job easier. If anybody needs information on this prodedure, let me know.

Scott

 

[AK98Taco]

Thanks for posting this. It's not something you read every day, especially here.

 

[dirthead1]

How's it run now? Mine is '98 with 110,000 and it feels a little tired. I had wondered if I had some valves out of adjustment.

 

[fisher112]

I should get it together tonight, so I don't know how it'll run yet. It had some very light valve 'ticking' at idle, and there was some excessive valve noise at high RPM too. I expect these noises to go away, and a small increase in performance / smoothness too. From what I understand, the valve timing is very sensitive to changes, even 0.001" changes. I had one valve out of spec by 0.002, about 0.004 from the midrange of the spec. Didn't consider these to be excessive for the mileage, but I hope it quiets down some and runs better too. I'm doing the timing belt & water pump at the same time too, so if the belt had stretched fractionally, it's possible it could increase performance / smoothness too. I'll keep you posted on the results.

 

[tacoma2k]

Hi everyone,

I am just finishing up a valve clearance adjustment on my 99 3.4 auto, 126k miles. I did a lot of searching for information on the forum and elsewhere before I got started, and didn't find much information, so I thought I'd offer some insight (and pictures soon hopefully) on the procedure and results. I run Mobil 1, and have since break-in, which may or may not affect the rate of valve clearance change. But of the 24 valves, only 7 were out of spec. When I pulled the shims on these 7 valves (this engine is a shim & bucket design, fyi), they were remarkably unworn. Where the cam lobe rides the shim, you can still see some manufacturing markings! I don't know if this is common or not, but in my experience there is usually some visible wear on the cam - shim interface, so I was happy with what I saw. I did not use a shim removal tool either, so it's not required though it would make the job easier. If anybody needs information on this prodedure, let me know.

Scott

how did you remove the shims without the tool?

 

[Toyotajoe]

I'm interested in any info you can provide on this subject. I currently have around 133,000 miles on my '98 3.4, and am about to get the timing belt/water pump swapped out within the next couple of weeks. Is this something that would be alot easier to do in conjunction with the timing belt change? I assume the valve covers have to be removed for the timing belt swap anyhow??

 

[boophoenix]

Sweet, I was fixing to do a write up on the valves after another write up. Can't wait to check yours out.

 

[fisher112]

I finally got it back together after the adjustments, and it runs great. I'm really happy with the results. Runs smoother all the way thru the RPM range, with minimal valvetrain noise. As I mentioned before, I did the timing belt & water pump at the same time. When inspecting related parts, I went ahead and replaced the timing belt tensioner idler pulley because I didn't like the way it sounded when I spun it by hand (could not tell for certain if it needed replaced, so I did it just to be safe) and I also replaced the bearing that is pressed into the A/C idler pulley, again, because it didn't sound perfect. It is NOT required to remove the valve covers to replace the timing belt. For the valve adjustment, it is required to remove the intake plenum. It is two pieces, the top one is attached to the throttle body. The bottom one is attached to a third intake piece. I got replacement gaskets for both (same part number), though I've heard they are reuseable since they are metal, not fiber. Again, better safe than sorry. I took pictures before disassembly so I knew how to get the vacuum lines and connections back together during reassembly. I recommend leaving the throttle cables mounted to the bracket that attaches them to the intake, so the cable adjustment does not change. Once the intake plenum pieces are off, CLEAN everything you see on or above the valve covers before you take the covers off. The wire harness and all hoses / lines will likely be dirty, and this junk will fall into the valvetrain when the covers are removed if you don't clean up everything. Then you can remove the covers. Once you have access to the valvetrain, you need to begin measurement of the valve clearances. INTAKE: (.006-.009"), EXHAUST: (.011-.014"). Use feeler gauges to measure the clearances between the cam lobe and the valve shim ONLY when the lobe is 'pointing' upward. Document all changes that need to be made on each valve, and label accordingly. Be organized. Once you figure out what size shims you need for each valve that is out of spec, order/purchase the shims from the dealer. To remove the shims: if you have the proper tools, this will be easy. If not (like me), you can CAREFULLY use a flathead screwdriver to compress the lifter. Then, use a smaller flathead screwdriver to pop the shim out of the lifter by prying in the slot on the side of the lifter. Once the smaller screwdriver is under the shim, you can stop compressing the lifter with the larger screwdriver. Now, grab a pair of strong needlenose plyers and grab the shim and pull it out of the lifter. This takes some practice, but it's not too difficult. During all of this, be extremely careful to not scratch the cam lobe. I assumed I would have to replace all shims, so I didn't care so much about them. Also, once a shim is removed, DO NOT crank the engine to align other cam lobes for shim removal! The cam will get damaged, and it will possibly break the lifter. You must replace the shim before the engine is cranked to align other lobes for shim removal. Once all the new shims are in place, recheck the clearances. If all is in spec, you're about done. I poured a small amount of fresh oil on all the cam lobes before putting the valve covers back on. Use new oring gaskets on the valve covers if the old ones appear cracked or damaged. On the front and back of each head, there will be a semi-circle that the gasket goes over. Put some RTV (gasket maker) it the corners where the semi circles begin and end before putting the valve covers back on. Other than that, reassembly is the same as disassembly. If anybody has questions or comments/corrections, please let me know. I think this is a great idea for all motors over 100,000 miles if you have the time to dig into it.

Scott Fisher

 

[Jerrym49]

Thanks a lot for the writeup. I only have 66,000 miles so I have some time before worrying about it.