2nd time burnt exhaust valve

Recently my 2000 2.7l burnt out the exhaust valve in the number 2 cylinder. The first time it happened was about 5 years ago. I'm curious if anyone else has had the issue? The truck is 4wd, 2.7l with CA emissions and just rolled 300k before the issue. I've decided to have the head rebuilt the 2nd time if possible, if not I'll purchase a new one. The compression on the other cylinders is great so the lower half of the motor is fine. I'm thinking of replacing the injectors, new head and a complete exhaust since it needs one anyways. I'm thinking the number 2 injector might be causing the issue, any ideas???

 

valve adjustments,,,? to tight on the clearance?

 

I've never adusted the valves and the dealer never mentioned doing that, is that required maintenence on it?

 

Apparently, the valves on these 3RZ motors are known to tighten up, causing them
to fail. Keeping them adjusted will decrease the likelihood of burning.

You should be, at least, CHECKING the clearances every year or so ( easy to do)
Then ADJUST if necessary (hard to do, for me anyways)

 

Thanks guys. I'm gonna go ahead with the rebuilt or new head but I'll be sure to check the things now every year or so. It might have saved me from having this issue come up a second time if I'd known. Oh well, lI've and learn!

 

it's required on my 95.5',, i've done mine, be sure when they put the head on or you, that you double check and that they ALL fall within tolerance's called for, especially the exhaust valves. i try and hit mine on the lose side,
ie. I think mine call for .010 to .012 on the exhaust, if I remember right, so i'll shoot for the .012. this is on the exhaust but i do the intake the same but it's just not as critical on the intakes, they still need to be within range though.
I know when i got my head back, some of the exhaust were at .003, way to tight.

 

I really really wish we didn't use shims. or at least had followers that could be moved out of the way.

 

The shim design is good. They take 100-200k miles to go out of spec. The only down side is people don't check them when they get to high mileage because they take so long to go out of spec. They're not in the habit of checking them.

I agree with what pulldo said. Double check the clearance after the head and cams are reinstalled. The machine shop or builder should check them but may not.

 

Kawasaki used a nice design on the old ZX DOHC engine that utilized spring loaded fingers that just slid over to get to the shims. This made taking the cams out to change shims unnecessary, Then there's the measuring/subtracting and buying of expensive shims when those followers could have been made adjustable. (cough, Honda)
Yea, I know some people can get the shims out w/ cams still in but I hate taking the chance of dropping a valve if those retainers fall out.

Oh well, they'll all be solenoids shortly anyway and we'll prob. be wishing for the good old days.

Yea, it takes quite while before they get real bad but most of us live with clatter on intakes for years 'til our exhaust finally gets so tight we have to act.

On a side note:
every sportbike forum I've ever been a part of had a 'travelling' shim kit. You replace the shims you use or the kit is short on and you get to have a whole set to draw from right in your hands when your doing your measurements. Then send it to the next guy in the sticky. All it would take to get one started is a call out for members to gut heads they come across and send shims to a person putting together a kit. The shims may even cross over to other models I dunno, on bikes they do.

 

These size shims were use on many Toyota models around this time.

The valve won't drop because the bucket stays over the valve if you are just removing the shim using the special tool.

There was someone on this forum a few months ago that was having a hard time using the tool. He was going to give up and remove the cams, but he said once he understood how to use it and practiced a bit, it became easy to remove the shims without removing the camshafts. So, I guess for a pro with the right tools the design isn't so bad.

 

I posted how I did it on here a few years back, if you're good enough to do the search to find it, I'm not. I ordered the "special wrench", it wasn't the toyota brand though, it was an aftermarket. It would work on probably two thirds of the buckets but the others not so much, really hard to explain why it wouldn't but it was the rough "casting" on the camshaft that made the wrench not work on some.
So i had to use the one in the video the guy uses for motorcycles, looked like a bent screwdriver. I couldn't find the particular model he used, i don't think it's made anymore, but I found a Kawasaki tool I think it was on Ebay and modified it to the pics in the guys video, very easy to do. It's a bent screwdriver, stubby in length. It made life way easier in pushing down the bucket to place the "holder" in to hold the lip of the bucket.
It is really not that hard, especially if a "old" 68 yr. old welder like myself can do it.

 

I found the video of the guy that I liked and found to be the easiest for me, way easier.

https://www.youtube.com/watch?v=pKEkOdQuJR4

 

Dam..no telling how many 'sludged' Camry engines I junked.

 

For all the vehicles with the same shims, see the Part Fitment section at the bottom of this page. There are 15 models/engines from the early 1990's to the mid 2000's.

https://www.toyotapartsdeal.com/oem/toyota~shim~valve~adjusting~13753-74210.html

That's just the 3.00mm thick shim part number. They are available from 2.50 to 3.30mm in increments of 0.05mm.

 

I looked and have an old set from a 4AFE.
Think we should make a sticky to put together a free set for the board?
That 7 bux a shim is ridiculous and who wants to open a head and have to run to the shop or even order?
All I'd have to do is buy an organizer.
That's what, 25 sizes. oops, 16.

 

And Pulldo, thanks for the video. Just like on most bikes I didn't really see how to get the bucket down when it's so close to a pedestal. Maybe make a tool part of a kit?
Looks like a bent screwdriver ( or brake adjuster?) and a hold down lever (which I could have water cut if I had a template) but what holds it in place to keep bucket down?

Ah, I think I see. In the design to stand up on it's own.

This was always handy also, especially if you're not using a metric caliper

http://crfsonly.com/calculators/crf450-valve-shim-calc.php

and this

 

Sub'd - cause I've been neglecting mine...

 

Love the traveling shim kit idea, crux.

 

I think if we keep up a sticky we can prob. keep it supplied from junk engines. Even if a person has to buy 1 or two small shims after a job is complete (nature of the beast, you'll use more skinnys than fats) we're only talking about 15 bux for a vlv. adj. that can be done in an afternoon instead of hustling all over town.

The bonus of having a few choices on hand means you can get closer to spec. These things don't run exact when you mic them.
Yesterday I looked at a couple and they were 2.92 and 2.88. They're not worn, these things are very hard. I'm calling them as 2.95 and 2.90 but it's always good to measure beforehand what your putting in. Then remeasure your gap and see if your as close as you're going to get with what you have on hand.
*My mic isn't the best in the world, it just gets me in the ballpark. Feeler gauge does the real work. Not having to remove cams would be a real lifesaver here.

 

Yeah definitely. That sst or making your own tool to be able adjust without removing the cams would be a huge plus.