NickB47

Hi Ya'll. Let me start by saying that I have done an exhaustive search to the best of my ability as to not add more posts on topics already covered. This topic HAS been covered, but I have not ready anything about this circumstance. Read on:

I started this project (https://www.yotatech.com/forums/f116...d-i-do-260539/) and decided to do valve cover gaskets and check valve clearances while I had it all apart. Well, guess what:

1 in - 0.006
1 ex - 0.006
2 in - 0.0075
2 ex - 0.0085
3 in - 0.0075
3 ex - 0.006
4 in - 0.008
4 ex - 0
5 in - 0.0085
5 ex - 0.008
6 in - 0.007
6 ex - 0.005

Now, I would probably have just left the 0.005"/0.006" exhaust clearances alone until after winter had #4 exhaust NOT come up with such a small clearance (actual result was that I could not get the smallest feeler [0.002"] to slide under the lobe). This seems like it could be a serious issue. I just bought this rig and therefor have no reference to previous performance, but the truck ran fine when I took it apart (minus the fuel leak, which is now presumably fixed).

What are the implications of <0.002" clearance between shim & lobe? If I go get a new shim to get this in spec how can I be sure I'm not just stretching an already fatigued valve stem to the point where it may fail/fall out of tolerance in a few thousand miles?

1993 Xtra-Cab ~185k miles manual 3.0 3VZE

TNRabbit

As the cams on the 3VZE directly actuate the valves (via the shims), as they wear, the clearance grows LESS. This means you might have a valve not closing completely, which can result in incomplete combustion, more exhaust emissions, higher wear due to inability for oil to get under the cam lobe, & possibly a burned valve. Need to fix that sooner rather than later.

NickB47

Rabbit - Thanks & agreed! I'm gonna pull the shim tomorrow morning, check the thickness (hope it isn't the smallest one), and go from there. Hopefully this is just a matter of getting one or two new shims.

Also - This is being done in-the-truck.

Really wishing I'd done a compression test prior to taking it down... maybe I still could?? Nothing keeping the engine from turning over... would have to disconnect the fuel pump & coil, but it should be do-able, right?

Other 3.0 valve clearance/adjustment threads for those of you in THE FUTURE who may have similar questions. READ:

- https://www.yotatech.com/forums/f116...stment-105218/
* https://www.yotatech.com/forums/f116...2-20mm-247426/
- https://www.yotatech.com/forums/f116...stment-243761/
* https://www.yotatech.com/forums/f116...8-3vze-246445/
* https://www.yotatech.com/forums/f116...-3-0-a-166528/
- https://www.yotatech.com/forums/f116...fusion-101013/
- https://www.yotatech.com/forums/f116...ustment-80991/

TNRabbit

Yes. It's supposed to be done WARM, so maybe you'll get piston ring leak-by--it shouldn't be anything tragic, just slightly lowered numbers. Disconnect the VAFM & igniter, ALL spark plugs out, & wide open throttle for the test. Crank over no more than 5-6 times per cylinder.

scope103

You could consider a leak-down test. You need a compressor and the gauge, but since the measurements are all relative an inexpensive tool would do. http://www.harborfreight.com/cylinde...ter-94190.html

I think your biggest concern is that the valve is not closing, and a leak-down test will tell you this more directly than a compression test could. An open valve will produce all the problems that TNRabbit described, including burning up the valve (the valve relies on sitting firmly in the seat to conduct away heat).

NickB47

Now that it is light outside I have some new info: my 0.002 & 0.0025 feeler gauges were stuck together (new tool + oil) so I was able to measure a gap of 0.0035"... NOT zero clearance.

I'm well aware that this is getting tight, but it is my understanding that as long as there is some clearance, the valve IS closing. As such, I'm thinking of buttoning it up until after winter (I have a winter truck and summer car) so that I can spend the time necessary to get the shim tool and do the job right. What are the implications of doing this?

scope103

I show the spec as .009-.013 (inches) Why isn't the spec .000? (Or .0035?) I would guess that .009 is room to allow the valve to expand as it gets warmer. I have no idea whether the valve expands the entire .009 (unlikely) or only .005 or even .003. But my guess is that you are running at least a small risk of propping that valve open. Any chance you could find a heated garage you could borrow for a day?

Dirt Driver

Valve clearance serves two obvious functions; to provide for thermal expansion and to allow there to be some interval where the valves can be left alone without running out of clearance.

One of two things are likely to happen:

1.) Your engine maintains at least some clearance and nothing bad happens before you can fix it.

2.) Clearance goes away and the valve/seat possibly get burned.

The problem is that you don't know how much the clearance shrinks between cold and running temperatures.

Pat8942

TNRabbit Say's &quot;As the cams on the 3VZE directly actuate the valves (via the shims), as they wear, the clearance grows LESS&quot;
You won't stretch the valve stem, it will only go up as far as the valve face will let it, and as the shims wear the clearance between the shim and base circle of the cam will increase, not decrease, if the clearance decreases you have wear on the bottom part of the valve and seat.

Dirt Driver

Which is why the clearance tightens under normal conditions. Wear between the cam and shims should be minimal over the life of the engine. If the clearance is opening up, then there is something wrong.

I missed the concern about stretching the valve, so it's addressed below:

As I said above, the reason for clearance tightening up is not from the valve stretching; it's from the seat and face wearing.

NickB47

Thanks for the input, folks. I officially decided to wait with it until Spring/summer. I'm going to keep an eye out for a 3.4 over the winter and if I can't find one I'll go down to the timing belt with the 3.0 next summer, giving me a chance to do new shims too.

I'll certainly be continuing this post in the event it doesn't run right when I hit the key tonight...

Thanks again!

j2the-e

Do the 3.4! You won't regret it. In the meantime, drive the ˟˟˟˟˟ out of that 3 point slow!
Burnt exhaust valve are common on both the 3vz and 22r because no one ever does the valve adjustment

Dirt Driver

It happens to the later engines too and for the same reason, but the 2RZ/3RZ are especially prone to neglect because there is no real replacement interval for the timing chain. The 5VZ-FE needs a belt every 90k, so it has a better chance of someone at least checking clearances while the rest is apart.

NickB47

Well, my fix on the fuel pressure damper did NOT work (still leaks). I also now know why one should NEVER RTV the valve cover gaskets (assuming you ever want to get them off again). This means I am back under the plenum and figured I may as well take care of the valve shims while I am in there.

NEW ISSUE - How the &*$#@ does one get the Toyota SST valve tool in to the #6 exhaust?!?!? The brake booster is right in the way! Seriously... I have to take off the brake booster to re-shim this? What a PITA!

scope103

?
Perhaps you're referring to RTV over the entire gasket? The FSM tells you the points where you must use RTV; if you don't, a leak is almost guaranteed.

I'm sorry I can't help you with #6E shim; just by luck I didn't have to pull that one.

j2the-e

Are you not able to get the tool in from the other side of the cam?

NickB47

Unfortunately not; intake gets in the way. Someone else HAS to have found a way to do this without taking off the brake booster...

j2the-e

Are you referring to the intake plenum? You need to remove it to do the passenger side anyway. No need to remove the booster

NickB47

No, the intake plenum is off. The [lower] intake manifold prevents me from getting the shim tool in on one side, the brake booster prevents me from getting the shim tool in on the other side. This ONLY applies to the #6 exhaust (farthest valve back on the drivers side).

I'll try to post a pic later, but without removing the lower intake manifold or the brake booster there does not seem to be a good way to remove the #6 exhaust shim with the Toyota SST. ANYONE with another method please chime in because I would really like to get this taken care of. If I don't get any response... the intake or booster comes off (whichever is easier).

j2the-e

Which tool are you having trouble with? The curved, scissor looking one that presses the valve open or the one that holds it open to remove the shim? I use a large curved hook tool to get in between the cam and the shim. Then pry it to open the valve just enough to get the sst holder in there.