Jump to content

Recommended Posts

I need advice before I take the dealership apart about my recent repair. If you have followed my two threads about a rough idle problem and subsequent burnt valves, I would like to know if the mechanic who did the original valve adjustment (2500 miles ago) would have been able to detect those burnt valves at the time of adjustment. Knowing nothing about the adjustment procedure, would he have been able to visually assess the valve condition when he adjusted them. They are claiming that the valves (#3 and #6) were burned before the were adjusted. Wouldn't that have shown up as a rough idle problem or lack of power at that time? I get the feeling that they didn't do a compression test until this recent problem and then only to find the burnt valves. What say you?

Link to post
Share on other sites

This is hard/impossible to answer based on net postings.
However here goes, yes it is very possible to have had burnt valves before the adjustment. The engine should have been acting like it is now and the adjustment would NOT make any improvement. The mech should have found valves with very tight or no clearance. A pre adjustment compression would have shown this but is not normally done unless the mech finds a tight valve and is a bit worried about things.
For a shim to jump out of the bucket ranks along with turning lead into gold, these engines have billions of miles and yet there is no net babble about this problem. A valve guide shifting is almost in the same class of possibilities. But by pulling the valve cover you could see if any guides have moved. To hang a valve the guide would have to drop almost 1/2 inch or be so cockeyed you would see head damage
The part of the valve or valve seat that "burns" can not be seen or felt from the outside of the engine, like during the adjustment.
Hope this babbling helps some.

Link to post
Share on other sites

It ran fine when you took it in. It ran great when you got it back. So the question is how could those valves burn in 2500 miles if the valves were adjusted properly. There has to be a reason for this to happen. Anybody got any ideas?

Linda S

Link to post
Share on other sites

It all boils down to a bad adjustment. The odds of two mechanical failures in the same engine and at the same time are very unlikely.
The only recourse is to go to a different mech and have him document the valve clearances. Which you pay for and you are gambling that it was done wrong.
The weird things are like a shim failed and wiped out itself or a cam lobe, this would explain it running good for awhile. This would mean the valve isn't burned but just not opening, so bad idle and bad compression.
??? Were 3 and 6 adjusted.

Link to post
Share on other sites

Hey thanks all for the responses! I knew that I was asking for the impossible when I asked the question. Exhaust valves before adjustment were from #1 to #6--.004,.009,.006,.005.,.009,.003. After the adjustment they measure .010, .009,.010,.013,.009, and .009. It was running fine before I took it in and it felt better when the valves were adjusted. Here we are, 2500 miles later and a rough idle had me taking it back to the dealer who did the adjustment. Before I took it in, and right after the service, I got a check engine light. Took it back then and was told there were three codes, the EGR, the temp sensor on the EGR and the O2 sensor. Was told none of these would affect the driveability of the vehicle, so go to Florida from Penna. and don't worry about it. They showed me how to turn off the light when needed. When we came back this Spring, I replaced the temp sensor and the O2 but it didn't make any difference. The rough idle was still there. Took it in and that's when they found #6 exhaust valve burned. After replacing this, they still couldn't get it right and found #3 exhaust valve burned. That is where we are now--waiting for a repair and a large bill to match. Just coincidence or their fault?

Link to post
Share on other sites

Let me tell you two burnt valves on different cylinders and that poor thing would not be able to get out of it's own way. The measurements would not have been too tight to burn valves prier to adjustment. They excuse my words but they @#$% up. I would very much like to see the "burnt" valves I still think the shim was out of place and the piston ticked the valve. I did automotive machine work many years ago and if you dropped a valve on the floor it was enough that it had to be reground. Except the temp sensor the rest of the codes reflected an improper running engine.

Link to post
Share on other sites

my engine is running good & I was going to adjust valves for maintenance reasons only & bought gasket kit talking to mechanic & Toyota Nation forum I decided not to do job because engine is running good at 72000 miles and don't want to have any problems after job from bad valve adjustment or just tightening valves to much....

Should I do the job?

or leave it alone because its running smooth.....

let me know what you guys think..

Link to post
Share on other sites

If it's a V6 I agree with that you could do a compression check and if they all are close to the same I would leave it alone. The V6 adjustment is complex and can be confusing it is not some thing you would want to do your self for the first time. If it's a 4 cylinder then they should be adjusted at each tune up.

Link to post
Share on other sites

I have 22re 4 banger

If it's a V6 I agree with that you could do a compression check and if they all are close to the same I would leave it alone. The V6 adjustment is complex and can be confusing it is not some thing you would want to do your self for the first time. If it's a 4 cylinder then they should be adjusted at each tune up.

Link to post
Share on other sites

Definitely do it your 4 banger. Very easy job. Only 2 positions to get all the intake and exhaust. You will be surprised at how much better it can run and better mileage too. The V6 in this thread is a completely different ball game. As you can see not even professionals seem to be able to do it correctly.

Linda S

Link to post
Share on other sites

From all I've read, the 22R-E valves clearances tend to increase with use. Increased clearances will lead to increased 'valve clatter'. But adjusting the valve clearances are a simple task. Removing the valve cover and CHECKING the clearances is even simpler. If they're out of spec and you don't feel confident adjusting them yourself you can always seek help. But better to know. :)

BTW, the FSM schedules checking them every 30k miles.

Link to post
Share on other sites

That is correct the 4 has many moving parts that wear and the valves trend to loosen rather that tighten. This retards the valve timing and effects engine performance and with 6000# behind you you'll need all the help you can get!

Link to post
Share on other sites

From all I've read, the 22R-E valves clearances tend to increase with use. Increased clearances will lead to increased 'valve clatter'.

There is no set rule. Yes, parts wear. If cam lobes and/or followers wear, the valve clearance increases. If valve-seat recession takes place, valve-clearance decreases over time. If an engine has had a recent valve-job with freshly ground valve seats and valves - rather then new hardened seats and valves - it's very likely to lose valve clearance until parts work-harden. Increased clearance leads to valve clatter. Decreased clearance leads first to slight skips at engine idle but good running at higher RPMs. Then as time goes on, the tightest valves burn out and the engine skips all the time.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...