How would a mechanic tell if my motor required new shims?

It is a 2000, 4x4, automatic with the 3RZ-fe motor.

My check engine light illuminated solid. During my stay, I should have worn a watch because my work order says "1 hour," but my appointment time seemed closer to 45 minutes. My work order does not specify what work was completed other than a "P0302 code" and two "P0302 codes" from their OBD scanner that was for "multiple misfires." My work order only has a written statement saying that they need to "check and adjust the valve clearance to confirm the issue." They estimated "$450-500 plus tax depending upon how many shims are needed." Then they want my vehicle to remain on their premises "for 2-3 days to check it when it is cold, order shims, and install shims and then recheck it." Everything in quotes is only what is written on my work order. Could they tell that my motor needs new shims during my initial appointment without removing the valve springs and other components associated with the shims to inspect them? I was charged $110 for labor, but I cannot tell what they did other then plugging in their OBD scanner.

My check engine light turned off, and when I told the owner, his reply was that "it has leaking valves," and then he added something like I will be fortunate if it does not burn one; but how did they discover all of that in one hour?

 

My opinion? Provide more info. What truck? What engine? Where did you take it? What state do you live in, northern Alaska where there is no dealers? What symptoms was the truck exhibiting? Just a code? A hour and $110 for technical diag is very normal, and a hour is probably the minimum charge.

 

To adjust one valve, the old shim (for that valve) would have to be replaced with a new (different thickness) shim. The only way to determine if it needs to be changed is to check that valve clearance, which is a fairly easy job (takes about an hour maybe).

If an exhaust valve clearance is too small, it could cause a burnt valve, which would cause a mis-fire. That is your worst-case scenario. Did they do a compression check?

 

Thank you for taking the time to tell me, they did not notify me if the valve clearance was checked nor that they completed a compression check on my work order or any other task other than an OBD II scan. In my first post, literally everything I typed in quotes is all they wrote on the work order which makes it seem as if they charged me $110 just to plug in their OBD device. I will call them back to double-check, I am hoping they took the time to check the valve clearance. Thanks again for the helpfulness.

 

$110 is normal for a diagnostic charge. It doesn’t normally include any labor or work outside of checking codes and reporting possible repair options.

 

I recently paid for both a compression check and a leak down diagnostic. The compression was 175 across all four cylinders and a 20% loss from the leak down check they said were both "good."
I re-read my maintenance log and had driven 5k miles over my spark-plug interval, but after replacing all four I noticed an increase in power (peppy), it revved more smoothly and the motor idled smoother; I suspect one or four of the spark plugs was the cause of the misfire but am still not certain.

 

Though I do not know that particular motor you have have the way you listed codes is confusing and impossible

as a P0302 is a misfire on cylinder 2, a random misfire is a P0300, it sounds like there was three codes for P0302 and thats not a thing. I presume that that you went to a dealer for this work and we have scan tools that can tell us moderately easily if its the coil or the plug that is causing the misfire, (we can view a power balance graph for all cylinders and see which is misfiring, then move the coil and if it follows the coil its the coil, if it stays on 2 then its the plug.) That being said from your next post I assume you changed the plugs after this visit where "they" told you that you would need a valve check and possible adjustment. If you have no codes after changing plugs then dont worry about it. There is no way to check if you need a valve adjustment without opening the engine up and checking, it would be normal to leave it for a few days since it must be cold when measured(metal expands when hot). However if you are not having any engine issues then dont worry about a valve adjustment, that is the opinion of both the independent shop I worked at and the dealership I am at now. As I said I dont know that engine but $450 to $500 is pretty good for a valve job in my opinion, that would be roughly 3 hours labor plus parts, which they wont know until they check what the valves are at currently. And yes $110 for a hour of diag is normal, dont get all bothered that you think it only took 45 minutes, sometimes it takes less sometimes more, I spent about 1.3 hours on a customers car for only 1 hour of diag.

 

How many miles do you have on the truck? If you are over 150k I would just have them check and adjust the valves. Once you burn one it will be a lot more expensive. $400-500 is a pretty good price, you might even get them to reimburse the $110 diagnostic charge if they do the work. A lot of shops will offer that.