Inspect engine valves?

Then I will tell you. That Geo Prizm (Corolla) I bought new back in 1990 is still going with 330,000 miles without ever -needing- a valve adjustment. I checked the lash adjustment several times as scheduled. That's a little

1600cc four cylinder with shims over buckets that is revving about 3,000 rpm @ 60mph. For review, an automatic lash adjuster is patch for variations in valve train clearances, be the reasons thermal or accumulating wear.

In consideration of the additional cost of these mechanisms and the increase in reciprocating weight these mechanisms incur, Toyota, Honda, and others have proven hydraulic lash mechanisms are not absolutely necessary. That's a fact born out by the very information you recently provided.

Do be careful with the nomenclature. The force behind all variable cam and valve timing that I know of is hydraulic pressure from the engine's oil pump. Hydraulically variable cam timing has nothing to do with valve lash.

Regarding your Avalon, I would simply look at the EPA sticker under the hood of your car. When that sticker calls out valve lash for Intake and Exhaust valves, obviously your engine is not fitted with hydraulic lash adjustment.

The information I provided indicated that even Toyota is moving towards hydraulic lash adjusters. In addition to the new Avalon V6, the new European Avensis Diesel includes hydraulic lash adjusters.

I don't think even you believe the BS you spouuted about superior metallurgy making valve adjustment uneeded. Afterall, you claim to check yours reguarly. While that might not be a big expense to you, the typical Toyota owner is forced to pay $300 to $800 for this procedure. A procedure that would be uneccessay if simple hydraulic lash adjusters were used. At those prices, I think I'd just take my chances.

The only other major vehicle manufacturer that sells a number of engines with mechanical lifters is Honda. I think you will find this article interesting -

. At least mostHondas use a simipiler adjustment scheme. And ironically, Hondaadvertises hydraulic lash adjusters as a major benefit on it's moreexpensive motorcycles. Ed

The proof is in the pudding. At the present mileage of 330k,000 that car

*has* *yet* to -need- any valve lash adjustments. And yes, I did do lash imspections at the scheduled intervals.

Indeed, the link you provide calls your $300-$800 valve lash adjustment bill into question.

"In conclusion .... It is our opinion that having the valve lash clearance inspected/adjusted at an interval of 30K miles (on any vehicle without hydraulic lifters) will provide the best hedge in fending off any potential major engine repairs as a result of valve failure. The typical cost to have the valve lash inspected/adjusted is between $82 - $120. A valve job can cost between $700 - $1800 or more depending on the extent of damage."

Obviously this is their informed opinion regarding HONDAs.

You mention a "simpler adjustment scheme" .... how is Honda's "scheme" different from say, a small block Chevrolet V8?

Not for Toyotas.

Unfortunately, I don't have the option of having the inspection done on a Honda. It's $450 on my Avalon, at the dealer. If I could have had this done for $100 we wouldn't be having this conversation.

I'm familiar with the innards of several large piston aircraft engines and they ALL use roller cam followers...I'd say for good reason.

Good for you. My Audi with solid lifters was still perfect at 50,000 miles. It has been 20 years since I owned a car that needed the valve clearance checked. That's at least ten valve clearance checks I managed to avoid by not owning a Toyota. If a solid lifters system is so perfect, why bother checking the valve clearance? Why does Toyota even bother to require it? Your own statements indicate that you believe routine checking is necessary. I assume you do the work yourself, so the cost is probably minimal as long as you don't have to actually adjust the clearance. But how much does it cost the typical Toyota owner to have the valves adjusted on one of the engines with the shims under the bucket style tappets? And if this is something that isn't going to need adjustment, why specify routine checking? If a typical Toyota owner follows your advice, they will spend hundreds, probably thousands, on valve clearance checking and adjustment over the life of the car. The next time someone talks about the reliability of a Toyota, I think they need to consider the added cost of valve adjustment. This is not a trivial cost. I also wonder how many Toyota owners put up with ticking lifters because they don't realize that Toyota is still using a system that when out of favor in most of the world 20 or more years ago.

They were providing the cost for Honda engines. Do a Google search on "Toyota Valve Adjustment Cost" and read a selection of the results. I could not find a Toyota dealer that listed a valve adjustment special, so I can't be sure of the costs. I did find one independent shop that had a $329 service special that supposedly included valve adjustment (of course it also said, some models higher....wonder which ones). A couple of people griped about valve adjustments that cost over a thousand dollars.

The $82 - $120 valve adjustment is for a Honda that uses finger type followers and set screws to set the lash. My Sister has a Civic. I believe I could adjust her valves in 90 minutes. I think this is in line with that cost range. It uses set screw adjusters and the only thing that has to be removed is the valve cover. I am sure the cost would be far higher on a Vee type engine with shims under bucket tappets. Just checking them is probably a two hour job. If you actually need to replace shims, I assume the labor goes through the roof. One reference I read claimed it was easier to remove the head than to do the adjustment on the car.

And Toyota are so much better because they are using those special material you are always talking about?

Modern Chevrolet small blocks don't require routine valve adjustments. So I guess the small block scheme is infinitely better than the Honda's scheme (or Toyota's)

Ed

"Tristan Shout" wrote in message news: snipped-for-privacy@z14g2000cwz.googlegroups.com...

Was the $450 for inspection and adjustment, or just inspection? Were other services included? From what I've seen if you have an engine with the shims under the bucket tappets, you might as well go for a timing belt replacement at the same time you get the valves adjusted. If the engine has shims on top of the buckets, then shim replacement is not hard. I had an Audi like that and, with the right tools, it was an easy job. I know at least some Toyotas are like that, since I've seen the tools advertised and they look very similar to the tools for my Audi. I do know that some Toyotas use shims under the tappets. These won't be so easy. It is not clear to me which engines use which style shims, although I think your Avalon has the hard to replace kind. If they will adjust valves for an engine with shims under the tappets for $450, it is a bargain. I know if I was checking the valves of that type engine and a few were loose (too much clearance), I'd just let it ride. Unless the clearance is really excessive, loose valves aren't going to do anything worse than click a little bit. On the other hand, if they are tight (too little clearance), adjustment is necessary to prevent having the valve being damaged (especially exhaust valves). I spent many "happy" hours adjusting Jensen-Healey valves. The Lotus engine in those cars used the shim under the tappet style system. Even though it was a longitudinally mounted inline 4 cylinder in a nice uncluttered engine compartment, I still needed the best part of an afternoon to check and adjust the valves. I can't imagine that you can just check the valves in a transverse mounted VS.-6 in less than 2.5 or 3 hours. And if any valves actually need adjustment, I guess the time could easily be doubled or tripled depending on how many valves are out of adjustment and how they are distributed (if they are all on one cam on one bank - it is not too bad, if all four cams are involved - look out).

I have to think most Toyota owners, either out of ignorance, laziness, or because the dealer recommended against it, aren't having their valve clearances "inspected" (much less adjusted). Otherwise I think there would be a lot more outrage over the cost of this service. The consequences of ignoring the service are potentially unpleasant in the worst case scenario (burned exhaust valves), but to be honest, it appears to me to be a good bet to ignore the whole service. It would not take too many $450 "inspections" to pay for a valve job. I had a valve job done a Mitsubishi V-6 year before last for less than $700 (one burned exhaust valve, both heads serviced). Probably a valve job on an Avalon would be a lot more expensive ($1500??) but still I suspect a couple of valve adjustments would cover the cost of just having the heads removed and the valves resurfaced / replaced.

Ed

How would you feel about paying $$350 higher purchase price for the car in order to get hydraulic lash adjusters?

Gord. Roller cam followers never have been synonymous with hydraulic lash adjusters. The immediate advantage to roller cam followers is the cam lobe opening and closing ramps can be made much more abrupt/aggressive without incurring undesirable wear on the cam lobe and lifter face (flat tappet/lifter face). Commercial diesel truck engines have utilized roller cam followers for generations.

I would ask you the question; Why do valves still burn with hydraulic lash adjusters present? Is there any doubt that hydraulic lash adjusters are more sensitive to varnish accumulations? I would suggest to you that the more aggressive opening and closing cam lobe ramps now sought for low rpm torque and improved emissions require roller cam followers and that it is the presence of the rollers that necessitate hydraulic lash adjusters to silence valve train noise by keeping cam lobe-2-follower distance (lash) near zero.

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Well then, rather than speculating, how about another list of engines identifying which ones have shims over, shims under, and those with NO shims (selective buckets) ?

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On these three points, I agree. :^)

You can burn a valve for many reasons. Personally I've never burned one in an engine with hydraulic lifters. I have burned on in an engine with solid lifters (actually a couple). My SO burned one in her van with a Mitsubishi engine. But Hers can be attributed to spotty maintenance, a second rate engine, and using the van to pull a 24' sailboat. She did the same thing to her Toyota. According to the mechanic that redid the heads, the problem was not a sticking valve (the engine uses followers with the lash adjusters on the pivot side). I looked over the disassembled head and despite the less than regular oil changes it looked OK. I was actually surprised how clean it looked despite the lack of routine maintenance. I suspect the actual cause of the burned valve was an intake manifold air leak that caused that particular cylinder to run lean. The problem showed up after she used the van to haul the sailboat back up I-95 from South Carolina.

No matter which way you cut it, there is simply no excuse for Toyota selling cars for the last 10 years with valves that require routine adjustments. If the valve trains are truly good enough not to require adjustment, then Toyota should drop the requirement from the service schedule. If they are not dropping the requirement so that they can cover their rear ends in case of burned valves, then they should be ashamed to exposing their Customers to hundred, or thousands of dollar worth of unnecessary maintenance. And if the lifter scheme does require routine checking/adjustment , they should be ashamed of themselves for sticking to an old technology because they were too cheap, or too stubborn to adopt a well know and reliable technology.

Ed

Why do you ask this question? Are you implying that it would cost this much to use hydraulic lifters? If so, I think you need to do some additional investigation. I looked up the cost for a single replacement lifter for my Thunderbird. It is less than $9 from a Ford dealer for a quantity of one. So, it is likely that $2 is a high estimate for an OEM buying in quantity. So for a 24 valve V-6, the cost of the lifters is probably less than $50. The part being replaced is not "free" so the incremental cost difference is probably less than $30. Selective assembly (adjustment of the valves during engine manufacturer) is avoided, so the actual "cost" might be negative. I'd guess the actual cost is probably close to $0. So again, where did you come up with the $350 increase in cost? Was it just a rhetorical question? Even if the actual manufacturing cost increased by $350, it is not likely that the selling price would be affected. Vehicle prices only have a tenuous connection to manufacturing costs. With the profit margin Toyota has on many models, the cost to update their engines to contemporary standards would not need to be passed on to the Consumers. And the Consumers would receive a real benefit - the avoidance of expensive maintenance procedures.

Ed

The 'many reasons' are: (1)valve erosion due to less than optimal metalurgy, (2)valve prohibited from seating fully under various conditions.

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That is your opinion which is yours to cherish for whatever it gets you.

WHERE is the evidence of your claim? The old Sludge Witch should have been on this one by now if what you say had any validity. LOL

There is more complicating and parts that ONLY 24 lifters. But admittedly, I picked the $350 figure out of thin air.

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Well now you're guessing more than I. Toyota has already "value engineered" every model they sell and I suspect the cost of this valve train redesign will be funded by cutting something elsewhere in the the vehicle.

You are the Toyota expert. I don't even play one on TV.

As far as I can tell, the following engines use the shims over the bucket tappets style of adjustment:

4A-G(Z)(E) 4A-F(E) 7A-FE 7M-G(T)E 3S-G(T)E 5S-FE 22R-E 3RZ-FE 2UZ-FE 3MZ-FE 2RZ-FE 1GR-FE 5S-FE

The following engines use the shims under the bucket tappets:

2TG 18RG

The following engines use selective thickness lifters

1MZ-FE 2AZ-FE 5S-FE 1NZ-FE 2AZ-FE 1ZZ-FE 3V-ZE

I wouldn't actually use these lists for anything. Maybe you know the right answers? As unbelievable as it seems to me, this is not even a complete list of recent Toyota engines sold in the US. Just how many variations do they have?

I also notice that the Toyota high performance engine experts (tuners) warn repeatedly again turning high rpms with engines using the shim over tappet arrangement. Apparently you can adapt these engines to the shim under tappet style valve train. From what I read, you cannot turn the shim over tappet type engine much over 6500 rpms without risking the shims coming out which can lead to severe head damage. That blows your mechanical lifters are better for high rpms that hydraulic lifters theory, doesn't it?

The whole Toyota product line is a quagmire. Apparently the engineers at Toyota cannot decide the right way to do anything. Hydraulic lifters, bucket lifter with shims over the lifters, bucket lifters with shims under the lifters, selective fit lifters, pushrods with hydraulic lifters, push rods with solid lifters. And this is just for recent US products. Throw in the rest of the world and the number of permutations seems endless. One other thing I noticed, the bucket tappets by themselves cost much more as a replacement part, than the lifter plus follower for my Thunderbird (when purchased as replacement parts). How does Toyota get away with soaking people like that? The individual shims cost more than the Tbird hydraulic lifter (as a replacement part). Oh what a feeling!

Let's net it out

Mechanical lifters

- expensive to buy (at least if you by the Toyota parts)

- increased engine manufacturing cost (need to adjust the valves on the manufacturing line)

- not good for high RPM (if you use the shim over bucket type)

- expensive to maintain (especially for shim under the bucket and selective fit lifter types)

Oh yeah baby...Moving Forward to the 1930s.

Ed