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1zzfe Valve Adjustments


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#1 ryanrcmt1

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Posted 16 November 2004 - 09:31 PM

Has anyone had a valve adjustment performed/recommended on their 98 or newer Corolla yet? Every one of these motors we've checked for valve clearance has not required an adjustment. I'm just coming up on 90k and wondering if I should bother. I haven't heard of this motor burning valves around here.

#2 fishexpo101

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Posted 16 November 2004 - 11:01 PM

I've asked the dealership - they just do an audible check. Others I've talked to have not required any valve adjustment on these 1ZZ-FE. I'm getting up there in mileage as well - but so far, no problems.

#3 jims99

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Posted 17 November 2004 - 05:35 AM

Maybe I've missed something but... these valve clearences are basically set by the factory and there's no possibility of the clearences doing anything except growing larger with wear. Therefore, no burning of valves can take place due to clearences drifting too tight, etc. So I for one will just enjoy the music of the valves and hope they last a long long time. Oh, I'm a new convert to the synthetic oil group and running Castrol 5-40 along with a new oil filter to keep any engine wear to a minimum, I hope.

#4 stewardc

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Posted 17 November 2004 - 07:03 AM

I presently have an 03 Corolla S with Mobil 1 and 170,000km on it. At the last service, I asked about valve clearance....he said you'll hear it when you need it.

#5 bwringer

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Posted 23 November 2004 - 01:53 PM

With their ultra-hard, and well-cooled valves and laser-welded valve seats, these engines are extremely unlikely to ever end up with decreased valve clearances unless something is faulty.

The cams and valve buckets are hardened, too, but it is just possible for these to wear at very high mileages. So you most likely would end up with increased valve clearances and thus noise at higher mileages. (Increased clearances are more noisy than harmful to the engine, up to a point. Decreased clearances are dangerous because they will cause the valve to overheat and eventually burn out.) However, the vast majority of Toyota engines will go to the junkyard far in the future never having needed a valve adjustment.

It's still important to check them every 60 k, though, especially if you've had any problems with overheating or oiling. It's also a good idea to replace that valve cover gasket every so often anyway.

It's kinda funny how many car people are stumped by adjusting valves -- anyone who works on motorcycles is intimately familiar with several types of valve adjustments.

I checked my Corolla at 80,000 miles and the clearances were still perfect. I recently sold a 1988 Corolla with 210,000 miles and its valve clearances were also perfect!

#6 ryanrcmt1

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Posted 23 November 2004 - 07:47 PM

The main reason I asked was that i have seen several of the 3VZ motors (3.0 V-6 in 88-95 trucks and 4runners) burn valves at 80-90k miles. I think I'm gonna pass on mine-I already had the valve covers gasket replaced with the timing chain tensioner o-ring right before my extended warranty ran out, and there isn't any extraneous noise from the motor at this time.

#7 bwringer

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Posted 24 November 2004 - 09:03 AM

A burned valve generally comes from the clearances being too small, which does NOT make noise.

A valve gets much of its cooling from contact with the valve seat. When the clearances are too small, it does not spend enough time in contact with the valve seat. The valve gets too hot, and after a while, the edge of the valve gets soft. The hot gases from the combustion chamber can even erode little canyons in the edge of the valve. This is a burned valve.

I've seen this happen on neglected motorcycles. The owner didn't want to spend the money to have the valve clearances checked because he thought he would be able to hear tapping if the valves needed adjusting.

When the valve clearances are too large, you'll hear the tapping noises, but the noises are generally not harmful unless the excess clearance is extreme -- the noise will drive you nuts long before any damage will occur.

So in the case of the V6 engines you're talking about (where there's a history of burned valves), you should DEFINITELY check the valve clearances. Shrinking valve clearances DO NOT make noise, and they can sneak up on you! The ONLY way to tell if you have this problem is to get in there and measure.