What to inspect if lift isn't working or is very weak. For 2ZZ engines.

[d_m_kolb]

Step 1 - remove Valve coverOnce you have it off you will see this Take a closer look at this area - the 2 10mm head bolts you need to inspect are pictured below: Take the bolts out and inspect them. I dont have a picture of a good one, but heres what they look like when worn (should be replaced) And heres what they look like when they have broken off Hopefully this will let you identify what the problem is if your lift isn't working, and this also gives you something to print out to show your Tech at the dealership what you're talking about. It is necessary to remove the broken off portion of bolt before you can put a new bolt in.The Part number for the bolt is 90105-06293 (there is also an older number 90105 06271 - I am not 100% sure which part is superior.)This is how to remove the broken off bolt.quote:take out the timing chain tensioner, pull off theexhaust cam drive sprocket, remove the intake cam and the oil control block for lift off the back of the head, tap the rocker shaft forward into the timing chain cover area, and remove the broken off peice from the shaft. I do NOT reccomend doing this yourself if you dont have to. Also be careful because sometimes teh rocker shaft is in there kinda stiffly (mine was) and when we hammered it out the broken peice of bolt jumped out of the shaft when it got free and fell down into teh timing cover. Luckily we were able to fish it back up with a magnet, but I could see it turning into quite the ordeal.This was the intake valve side. Exhaust side would be quite a bit easier. You would only have to remove the cam drive sprocket and the oil control block on the back.If your engine has 40,000 miles or more I'd inspect them. I would definitely recoment inspection and replacement if you find any signs of wear. The bolts are only 50 cents so you may as well have them on hand when you do this to save having to pull the valve cover twice.I would recomend inspection once every 6 months. Just keep a set of bolts on hand and if worn replace. Cheap and easy and sure as hell beats the alternative.I havent seen a torque spec. Frankly just good and tight with a normal 1/4 drive ratchet should be fine. Dealer says that on this engine they are recommending that the serpentine belt be replaced every 20,000 miles due to excessive glazing even with the revised tensioner.These bolts keep the rocker shafts from rotating. Technically as long as your engine is running there is going to be SOME amount of force on your rocker shaft every time a cam lobe depresses a rocker (which is once per ignition cycle per cylinder, so twice per crank rotation. The rocker then exerts a roughly opposite force when the cam lobe comes off the rocker and the valve springs force the rocker back up to its normal position. However due to the nature of the load this force is a lesser force than the force applied during depression. Since the sheer rate of oil is a constant it stands to reason that these forces are magnified greatly during higher engine RPMs. The engagement of high lift also causes a greater range of motion in the rocker shaft as well as the normal increased drag of higher RPM. So yes this bolt is always under SOME amount of stress, and while an Over-Rev could certainly accelerate its failure by virtue of lack of proper oil pressure and even more magnified forces, it would by no means be necessary to cause a failure.[quote]well... i just did it... looked at the front one (intake rocker shaft) and noticed it was worn.. then i took off the exhaust one, and it was less worn but worn nontheless. Here's the picture: heres an up close picture... Chris was wondering if it was just the finish rubbing off... but upon closer inspection (using all 5 megapixels in macro mode.. lol) you'll notice that its digging a trench and quite obviously can shear if left untreated. Okay - I ordered the 2 bolts from the dealer last week (I figured it would be worth a buck ro 2 to verify)the 90105-06271 is the blunt ended bolt and the 90105-06293 is the pointy one.2) 90105-06293 Shaft Stay Bolts(1) 11213-88600 Valve cover Gasket(1) 12255-88600 Crankcase Breather Tube Gasketif you buy all the supplies from partznet.com by using their OEM toyota catalog the total cost would be $13.80 for everything!

[Cubanpete]

When I see stuff like this, I am not happy, for one I am not a Mechanic and do not have the technical engine knowledge like most here, and from what I see in the photos this is not good, Pontiac should release a recall bulletin and fix this problem, if they can notthen I believe I just got sucked into buying a crappy motor

[bouleric]

Wow. Isn't this a pisser. Just when you thought Toyota had a pretty solid product, this came along.Ok, so it's another scheduled maintenance item, which isnt' so bad.Here's what I'm wondering though - for those of you who've inspected and found worn bolts, what type of oil were you using? I'm wondering if synthetic vs. petroleum based has a big effect on these wear rates.I've been running full synthetic since oilchange #1, so I'm looking forward to seeing what my bolts look like when I crack the valve cover open this spring.Cheers, Marc

[Lorin]

Thanks for the great post! Its always better to know these things in advance, rather than learn about it the hard way by paying a dealer to fix something at say, 50K miles and out of warranty. With a high-tech engine like the 2ZZ, there are bound to be issues. That's one of the great things about having a resource like genvibe where we can share information and experiences on how to deal with them.Lets look at the bright side: a couple of bucks for some bolts that can replaced on a sunny afternoon is a lot better than having a turbo go out!

[DABEAR95]

Admin, where did this information come from?Thanks,Jason

[Cubanpete]

Hey admin! At How many miles/Kiloetres did you change these bolts ion your car?

[johnsoax]

My lift seems to be very weak and I only have just under 6k miles. I've only hit lift three or four times, but it just wasn't what I was hoping for (don't get me wrong, it is fun to rev the engine that high, but I thought it would have more kick.) (I bought the gt mainly for the 6 speed not the engine. I love to drive a stick and thought the 6 speed would be more fun than the 5)

[Cubanpete]

I know exactly what you mean in terms of kick, I do find it very good on the freeway, but in the city, it's not the greatest, I too have the same like you, 6 sp. GT. It puzzles me why this car could not come straight from the factory with at least 160 -175 lbs of torque.........especially in the lower end. 180HP is fine for me .............the torque should have matched the HP...............at least to classify it as "Genuine" GT performer.

[viberations]

to all 2zz engine owners, first of all donot blame toyota, becauseif we would all remember the stamp on the sideof the 2zz head/block, and if im not mistaking they get put togetherat a yamaha plant and are specs out and sent then to gm/toyotatoyota has great engine tranmissions, etc.......

[d_m_kolb]

I got this info from http://www.newcelica.org. They have been having some trouble with this.

[Kissfan79]

To check/replace those bolts, do you just un-bolt them and bolt the new ones in? I guess what I mean is is there anything that will go out of adjustment or need reseating if you take those bolts out? Will the dealer check them for you under warranty if you ask them to?Jim

[dmitri]

nah dont worry kiss. i do have a pretty important question though.....what do you torque these bolts to when you reinstall them????

[cohocarl]

quote: but this would be a warranty issue!I'd have to agree. Anything as critical as valvetrain operation should be handled by the dealer while under warranty. I wouldn't even think of pulling the valve cover off before the warranty is up.

[Cubanpete]

After doing some research and I presented this link to some friends that are Service Mechanics, they said the following;1) If this is a known issue on ALL VVTL-I engines, then a factory recall should be in place. ...as this is not "NORMAL" operationm, and they are aware that this part will fail and could really screw up the engine if it gets trapped inside will you are driving. It does not matter who made the engine(yamaha). It falls to the responsibility of the car manufacturer, in this case Toyota and GM2)They also told me If these are isolated cases (user) problem where the user "Boots/floors" the car consitently and stresses the engine thus the bolts wear out and snap. Then they MFR will charge the user for the repairs. They also told me if you do the job yourself and the dealer finds out, your whole warranty is out the window.So I know that big GM guys read this forum, and should please take 10 minutes of there time and honestly clear this issue onece and for all, If we should take our cars in to get the parts changed then be it!

[ragingfish]

quote:If this is a known issue on ALL VVTL-I engines, then a factory recall should be in place. ...as this is not "NORMAL" operationm, and they are aware that this part will fail and could really screw up the engine if it gets trapped inside will you are driving.I was under the impression this was normal wear and tear? Regardless though, absolutely, leave it to the dealer. You're messing with a crucial part of the engine, and one false move might be disastrous. Let the dealer mess it up, then THEY have to fix it...

[Cubanpete]

Wear and tear? Are you telling me then these are isolated incidents?

[joatmon]

AOTOTB (attack of the old thread bump) I remembered this thread on the way in to work today, and even though I don't have a GT, I was wondering if anyone has had any problems with these bolts. it seemed like this was going to be a potentially big problem for the 2ZZ engine, but nobody has brought it up for a long time. Any updates? Is this a non-issue?

[Mase]

I checked them last year when I had to remove the valve cover to get to the header. They looked used, but not damaged or severely worn. I think the newer bolts are designed with more taper to promote less severe wear.

[tcam]

Quote, originally posted by dmitri »i do have a pretty important question though.....what do you torque these bolts to when you reinstall them????yeah, I really wanna check these pins out but I have no idea what the the torque specs are. does anyone know??