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Discussion Starter · #1 ·
Few time ago I changed the intake camshaft, all intake lifters and lift rod because intake camshaft started wears off.
I drive few kilometres and get off the valve cover and I see damaged intake camshaft again!!! WFT? why is this happen again?! I cant believe it :confused:
 

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what part of the valvetrain is damaged? the rocker arms/lifters themselves? the camshaft lobes? if the lifter arms are damaged then it might be an out of clearnance problem where the cam lobes are smashing against the rocker arms/lifter. i will say however that my car didn't have shims on it and i put about 20Km on it before realizing the problem; the rocker arms didn't yet show any signs of wear
 

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Discussion Starter · #3 · (Edited)
Here are photos. On first photo is first camshaft. The most damaged was first "lift" lobe but on the second cylinder lobe was not okay also. The rockers under damaged lobes was bad also. That rod which come through rockers was curved and it was really pain to get it out and replace.
So intake camshaft, all 4 intake rockers and the rod was replaced.

On second picture is replaced cam, witch have only few hundreds km in my engine... And the damage on the first lobe occured again. On rocker too..

After replacing the cam was posible to hear some ticking noise, but only when is engine warmed up. (and I think that car still have no power in low rpm)
So do you think it could be the valve clearance issue?

old cam


new cam
 

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Wow that is pretty worn. How is the non-lift lobe? What about the roller bearing on the rocker arms? The lash pad? Is that worn? If the lift lobe is that damaged there is no way the lash pad is not worn. If it is, that was probably the route cause of the problem - which is why your new cam became damaged.

From your details it sounds like you need to replace your rocker shaft, arms and that camshaft. the rocker shaft shouldnt be hard to remove and definitely not bent - it should be pretty easy to tap out through the VVL ocv slot with a flat head screw driver and mallet.

However, if that second picture you posted is the normal, round side of the lift cam lobe, and not the actual lobe protrusion, then you have a serious clearance problem somewhere. I'm fairly sure the lift lobe and lift lashpad are always in contact, but yours appears to be forced too close together with too much force. Have you checked valve shim clearance?
 

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-Check your oil feed to the head valve cover, the little holes that squirt oil might be blocked.
-Check oil pressure.
-How many KM on the engine?
-Valve lash might have been to tight.
-You might have gotten a bad batch of cams......it's been kown to happen.
 

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My cam did that exact same thing.
Thought it was just a Lotus problem though.


Set intake valve lash to 0.013"

Use Mobil 1 5W40 synthetic.

as many was saying about the spray nozzles in the valve cover, connect a water line and run water into it so you can see how the nozzles spray. some of them spray off angle, but then again the nozzle sits only 1/2" above the lobe so it has to be way off to miss.

Many of us are to coming to the opinion that the valves stick and that is what is causing this.

If that is true, the next thing that will happen is a valve is gonna stick open and the piston will knock the head off.
You will find it in the pan along with the pieces piston.

If you feel like pulling the head, I would think you'd do well to replace the valves, invest some time in the valve guides, making sure there is no sticky gunk up in there.

And again, make sure to make your intake valve lash 0.013"


Good luck bud.
I hope you get it straight
 

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Discussion Starter · #7 · (Edited)
Wow that is pretty worn. How is the non-lift lobe? What about the roller bearing on the rocker arms? The lash pad? Is that worn? If the lift lobe is that damaged there is no way the lash pad is not worn. If it is, that was probably the route cause of the problem - which is why your new cam became damaged.
Non lift lobes are absolutely okay and were good on old camshaft also. Problem was only on the lift lobes. On the old cam the first lift lobe was most worn but second was "touched" also. Sure, lashpads worn too. All were replaced.

-Check your oil feed to the head valve cover, the little holes that squirt oil might be blocked.
-Check oil pressure.
-How many KM on the engine?
-Valve lash might have been to tight.
-You might have gotten a bad batch of cams......it's been kown to happen.
- I checked oil feed holes in cover by blowing the air into it and all holes looks fine
- Im not sure about oil pressure but hope it is ok, exhaust cam is fine
- about 110 000km

I really made mistake that I did not check the valve clearance when I was changing the cam and rockers. I thought it was caused by rocker shaft failure. Now I doubt the clearance is set right.. Also that ticking noise which starts before the cam became worn..

Many of us are to coming to the opinion that the valves stick and that is what is causing this.
Also thinking about that but I hope it is not true. I really dont want to pull the head now.. Just finished the TK installation :(
I will check the clearance asap and post the result here
 

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You have to check the clearance it is really crazy how tight the tolerances are and how that may change from camshaft to camshaft.
 

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Many of us are to coming to the opinion that the valves stick and that is what is causing this.
I'm still out on this one as it's difficult to prove what comes first on the 2ZZ: Valve float causing piston to hit valve, bend it and damage guide or guide stick that causes piston to contact valve and bend it. I have found one sticky guide (cylinder 1, intake valve 1) in mine but it wasn't the original engine that came from the factory with the car so who knows what happened before with the engine.
 

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.013 is waaay too loose! the intake clearance is .004 to .007
Ok, how many exhaust cam has anyone seen wiped like this?

I have not heard of a single one since I started following this issue almost 2 years now.

What is the difference? Lash......So, set the intake lash to exhaust specs all around 0.011 - 0.013. That was the last I saw of my cam wear and everything was awesome until the head of my valve fell off into the cylinder. Or maybe it was just a bad cam.
The point is that nobody knows. No one can give a definitive answer.

The specification could be wrong with so many of us having this same problem. We gotta try something because toyota isn't helping and I don't think they care. They are selling parts. Good for them.

None of my sprayers were plugged or even spraying at an angle.
that was on the money. My lash was set to 6's Didn't help me any.

http://youtu.be/w5_wgutrUfI

Sound familiar?

http://youtu.be/UcjbMUhuiuM

sorry the video is not so good it was very dark out that night that I was able to get to it.

It only happens on the slipper side and to me it was a throw back to the old days when you could expect that someone was trying to get a little bit more lift and set the valve lash too tight.
Yes, if you saw cam wear like that it was a given that lash was too tight.

That is all I'm saying.
Smaay is telling the truth, and all his information I have found to be perfectly accurate.
 

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dwebb and smaay, i think you guys are playing with different units. the manual, on the intake side, calls for .004-.007 inches, otherwise known as .1-.16 mm. if dwebb's reference of ".013" is actually .13, mm, then you guys are both right
 

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No Sir,

Smaay is correct about the specification.

I am talking in terms of thousandths of an inch. 0.011" - 0.013"

I'm saying the engineers were too cocky and set the specification wrong.

4-7 thousandths is a good lash for a roller cam but too tight for a slipper follower side and the lobe is not able to take it.

It is not an argument over book facts. I agree the spec is 4-7 thousandths.

And the engineers forgot history or they were in diapers and considered the lessons learned 30 years ago irrelevant.

They got greedy and you and I are paying for it.

The purpose of valve lash is to allow for the expansion of the valve stem.
The exhaust valve is expected to grow more as it hasn't the intake air and fuel to help cool it. So it has a lot of lash. And coincidentally, you never see exhaust cams wiped. The intake valve lash specification is set extremely tight for a non-roller cam and results in the same exact failure as our flat cams of the past when we tried setting lash too tight.

Now is this all coincidence, or are these things related.
I don't know, go and ask an expert.

Just because a guy got an engineering degree and someone hired him to design an engine, doesn't mean he is incapable of making a mistake. Like setting a roller-cam lash to a slipper/flat cam.

I've never heard of an intake cam wiping once lash was set to 0.011"- 0.013"
If you do please let me know because that would settle it.
Many of us are running exhaust lash on our intake cam.
No one is complaining.
 

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I know some of the people who have built engines have called for loose lash on engines with upgraded cams. It's been more than two years since I built mine and I might just open up the valve cover and have a look at things. I have to look for the chart somewhere but I remember setting lash loose on the two cylinders that had mushroomed valves. Would be interesting to compare lobes between cylinders 1-2 and 3-4.
 

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There's also another probable cause to this, on a high mileage engine the bearings wear out and the tolerances will grow...making the oil flow more through them.
Add a turbo, that T's off from the pressure switch and you have effectively reduced the oil available to reach up top.
Given that the angle of the 2ZZ resting in the engine bay has the intake cam at the highest point.....it might be just enough to reduce flow to the squirters. Take a look at his picture.... piston #1...it's the farthest one for the oil to reach the squirter.
 

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There's also another probable cause to this, on a high mileage engine the bearings wear out and the tolerances will grow...making the oil flow more through them.
Add a turbo, that T's off from the pressure switch and you have effectively reduced the oil available to reach up top.
Given that the angle of the 2ZZ resting in the engine bay has the intake cam at the highest point.....it might be just enough to reduce flow to the squirters. Take a look at his picture.... piston #1...it's the farthest one for the oil to reach the squirter.
__________________
Correct!
 

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At Idle maybe, but not while on cam.

The regulator does not make up for low pressure or volume.
The regulator dumps excess volume to maintain pressure at a predetermined level.

Over 6K RPM's if the pump is not able to keep up with the volume demands of the engine you have worse problems than a cam lobe wipe.
You would be experiencing low pressure problems.

Pressure in a hydraulic system is constant throughout. You don't run out of pressure at the end of the line. The only way to have a pressure differential is to add a restriction. Or to exceed your pumps capabilities.

If you were exceeding the pumps capability at "ON CAM" rpm you'd be seriously eating sh!t at highway rpm's.

Our problem is happening at over 6K, there is no load if the slipper lock pin is not locked in.

bull****.
 

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Discussion Starter · #20 ·
I have checked the valve clearance today..
#1 0.25-0.30mm
#2 0.35-0.40mm
#3 0.30-0.35mm
#4 0.30-0.35mm

I checked old cam and found the #2 lift lobe had same damage as #1. So sorry for disinformation that it had less damage. But I remember #2 wear really fast. First I have checked the cam there was only first lobe worn after few km second lobe too..

There is one another thing. When I was replacing old cam the lift bolt was broken. I replaced it with bolt which had a little wear on its top(only until I get a new one)..

I dont understand why is #2 lobe fine now when #1 is damaged now..
Is not this only big coincidence of rocker shaft failure?

I will try to check oil pressure and record the engine sound.

overall




 
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