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Discussion Starter · #1 ·
Hi all! I'm new here and I'm "rebuilding" a 2zz which will be installed in my mr2 spyder.
Thing is, my 130.000km engine has a wiped intake cam, which i'm replacing with a new oem cam and rockers i bought from Partsouq. Since i pulled the head to replace the valve steam seals which were leaking and im trying to do everything as right as possible, i wanna try to fix this issue for good. The car will see daily and track use, i also bought a brand new oem oil pump and a seriously lotus baffled sump. Here's the info i've gathered as to why the intake cam may have wiped:
-I measured the valve lash with the new cam (the proper way, installing only 1 shim per rocker, measuring between cam lobe and roller, pulling the cam again, removing those shims and installing the other ones, install cam, measuring again...). Long story short, the loosest clearance was 0.09mm and the tightest 0.06mm. I already ordered 8 shims from toyota to set all intake valves to a 0.20mm lash (0.02mm looser than the max tolerance the manual allows). As usual, the exhaust cam shows no wear and the lash was 0.25mm on all 8 valves, so i'm not worrying about that one and let it be.
-The rest of the engine is pretty good looking aside from a bit of sludge, the rod bearings and cylinder liners look mint so i dont think it used bad engine oil on its previous life.

The question is, what more can i do to prevent the cam from wiping again? I've read a lot and couldnt come to a conclusion. On the first 100 miles of engine testing, im thinking of running some cheap 5w40 oil (total classic) and a xenum flush to clean a bit of sludge. I've read that some people strongly advice to break in new cams, specially in engines with flat tappets (which is the case for 2zz lift lobe), but i dont know how to bed that, i dont think it would be healty to drive the car for a few minutes at a constant +6000rpm, since it would be useless trying to bed the lift lobe with the tappet without lift being engaged, dunno if im making sense?

Thanks a lot in advance, regards, Ivan.

Btw, here are some pics of my wiped cam, it wasnt terrible, but... i think it only was a matter of time.



 

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As far as iv been made aware about the cam issue is its due to improper clearance or oil starvation. So replace the cam make sure the oil passages are clear of obstructions and you should be good.

In regards to the lift lobe it rolls against a slipper pad when not engages so regardless it has contact with the rocker just doesnt do anything unless the slipper is locked via oil pressure for lift.

Take that oem oil pump and chuck it in the fuck-it-bucket. Get one with upgraded internals from mwr, 1 miss shift or constant high reving and youll shatter that thing and ruin ur engine. Mine is billet.

2000 GTS Turbo
 

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Discussion Starter · #3 ·
As far as iv been made aware about the cam issue is its due to improper clearance or oil starvation. So replace the cam make sure the oil passages are clear of obstructions and you should be good.

In regards to the lift lobe it rolls against a slipper pad when not engages so regardless it has contact with the rocker just doesnt do anything unless the slipper is locked via oil pressure for lift.

Take that oem oil pump and chuck it in the fuck-it-bucket. Get one with upgraded internals from mwr, 1 miss shift or constant high reving and youll shatter that thing and ruin ur engine. Mine is billet.

2000 GTS Turbo
Okay, so the clearance problem is going to be solved, and the oil jets on valve cover were tested with compressed Air and they are not blocked.
About the oil pump gears, that was something i was debating and ended up deciding i dont need them. As far as im concerned, those also break when over revved, they might be beneficial if running a bit higher redline than stock, but i wont go over 8250rpm. Also, the budget and time for the swap have already Been exceeded, i cant afford to wait a month or more for the oil pump gears to get here (Spain) from the US.

Thanks for the quick answer!
 

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There are so many things that can play into cam wiping, but the major factors are valve clearance/lash, oil spray, and oil temperature/pressure. Some 2ZZs had the overhead oil lines improperly aligned, resulting in the stream of oil not hitting it's target. Others hit lift too cold, or with improper oil, causing wear. Yet more had improper valve actuation that grinds the lobe down, and really early in the 7th Gen's life the cams apparently weren't hard enough and Toyota had to update them.

Resolving all of these should minimize your cam wiping, but it's my personal belief that our intake cams are doomed to wipe. I think it's due to just how demanding the design of the head is and without fortifying both the cam lobes and rocker arms, they'll always wipe on some small level. Similar story applies to the oil pump.

Your cam is exactly as wiped as mine was at the same mileage, and it ran for another 30k until I spun a rod bearing. Just make sure the new one is set properly, and that your overhead oil lines are properly spraying on the friction points.
 

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Discussion Starter · #7 ·
It's my personal belief that our intake cams are doomed to wipe. I think it's due to just how demanding the design of the head is and without fortifying both the cam lobes and rocker arms, they'll always wipe on some small level. Similar story applies to the oil pump.

Your cam is exactly as wiped as mine as at the same mileage, and it ran for another 30k until I spun a rod bearing. Just make sure the new one is set properly, and that your overhead oil lines are properly spraying on the the friction points.
I dont know man, i'm starting to believe that as well, but i refuse to accept It lol. If that was the case, why are there 0 cases of wiped exhaust cams? As far as i can think, they work under the same demanding circumstances. The only differences are valve lash (looser on exhaust side) and maybe the fact that the engine is tilted making the intake cam the furthest away from the oil pump.
 

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The exhaust cam has a much less demanding job than the intake cam, hence the looser tolerance. I've read that Lotus owners had to come up with their own valve lash in order to minimize the issue, but cam wiping still occurs for them. Often they needed a multi-faceted fix just to minimize the wear, and it doesn't help that Toyota kept changing the spec: Need help with shim dilemma

It's a perfect storm of factors that lead to the issue, and fixing it means narrowing down all the points of failure and ensuring that whatever fix you apply doesn't break something else. Early on people got harder cams only to find out they wiped the rocker arms more instead.
 

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Hi all! I'm new here and I'm "rebuilding" a 2zz which will be installed in my mr2 spyder.
Thing is, my 130.000km engine has a wiped intake cam, which i'm replacing with a new oem cam and rockers i bought from Partsouq. Since i pulled the head to replace the valve steam seals which were leaking and im trying to do everything as right as possible, i wanna try to fix this issue for good. The car will see daily and track use, i also bought a brand new oem oil pump and a seriously lotus baffled sump. Here's the info i've gathered as to why the intake cam may have wiped:
-I measured the valve lash with the new cam (the proper way, installing only 1 shim per rocker, measuring between cam lobe and roller, pulling the cam again, removing those shims and installing the other ones, install cam, measuring again...). Long story short, the loosest clearance was 0.09mm and the tightest 0.06mm. I already ordered 8 shims from toyota to set all intake valves to a 0.20mm lash (0.02mm looser than the max tolerance the manual allows). As usual, the exhaust cam shows no wear and the lash was 0.25mm on all 8 valves, so i'm not worrying about that one and let it be.
-The rest of the engine is pretty good looking aside from a bit of sludge, the rod bearings and cylinder liners look mint so i dont think it used bad engine oil on its previous life.

The question is, what more can i do to prevent the cam from wiping again? I've read a lot and couldnt come to a conclusion. On the first 100 miles of engine testing, im thinking of running some cheap 5w40 oil (total classic) and a xenum flush to clean a bit of sludge. I've read that some people strongly advice to break in new cams, specially in engines with flat tappets (which is the case for 2zz lift lobe), but i dont know how to bed that, i dont think it would be healty to drive the car for a few minutes at a constant +6000rpm, since it would be useless trying to bed the lift lobe with the tappet without lift being engaged, dunno if im making sense?

Thanks a lot in advance, regards, Ivan.

Btw, here are some pics of my wiped cam, it wasnt terrible, but... i think it only was a matter of time.



Do a Google search for how to break in a new cam. Also use Break in lube for camshaft.
 

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Discussion Starter · #10 ·
Do a Google search for how to break in a new cam. Also use Break in lube for camshaft.
When i search how to break in a cam, they are always talking about old V8 with flat tappets and pusrods, which work differently to our 2zzs. They usually say to Rev the engine Up to 2000-2500 rpm during a certain amount of time and use oil with a lot of zddp. But doing that in a 2zz wouldnt make sense, unless you are in lift (over 6000rpm with jdm ecu), the lift tappet on the rocker Will just be compressed on its spring without doing actual work, so that wouldnt be a break in.
 

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When i search how to break in a cam, they are always talking about old V8 with flat tappets and pusrods, which work differently to our 2zzs. They usually say to Rev the engine Up to 2000-2500 rpm during a certain amount of time and use oil with a lot of zddp. But doing that in a 2zz wouldnt make sense, unless you are in lift (over 6000rpm with jdm ecu), the lift tappet on the rocker Will just be compressed on its spring without doing actual work, so that wouldnt be a break in.
There is NO special procedure to break in a 2ZZ camshaft, the only thing that needs to really be broken in for our engines are the piston rings, which is extremely important considering the MMC layer.
 
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