Cam timing!

[Low Style]

Hi all,

After a bit of 4age manual reading and help from 70XIN and Timbo Cam and ignition timing was spot on.

Timbo and I took my car for a drive and it ran and drove perfectly, while pulling up to a set of lights the engine just shut down and would start..

After pulling off my Cam covers and making sure it was TDC, I noticed that it appears my Intake Cam is nearly 180 degrees out. I made sure it was TDC 4 times to be sure i wasnt being a sped.

Belt is still tight and I can't see any marks where it was slipping. The odd thing is this is the SECOND time this has happened.

I can not see anything interfering with the belt or that could be making it skip, there was not weird noises it just shut down.

The only thing I can think is that the Tensioner has moved(was/is still done up super tight). I also do NOT have the little spring for the Tensioner could this be the reason?

Any help in why this would be occurring is greatly appreciated.

[timbo]

Wow, wtf! You need that spring for the tensioner , also take the the cam pulley off and make sure it still has a knock pin.

[Low Style]

I haven't pulled the cam pulley off but can see a knock pin - will try and pull it off either tonight or tomorrow night.

Will be picking up a tensioner spring tomorrow night as well.

[timbo]

Sounds good. Such a pain when this stuff happens, hopefully its an easy fix. Still such a weird thing to happen...

[70XIN]

The spring isn't really necessary though - alot of people actually remove it because they worry that it can come off and chew up their timing belt (club4ag and toymods). At the end of the day, he still has good tension once the engine has stopped and the belt has skipped, THAT is the wack shit.

This one has got me stumped. Has anyone heard of a magic timing belt that stretches when running? Haha. But seriously, i can't think of any logical answer to this.

[70XIN]

When it skips, are you checking the timing belt tightness between the tensioner and the intake cam gear? Because everywhere else will be tight no matter what. Just checking you're not doing a herp-derp.

[ke_70]

so nothing's loose/worn/fucked? balencer/cam/oil/water pump pullys, bearings ect ect

i would check all this without the belt on.
theres somthing broken. it's a fairly simple mechanical component. there must be somthing up.
i'd pull everthing off and inspect it.

[Rice86]

when i had my 16v rebuilt with everything new, standard cams from a 4age expert, supposedly all timed up and TDC already, ready for a drop in replacement job, after a few cranks of the engine it wouldn't start..timing was spot on...more cranks and then belt jumped a few tooth..didn't release this until a week later though hahah

lined it up again and never did it again afterwards.. so not sure what cause it but yeah has happened.. we could only think it was the tensioner so we made sure the tensioner was tight tight! and seemed to help

now i think about it, the brand new timing belt must of stretch while cranking the engine which jumped a few tooth, after a reline and made sure its tight, was ok..or it was just loose to begin with

[Matt]

The spring isn't really necessary though - alot of people actually remove it because they worry that it can come off and chew up their timing belt

All the spring is meant to do is give you correct tension during installation.

[Low Style]

70XIn – Checked and it’s the same tension all the way around – will triple check since I’m prone to herp=derping

Ke_70 – stock cam gear, new water/oil pump, tensioner and belt – balancer seems fine as well as bearings

Will be pulling it apart tomorrow night to see what/where if anything is causing it to skip

[timbo]

Truly an odd problem considering how well it went!

[Jimmee1990]

Possible that the cam/crank pulleys are worn? Not likely but can still happen.

[FoldKing86]

Bottom timing belt pulley off the crank have its keyway.

Super odd that only the inlet cam effected.

I suggest another inlet cam and pulley and try again.

[Gunner]

Imo, either your inlet cam caps/journals are to tight, the cam is bent, or the pulley is buckled.

[tottacrolla]

Might be worth checking TDC is correct by removing a spark plug and the checking the piston is at the
very top of its stroke.
The crank pulleys have a habit of slipping on the rubber insulator and the part used for timing the engine
moves in relation to the crank, you then get false TDC readings.

How are you getting tension on the timing belt without the spring fitted ?

[Low Style]

This occurred on two different sets of Cam gears, swapped out adjustable to stock ones to make sure it wasn't them.

Getting tension by leveraging to ensure it was as tight as possible.

Will triple check everything and report back if i find anything.
I suspect its the crank pulley + tensioner

[timbo]

Give me a bell if you want a hand again, it is actually pissing me off too!

[Low Style]

got everything working again and put a spring on the tensioner, worked a treat drove well. pulled over to call the gf when I took off i could here the belt skipping then shut it down.

rolled it home again and looked into what occured.

Intake came could not be moved to TDC and was stuck,

So took everything off and it looks like the cam is wearing one of the retaineers. so assuming it is a bent cam that has caused the issue...

So my questions:

Does this mean my heand needs to be machined?
my cam is throw away item now?
can you run just a exhaust cam and a stock intake cam? if so pros/cons?

[timbo]

Oh really? I have some smallport cams if you want to pop one in and try it out. At least you've finally got to the bottom of this. Give me a bell if you want a hand or those cams/need to get my timing light some time.

[Gunner]

I love being right :) but yeah id have the head checked, fair chance things may need to be touched up.

[Low Style]

Can small port cams fit in a big port head?

[Matt]

Allot of people used to swap bigport cams into a small port head.

[Low Style]

IF ANYONE HAS ANY BIG PORT CAMS FOR SALE LET ME KNOW ASAP - may also need a head

[timbo]

Yeah Jon, you can use smallports I'll pm you now.

[lolwat]

All the spring is meant to do is give you correct tension during installation.

yea you say that, but i ALWAYS put a bit more tension on them, i find there not tight enough for my liking when jsut spring tension and considering for all you know that spring can be stretched to the shit house