VZ Timing Chains - hard to replace?

[dharry]

So my VZ with only 135k on the clock has died... Holden tell me that although the cams are turning, the chains have probably streached and slipped a tooth on the gear hence it wont start.

They tell me it would be cheaper to replace the engine than to have the chains replaced...wtf?

SO how hard can it be to change the chains on this thing?

Any thoughts most welcome, or guids on how to do it or anything really

Cheers
Dean

[dharry]

oh, I should add that the compression on the cylinders is really low... around 75psi, they also tell me it should be up around 200-250... another sign of the timing chains...

[impulsive]

Possibly Timing Chain Tensioner, had one die on me, resulting in a 'tapping' sound and reduced performance..

Broken Tensioner, see the split?


Cost me $1100 to diagnose and repair and inc the cost of a service

Here is a pic of the Alloytec exposed!

[impulsive]

Looking at that bottem picture, i wonder what could possibly cause one of the timing chains to 'Stretch' and how could they possibly diagnose it without having it apart like that? I would recommend getting a second opinion.

If you find yourself in need of a new motor Alloytec are about $4000

[impulsive]

This is what it sounded like too

YouTube - DSCF7800.AVI

[2005vzute]

are they running the crankshaft sprocket to the 2 lower sprockets..then another chain up to the 2 top camshaft sprockets on each side?..what'd they do to get all that exposed? take off the serpentine belt and things that run a pulley(power steering, A/C etc), was it a plastic cover over the timing chain? then take rocker covers, plenum and inlet manifold off?

[dharry]

hmm, see mine didn't make any bad sounds like that... one day it was fine, the next it was just gutless and struggled then it just didn't start.

At no stage was there any bad noises :-S

This is what it sounded like too

YouTube - DSCF7800.AVI

[2005vzute]

so is your car just losing power? does it feel very sluggish and like it's running off 5 cylinders?..we've all seen those beaten up VT's going around where the driver plants their foot and the car just goes brrrr, and goes next to no where...i've worked on a couple of ecotec where they've had valve springs broken..there's nothing wrong with the engine, its just one cylinder fighting against the valves and compression therefore losing power and feeling sluggish...so yea if you can, or get a decent independant mechanic to, just check your valves and springs and camshaft wear etc

if everything seems ok there, get a compression test done...at an indepedant mechanic with a reputable name..if you ask them to diagnose something, they'll do it right for you so they can get your business to fix the problem..get them to do a wet and dry test..just incase you don't know i'll give you a little bit of info on it.

dry test- spark plugs are taken out and a pump like device is scrwed into the spark plugs place...they put pressure into the cylinder to make sure it's holding compression..if it holds pressure, it's fine, if not, it could be a number of things that won't allow it to seal eg, piston rings, cracks in the cylinder, bent valves or they aren't seating properly etc...leave the mechanic to diagnose whats precisely wrong.

wet test-, they will put oil into the cylinder..gravity will cause the oil to drop straight onto the piston and around the rings...they do the same thing as a dry test now, put pressure in it and see if it holds pressure...if it holds, it's almost guaranteed it wil be rings..seeing as though the oil will help form a seal around the rings, therefore, better compression.

well thats just a bit of basic information about it...and what you could be up for...but don't trust holden, i've worked there and i've even been asked to do a bodgy job for a customer just to keep him happy...i got into an argument koz i didn't want to do a dogy job...independant well known mechanic..maybe even a performance place will be a good place too.

if you can describe to me what exactly and every single symptom you can tell me..any observations you've had, just tell me..i have a bit of handy info(service manual) that may help you out to diagnose it.

cheers mate

[impulsive]

Pretty much to expose the motor like that you have to remove intake manifold, rocker covers, all accesories in front of the timing chain cover. Belt and im pretty sure there is another bit part of it.

[dharry]

Hey mate,

Well basically the symptons are like this...

Saturday it was running fine, started it up Sunday morning and it was a bit rougher than normal, took off and felt there was just no power, got on the freeway and put the cruise control on and it was just gutless... every slight rise in the road it would kick back 2 gears just to keep going. Drove for about 20 mins then stopped at a petrol station, put some more fuel in and it just wouldn't start again. Cranks over just doesn't fire.

Thought it might have been the fuel pump or blocked filter so had a guy change those but same result, wont fire.

I've had 2 different people (1 independant, 1, holden) compression test 3 different cylinders and they were all pretty low, around 75psi.

The holden guys told me the timing chain may have slippled a tooth on the gear but to find out for sure they said they would have to start stripping the ewngine down and wanted a fortune to do so.

So basically that's where it is at... spent close to $1000 on it in fuel pump, filter, diagnosis and towing in the last 4 days for no result :-S

What so you think?

Cheers,
Dean

[impulsive]

If you are handy with a spanner, start stripping it down yourself, i pretty much did that with mine saving myself a fair bit of cash, just a shame i didnt have the time to completely strip the motor, down to the exposed pic about, would of saved heaps..

[dharry]

hey mate, yeh that's what I plan to do... I can strip an old 253 with my eyes closed but never tried it on one of these new engines so should be fun lol

[impulsive]

Take lots of photo's!

[cpbait]

typical GM engine with timing chains the Alfa Romeo 159 2.2 ltr twinphaser motor is a GM motor with basically the same type of timing chain setup on a 4cylinder motor and they stretched the chains all the time, we were doing heaps of them under warranty and customer cost, saw a couple done by there first service, they would bring up the engine light with a certain fault code and that was it, the tensioner looks the same, ask around, it would be cheaper to fix than replace engine unless its bent valves in the head which would result in the very low compression which then could be very costly maybe resulting in cheaper and easier to replace motor.

[2005vzute]

so doing 3 different cylinders and showing the same result...have a think about the possibilites here, what do they all share in common or links them together that could cause pressure to get out...well, they all have the head sitting on top, could it be cracked? could it be a blown head gasket?, what are the possibilities of the valves being bent in all 3 cylinders? doubt that would happen...could lack of coolant or coolant system problem have caused cracked cylinders in all of them? i doubt that too, you woulda seen temperatures spike and codes etc...at TAFE we've had guys talk about retarding the timing by 1 tooth on both intake and exhaust on these engines to improve power...my tafe teacher said he's heard of it, but at high rev it will cause serious problems (he races a v8 commodore...have a look at my facebook page video if you want..plus we have 6 alloytecs at tage)...pretty much..at lower rpm it will be fine, but at high rpm due to the dwell angle it's almost gauranteed the pistons will hit those valves..even though my tafe teacher is a qualified mechanic with certificate 4(performance) and has rebuilt many engines and is constantly pulling stuff apart, he wouldn't recommend retarding the timing...but it should still be ok if it has skipped 1 tooth..really, the only way i can see the timing chain affecting this, is if has majorly stretched , therefore throwing out the precise mechanical system of the valve train, or if it has skipped a tooth koz the tensioner is ****ed

[dylanstone]

nice pics

[dharry]

yeh, I thought about heads but they were cylinders on both sides, it would be pretty unlucky to do both heads at the same time, or both gaskets... plus the oil is very clean so no water getting mixed in with it.

[cpbait]

it is possible to have valves bent on all cylinders, iv seen this before on vehicles a number of times both with timing chains and timing belts letting go, had a guy at work and the guys at his trade school including teachers didn't believe him and when the valves were replaced he took the old ones in and they were shocked, so this is possible and don't forget the engine was spinning at x-amount of RPM's when it let go either running or on start up and if you keep cranking can cause more damage on some vehicles, i know of some diesels that are designed to snap the rockers before the valves bend.

also if the valves bend you won't necessarily do a head gasket as the valves are inside the head and seperate from the gasket.

could try a new chain and tensioner, (chain doesn't have to stretch by much the Alfa's with the same type of chain stretched by about 1 link as we measured them and it was enough to cause engine light/codes and sluggish running and this was even in new and newish cars) if the problem and then you'll know from there if that's ok and if compression still down and won't start.

had any luck on further diagnosis yet?

[torana355]

so doing 3 different cylinders and showing the same result...have a think about the possibilites here, what do they all share in common or links them together that could cause pressure to get out...well, they all have the head sitting on top, could it be cracked? could it be a blown head gasket?, what are the possibilities of the valves being bent in all 3 cylinders? doubt that would happen...could lack of coolant or coolant system problem have caused cracked cylinders in all of them? i doubt that too, you woulda seen temperatures spike and codes etc...at TAFE we've had guys talk about retarding the timing by 1 tooth on both intake and exhaust on these engines to improve power...my tafe teacher said he's heard of it, but at high rev it will cause serious problems (he races a v8 commodore...have a look at my facebook page video if you want..plus we have 6 alloytecs at tage)...pretty much..at lower rpm it will be fine, but at high rpm due to the dwell angle it's almost gauranteed the pistons will hit those valves..even though my tafe teacher is a qualified mechanic with certificate 4(performance) and has rebuilt many engines and is constantly pulling stuff apart, he wouldn't recommend retarding the timing...but it should still be ok if it has skipped 1 tooth..really, the only way i can see the timing chain affecting this, is if has majorly stretched , therefore throwing out the precise mechanical system of the valve train, or if it has skipped a tooth koz the tensioner is ****ed

You should only change cam timing if you are raising compression (shaving the head) Though you can change the timing to bring the torque curve lower or higher up the rev range. Also it is 100% possible to bend every valve in the motor if you do something silly like down change gears when at the top of third gear, ive had this happen when the timing chain let go in my SSS.

[2005vzute]

certainly is possible..but reading his situation it doesn't sound like its the case...and it sounds like it's an auto..he said when it was on cruise control, going up the slightest hill would cause it to kick back 2 gears...which implies it was an auto...unless he used the shifter to knock it back through the gears to do it, which i doubt koz that would be rather silly haha.

i'll tell you what..if you still don't have an answer by tuesday next week, i'll ask my tafe teachers what they reckon it could be and i'll come back with some more info for ya=]

[dharry]

yes, it is an auto no, no diagnosis yet... Ive just started stripping the engine down this morning, so will be a while yet until I get to where I need to be...

On the bent valves, I would expect that if one or all of them were bent then you would hear something other than normal when it cranks over? or am I wrong?

Dean

[2005vzute]

if they're bent all compression would be lost..you'd have about 2 parts of **** all for power not whether it woul deven idle or not i don't know..depends how bad it is i guess...if they were really bent, that piston might kiss the valve and you'd be up for all sorts of vital things haha:P i doubt it's that bad tough

[dharry]

ok, so the rocker covers are off now... the left timing chain seems to have more play in it than the right... does anyone know how much play there should be in the chain between the 2 cams?

the right moves about 1/2 a cm and the right about 1cm...

Dean

[alex777]

would you know the correct lengths of the the 3 timing chains thanks jl

[VZ_commo91]

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