Repair after timing belt failure....pic heavy.

Nissan doctor

I posted in another thread that I got a Chevy Nubira for €100 which had suffered a timing belt failure. A couple of people mentioned that they might like a thread on the repair so here it is.:)


First, some pics of the timing belt issue. Identical to another posters thread recently on their Nubira, the teeth on the belt failed due to being left well beyond its replacement interval. In this case, the guide pully also failed.

Failed guide pully:



Teeth stripped on the belt:



At the crank pully:



Broken pieces and stripped belt:





Onto the strip down, manifolds removed:



Rocker cover removed:



The head off and the impact marks from the pistons contacting the valves is pretty obvious:





And the view of the valves....all 16 flattened by the pistons:eek: The cars was seemingly doing 120kph when the belt failed.

Nissan doctor

Cylinder head ready for disassembly:



With the cams removed, the hydraulic tappets come out and get stored in fresh oil to prevent then running try and a noisy start up when refitted:



Compressing the valve springs to release the retainers/collets and remove the valves:



The valves needed to be driven out with a rubber mallet and punch as they were jammed into the valve guides:



And here is why:eek: All 16 were exactly the same:



With all the valves out, the stem seals are next:



Cylinder head stripped and everything stored in position for correct re-assembly. Waiting now on all the new parts and the head will be getting sent for new valve guides too:





Thats it for now....tune in next time:P

George Dalton

Nice post, I would have put the thing out of its misery though, scrap metal is making good money these days

therewillbe

You must be good at the Lego! Fair play to you. I wish I had your patience.You saved quite a few quid doing it yourself .Keep us up to speed.

tuxy

Interesting post, thanks

Jimdagym

Great work Doc. Thanks for that,

Can't believe how bent those valves are :eek:

MugMugs

Good Job Doc!

trixyben

love to see these quality step by step photos like these, makes alot more sense to me seeing it done like this than just reading it from books or the net...

Doc you say you have to send the head away for new valves, can you not fit new ones yourself or do they have to be installed by certain machine?

Would really like to see this type of step by step guide for changing head gaskets, replacing clutches etc... As a keen amature dear I say mechanic these are the best ways if find I learn an awful lot...

Anyhow fab job Doc

kona

trixyben wrote: »

Doc you say you have to send the head away for new valves, can you not fit new ones yourself or do they have to be installed by certain machine?

The Valve guides need to be pressed into the head. The head will also need to be reamed to the correct size to ensure a proper fit. So the use of a hydraulic press and a pillar drill with the reaming tool is needed. However, the valves, springs and collets are reinstalled with the spring compressor you can see in the pics above, when the shiney new guides are installed, the oile seals are like a top hat and sit ontop of the guides.

Mar4ix

will pistons goin to be replaced also ? well... i suppose.

in seventh picture where rocker cover off, is it just light or it is red ish on head walls ... indicating wrong oil in engine.

Nissan doctor

Mar4ix wrote: »

will pistons goin to be replaced also ? well... i suppose.

in seventh picture where rocker cover off, is it just light or it is red ish on head walls ... indicating wrong oil in engine.

There is no damage to the pistons, there rarely is unless the failure has happened at very high RPM or the valves have actually broken.

trixyben

kona wrote: »

The Valve guides need to be pressed into the head. The head will also need to be reamed to the correct size to ensure a proper fit. So the use of a hydraulic press and a pillar drill with the reaming tool is needed. However, the valves, springs and collets are reinstalled with the spring compressor you can see in the pics above, when the shiney new guides are installed, the oile seals are like a top hat and sit ontop of the guides.

who and where does that job out of interest?

jimmyw

Mr Foxman of this parish/forum is doing the same job on a Renault Megane he picked up for free.I have seen his youtube channel (and no he is not paying me;)), you can check it out, if he doesnt give out out to me:o for the mention.

If anyone is reluctant to have this job done, then this is the result and a warning for not changing your timing belt.

Nissan doctor

trixyben wrote: »

who and where does that job out of interest?

I'm using cylinder head services in Kilbarrack to fit the guides.

All 16 guides in this head where cracked due to the valves being forced sideways into them by the impact.

Row

Nice one Doc...I see you keep your surgery impeccably clean....:cool:

Nissan doctor

Row wrote: »

Nice one Doc...I see you keep your surgery impeccably clean....:cool:

Don't want any infections getting in:p

That's a room we have out the back which I emptied out and cleaned for engine assembly work. Could do with a lick of paint though:P

Row

Nissan doctor wrote: »

Don't want any infections getting in:p

That's a room we have out the back which I emptied out and cleaned for engine assembly work. Could do with a lick of paint though:P

Its good to have a room away from the dusty Environment of a shop
floor....:)
Last thing you want while doing this kind of work is some lad cutting off a section of an exhaust and covering the place with dust...:eek:

engrish?

This is fantastic! I was the poster with the timing belt gone in the Nubira.

It is my intention to deconstruct the engine during the summer and have a go at repairing it. I will be following this with a lot of interest!

Can you tell me how much the parts and repairs will set you back?

Thanks

shamwari

I know its a Chevy but it looks very similar to a GM 16V ecotec. Are the bits the same by any chance ?

Nissan doctor

engrish? wrote: »

This is fantastic! I was the poster with the timing belt gone in the Nubira.

It is my intention to deconstruct the engine during the summer and have a go at repairing it. I will be following this with a lot of interest!

Can you tell me how much the parts and repairs will set you back?

Thanks

I stuck a link to it on your thread....though it might be of interest to you alright.

Nissan doctor

shamwari wrote: »

I know its a Chevy but it looks very similar to a GM 16V ecotec. Are the bits the same by any chance ?

Its basically the same engine...Chevy part of GM too.

Nissan doctor

Few parts arrived..

TURRICAN

Is this irish eric the car guy?:D

engrish?

Nissan doctor wrote: »

I stuck a link to it on your thread....though it might be of interest to you alright.

I am so excited about taking this on. This will be my summer project!

trixyben

Nissan doctor wrote: »

I'm using cylinder head services in Kilbarrack to fit the guides.

All 16 guides in this head where cracked due to the valves being forced sideways into them by the impact.

again just out of interest Doc how much roughly would ya be paying for the new guides to be put in?

Is it pretty much the same with most engines that have a snapped timing belt to be repaired in the way you have shown?

Nissan doctor

trixyben wrote: »

again just out of interest Doc how much roughly would ya be paying for the new guides to be put in?

Is it pretty much the same with most engines that have a snapped timing belt to be repaired in the way you have shown?

I'll post prices when I've the total job done to give people an idea.

Almost every belt failure is the same repair with varying degrees of damage. If the belt breaks on start up, as often happens, then the guides are often ok and all the valves may not be bent but if at very high speed or RPM then pieces of the guides or valves can break causing damage to pistons etc but this is rare in your average road car.

trixyben

Nissan doctor wrote: »

I'll post prices when I've the total job done to give people an idea.

Almost every belt failure is the same repair with varying degrees of damage. If the belt breaks on start up, as often happens, then the guides are often ok and all the valves may not be bent but if at very high speed or RPM then pieces of the guides or valves can break causing damage to pistons etc but this is rare in your average road car.

If say half of the valves or bent and guides cracked would you replace all anyway as you have it stripped down or just repair whats needed?

Im in the process of buying a cheap banger to start experimenting on, cant wait to start stripping it down and doing timing belts, clutches, engine rebuilts etc, only want to spend small money on one but hard to find as price of scrap so high!!!!

I actually went to look at a car yesterday evening it was a 1996 punto, no test or tax his long time, fairly rough was sitting up over a year with green algae all over it and rust patches, was advertised at €350 ono... Offered €200 and he wouldnt move a cent, said the car was going perfect and he was selling it cheap :eek: (I was thinking are we talking about the same car here :pac:

Nissan doctor

If there are any visible cracks in any valve guides I'd replace them all as there could be hairline cracks in others that you wouldn't see. As for the valves, it depends, my preferance would be to change them all as, depending on the engine, they are not expensive in the scheme of the whole job.

You'd normally do a leak down test on an engine with a failed timing belt and if you got readings of less then 20% leakdown on any cylinders then the valves are fine and you could leave them in place if you wanted.

I don't like threads like this
The ZT is on the factory belts :pac:

Only joking ND, great thread, fair play for taking the time to take the pics and lash them up

Nissan doctor

RoverJames wrote: »

I don't like threads like this
The ZT is on the factory belts :pac:

Only joking ND, great thread, fair play for taking the time to take the pics and lash them up

You'd better takes notes so.:P

Nissan doctor

Nissan doctor wrote: »

You'd better takes notes so.:P

I'd need more than notes to tackle a KV6 before it snapped a belt, not to mind after

Nissan doctor

RoverJames wrote: »

I'd need more than notes to tackle a KV6 before it snapped a belt, not to mind after

Sure they are easy:eek:

Nissan doctor

Nissan doctor wrote: »

Sure they are easy:eek:

For you no doubt, me not too good with spanners.
That crowd your man that used to be on TV owns (KC garage is it ?) quoted me €1100/€1200 to do the belts and water pump

Nissan doctor

:PI was joking....I'd cringe at the thought of having to do one of them again TBH

... bad enough to do the rear three plugs on the bastad (for me) :pac:

john reilly

why?

Nissan doctor

john reilly wrote: »

why?

Why what?

john reilly

why would you waste your time and money

Raiser

Well ignoring ****head..... ^^^

- Thanks a million for posting that Doc, great to get a chance to see actual mechanical surgery taking place, class post

Raiser

Is there any reason why more/all engines don't just use a timing chain?

- Do timing chains have any interval or warning signs before requiring a change?

Nissan doctor

Raiser wrote: »

Is there any reason why more/all engines don't just use a timing chain?

- Do timing chains have any interval or warning signs before requiring a change?

Belt driven engines are quieter and simpler to design, they are also lighter so create less drag on the engine. Chains naturally create more noise and also run in oil and need an oil supply to the tensioner but should, in theory, last the life of the engine.

Some manufacturers are now developing belts which run in oil and are supposed to last the life of the engine.

Nissan doctor

Part 2:


A view of one of the new valve guides:




On to lapping the valves, Lapping compound applied to the valve:




Lapping stick on the valve:



And getting stuck in....its a bit of a tedious job:




After the valves are finished, remove them again(keeping them matched to the positions they were lapped in) and fit the valve stem oil seals:



Then in with the valve springs, compress and fit the collets:



Collets in place:




All valves in place and everything nice and clean:

Nissan doctor

Next the tappets go back in:




Cams in place but before they are tightened down, the new camshaft oil seals go on:




Next, a bit of block preparation before fitting the head. A nylon grinder gives a clean, smooth surface to cast block decks:




And fully cleaned:




Head back on at last, this head requires a combination of torque and angle measurements to tighten correctly(25nm of torque, then 70 degrees X2 and finally 50 degrees):




With the head tightened down its on to the external componants. Exhaust manifold:




Old water pump being replaced too:




New pump in place:




This engine is unusual in that you actually use the water pump to tension the belt. The water pump id offset so you rotate it to tension the belt:




And the engine back looking fairly complete again:




And the moment of truth......:D

http://www.youtube.com/watch?v=n7N5iRa_bqE&list=UUf2FXl96khtO_Jl43BrAzuA&index=1&feature=plcp

Please excuse one of the lads shouting in the backround:P

Nissan doctor

Required tools(in addition to normal sockets etc)

-Torque wrench
-Angle gauge
-Valve spring compressors
-Lapping paste and stick
-stem seal pliers(ideally, to prevent damage to the seal)


This head had standard 14mm heads for the cylinder head bolts but many manufacturers use various spline/ribe/torx head bolts which would require specific sockets.
This engine also requires at 38mm spanner/tool to rotate the water pump when tensioning the belt.

Total (retail price) cost totalled approx €600. I left the invoices in work so will post the exact costs when I'm back from my hols.


A youtube video showing the action of lapping the valves:
http://www.youtube.com/watch?v=fhXsH12Rg6s



Hopefully I might help anyone who wants to try it themselves or at least gave people an idea of the work involved.

Thanks for reading:)

Fiona

Where was the qualified adult while you were doing all this playing?
Fair play! Hope I NEVER need you to do this type of work for me however!

Avns1s

Well done ND.

A well structured very informative thread which will help many. It makes the job look a lot simpler than it actually is, though. (Meant very much as a compliment rather than a criticism btw!)

You still need a fair bit if mechanical cop on and experience IMO, before tackling this job and expecting 100% success.

Nissan doctor

mrs crilly wrote: »

Where was the qualified adult while you were doing all this playing?
Fair play! Hope I NEVER need you to do this type of work for me however!

Hmmm, come to think of it, your timing belt looked a bit dodgy:P

Fiona

Nissan doctor wrote: »

Hmmm, come to think of it, your timing belt looked a bit dodgy:P

* runs to car with torch and Haynes manual

Raiser

Thanks Doc, your expertise, photography and writing skills combined with my ability to skull good german beer has given me all the courage I need to rebuild my own, perfectly functioning engine tonight, armed with nothing but dreams and an shiny unworn socket set

- I'll post pics tomorrow of what, ahm remains.......

trixyben

at the stage where you are lapping the valves what exactly does this mean and what does it acheive Doc?

Jimdagym

trixyben wrote: »

at the stage where you are lapping the valves what exactly does this mean and what does it acheive Doc?

You use a grinding paste to clean up the valve seat. A better seal means you don't lose compression. I done it once years ago and it's a pain.

Fair play Dr Nissan. Very interesting thread.