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Valvematic

Tappets

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Toyota say the tappets should be audibly inspected every 40,000 miles using a stethoscope, if the tappets sound noisy the valve clearances should be measured for correctness, if there is an issue with clearance then the camshafts have to come off and the tappet for the valve at issue measured and then replaced with a new tappet with a larger/smaller measurement.

The best trick is to measure all the clearances and then it is often possible to swap tappets from one valve to another reusing some of them and only replacing the tappet left over with new ones of the correct thickness.

I have worked for Toyota for 15 years now and have never seen an Aygo needing tappet replacement.

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See I said that this man is the oracle when it comes to the Aygo :clap:

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Not just the Aygo ....

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Thanks for the replies. Is this engine known to be pretty vocal until it has warmed up?

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I think it is injector noise as it is consistent with load.

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Have been doing these on my bikes for years.
They are a pain in the neck.

However......I honestly don't think people go to these lengths on cars like Aygos these days.

If mine required cams out & re-shimming I'd buy a low mileage engine and do a swap.

By the time you've paid for gaskets, new shim / buckets, time etc.

It makes far more sense.

While they're rattlin', there are probably OK anyway.
If they go quiet, due to closing up, you are having serious issues.

Don't worry about 'em.

Ian.

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Thanks Ian so they won't suddenly fail.

All quietens down when engine is warm.

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There is nothing to actually "fail"
As the camshaft rotates, it pushes down on the top of a valve to open it.

There has to be a tiny gap so that the valve can completely close.

Because if the valve doesn't seat properly, combustion gasses at very high pressures can be forced past.

Rather than have some kind of adjuster between the moving parts as in days of old,

The engine is assembled, clearances checked then an appropriate sized bucket / shim

or both are fitted to give the perfect, tiny gap.

The gap NORMALLY becomes slightly wider over time (therefore, noisier) just down to wear.
Modern oils and materials mean you should get hundreds of thousands of miles with negligible wear.
If they become noisy, measurements are taken, the engine is dismantled and thicker parts fitted.
Main cost is time.
ie......Take off air filter, coils, covers, bits & bobs.
Measure some gaps. Turn engine a bit, measure some more gaps................Write down 12 gaps.
Remove camshafts ......Time......more of it.
Lift out all 12 buckets / shims......Write down the 12 sizes.
Look in the big book of words. Find out what the gap IS what the gap SHOULD be.
Work out the size of the shim needed (X 12) Have you any already in that size?
Substitute some that fit for those that don't. Order the ones you need.
Forget what went where. Parts arrive. Assemble in clinically clean conditions.
Final last measure to check......Oh dear, one is just out of spec......Do it all again.
Or simply swap in a young engine......just nuts & bolts.

IF......the tolerances become too tight and the valve doesn't shut completely, the burning gasses

will eventually wear away the valve seats. At this stage repair is uneconomic. Just swap engines.
Tight tolerances should not occur in the Aygo engine as there is no adjustment for people to mess

with and get too tight.

Regular Oil changes with top quality oils and......completely forget about them.
I am the sort of bloke who lays awake at night worrying about stuff like valve clearances

and other nonsense on my bike. As far as our Aygos are concerned, I sleep easy.

Ian.

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It could also be the spark plugs not being tight enough.

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Don't think it is the valves as they would be noisy all the time. Noise only occurs under engine load, think it could be an exhaust problem.

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The exhaust is very "raspy" as standard. I saw one here the other day where some numpty had put a big bore back box on it, sounded awful and was hitting the body and bumper, lovely sound......NOT

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Shims eh? Mine's a bit noisy but I assumed the tappets were adjusted as on a Subaru....ie no mucking about removing cams and fiddling with shims.

Noisy I can cope with....

I had to re-shim the head on my Caterham, as it's a PTP Evo 220 full endurance race engine which cost £12,500 way back in 2000. It had allegedly been 'topped and tailed' by John Wilcox race engineering, only when I stripped it, there wasn't one single clearance that wasn't wildly out, and all the shims were hammered to hell, I had to replace the lot.

I clamped the head to the kitchen table to do it. I had to, as I'd just paid Rog at Sabre Heads in Wisbech to finesse it, put new longer Colsibro guides in, and new lead free valve seats. Rog had actually built the head back in 2000 for Janspeed, who were commissioned by Rover's race team PTP, so he de-did the breathing incorporating what he'd learned since.... .

I'd found a mismatch in the induction tract, a 5mm step between the Titan Phantom injector bodies and the head, so after fixing that I dragged the car to the UK and we set up the Emerald ECU on Emerald's dyno. It only made 213 bhp, but would have gone over 220bhp only the technician bottled out as it was clearly running well over 6000rpm, so though it held together to 8500rpm, he was backing off.

He said the fuel pump was inadequate for a 220+ engine and I realised I hadn't upgraded it from the original 120bhp rated pump!

It now has the full R500 pump, good up to 250bhp.

So any way I can avoid re-shimming I will take it!

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" the technician bottled out as it was clearly running well over 6000rpm, ...."

That should have read 'weak' not 'well'.

Maybe 'well weak?'  😉

 

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