4Y Timing Chain/Cover Fail

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Ierfaan
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Joined: Mon Mar 02, 2020 12:20 pm
Town: Cape Town
Vehicle: Kombi with 4Y engine
Real Name: Ierfaan

4Y Timing Chain/Cover Fail

Post by Ierfaan »

Good Day to everyone.

I am formally a member now.

I have been getting information and advice from this forum for a long while now and most of the time a simple search would suffice.
I drive a VW Kombi with a 4Y engine fitted. I bought the vehicle like this. It has served me well'ish' to date. I have now come across an issue that I think would be interesting and which I wish to understand.
Ierfaan
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Vehicle: Kombi with 4Y engine
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Re: 4Y Timing Chain/Cover Fail

Post by Ierfaan »

Apart from the higher fuel use, for the carbed engine, the vehicle had been driving well before and on the 2 day 550km round trip from Cape Town - Arniston- Rooiels where it cut out after freewheeling descent to 60 km zone.

Only after realising that it had cut out I tried kick starting in 4th without success. No noises were heard or anything un-toward experienced. When turning over, with starter motor, I could hear the typical 'no compression/incorrect timing' issues. On inspection, I found the timing cover broken with chain and tensioner exposed. This I believe is very uncommon for the Toyota engine. I remember my 1976 Toyota I named 'Old Faithful" many moons ago. only for it eventually succumbing to rust.

Can anyone explain why how would this could happen?
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Mud Dog
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Re: 4Y Timing Chain/Cover Fail

Post by Mud Dog »

Hi and welcome Ierfaan. :thumbup:

The "Y" series motors were tough and reliable with a reputation to match. They just went on and on and on ......

That may be part of their downfall .... we get into a trusting mindset and neglect to service things like replacing the timing chain, tensioner, sprockets and guide. Although perhaps over-engineered, the chain does stretch a little over time and the teeth on the sprockets as well. The tensioner and guide wear a lot quicker bur even when they do, the motor still runs well albeit a little noisier than it should be. This noisiness comes on slowly over time and often we don't realise it because we become accustomed to it as it slowly gets worse.

What I think has happened in your case is that those components wore to such an extent that there was enough slack for the chain to jump a tooth or two ..... valve timing now out. I also suspect that the most likely scenario is that the guide or tensioner disintegrated with pieces getting caught between the cover and the sprockets or chain and damaging the cover.

I hope that you haven't damaged valves or pistons with the valve timing being out, it is an interference motor.

Get a replacement cover or if possible have that one repaired / welded. Fit new sprockets, chain, chain guide and tensioner and set up the valve timing (crank on TDC and cam on compression cycle for no.1 cylinder and on the timing mark). Turn the motor with the plugs out and tappet cover off through two full revolutions at least to make sure that nothing is catching internally. Also watch the valves while you do this to see that they are not "sticky" and move freely. (I would also swing it over with the starter a few times after the manual check, just to be sure). If all is good, put the plugs, covers back and start it.

Good luck. :winkx:
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Ierfaan
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Re: 4Y Timing Chain/Cover Fail

Post by Ierfaan »

Thanks for the welcome and feedback Mud Dog)

So this engine is an import engine, fitted by the previous owner, has sounded good, ran well and was properly serviced (I have done 2 oil service changes myself) and has done less than 3000km in the 4 years that I have had and driven it.

Kindly confirm that the motor is an interference engine as I have heard otherwise. I have not been able to get verification either way. If it is interference, then I might as well strip down the head.
Ierfaan
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Re: 4Y Timing Chain/Cover Fail

Post by Ierfaan »

I see the guys are not really as responsive as I would have expected.

Here is some feedback.

I replaced the timing casing, cover, sprockets, chain and tensioner kit. To Mud Dog and others in general, am glad to say that the 4Y is NOT an interference engine.

I say this because I was able to start the vehicle at the first attempt. Still not being sure whether I would have to strip the engine down for bent valves, as a check I run the engine for a short while before fitting the water hoses. Everything sounded and felt fine. I fitted coolant hoses and filled with water without bleeding (remember this engine is in a VW T3 Kombi) All is well until a while later the low oil pressure buzzer comes on after increases revs. So I am not sure whether this is because of the engine 'overheating" or because of actual low pressure. I will check with a pressure gauge after thoroughly bleeding the VW coolant system which is typically a bit of a pain.
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Re: 4Y Timing Chain/Cover Fail

Post by Mud Dog »

Thanks for the feed back. Good to hear but the oil pressure warning is a bit concerning. Ive never had to work on a 4Y oil pump and cannot remember if t runs off the cam behind that chain cover.

Was there any disintegration of the old guide or tensioner?
When your road comes to an end ...... you need a HILUX!.

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Life is like a jar of Jalapeño peppers ... what you do today, might burn your ass tomorrow.
Don't take life too seriously ..... no-one gets out alive.
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The Legend
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Re: 4Y Timing Chain/Cover Fail

Post by The Legend »

Andy the oil pump of the 4y is driven by the distributor shaft.
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Mud Dog
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Re: 4Y Timing Chain/Cover Fail

Post by Mud Dog »

Thanks Dawie, good to know.

What I'm trying to figure out is if there is a direct link between Ierfaan's mishap and the now lesser oil pressure. Like if there has been any disintegration of the old tensioner or guide, and if pieces of which could get into the oil pump or oil galleries. Usually such bits fall down into the sump and although the possibility exists that they might marginally restrict oil flow into the pick-up, I doubt it will be significant enough to result in reduced oil pressure, even at revs. The shape of the pieces would have to have significant coverage of the sieve on the pick-up. I don't see that happening. I also can't imagine any large enough pieces getting through the sieve to cause damage to the pump. :think:
When your road comes to an end ...... you need a HILUX!.

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Life is like a jar of Jalapeño peppers ... what you do today, might burn your ass tomorrow.
Don't take life too seriously ..... no-one gets out alive.
It's not about waiting for storms to pass. It's about learning to dance in the rain.
And be yourself ..... everyone else is taken!
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