ZT190 Engine knocking/rattle help

[SD1too]

Originally Posted by Lovel

Removing 3 x 8mm A/F set screws from the front plastic cover and peeling it back is all that is required to establish if the belt is turning/one-piece/failing/slack and/or slipped a tooth.

Hi Gary,

I have tried this. I grant you that the cover can be moved back only half an inch until it hits the dipstick and the ancillary belt idler wheel. That gives a very partial and poor view of the timing belt but I agree that it can be seen turning and establish that it's in one piece. But in this case we know that already because the engine runs.

As for assessing whether the belt is failing, slack or has slipped a tooth through this letterbox shaped gap which reveals only half the width (if that) of the belt, I have to disagree with you Gary. Most importantly, you cannot inspect the tensioner and idler wheel at all unless major dismantling is carried out and those are the components most likely to be causing the noise, not the belt.

Simon

[SD1too]

Originally Posted by zeemax_mini

How involved would it be to check the belt tensioners?

As Cliff says, it's very involved. Access is through the OSF wheelarch. The engine has to be supported whilst the top mounting is disconnected. This allows the ancillary belt to be removed then the engine front mounting plate. Behind that resides the timing belt and its tensioner and idler wheel.

The significant piece of evidence is that the engine cut out, twice. You've also said that performance is reduced. Is more cranking than usual required for a cold start?

What's the car's history as far as timing belt replacement is concerned? If it's been renewed at what mileage and were the all-important tensioner pulley and idler wheel renewed as well? What's the car's current mileage?

Simon

[zeemax_mini]

Originally Posted by SD1too

The significant piece of evidence is that the engine cut out, twice. You've also said that performance is reduced. Is more cranking than usual required for a cold start?

What's the car's history as far as timing belt replacement is concerned? If it's been renewed at what mileage and were the all-important tensioner pulley and idler wheel renewed as well? What's the car's current mileage?

Simon

I wouldn't say more cranking is required, no. It was definitely more laboured on the hot restarts but from cold now it's the same as it always has been (starts easily).

I've just "topped up the oil" and somehow it's taken 3 litres, so I'm assuming this may well be the cause of the knock unfortunately. It was serviced last year but to be totally honest I've probably not checked it since then so couldn't say whether its slowly been burning it (no smoke though) or if its suddenly lost a load, though I can't see a leak now it's topped up again.

The mileage is approx 95k miles and whilst I'm told it had the belts done around 40k miles I didn't get any paperwork at all with it so couldn't be guaranteed. I bought the car cheap and it's a bit of a hack so I couldn't justify the outlay for the belts etc. Now that seems it was probably a false economy, surprise surprise.

Cheers, Dom

Eta: car idles absolutely fine with no noises, though on initial cold start up the knocking is there for 1/2 seconds (less than before oil top up) but no on subsequent starts. Engine possibly smells a bit hot after a few minutes idling

[SD1too]

Thanks for the information Dom. Having corrected the dangerously low oil level, I think it's a case of 'keep under observation'.

At 95,000 miles your tensioner pulleys and idler wheels are at risk of having worn bearings (mine did at slightly lower mileage) if they weren't replaced at 40,000 miles. That might be the cause of the noise but we can't be certain.

As you bought the car cheaply, I'd have thought that does justify the cost of fitting a timing belt kit; your total outlay would still be low for a really nice car.

By the way, I noticed from your video that your upper ancillary belt cover is missing. This might indicate slovenly past maintenance.

Simon

[zeemax_mini]

Thanks Simon, apologies I don't think I was clear - the ongoing knocking/noise is still there when revved. It's just less pronounced on startup with the oil now topped up.

As you say it probably is worth the investment if I can now find someone local to do the belts/tensioner etc, it's just whether that is the actual cause or if I'd be throwing good money after bad.

It doesn't sound like there's an easy way to determine whether the noise is tensioner/belt related?

Cheers, Dom

[Teflon]

Another possible course of action is to have your engine oil tested.

£30 or so will get you a comprehensive spectrochemical analysis on the state of the oil, detailing whether it contains any nasties that may indicate excessive bearing wear etc. Not a lot of money considering what could be at stake .

Cliff

[Lovel]

I would suggest with the engine hot carry out compression test on all cylinders with throttle full open and fully charged battery.

Are all spark plugs the same colour?

Additionally a failing and/or blocked dirty hydraulic tappet will make a metallic noise on start up-leading to uneven compression results, emanating higher up in the cylinder head area.

[zeemax_mini]

Hey guys,

Sorry for the delay in replying, hectic day.

I've done a bit more investigation today, taking off the aux belt to see if this makes nah difference and trying to pinpoint the sound. I'd say the noise is definitely reduced now but still there, coming from low down on the engine I which I guess is near the crank pulley? Could this help identify what it is? Not taken the plugs out yet but can do that. It idles and revs absolutely fine aside from this noise.

Cheers, Dom

[SD1too]

If you've done as much work as that Dom you might as well keep going and expose the cambelt. The cambelt tensioner can be seen on the far left of this photograph just below the water pump :



Simon

[zeemax_mini]

Thanks alot Simon. Annoyingly I'm working on my my driveway with extremely limited tools (not even a jack) as everything is at my folks house and obviously I can't get the car there.

As I need to be mobile again urgently it's a sad state of affairs that I think I'm going to have to get rid of the car and replace it with another cheap runaround. There's no specialists near me to do the cambelt and even if there were I'm guessing it'd be something like £700 which I can't afford, and if it's not that then I assume it'd be something terminal. Very sad as its been a fantastic car, but I think it may have had its day.

Thanks for all the help!

Dom