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Discussion Starter · #1 ·
My engine used to tick for about thirty seconds after startup. All of a sudden, the ticking has remained constant (it doesn't stop).

3 questions:

1) Is it likely the valve tappets?
2) Could it be the timing chain?
3) How long can I run like this?

Its an '86 9000 turbo with 335,000km on it.

Also, the oil was recently changed (<2000km ago).

Words of wisdom, anyone?
 

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Sounds like valve tappets. I had mine cleaned when I did the head gasket job, because they were all clogged. It cost me 30 euros to clean them all, at an engine shop.

I don't think it's a job you should be doing so soon. Engines can live for a while with noisy tappets, at least mine did at least 50k km, because it did it since I had the car until the HG job, and I don't know for how long it had been doing it before I bought it.

To be sure it's not the timing chain (wich could also be seen the mileage), remove the valve cover when the engine has been sitting for a couple of days and try to see if there's any gap between the tappets and the cams, when the valves are closed. It should be possible to fit something 2mm thick without opening the valve, ie without comepressing the valve spring.
 

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My 91 turbo had this problem if it hadn't been driven for a few days.

The odd thing was, that when it was doing it, it wouldn't go above base boost until the tappet cleared.

I never figured out why that was, but I mention just to point out that a noisy tappet can affect the engine in some way

I assume the valve was not opening properly and that the APC was detecting this as a misfire, but that's just a guess, since I don't really understand hydraulic tappets (last engine I dismanteled was an OHV with pushrods!
)
 

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Most modern oils get thrown away because of contamination by carbon (soot), unburned fuel or water (a by-product of combustion). Some readers may recall the ancient rituals of de-coking (on four strokes !) and "flushing oils". These were necessary evils to rid an engine of excess deposits. Crud built up around the piston rings, and valve stems and in the smaller oilways and passages. Some of this crud was due to poor combustion, some to fuel impurities, some to the relatively poor performance of early multigrade oils. One major source was the comparatively low operating temperature of older engines (poor thermal efficiency): to this day, an air-cooled engine gives its oil a harder time than a water-cooled one. This is often not because the oil is getting too hot, but because it is not running hot enough to burn properly or to evaporate the water formed by burning petrol in air.

These deposits cause the need for de-coking and flushing. You either mechanically scraped and polished them off the pistons or "washed" them out of the narrow passages with a high-detergent oil. This "flushing oil" was very good at getting out deposits, but a poor lubricant, so it couldn't be left in with the vehicle on the road.

Engines still make all these deposits, but the rituals are mostly dead and gone. Why? Because modern oils contain much more robust detergents, all through their service life they absorb the carbon and unburned petrol and water and acids and lock them in with nice safe, inert detergent molecules: protecting your engine. In passing, all these contaminants are far, far smaller than the particles the oil filter is designed to trap.

That is why we need to change the oil: to get rid of the contaminants, not because the oil has degraded in any way. A given volume of oil can only hold a given volume of contaminants, after that all the detergent molecules are busy and the contaminants start to settle on (and attack) the engine. Even if a very expensive oil can trap a bigger amount of crud per litre of oil (and the difference is marginal at best), a sump full of new, clean, unpolluted oil is the best way of ensuring a clean engine.

Something to beware of when using flushing oils, as they are not supposed to be run in the engine for a long time, if there are a lot of deposits in the engine and sump areas it will soften it only and when you put new oil in, it can then break away in lumps which can be big enough to block vital oilways. On cars with hydraulic tappets the flushing oil will get thru to the oil chamber but how long will it remain there before it is replace with good oil?, because when you drain the sump, oil remains in the tappets, also in numerous other places in the engine.
I would never recommend using any type of flushing oil, but if you do be prepared to a couple of cheap oil changes afterwards before putting in the good oil.
This is of course IMOA
 

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Mark, normally i would agree with you in the case of a newer engine, but this engine is 17 year old and has a really high amount of miles on the clock, and you have no way of knowing what kind of oil has been used in the past, i have seen cars bought at the same time but not run by the same people and after 100,000 miles the tappets in one were ticking away like hell and the other was running sweet, the diff the type of oil used in the 2, one used mobil 1 the other oil from the work, so we used an good quality engine flush in the dodgy one and all but one of the tappets shut up and went on for a further 50,000 miles till we got rid of it.
 

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That is why we need to change the oil: to get rid of the contaminants, not because the oil has degraded in any way. A given volume of oil can only hold a given volume of contaminants, after that all the detergent molecules are busy and the contaminants start to settle on (and attack) the engine. Even if a very expensive oil can trap a bigger amount of crud per litre of oil (and the difference is marginal at best), a sump full of new, clean, unpolluted oil is the best way of ensuring a clean engine.[/b]
Interesting, Mark.
Since I run on LPG, I noticed that the oil remains amber and doesn't turn black even after 10k km (or 6k miles). I think this is due to the fact that LPG is much more cleaner that fuel to burn, right?

So, if what you saied above is correct, I wouln't need to change oil so regulary, I could change it just every two years, or 50k km (when some oil degradation might start). Do you think so?
 

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I used to be a marine engineer and most ships I worked on ran rather big diesel generators. we used to run the oil for a certain period of time and used to do particle analysis tests to determine when the oil need to be changed. However, we never threw any of the old oil away, we pumped it to a settling tank and ran it through a centrifuge until all the contaminants and water were cleared out then we pumped it to a clean oil tank ready to be re-used again.
The cost of these pieces of equipment cost around £500000 to 750000 each, so you could say we had total confidence in the ability of the oil to do its job once the contaminants had been removed.
I would get in touch with the oil manufacturer regarding your application but reckon you could extend the oil change time.
When you think about it, gearbox oils are sealed for life nowadays.
 

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Discussion Starter · #11 ·
I think if I do anything I'll replace the misbehaving tappet, assuming I can tell which one is faulty. I don't feel comfortable with flushing the engine because of its age and mileage. In my opinion, I think I may dislodge too much crud from where it has naturally and nicely settled over the life of the car. I would be concerned with clogging the other tappets and/or smaller oil passage ways. Make sense?

Any chance that the cylinder is contacting the valve?
 

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It sounds as though the new thinner, unpolluted oil is allowing more movement of the tappets than the old oil.

You may find that the sound will slowly return to happening just on startup like before, as the oil becomes used.

Skiddins
 
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