Post by Eric Sabatier on Oct 21, 2017 21:30:15 GMT
Hi There
I remember that we discussed octane before ECM2017. Does any one noticed any engine related trouble after the ECM? I am asking because my engine that had a slight noise before ECM, finished with a major problem and I am wondering if petrol might be the x-factor making things going worst.
The thread you referred to was about octane levels and ethanol (E10/E15/E20 etc) content in the petrol in CZ. Too low an octane level causes detonation/"pinking", and is normally quite easy to detect. Ethanol damages rubber seals, diaphragms etc. Unless you had really severe detonation, I think it's pretty unlikely that poor fuel over a weekend would cause severe engine damage.
What is the problem you had with your engine, and in what way did it get worse? There are quite a few engine experts on here who might be able to offer some advice if we have more detailed information about the symptoms - so please feel free to give some further details to help with diagnosis!
Post by Eric Sabatier on Oct 22, 2017 15:00:12 GMT
Thank you Alan For months before I had a very sluigh noise I cna heard when passing along a wall where this noise echoed from. I had concerns about rockers in need of adjsutments but as I had hydraulic pushers, I left it for later. Then during ECM I had a much more distinct "steel" noise. Looked like something was coming loose and ready to fell. Noise stopped when car stopped so I thought about sme steel plate loose from under the car. Until Michel stopped me on our return trip when he heard the noise while I followed him. We took of the rocker cover to find that one rocker has a lot of play. OInce home I removed the cover, run the starter to find that the admission rocker on cylinder #8 was not moving at all when exhaust rocker was moving but not enough to reach the valve tail. Removed the rocker ramps to find out : Ramp (I mena the rockers on the ramp) was partially seized on #8, much less on 7 and 6 Admission Pusher Rod on #8 was bent Pusher on Exhaust one #8 was collapsed and machined by camshaft, loosing 3-4mm in the process. Camshaft damaged as it still do not uplift enough a clean pusher on #8. So out the engine and it's now with an expert. He picked up the engine 2 days ago and should be able to let me know his findings after he starts working on the engine in a couple of weeks. In the meantime still looking for possible causes although he should be able to find it when he'll have the engine opened.
Thank you again.
Last Edit: Oct 22, 2017 15:09:50 GMT by Eric Sabatier
More general cam lobe failure (i.e. multiple lobes) is usually due to a failure in the lubrication system - or, if you don't have a roller cam, an incorrect cam break-in procedure. But a single worn cam lobe suggests that the associated valve or rocker arm has either seized and/or put extra pressure on that lobe. You've already identified signs of seizure on the lifter/arm, so this is most likely the cause.
As the associated pushrod is bent, your mechanic will need to take the head off to check the associated valve and spring, and that the valve hasn't made contact with the top of the piston. The top end repair work should be quite straightforward - but as there's been metal-on-metal wear, I suggest your mechanic also checks whether any metal swarf/filings have caused wear to the bores, big-end bearing shells etc. - hopefully not.
As for the underlying cause, was the engine over-revved by any chance (possibly in the drag race)? That is quite often the cause of a bent pushrod or broken valve spring.
Good luck - I hope it's a straightforward repair and that you're back on the road quickly!
The mechanic is going to take apart the whole engine and rebuild it after having measured everything on it and replaced the parts that need to be replaced. So I should end up with a better engine. I did what I could and now I leave it to him and the only think I can do is think about it. As for over-revved, I don't think so as even during the drag race I didn't really pushed the engine (as my results shown) and even then not beyond its limits. If the engine can't not be used up to the ruptor anyway, it is useless and need to be adressed. A friend of mine that had the same symptoms had the engine repaired by the same mechanic and the cause was over rated valve springs. We'll see what he found out for me.
it´s always bad when an engine is not working fine. I am sure that the czech petrol is not the reason for your lifter break down. I suppose something in the oil circuit was the reason. Maybe an metal particle enterd the lifter area. It seems that all will be fine again in Davos. Kind regards from bavaria Hans