After my report to the factory customer service telling them my experiences with their aftersales manager and the dealer they informed the European importer and urged him to solve the problem once and for all. So they called me and we discussed the issue.
After replacing the defective oil pump output O-ring the ticking sound has gone, but during the test ride reappeared, but slightly more intense. As I had ground and polished the rocker arms surfaces where they contact the top of the valves before I was curious how they look after the test ride. And as the ticking sound during the test ride suggested, there again was a good sign of wear after the test ride. Now it was very clear that a sufficient amount of oil in the cylinder head was missing.
The importer confirmed my assumption that that a lack in oil pressure will be responsible for the abnormal noise rather than defective hydraulic lifters. We agreed that I will fix it myself without the support of the doubtful dealer and the importer will send me all the required parts in exchange of the old parts for free if I will send him a list of the parts I need.
So far, we found a way to handle the issue in a way that both sides are happy. Well, the dealer and the aftersales manager may not participate in the happiness, but that is a different story.
But there is still the question what really is the cause for the lack of oil in the valve drive. The O-ring was replaced, all holes and channels for the oil checked for free passage with no negative results. The one and only item that can be responsible is the oil pump itself. So I disassembled and investigated it with not much results. It looked good inside. So what is going on in the engine ?
I found a very good explanation for the UCE oil distribution system at LinkedIn Here is the link :
https://www.slideshare.net/classicmw/ro ... ubrication
On the second page, point two, I found the most important fact concerning the relief valve. This valve will open when starting the engine to ensure an instant oil supply for the cam gears. When the engine is running, the gears are lubricated by the oil flowing down the tappet compartments back to the oil sump. The crank shaft and the hydraulic lifters are fed by different channels.
The relief valve is opened by the oil pressure parallel to the pump’s oil output. The valve in my engine opens too early / too wide by a too low oil pressure and the resulting oil pressure is too low to feed the rockers and especially the small channel that ejects the oil to the tips of the rocker arms. This lack of oil leads to a heavy wear of the rocker arm tip surfaces touching the top of the valves. This effect is accelerated by the lack of cooling by the missing oil.
I disassembled the relief valve and there were no signs of malfunction. The only thing that is wrong is a too soft spring, resulting in opening the valve at a too low oil pressure. Replacing the spring by a harder one would fix the problem, if you find a harder spring with the same mechanical dimensions. As an alternative and easier to realize is placing a washer between the spring and the cover of the spring held in place by a circlip. I will attach pictures of the pump and the disassembled relief valve.
As there are a lot of guys outside there that have trouble with their ticking EFI UCE I hope this post may help locating the source of trouble more easily. It looks like that the oil pump is a very common problem within the UCE.
There are aftermarket oil pumps available with a higher oil flow capacity. I would suggest to replace the factory oil pumps by this.
