What a big problem

Its been almost a week now since I started cleaning and fixing the van for it has an oil deposit in its radiator. I am so much worried about it because this problem can damaged the vans engine if not fix immediately That's why I went to the auto shop where I used to go if there's something going wrong with it and the chief mechanic told me that that there were only two options to perform first was to see if there's something wrong with the oil cooler or it might be in the head cylinder gasket. I tried to check and pull out the oil cooler with my partner Richard and we booth agree that oil cooler was still in good condition so we decided to pull out the cylinder head and bought the necessary replacements but when we reach the time where the cylinder head will be the part to pull out we have change our mind because we don't know where the bolts located to give way for the timing chain cover. We really need to see the timing chain because this is the only part where we can see the timing chain mark and we really don't know where it is located, so we just assembled it back according to sequence and decided to just observe the vans performance for the first week and if there is still an oil in its radiator. If the problem will still arise that's the time that I need to bring the van to the shop for an immediate replacement of head gasket.