My friend Franck in Paris send my the alarm below about the chain tensioner quality problems. I never heard about this here. Anybody has any more input on thiss?
" Different magazines or forums warned the Sunbeam owners not to fit new fabrication rubber chain tensioners. I CAN CONFIRM THIS ! A new one which has been enlarged about 50% on the lower half, the upper being transformed in black porridge in the sump. Fortunately the bearings didn’t suffer, but you know how difficult it is to fit the 2 side paper gaskets, and the 2 rectangular cork gaskets. Please recall this information to any who would be rebuilding his engine. Franck "
We discussed this with our supplier Rootesparts.com. Already many years ago, he mentioned that the original rubber tensioner is not fit for modern engine oils. He had remanufactured new tensioners which were made of a correct rubber, even for use with modern oils. His website has a relevant remark. You can imagine that anyone who uses modern oils with additives in his original engine is bound to get trouble.
In one of the workshop manuals on rootes.com there is a mention:
ENGINE CAUTION: NEVER USE AN ENGINE OIL SUPPLEMENT OR “HIGH MILEAGE OIL” TO TRY TO REDUCE ENGINE OIL LEAKS. THESE ADDITIVES WORK BY SWELLING THE RUBBER SEALS WHICH THIS ENGINE DOES NOT HAVE. HOWEVER, THE TIMING CHAIN TENSIONER IS RUBBER & IT WILL SWELL AND BE DESTROYED IN THE ENGINE REQUIRING AN ENGINE TEARDOWN. THIS IS VERY IMPORTANT