timing chain/oil pressure issues

[MDE3]

My 87 16V auto has had progressive timing chain clatter at start up of late...I know that this car is probably in need of chain, guides and new tensioner. However it only made the sound on start up, so I was nursing it through till one of my others was back on the road...major problems with them. The noise got worse when I recently changed oil, and the tech insisted I should try a little thinner oil (was running 15-50 synthetic)...My feelings were that the thinner oil was letting more oil by pass in the tensioner at start up until full oil pressure was achieved..taking longer than the higher viscosity oil.

Then it got more and more pronounced, and I began to suspect that the oil was draining from the circuit, and therefor taking a longer time for the tensioner to do it's job at start up. (build pressure and I know I was playing with fire). Then a couple of days ago, as I was pulling into a mall, and the motor was decelerating..I heard what I believe to be timing chain slap on deceleration...I turned around and headed for my INDY..about 1 mile away. As I got there the oil pressure began to fall, to where I was only holding 2 bars at 3000 rpm's....My feeling is that over time the oil pump relief was beginning to stick open a bit..allowing the oil from the tensioner circuit to drain down, and now not holding enough pressure to keep tension on it.

We are pulling it down first to see if the oil pump relief is stuck, and removing the valve cover to inspect the chain and guides...If the relief valve appears to be sticky upon dissembly, and all the chain guides appear to be in place, I will probably simply change the tensioner, and repair the relief valve to get it back on the road until I can take the time to do a full timing chain and guide swap.

has anyone else experienced this same sequence?