Valve tap or loose rocker

[87mefull]

The merc just got a valve tap on the passenger side head, its not too bad but you can hear it at idle. It sounds like a loose rocker at higher rpms, but I don't know if they are adjustable or not. I didn't really notice it before I removed the smog pump though, but the pump was about to seize though. I removed the pump, plugged all the vacumm lines not in use by it and left the belt for the AC off also.

Should I run rislone or an oil stabilizer the next time I change the oil. I had pretty good results with it in my truck, but I ran 20w50 in it also.

[gadget73]

Probably just a lifter getting tired. The valves on a 302 are not adjustable. If it rattles and goes away after a few moments or when the motor warms up, I wouldn't pay much mind to it. I'd also suggest not running 20w50 unless the bottom end is really bad. 10w30 or 10w40 would be what a 302 wants. You can try some of the oil treatment stuff but I've always been afraid of breaking loose some chunk of sludge and having it clog the pickup. Unless you're certain that motor is clean inside, I wouldn't suggest it.

[87mefull]

I wouldn't run 20w50 in this motor, it doesn't burn or leak any oil and has good compression from what I can tell. I ran it in my truck because it wouldn't run with 10w30 in the summer, it would randomly stall out or have an excessive amount of valve train noise. I've been running standard penzoil 10w30 in the merc since I got it with good results.

I had pretty good results running a quart of rislone treatment with 10w30 in the winter with my truck. It really makes the engine run quieter (I had no valve noise once the car warmed up), but I wouldn't run a whole quart in the merc.

[gadget73]

I'm guessing Ristone is one of those sludge-like additives similar to Lucas that you can put in the oil? Lucas does good things to silence valve noise so that stuff will probably do the same.