77 C10 350 valve clatter during long drives

[Steppin Razor]

Hi all. I have an issue driving more than an hour. Oil pressure gauge drops a couple marks from full on the gauge and I get valve clatter. When it's cold, it's fine. 45min drive, it's fine. Hr+, not fine. Any ideas? I'm using chevron delo 400 oil. Thanks

 

[Ricko1966]

You need to have 10 psi per 1000 rpm oil pressure. Put another gauge on it see what you actually have. Problems that come to mind crap in the oil pan getting sucked into the pump screen,a sticky oil pressure relief valve,worn engine bearings. Check pressure with another gauge first.

 

[Steppin Razor]

Thanks. The pan I can drop and clean just for good measure, maybe the valve too once I find it. I don't have a tach, but I think I bought an oil pressure gauge from HF to test my erstwhile F150.

 

[Rusty Nail]

Valve adjustment is my idea

 

[KnuckleBuster]

First thing that comes to mind...when most people complain of "valve clatter" it is actually pre-ignition / detonation that they're hearing. Timing check is easy enough. Make sure the mechanical advance is not sticking or stuck.

Not enough info was provided to help. Other than after warm-up, under what conditions does it occur? At idle, steady cruise, acceleration? Every time it gets fully warmed up or only on Tuesday's? If you suspect an oil pressure problem then get an idea of what it's actually doing. The more info the better.

 

[Rusty Nail]

Dude.

I needed to add a quart the other day and decided to give this stuff a shot.
O. M. G.
The truck really, really likes it.
Screw a valve adjustment, now I vote for this mechanic in a can. Bet it works.

Oil.Stabilizer.
How long on your oil change BTW?

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