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Wed Nov 11, 2009 8:21 am

My hydro lifters on cyl #3 and #2 have a hard time staying pumped up.
So I replaced them, thinking they were bad. I primed the new lifters before I put them in and within a week they were back to the same old tap tap tap. For curiosity I left the valve covers off and ran the motor at fast idle and noticed that all the valves except the ones that weren't priming had ample oil running off the rocker arms. Push rods are clean inside and out, any chance the galleries that feed the lifters are clogged? Anyway to blow them out or use a fine bottle brush in there? Any suggestions?
78' 2L FI
many thanks!

Wed Nov 11, 2009 8:52 am

Is this a single or dual relief block?

Wed Nov 11, 2009 9:02 am

single screw on the bottom

Wed Nov 11, 2009 9:28 am

Are you parking maybe with the nose of the bus down, like down a ramp?

When I was running hydraulic lifters, I would get clatter from 3 or 4 as they were 'higher' as I'd park on the slanted side of the road, and they'd lose their prime.

I've read that this is at the heart of hydraulic lifters being a bad Idea in these engines, that even when parking level there will always be lifters that are out of the oil bath. Parking slanted, I found made it worse.

It does seem like if your lifter wasn't primed, oil wouldn't flow through it, thus no oil at the rocker.

Wed Nov 11, 2009 9:37 am

Certainly sounds like something is affecting your oil supply. It used to be common to see small oil passages clogged with the water/oil/lead slime that would all but fill some engines, but with the removal of lead from the fuel and typically better crankcase ventilation I haven't seen this in years.

You might remove the offending lifters and then make yourself a thin air nozzle with a 90° bend in the end to blow into the passages. You might be able to use a piece of soft copper wire as a probe as well.

What brand oil filter are you running?

Wed Nov 11, 2009 10:25 am

usually purilator pure one, but have a Mann on there at the moment, yeah the whole air nozzle thing has come to mind, I assume the oil passage is on top of the lifter bore inline the the recessed ring on the lifter itself?
anybody every blown out an oil passage on a lifter bore before?

the bus is parked on level ground

Wed Nov 11, 2009 12:44 pm

you can take the whole lifter apart if that's what you mean, with circlip pliers. That would be step 1 for me, to remove any particles that might be clogging.

If you got new lifters and they are clattering also, then it may not be the lifters that are at fault.

They get fed through the hole in their center by the lobe/ pump action of the cam. Oil goes through them, through the pushrod, through to the rocker arm.

If they're not getting/ keeping their prime, it could be they're clogged from dirt in oil, maybe something wrong with cam profile preventing pump action, or it could be there's not enough oil pressure in lifter galleys.

This 3rd, maybe it is caused by too weak a spring in relief valve, or if lifter bores are outside of tolerances. How is your oil pressure?

Wed Nov 11, 2009 4:27 pm

oil pressure is fine
so how does the oil get to the lifter?