hydraulic lifter question

I have the head off for work at the moment and thought I would replace the lifters while I'm in there.
I have submerged all of the new lifters in a bath of oil and pumped them repeatedly to get the air bubbles out but they still don't feel the same as the old lifters that I'm taking out. New ones are still very easy to depress, the old ones are very firm. Are the new ones pumped up by the oil pressure on start up?
Thanks,
Chris

Sounds like they are just pumped up.

MJR said:

Sounds like they are just pumped up.

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That's just it, they are not pumped up, they are very easy to push in.

If you have a drill press it works grate for pumping up lifters.If you are trying to do them by hand you will not likely get them to pump up with out a lot of work

Hydraulic lifters should leak down slowly. Once the air is all pumped out, in a container of oil, the lifter should collapse slowly under a load.

87m6chris said:

That's just it, they are not pumped up, they are very easy to push in.

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I meant the old ones. Just put some oil on them and install'em. It's not like you are going to be able to apply 40psi oil pressure to them on a bench.

There is an oil hole in the side of the lifter that get high pressure oil from the oil pump via the oil gallery when the engine is running. You will not be able to fill them solid with oil unles you have a way of injecting oil at 30 to 70 PSI into them. Lube them well and install them. There is also a special break-in lube that should be applied to the heal of the lifter (the part that contacts the cam) when a new cam and lifters are being installed. This is more like a grease that should aid in the break in.

When the engine is running, the pressure that is applied by the rest of the valve train and then released when the cam is on the low side works like a pump to pump oil through the push rod to lube the rocker arm. This is done at a rather high pressure ie; the pressure of the oil from the oil pump against the tension of the valve spring. Because of this, I think it will be difficult to bench prime them.

Hey guys, some success, spent the day periodicly going back to the drill press and pumping the new lifters as hard as possible in long slow compressions while still in the oil bath, lot of air in those little suckers. I have them pumped up alittle more than halfway now so feel pretty good about installing them with lots of prelube.
Thanks for the advice.
Chris

87m6chris said:

with lots of prelube.

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Couldn't resist. :roflmao: