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  #16  
Old 02-23-2003, 01:24 PM
Chris Martens's Avatar
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George ang Gilly,

maybe I'm completely wrong and this is not a first hand experience - but nevertheless:

The hydraulic lifters grow when under a no load situation, like laying in the box. The lifters shrink when under pressure, slowly and not much, but they shrink.
That is the way they are compensating more or less valve clearance automatically (of cause they are supported by oil pressure in the running engine)

If you get new hydraulic lifters into the rockers (new or old) and tighten the rocker arms - the valves will open because of the grown length of the lifters. Just let the head sit overnight and check the valves again.

A buddy from a german forum reported that he changed his hydraulic lifters and afterwards the car didn't start! No compression at all.
So he took off the head to check for any damage, but everything looked well. He mounted the head and the next day: engine started and ran.

If this is nonsense - please forgive me

bis denn,
Christian

1989 300TE
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  #17  
Old 02-23-2003, 01:39 PM
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One other consideration.

One must understand what the tool is measuring before one can understand how to use it. A hydraulic lifter has a physical range of possible compression. It can be all the way compressed or it can be all the way out. This distance is significant (large). It probably is an 1/8 inch or more. The desired state of compression is the distance that one wants to measure as that is the working relationship in question. The permissable difference in the acceptable compression is also a large number. What is most important is that the lifter isn't going to bottom out. In other words. The design is such that the lifter is intended to be in a state of collapse. The amount is what you measure. In a running motor the spring in the lifter takes up the clearance (with a prescribed amount of collapse) and the oil behind it makes it semi-ridged in this floating position - thus "hydraulic" lifter.

Now for the consideration. The measurement will be eventually made after the lifter is collapsed to its working height. I don't do this work anymore but on V8s where I did we had to squeeze the lifters in a vise to get the oil out so that they would collapse to their working height on assembly. The spring inside the lifter will bring it to full working extention for measuring. If one assembles an extended lifter FULL of oil it will not collapse (It stays extended). Be sure this isn't your original problem as you will have to know this to measure the collapse.
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  #18  
Old 02-23-2003, 01:45 PM
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Location: Atlanta, GA
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That is an interesting point you make. I ordered two sets of hydraulic lifters from two different companies and one of the companie's lifters were pre-collapsed and the others weren't. I didn't know about this pre-collapsing though. I will take out the lifter and put them in a vice and see if I can pre-collapse them and see if this solves my problem. Thanks for the help!
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  #19  
Old 02-23-2003, 01:50 PM
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The point is not so much precollapsing them as being sure they ARE collapsing when installed. The pre-collapsing of them does get the oil out of the way though and was necessary on the V8 lifters or the valves would stay open for a number of revolutions untill they collapsed to the working height.
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