Case study : WGA loses preload
Apr 10, 2012, 01:54 PM
#1
Case study : WGA loses preload
From this thread : https://www.evolutionm.net/forums/ev...ailures-4.html
It seems that some HKS 7460 have this problem. I have encountered it on two regular (non kai) 7460 and also on a stock evo 9 turbo!
One of the 7460 was sold, the other 7460 and the stock turbo are on the relative cars.
The stock 9 turbo case was emblematic : I have changed the housing because on the last one the flapper completely come off : the owner began to hear a rattle coming from the turbo, but when I diagnosed what was causing the rattle, after a lot of miles, the flapper had rotated so much on itself that on the successive road test came off and we loses it from the exhaust. So I completely changed the housing, re-used the WG actuator and give it the correct preload. After few miles the turbo started again to rattle : the WG is without preload...again.
Fact : noone of this actuators are loose from the beginning, or have the nuts loose.
Fact : all these turbos have very few miles on it, in the range of 1000-1500.
Fact : I cannot see anything wrong in the flapper or housing that I have inspected.
Fact : All these actuators seems normal from the outside and are OK in the vacuum-pressure test.
It seems that some HKS 7460 have this problem. I have encountered it on two regular (non kai) 7460 and also on a stock evo 9 turbo!
One of the 7460 was sold, the other 7460 and the stock turbo are on the relative cars.
The stock 9 turbo case was emblematic : I have changed the housing because on the last one the flapper completely come off : the owner began to hear a rattle coming from the turbo, but when I diagnosed what was causing the rattle, after a lot of miles, the flapper had rotated so much on itself that on the successive road test came off and we loses it from the exhaust. So I completely changed the housing, re-used the WG actuator and give it the correct preload. After few miles the turbo started again to rattle : the WG is without preload...again.
Fact : noone of this actuators are loose from the beginning, or have the nuts loose.
Fact : all these turbos have very few miles on it, in the range of 1000-1500.
Fact : I cannot see anything wrong in the flapper or housing that I have inspected.
Fact : All these actuators seems normal from the outside and are OK in the vacuum-pressure test.
Last edited by eTiLiKo; Apr 10, 2012 at 02:05 PM.
Apr 10, 2012, 02:04 PM
#2
I have an actuator lying around in the shop so I have opened it to see what into it can cause the problem
My conclusion is that INSIDE THE ACTUATOR, only the small nut that come loose can cause the loss of preload.
The external factor can be the rod that lenghten itself....very difficult, or the compressor housing that slyghtly rotate, also very difficult.
Ideas?
My conclusion is that INSIDE THE ACTUATOR, only the small nut that come loose can cause the loss of preload.
The external factor can be the rod that lenghten itself....very difficult, or the compressor housing that slyghtly rotate, also very difficult.
Ideas?
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