X180 External waste-gate renovation.
External waste-gate was made by NormaiAir-Garrett Manufacturing, Melbourne, Australia. Originally, it was made for aviation industry (hard to believe, it weighs a ton!).
Faulty w/g may lead to poor performance or even the engine destruction. See https://www.lotustalk.com/forums/f164...-issue-121943/
After 25 years of service this part needs to be refurbished and improved.
The easiest way to remove it (at least for me), is a partial disassembly on the vehicle.
-Slacken 4 M6 bolts (10 mm heads) along the rim to get a 3-4mm gap, paying particular attention not to tear the diaphragm. Use a plastic spatula (piece of rounded off Visa charge card), to separate diaphragm lip from the lower half.
-Next, support the lower half with a piece of wood (contoured to the outside of the lower bowl) and a floor jack.
-Remove 4 bolts and slowly lower the lower bowl.
-Wiggle out the spring from the aluminum dish/locator and put it aside.
-Carefully remove the shiny aluminum spacer ring***.
Use WD-40 to separate the silicone diaphragm from the rim, CAREFULLY.
Diaphragm is held in place with a large alloy disc at the top; "dish" retainer and two "Fuji-Lock" nuts at the bottom.
Use two open end wrenches to slacken two Fuji nuts. Never put any strain on the diaphragm.
Clean and examine the diaphragm for any tears/damage. Mine started melting down due to exhaust gases blow-by.
Remove remnants of the old paper (!!!) gasket(s), which, by now, turned into flakes of charcoal.
Make 2 new ring gaskets using 0.3 mm Graphoil substrate (from the eBay). Diaphragm insulation will be discussed later.
To evaluate the radial gap of the poppet valve move the stem side to side by hand. Any significant movement necessitates re-sleeving.
To remove the housing, remove the boost signal line (17/32" or 13.5 mm wrench), turbo oil return line (2x10mm head bolts) and break two large nuts (PITA!). To make it easier, soak everything overnight with CRC Screwloose penetrating oil.
Next, make a special tool by grinding a 17 mm ring wrench. It has to be thin enough to clear the end of the large mounting studs.
Once two large nuts are loose, remove your special tool and continue with an open end stubby and crowfoot extension wrench. When nuts bottom out on the housing flange, keep going, alternating the sides to keep the housing leveled.
Nuts will pull the housing out of the header extension bore. Do not use any crow bars or chisels.
Please notice the signs of diaphragm "melting" due to the excessive thermal stress caused by gas blow-by and lack of adequate insulation gasket, (paper won't work well at 700F!).
*** These rings were added to re-calibrate the boost level at which the w/g opens. Proper length of the spring should be 105-110mm.
Normally, it happens at 7-7.5 psig with the ring, and at 9-9.5 psig without it.
Majority of 84-87 (and some 88') Turbos had their boost restricted to 7.5psig by the means of installing an aluminum spacer ring between two halves of the waste gate.
There was an issue in the early turbo cars, which had to do with the (early, cast) pistons crowning and causing excessive clearances causing hot blow-by contributing to the ring land failure resulting in broken rings/ pistons. HCI and later cars received forged Mahle pistons, which solved the problem.