External wastegate rebuild
February 9, 2019(This post contains affiliate links. Check out the affiliate disclosure here)
Let us jump straight into how rebuilding your external wastegate can save you big $. What I want you to take with you from this is that it is not always necessary to replace a problematic wastegate.
Rebuilding it can save you lots of cash, spare parts like a spring or membrane is cheap compared to buy a whole new unit.
Time needed: 1 hour
How to rebuild an external wastegate. Time may vary depending on parts availability.
- Identifying your wastegate
The first thing you need to do before rebuilding it, is to identify with kind of gate you have. For this i will use my own unit that needed a check. ( HKS 38mm Replica )
Knowing what type it is can be tricky. If it’s a stock unit, google the car and add “stock wastegate type”. Aftermarket units are harder, if there is no numbers on it try googling around or ask if a speed-shop can help you. This is what you need to know to find replacement parts. - Take it apart
What components is in a external wastegate unit?
Described from left to right.
Top row
– Top housing
– Bottom housing
– Spring ( adjust base boost pressure by using harder or softer spring )
– Membrane and valve retainer.
Bottom row
– Valve
– Valve body / Exhaust housing
– Lock-nut for bottom housing
– Bottom housing o-ring
– Pressure nipples
– Valve seat
- Assembly of the bottom half
Inspect all parts for damage or unusual wear. Replace if needed.
You need: valve body, lock-nut, bottom o-ring and bottom housing.
Put the bottom housing on the valve body. Lube up the o-ring and put it on the threaded shaft. Clock the bottom housing to your desire and tighten the lock-nut. the dent in the bottom housing needs to match the lock-nuts hole. Apply some medium thread-lock to the lock screw and tighten it. Cover the valve shaft with a light oil film and insert it from the bottom in the valve body. ( All pictures in gallery below )
- Assembly of the top half
Inspect all parts for damage or unusual wear. Replace if needed.
You need: membrane, spring, top housing and pressure nipples.
Cover the membrane with a light oil film and let it sit for a while. Wipe off any excess oil with a clean cloth. Compress is so it looks like a bun. Put it on the top of the valve and tighten the lock screws. Always use medium thread-lock for these parts. Apply some oil to the spring and put it on top of the valve retainer. Put on the top cover and compress it, it may require a lot of force if you are using a hard spring. Lightly tighten the cover screws, check that the membrane won’t get squished between the mating surfaces. Now you can fully tighten the screws.
( All pictures in gallery below )
- It’s done and ready to serve you boost
You have now rebuilt your external wastegate. Not so hard and you can use the rest of the money you saved on not buying a new unit on cookies or some more speed-parts.
Gallery
