Lockdown makes things tough, but my Coupe is safely with my buddy who has installed a new engine.The boost has been wonky though - heading up to 0.8 bar then dropping right off... The turbo is an oily mess, but I also reckon the boost solenoid is knackered, so I have bought one of the 'GM' ones from www.rockauto.com - part nr. 214-474.

Because it's such a pain to arrange shipping of exchange parts etc right now, we're going to have a go at rebuilding the turbo. I actually have two, thanks to the ebay engine coming complete with a turbo.

I am going to buy a rebuild kit:
https://www.turborebuild.co.uk/webs...T28-Turbocharger-Bearings-and-Seals.html

and a CHRA cartridge:
https://www.turborebuild.co.uk/webs...artridge-454154-Turbocharger-TB2810.html

What do y'all think?

Do I need anything else?

I've read on here of several members tackling this. My only concern would be the proper balancing of the turbo after it's been put together, or does the cartridge come balanced? I'm sure someone with more experience will come along & give you advise.

Slap a new cartridge in. Shouldn't need a balance or that bearing kit. Literally undo the pipe work from your old core, undo the compressor housing, then undo the exhaust housing.

You need new copper washers for the water pipes, a hex key to undo the oil drain (can't remember the size), and some high temp thread sealant for putting it into the new core.

Take lots of photos and measurements as you'll need to clock everything just right else it'll clash/rub. Nothing is keyed and can therefore be set at any orientation. And you might fight some rusty bolts on the exhaust housing.

11m hex key for the turbo oil drain pipe, an usual size not usually found in sets so may need to be sourced separately.

Helpful, thank you.

New turbo cartridge fitted. I have the “GM” boost solenoid replacement ready to go in.

On the original boost solenoid. with the new cartridge the boost gauge indicates only 0.5 bar of boost. The car feels faster so I am wondering if the boost gauge - a cheap eBay job - is malfunctioning... but when I do what countrycruisin suggested and bypass the boost solenoid, I get no boost whatsoever. Like, zero.

The wastegate is definitely closed.

Going to try running it with the new boost solenoid but anyone have any thoughts about why I’m getting so little boost, and apparently none with the solenoid bypassed?

0.5 or around that is waste gate pressure

Have you got the hoses the right way around on the solenoid?