Fitting a new CHRA to a worn 1.8t K-Series Turbocharger. - Forums
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post #1 of 2 (permalink) Old 02-04-2017, 22:36 Thread Starter
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Join Date: Jul 2003
Location: Gloucestershire - Cotswold Cockney
Car: MG Montego Turbo; 620ti x3; MG ZS; MGF and MG ZT 1.8t x2; MG ZT-T x1
Posts: 21,215
Cool Fitting a new CHRA to a worn 1.8t K-Series Turbocharger.

CHRA. :~ Centre Housing Rotating Assembly.

Those who have followed my "No know cure" MG ZT-T 1.8t project thread


will have read of the project car developing a badly smoking Turbocharger.

Having removed the old oil burning worn unit, decided to disassemble the unit and fit the new CHRA I purchased off ebay a few days ago.

This is what the Unit looked like prior to starting work.

Decided to work outside in the garden to take advantage of the fine Sunshine. One of the best weather days so far this year. I worked in between watching the three BTCC races covered by ITV 4 on Freeview Channel 24. So lots of stoppages and tea breaks...the way I like to work now...

Here's why there was lots of blue smoke from the Exhaust Pipe.... lots of engine oil escaping from the worn shaft seals :~

After undoing and removing the large circular clamp, it needed several sharp blows carefully placed on the Turbine Housing with a Club Hammer to separate the Housing from the old CHRA. It was then that I saw obvious heavy Hammer marks on the Housing confirming this was not the first time this Turbocharger had been worked on. Maybe not the original unit the car had fitted on the production line. Never any need to hit these things that hard. Just patiently work around with Hammer Blows and it will separate like this one did today. :~

After removing the four 8mm small bolts securing the old CHRA to the Alloy Compressor Housing, I was delighted to find it simply pulled about... no need for heavy hammer treatment. :~

Old and new CHRAs compared :~

Next task to thoroughly clean both Housings. First with petrol soaked rags to get rid of the old oil everywhere. Then followed that with a wash in hot soapy water. Came up nice and clean. I also used some 180 Grade wet and dry to clear away old oil crud hardened over the years to ensure good clean interfaces of the old and new components. :~

That cleaning enabled the new CHRA to fit in the old Turbine Housing with a nice sound as it dropped in place without needing to be pressed home with much effort. Then fitted the new thin orange-red seal which came with the new CHRA. :~

Soon had the Alloy Compressor Housing in place and carefully aligned ~ there are holes ( drain ? ) to be positioned here. I had used a Junior Hacksaw to lightlymark matching location points to aid reassembly and that was a useful aid. This is the finished assembly just needing oil supply and coolant supply Unions and drain pipes to be cleaned up and fitted. :~

Opposite view :~

Used a wire brush in an Electric Drill to remove nasty corrosion and hardened escaped oil crud from these components. Followed up with some wet and dry Grade 180 finishing treatment. Clean up nicely including the important screw threads enabling easy refitting using just fingers :~

That above coolant pipe was badly corroded in places but came up nicely. The short bracket to anchor it to the body of the Compressor Housing lacked a screw and will need straightening to get it to fit correctly. Another oversight by whoever worked on this car before.

Note above the use of non-OE Garrett Retaining Clip ( unsuitable, flimsy and most of it corroded away ) to secure the Actuator Rod to the Wastegate. I bought a few of the OE clips when working on Rover T-Series T25 Turbochargers ages ago... glad I bought a few more on a come in handy basis one day. They always do.... One thing I did not like, unlike the Actuators on the very similar Turbochargers used on Rover T-Series Turbochargers which are bolted on with small bolts, the K-Series Actuators on these ZT/75 units are riveted on! Much prefer the earlier versions with easy to remove bolts. This is the first time I've worked on a 1.8 K-Series Turbocharger ... not quite true, have removed and fitted several but this is the first time I've disassembled and fitted a CHRA to one. Have done that with the T-Series versions in the past.

Yet more evidence of heavy handed treatment in the past. Someone has used a chisel on this coolant stub tube. It cleaned up well though and I will reuse it.

All being well, I may make a start tomorrow getting it all back on the car ...

Also, when time allows, I will dismantle the old worn CHRA core and consider a rebuild using one of the rebuild kits available. A job for those long winter nights.

Apparently ... in a parallel universe MGJohn drives .........A.......

B>>M>>W ....

Arrrrrggghhhhh......... ......
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post #2 of 2 (permalink) Old 21-04-2017, 17:26
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Join Date: May 2007
Location: Warwickshire
Car: Rover 75 CDT, Metro 116,MGF VVC,Mrs JoCoLo's Panda 1.2 and Mstr JoCoLo's TF 115
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Nice job MGJ, I've seen a fine looking red MGF in Blackpool on FB today. It might be broken because of a cracked liner. If you had been the owner I guess it would have been saved for certain.
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