DKZ XU9JAZ pistons and rebuild headaches

[Moeozz 0]

Hi All,

I've resisted the urge to post here because I'm from Aus and 1) I'm a complete noob with Engines and 2) I believe the DKZ over here has slight differences to the ones in Europe? I could be wrong so please correct me.

Anyhow, I've recently purchased a project 205 CTI with engine knock. I've pulled it apart and found a bent conrod likely caused by liquid entering the chamber. Engine pictures here

 

I found a local set of DKZ pistons and trying to put a parts list together for everything else. To the naked eye I thought they were identical, but upon measuring, there are some slight differences with ring size (old = 1.5mm, new =1.75) and crown height (old = 36.2, new = 37.5).Piston pictures here

 

I'm going insane trying to figure out which is the correct piston as there is an obvious flow on effect with all the other parts I purchase.

And to complicate matters, this vehicle is an import model from Asia, and the engine was replaced and rebuilt many years ago.

 

Can someone please review the 2 albums and help make sense of it? My main concerns:

• Are there 2 different types of DKZ pistons? I'm told there might be a low comp and high comp version, but you can usually tell from the dish shape which these are identical?
• Are these old + new pistons cross compatible for an DKZ/XU9JAZ engine regardless of height?
• Or put simply, is it possible my engine is a Frankenstein of different parts done by the previous owner and cannot trusted anymore?

 

Many thanks in advance!

[Thijs_Rallye 90 4 Cars]

Maybe this will help: https://www.miamistu.co.uk and https://www.miamistu.co.uk/pug/GB/205N/0/01G50A.HTM

 

There is a difference from 1992 onwards, but PSA doesn't specify what it is exactly. I do know that for these 1.9 8V engines all compression and oil control rings are the same. 

 

 

[Moeozz 0]

On 4/16/2026 at 3:26 PM, Thijs_Rallye said:

Maybe this will help: https://www.miamistu.co.uk and https://www.miamistu.co.uk/pug/GB/205N/0/01G50A.HTM

 

There is a difference from 1992 onwards, but PSA doesn't specify what it is exactly. I do know that for these 1.9 8V engines all compression and oil control rings are the same. 

  

 

I have been using service box to find OE part #, but it's still difficult to know what these "new DKZ pistons" are exactly .

Closest match I could find is the  Mahle 039 79 00. But that requires 1.5mm rings and not 1.75.

And also it looks like my used pistons are Mahle 039 85 00, which I hope is the correct one for an Aus spec DKZ.

 

I dont know any better, so I'm scared to use these new pistons and introduce other issues further down the rebuild. Or end up needing the change a bunch of stuff because I messed up with the compression ratio.

[Thijs_Rallye 90 4 Cars]

My guess is that the 039 85 00 is intended for the low compression DFZ engine. Those had the shallow bowled pistons, whilst the D6B / DKZ had the ones with a deep bowled piston. 

 

What I see in the web cat from Mahle:

1) Shallow bowl piston: 039 83 00 superseded by 039 76 00

2) Deep bowl piston: 039 85 00

[Moeozz 0]

26 minutes ago, Thijs_Rallye said:

My guess is that the 039 85 00 is intended for the low compression DFZ engine. Those had the shallow bowled pistons, whilst the D6B / DKZ had the ones with a deep bowled piston. 

 

 What I see in the web cat from Mahle:

1) Shallow bowl piston: 039 83 00 superseded by 039 76 00

2) Deep bowl piston: 039 85 00

Sorry did you get the part numbers confused? Because there's some contradictions.

 

The DFZ pistons I've seen online don't have the ramped bowl like the D6B or DKZ. So 039 85 00  cant be for DFZ.

And whilst D6B + DKZ have the same/similar bowl style, 039 85 00 is listed as 36.2 compression height, and 039 79 00 has 37.5.

 

What I'm trying to ascertain, is if they are cross compatible without any additional mods or follow on effects.

If so, I'd rather stick to the used pistons (look to be 039 85 00) rather than the new ones I have (look to be 039 79 00 but with 1.7/1.75/4mm rings)

 

Hopefully this makes a bit more sense sorry!