K Series Turbo Engine Low Compression

[JefferiesFarnol]

Hello chaps,


I'm embarking on my long-planned engine swap, moving a 1.8T engine into my 1.8 n/a tourer (along with the gearbox and driveshafts etc.)


I'm hoping to get the donor engine out this weekend and did a preliminary compression test while it's still plumbed in and got about 8.25 bar on all four cylinders with the engine hot. Haynes says that anything below 10 bar is low so I tried a bit of oil in one cylinder and it went straight up to about 10.5 bar. I understand this may well be worn piston rings or liners.

Once the engine is out, I'll take the head off and see the situation but my question is, assuming I get the piston rings changed, would it be worth having new liners as well and if I did get new liners, would they make the engine suitable for the multi-layer gasket? I have read that the liners sink because of compressed metal in the block so new liners drop again anyway. I'll naturally check the liner heights when I get the head off but I'm fully expecting them to be too low for the MLS gasket.

[Matt_75]

Hi Hector,

The Haynes manual states "compression pressure (typical)" and goes on to say that "although MG Rover do not specify exact compression pressures, as a guide, any cylinder pressure below 10 bar can be considered as less than healthy. Refer to an engine specialist if in any doubt as to whether a particular pressure reading is acceptable".

The problem is, Haynes doesn't differentiate between both engine types, 1.8 NA and 1.8 Turbo, when it comes to compression pressure. The turbo is a lower compression engine (9.2:1 instead of 10.5:1) so you would expect lower compression test readings. It might be worth asking around to see whether anyone else has done a 1.8 turbo compression test and what their results were.

Hope this helps a bit.

[JefferiesFarnol]

Originally Posted by Matt_75

Hi Hector,

The Haynes manual states "compression pressure (typical)" and goes on to say that "although MG Rover do not specify exact compression pressures, as a guide, any cylinder pressure below 10 bar can be considered as less than healthy. Refer to an engine specialist if in any doubt as to whether a particular pressure reading is acceptable".

The problem is, Haynes doesn't differentiate between both engine types, 1.8 NA and 1.8 Turbo, when it comes to compression pressure. The turbo is a lower compression engine (9.2:1 instead of 10.5:1) so you would expect lower compression test readings. It might be worth asking around to see whether anyone else has done a 1.8 turbo compression test and what their results were.

Hope this helps a bit.

Hello Matt, very sound advice and not something I had considered, thank you!

[Terry00H]

Hi,

My 1.8 T tourer had low compression. I bought a 2011 MG 6 engine from a scrap yard .The donor car had been involved in a rear end collision. This engine was then put into my tourer .The 1.8T runs on higher compression and so an aspirated engine will not work with a turbo. I’m not an expert but this is what I was told by an experienced Rover mechanic. The MG 6 engine is the same K series but with all the problems sorted out .The MG 6 block had a space on the block for a sensor which had to be blocked up.

All the best