7 replies to this topic

[sam138]

Just wondering if someone could help please with a diagnosis on my 1380cc engine. It’s done around 500 miles since fully rebuilding. Upon use at the weekend I noticed smoke coming from the transfer case breather.

Remove spark plugs which showed cylinder 3 and 4 with some oil on the plug. Done a compression test which showed the below.

1 - 190 psi
2- 190 psi
3 - no compression when dry then with small amount of oil 210psi
4 - 205 psi dry test - did not add any oil to this bore

I’ve attached some images of cylinder three from an endoscope check with spar plug colours, does this look like bore wash which has caused this ?

Would this mean a full strip down and hone/ new rings ?

Engine spec as follows

1380 block offset bored
Powermax 73.5mm pistons 20659
All new bearings and centre main strap
Ac Dodd Rs camshaft with new followers
Minispares MSE 4 head
1.5 forged rockers
ST2 MED clutch kit
Guesswork fully rebuild helical box with minispares x pin diff


Oil pressure around 65 psi on start up and 40 when hot idle with 50-60 psi around 2-3k rpm

 Image_2026-08-22 16_35_29_873.jpeg   47.9K   5 downloads

 IMG_8534.jpeg   228.8K   6 downloads

 Image_2026-08-22 16_33_21_107.jpeg   40.56K   5 downloads

Edited by sam138, 02 September 2026 - 08:56 PM.

[Earwax]

Was it running any differently - ie did you also notice it was running on 3 cylinders. Transfer case breathing is typically pressure lower down, not at the head  but  I would run it up to temp - go up a hill and feel the pulling power, take off lead 3 and feel the pulling power just to ensure your compression reading isn't inaccurate. 

[sam138]

Was it running any differently - ie did you also notice it was running on 3 cylinders. Transfer case breathing is typically pressure lower down, not at the head  but  I would run it up to temp - go up a hill and feel the pulling power, take off lead 3 and feel the pulling power just to ensure your compression reading isn't inaccurate.

Before I actually noticed this when I returned home with the car it was running fine with no sign of lack of any power whilst driving.

Could I try the plug lead off to see if the engine cuts out or starts running rough to tell if running on three cylinders ?

[Earwax]

Yep pull a lead , - for one or two cylinders down _ (if Head Gasket related it is often the middle two - so pull lead 2 then replace pull lead three and i would even check the leads and spark plugs through elimination - always good to x things off a list) but if it is rings only the one cylinder -- - but crossed fingers it is not anything dire.       Note there could still be a potential problem with valve stem seals or ring seal or plug fouling up - but you can often live with those things for a while , whilst keeping an eye on them.  If the engine build was outsourced - it would be good to run the situation by the engine builder

[sonscar]

Is the edge of the piston showing detonation marks?Steve..

[Quinlan minor]

Just wondering if someone could help please with a diagnosis on my 1380cc engine. It’s done around 500 miles since fully rebuilding. Upon use at the weekend I noticed smoke coming from the transfer case breather.

Smoke or steam?

Carefully wave it towards your nose. If it's odourless, its steam, if it smells of burning and lingers, it's smoke.

If it's steam, carry on as normal, but monitor the amount and the fluid levels.

[Lplus]

Just wondering if someone could help please with a diagnosis on my 1380cc engine. It’s done around 500 miles since fully rebuilding. Upon use at the weekend I noticed smoke coming from the transfer case breather.

Remove spark plugs which showed cylinder 3 and 4 with some oil on the plug. Done a compression test which showed the below.

1 - 190 psi
2- 190 psi
3 - no compression when dry then with small amount of oil 210psi
4 - 205 psi dry test - did not add any oil to this bore

I’ve attached some images of cylinder three from an endoscope check with spar plug colours, does this look like bore wash which has caused this ?

Would this mean a full strip down and hone/ new rings ?

Engine spec as follows

1380 block offset bored
Powermax 73.5mm pistons 20659
All new bearings and centre main strap
Ac Dodd Rs camshaft with new followers
Minispares MSE 4 head
1.5 forged rockers
ST2 MED clutch kit
Guesswork fully rebuild helical box with minispares x pin diff


Oil pressure around 65 psi on start up and 40 when hot idle with 50-60 psi around 2-3k rpm

Image_2026-08-22 16_35_29_873.jpeg

IMG_8534.jpeg

Image_2026-08-22 16_33_21_107.jpeg

Can't say I believe zero compression and then 210 with a bit of oil.  The bore looks ok and there's no clean zone round the edge of the piston to indicate oil burning.  The plugs look just fine.  Maybe the dry test wasn't done correctly.

 

A bit of oil fume from the breather is likely when the engine is hot and the breathers are venting to atmosphere only.  A positive crankcase ventilation system would drag all that into the engine and keep it clean without losing any significant performance.

[sonikk4]

Just a quickie but an easy check, are the tappets adjusted correctly??

 

Bizarre to see no compression but then get 210 with a small amount of oil??

 

Something doesnt quite add up, so i would check your tappets, look to see if you are getting the same movement across the whole set. The fact the car appeared to be running correctly is maybe adding a curveball to all of this. If you are not loosing fluids then i would question a hg failure. Yes you can get blow by from piston to piston but that makes a heck of a noise.

 

With regards to the smoke from the breather it could be the oil control rings are not fully bedded in.

 

Lots of possibilities to look into but start with the basics before diving deeper.