Compression test

[Chiefmechanic]

I need to do a compression test on a 90 tdi. Can this be done using the glow plug holes or must I pull the injectors out. Timing belt lost some ridges but did not break.
brian

 

[audifan]

It would be far easier using the glow plug holes due to the design of the injectors. First thing I would do though before trying this is to replace the cam belt and retime correctly and rotate the engine by hand four revolutions. Cranking with the timing out could well cause more damage. Remember to disconnect the injector harness before cranking as you do not want any chance of the engine firing.

Lastly make sure your pressure gauge is capable of reading the pressure generated by the diesel engine compression.

 

[Chiefmechanic]

Any idea what the compression pressure should be. I’ve done a test and it’s reading around 250 psi on two cylinders and 180 on the other one. I think it has dinked a valve on one cylinder. Any thoughts.

 

[audifan]

Engine data

Code letters	​	AMF​	ATL​	BHC
Capacity	ltr.​	1.422​	1.422​	1.422​
Power output	kW at rpm​	55/4000​	66/4000​	55/4000​
Torque	Nm at rpm​	195/2200​	230/1900 … 2200​	195/2200​
Bore	Ø in mm​	79.5​	79.5​	79.5​
Stroke	mm​	95.5​	95.5​	95.5​
Compression ratio		19.5:1​	18.5:1​	19.5:1​
CN	at least​	49​	51​	51​
Firing order		1-2-3​	1-2-3​	1-2-3​
Emissions standard		EU3​	EU4​	EU4
Exhaust gas recirculation		yes​	yes​	yes
Turbocharging/supercharging		Turbocharger​	Turbocharger​	Turbocharger
Charge air cooling		yes​	yes​	yes
Catalytic converter		yes​	yes​	yes
Valves per cylinder		2​	2​	2

 

[Andrew]

This any use.

Audi Workshop Manuals > A2 > Power unit > 3-cylinder TDI unit injector engine (1.4 ltr. 2-valve), mechanics > Engine cylinder head, valve gear > Cylinder head > Checking compression

A2 > Audi Workshop Manuals > Power unit > 3-cylinder TDI unit injector engine (1.4 ltr. 2-valve), mechanics > Engine cylinder head, valve gear > Cylinder head > Checking compression

workshop-manuals.com

Andy

 

[Chiefmechanic]

Thanks. Very helpful info.