Compression & Cylinder Leakage - Tuesday 14th October 2014

Compression Tester
(Connected to Cylinder No4 - Not Live)

Today I was assigned to undertake compression and cylinder leakage tests on a live rig, namely a 1.25 Endura-E engine (of Ford Escort origin).  This task really got my brain working, as the individual coaching I received from my Supervising Tutors was most beneficial in terms of getting me thinking "outside of the box" (something I enjoy doing a lot)!  Due to the fact I was working solo on this task my photographs are "cameo'd" (ie; post event), and are shown purely for the demonstration of the equipment used, and for their means of connection (ie; not live results but taken in hindsight to demonstrate understanding of the process's involved).  I initially gathered all of the relevant vehicle manufacturer's information and recorded it on the job card, and then retrieved the necessary tools and equipment that would be required in order to undertake the specified tasks set to hand. Having first checked all fuel and fluid levels, an initial test of the unit was undertaken to ensure its proper prior functioning. Having satisfied myself that the unit was indeed functioning, I then disabled the fuel supply, by disconnecting the pump, and then the ignition, by removing all of the HT leads, the connector from the Coil Pack (Wasted Spark) and all of the spark plugs.  The latter were all cleaned and re-gapped to manufacturer's specification prior to re-installation. The initial set of compression readings were taken as "dry", and the second set as "wet" (ie; with a squirt of oil added to each cylinder and then re-tested in turn).  The results recorded from both tests produced results indicating that there was a distinct loss of compression in Cylinder No4. Having recorded the results on the Job Card I then proceeded to the Cylinder Leakage Test, using a compressed air line and associated measuring equipment.

Cylinder Leakage Tester
(Connected to Cylinder No4 - Not Live)

Testing each each cylinder in turn and with the piston at TDC in each case, the results were noted and recorded on the Job Card accordingly.  Upon testing Cylinder No4 there was an audible hissing noted from the dip stick tube, initially indicating worn piston/oil rings, which I "prematurely" noted as a probable cause.  However upon further questioning and prompting by my tutor, It was suggested that "other" factors could also still be at large? After a swift "tutored revision" of swept volume calculus, I then proceeded to "approximately" measure (using an extended Vernier Gauge) the height of the piston at TDC of Cylinder No4, and then compared it to the height of a piston at TDC in one of the other 3 known "good" cylinders.  The results were quite surprising and actually proved a bent Connecting Rod in Cylinder No4!  This really did bring home the need to be thorough and consider "all" possibilities, prior to jumping to any hasty and potentially "expensive" decisions at the ultimate expense of the service provider concerned!  The task remains incomplete as there is a further test that can be undertaken using a Picoscope - a Cylinder Balance Test - to be resumed next Monday morning!   Great day and very enjoyable - thank you!

Extended Vernier Gauge
Measuring Approximised Distance of Piston
TDC & BDC Cylinder No4