IN­SPECT­ING THE CRANK, BLOCK CAPS & PIS­TONS

Car Mechanics (UK) - - Project Vauxhall Insignia 2.0 Cdti -

Our lo­cal 1 ma­chine shop, W Drake, took one look at our main bear­ing caps and could see they had been work-hard­ened. Due to the bear­ings hav­ing spun around, the heat build-up hard­ened the metal and dis­torted the shape of each cap.

Re­fit­ting the 2 old main caps to the block re­vealed fur­ther prob­lems. Hav­ing dis­torted, they were not a tight fit. W Drake rec­om­mended sourc­ing and fit­ting an ear­lier set of se­cond­hand caps, which we found were a tighter fit. These will need to be line-bored.

We were 3 wor­ried the cylin­der bores might be dam­aged, but W Drake mea­sured them and vis­ually in­spected for score marks – they were all in good con­di­tion. Note the mark­ings around the top of each bore; this is a hard­ened ma­te­rial to pre­vent wear and seems to have worked.

We were sim­i­larly 4 lucky with our pis­tons. There was no sign of dam­age to the tops, sides or con­nect­ing rods, and the big end bear­ing caps and ad­ja­cent con­rod were not dis­torted. All we needed was a new set of pis­ton rings.

Sadly, our luck ran 5 out on the crankshaft. A crack test re­vealed a hair­line frac­ture across one of the jour­nals. W Drake man­aged to source a se­cond­hand crankshaft for £300, which will be tested and then ground and pol­ished next month.

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