Mongrel
Automotive
- May 25, 2018
- 60
Hi all, I've been lurking here for a few years soaking up useful information. Now, I have a question for you all;
Engine - 3L Toyota diesel. Lost oil pressure and chewed up the conrod bearing on no.4. Bearing remnants were still in the bigend, thickest part was down to 0.5 mm. Total clearance in the joint was measured roughly using a feeler gauge at 2mm, with the top of the joint resting on the crankshaft. So about 1mm clearance all round the bearing area.
Now, the question - this engine had no rod knock whatsoever. Just a light tapping sound which exactly mirrored diesel rap. Compression was even on all cylinders at 250 psi, +/- 10 psi. The top of no.4 piston was clean of soot, showing signs it had been touching the head and intake valve, although there was no damage.
Has anyone encountered this before, or could tell me why this might happen? I've been in the game a relatively short time at 15 years, and have never seen or heard of this before.
Appreciate any replies!
Engine - 3L Toyota diesel. Lost oil pressure and chewed up the conrod bearing on no.4. Bearing remnants were still in the bigend, thickest part was down to 0.5 mm. Total clearance in the joint was measured roughly using a feeler gauge at 2mm, with the top of the joint resting on the crankshaft. So about 1mm clearance all round the bearing area.
Now, the question - this engine had no rod knock whatsoever. Just a light tapping sound which exactly mirrored diesel rap. Compression was even on all cylinders at 250 psi, +/- 10 psi. The top of no.4 piston was clean of soot, showing signs it had been touching the head and intake valve, although there was no damage.
Has anyone encountered this before, or could tell me why this might happen? I've been in the game a relatively short time at 15 years, and have never seen or heard of this before.
Appreciate any replies!