[Shop-talk] Chevy Suburban oiling mystery

[john niolon]

here’s one for you....

2008 Chevy Suburban 5.3L  with 132K miles   I bought it at 60K five years ago... every oil change w/filter of course has been 5000 miles OR LESS.  Castrol or Valvoline full synthetic oil.  Last week after a short (100mile) freeway round trip I heard a ticking in the engine... like old rockers used to tick.  probed around with a stethoscope and heard it louder on Idler Pulley mount.  Belts were sketchy so changed all three idler pulley/mounts and two new belts..  ticking sounded different... more probing and it was loudest at the oil pan.

Took into my mechanic and he was puzzled... settled on deactivating lifters (history there) and pulled the top end down.  Found something strange... right side of engine looked normal and clean, left side looked burnt on the lifters like it wasn’t oiling properly.  Put in the new lifters and tried it again... still ticking but this time he noticed that the oil pressure was fluctuating.. might explain the no oiling problem...

so then he pulled the pan to look around.  The oil in the pan was ‘thick’  like syrup thick.. it had just been changed 1000 miles before this.  All the bottom end looked fine, no slack, no discolor, etc

Went to the front and pulled the timing chain cover and found same discolor on chain and pretty bad wear... deeper still  ... examined the camshaft and found several lobes rounded off on the side that showed the discoloration

so at this point we’re looking at new cam and bearings, timing chain set, new lifers, oil pump and screening stuff...all the gaskets and labor...  tipping point reached...   do all this on a 132K mile engine or go with a new GM Long block... I opted for the long block.

I would trust this guy with my drunk wife.  Been doing my mechanic work for 30 years and never had a problem with his diagnostics or his work.   Honest guy.  We still haven’t pinned down the exact problem but consensus is that the oil pump has been intermittently losing pressure causing the oiling problem on that side (although the cam should have been fully oiled if anything was.
Can’t explain the thick oil..   all this going on and the car ran perfectly... never a problem, never saw oil pressure fluctuation in pressure ON THE GAUGE and no idiot light, no codes thrown...had the tick not showed up, I would have never suspected a problem...   so now I have an engine that should outlive me, I hope..

anyone ever seen anything like this on GM products ??  or am I the lucky one that found it first ???

john
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