1.6 TDI Caddy Low Oil Pressure query

September 15, 2021, 09:51:38 PM

I think I'm answering my own question but I'm delving outside my comfort zone!
So back in May I bought a damaged repairable 2011 Caddy 1.6TDI, non runner 81K genuine miles (MOT and condition back it up). What a bad decision that was. The damage was the easy part but the reason it wouldn't start was a dodgy earth to the starter.....
Anyway damage repaired take it for a run, fine for 15mins but then got the low oil pressure light. Did a few more short journeys and the dreaded glowplug light...That turned out to be 2 x failed injectors, sorted that then it dumped all its coolant. So a new radiator has been fitted, however the low oil pressure light comes on when warmed-up. Got a pressure gauge and plumbed that in, 24psi when cold (should be 29psi) and quite a lot less when warm!
Have removed the sump this week with a view to replacing the oil pump but there is evidence something wasn't right before. The oil pump is powered by a toothed belt from the crank. Took the oil pump off and it looks fine, no worn lobes and makes a nice squelchy sound. Belt looks fine with no teeth missing...Hmm its a DAYCO belt dated 2017 (van is 2011). So me thinks the oil pump is probably recent. So that must mean the big-ends / main bearings are worn??
I'm tempted to take the "big-end" caps off and see the state of the bearings, I assume if the crank isn't scored but if the big end bearings are then I can possibly just replace them (That might sound naive!!). I guess I will have to put the caps back in their original position / orientation and replace the bolts (assume stretch). If they look fine then I guess it could be the main bearings, but I assume they can't be replaced without removing the engine?
I do realise that the low oil pressure could mean that the top end inc turbo may have some future issues but I also realise that buying a second hand engine can also be a gamble let alone the fact that I don't really want to go to the extent of swapping it time/lack of experience...edit1 AND MONEY!
Be grateful for your thoughts.
edit2: It doesn't smoke when running and yes there were some bits of fine metal when the oil was changed.

Re: 1.6 TDI Caddy Low Oil Pressure query

Reply #1 – September 16, 2021, 06:20:53 AM

I've subsequently watched some You Tube vids and both bearing tasks look doable. Noted that a couple of the big-end bearings do have minimal side to side movement which seems normal, not sure if the other two are sticking. None have any upward movement.

Re: 1.6 TDI Caddy Low Oil Pressure query

Reply #2 – September 16, 2021, 02:28:41 PM

have you tried a compression test to eliminate worn or damaged rings?
scs

Re: 1.6 TDI Caddy Low Oil Pressure query

Reply #3 – September 16, 2021, 02:57:53 PM

Thanks scs.
No I haven't..But I've started at the bottom thinking faulty oil pump = low oil pressure and wondering if worn crank bearings could be the cause.

Re: 1.6 TDI Caddy Low Oil Pressure query

Reply #4 – September 16, 2021, 05:37:50 PM

Diesel engines usually have fairly robust bottom ends due to the high compression diesel engines have. I do know of a diesel engine that required an engine rebore at fairly low mileage although that was a Vauxhall.
scs