156 2.5 v6 - knocking

Quick background on my problem:

- My engine started knocking horribly (it had done 130k) so I had it replaced with a 166 engine for a hefty sum.
- The second engine failed after about 2000 miles, with no loss of oil, no overheating, no warning signs whatsoever. It just died on the motorway as I was doing 90 in the 5th - 3500 rpms. No knocking, just refused to start. The AA said about the engine that "it's mechanically knackered". The car eventually started a week later and it was blowing white smoke through every possible orifice... now is that the engine or the workmanship?
- Now it's been replaced under warranty by yet another 166 engine, again with about 40k on it (allegedly), but the garage just took the car for a drive before delivering it, and this engine is knocking as well!

They're saying that because 3 engines practically failed with the same symptoms there must be something outside the engine causing the problem, such as the oil compressor or the oil filter housing.

But how can it be an oil problem when the car has not lost one drop of oil or overheated in the 2000 miles I drove it since the 2nd engine was installed?

Can someone with more technical knowledge express some opinions?

Thanks

Well the oil pump may not be pumping the oil round properly, but I'd think because the oil pump is kinda "inside" the engine, unlike the alternator, then this is unlikely, unless all the engine have the same initial problem.

How do you know that the engines haven't been run low on oil before fitted to your car ??

How do you know that the engines haven't been run low on oil before fitted to your car ??

I don't, and that's another problem, I have pretty much no visibility on what they're doing to the car, or on the quality of the engine and the parts they're fitting.

Best suggestion I can think off - find the healthiest engine, flog anything worthwhile from the other two, and put the money to getting the best one rebuilt.


Also make sure you get everything external tested - have they been re-using the same oil filter housing for all 3 engines?

Its not something like overheating causing the problems is it? Like a damaged radiator? I would say that is obviously something external to the engine causing the problems.

Maybe there is a blockage in the oil filter housing or associated pipes ?? Has the filter been changed ?? Maybe that's blocked.
After the 1st engine went, maybe something like engine bits have got lodged in the system somewhere ??

The 2.5 doesn't have/need an external oil cooler whereas the 3.0 does have one. Have you fitted an external oil cooler? Maybe the oil is getting too hot and losing viscosity and breaking down very quickly? It might explain low oil pressure and big end failure.

Alternatively, unless you have a blockage you are very unlucky with engines

This might be a stupid suggestion but are you using the same dipstick on all the engines? It is possible you have the wrong one, like from a twinspark and you are running low on oil all the time but not knowing it.

Its a long shot but stranger things have happened...

Originally Posted by marlon

Maybe there is a blockage in the oil filter housing or associated pipes ??

That's exactly how they've described the problem, I'll just have to wait and see what it actually is.

Originally Posted by symonh2000

It is possible you have the wrong one, like from a twinspark and you are running low on oil all the time but not knowing it.

I suspected the same thing myself, and funny thing is after the 2nd engine broke down the garage said I had about a gallon of oil too much!

Anyway, thanks everyone for your replies, I'll update you once I know more...