Thread: Crushed Oil Filter - TDV6

Good question Gary!

Originally Posted by garrycol

This thread follows on from this thread concerning TDV6 engine issues http://www.aulro.com/afvb/d3-d4-rrs/...ed-engine.html . I will post my questions here rather than start a separate line of discussion in that thread.

For the Brains Trust:

A lot of posters both here and overseas have indicated the oil will not circulate correctly if the oil filter is not seated properly so some questions based on this hypothesis.

1. If the oil filter does restrict the oil flow enough to cause damage why does the oil pressure valve in most oil filter housings (and I assume there is one in the TDV6) open and allow the oil to circulate unfiltered? At least there would be oil circulated and in the could old days engines did not have oil filters and survived OK in the short term.

2. If the crushed oil filter does restrict oil flow and reduce pressure enough to cause engine problems why is this not detected and the oil light - check engine light come on?

Thanks

Garry

Pressure switch works on pressure not flow they are 2 different things.

Crushed filter would give you reduced flow not pressure.
Cheers

Originally Posted by garrycol

This thread follows on from this thread concerning TDV6 engine issues http://www.aulro.com/afvb/d3-d4-rrs/...ed-engine.html . I will post my questions here rather than start a separate line of discussion in that thread.

For the Brains Trust:

A lot of posters both here and overseas have indicated the oil will not circulate correctly if the oil filter is not seated properly so some questions based on this hypothesis.

1. If the oil filter does restrict the oil flow enough to cause damage why does the oil pressure valve in most oil filter housings (and I assume there is one in the TDV6) open and allow the oil to circulate unfiltered? At least there would be oil circulated and in the could old days engines did not have oil filters and survived OK in the short term.

2. If the crushed oil filter does restrict oil flow and reduce pressure enough to cause engine problems why is this not detected and the oil light - check engine light come on?

Thanks

Garry

Pressure switch works on pressure not flow they are 2 different things.

Crushed filter would give you reduced flow not pressure.
Cheers

Originally Posted by Piddler

Pressure switch works on pressure not flow they are 2 different things.

Crushed filter would give you reduced flow not pressure.
Cheers

Is your comment based on actual knowledge of the TDV6 system or a general observation.

Basic fluid dynamics would indicate that if flow is reduced by a restriction and the pipe size on the downside remains the same size then pressure must decrease.

I am after information that relates specifically to the TDV6.

Cheers

Garry

Garry,

AFAIK the lubrication system (if the filter became fully blocked for example) will still bypass and allow oil circulation to the rest of the engine, unfiltered of course.

I have personally removed several filters from Tdv6 D3 looking like the one mentioned in the other thread, neither engine had/ has had any adverse effects.

JC

I think terminology needs to be clarified here. An oil pressure relief valve normally located on the block returns oil directly to the sump so that there's enough pressure at low revs and not excessive pressure at higher revs.

Some filters are fitted with a non-return valve to prevent draining the lines when the engine is stopped whereas others may be fitted with a pressure bypass valve that allows oil to circulate unfiltered if the filter becomes blocked. Note that the valves inside filters have varying opening pressures so just because a filter physically fits, its not necessarily suitable.

Extract from the 2.7 WSM...

The pumping element is an eccentric rotor, which is directly driven by flats on the crankshaft. An integral pressure relief valve regulates pump outlet pressure at 4.5 Bar (65.25 Psi).

The front crankshaft oil seal is housed in the oil pump casing and is fitted such that its front face is 1mm underflush with the machined front face of the oil pump.

:
The seal is not to be pushed all the way into the bore as this will block the seal drains.




Oil Filter

The oil filter is a replaceable cartridge installed on an adapter in the centre of the 'vee'. An internal bypass facility permits full flow bypass if the filter is blocked.


The oil pressure switch, located in the 'vee' at the front of the LH cylinder head, connects a ground input to the instrument cluster when oil pressure is present. The switch operates at a pressure of 0.15 to 0.41 Bar (2.2 to 5.9 Psi).


If an impropery fitted filter element is causing engine failures due to insufficient lubrication because the bypass valve is being used then I can only conclude that the bypass valve requires too much pressure to open.

If the oil pressure switch is after the filter then it still only requires 2.2 psi to cause the light to be off, which is way too low a pressure for higher revs or hard work.

Originally Posted by justinc

Garry,

AFAIK the lubrication system (if the filter became fully blocked for example) will still bypass and allow oil circulation to the rest of the engine, unfiltered of course.

That is exactly what I would have thought as well. Certainly most engines I have owned certainly do that.

Originally Posted by Graeme

An oil pressure relief valve normally located on the block returns oil directly to the sump so that there's enough pressure at low revs and not excessive pressure at higher revs.

Some filters are fitted with a non-return valve to prevent draining the lines whereas others may be fitted with a pressure bypass valve that allows oil to circulate unfiltered if the filter becomes blocked.

The oil pressure relief valve I am talking about lives in the oil filter housing (not the oil filter itself) and bridges the inlet and outlet oil passages to and from the oil filter. In the Rover V8 it is a ball bearing on the end of a spring. If there is an issue with the oil filter, saying being blocked or squashed, and inlet oil cannot correctly pass through the filter, the pressure from the oil pump opens the relief valve allowing the oil continue on its way but unfiltered.

If the TDV6 has one and indeed the squashed oil filter is blocking oil flow then the bypass is specification is too high.

Originally Posted by Graeme

Oil Filter

The oil filter is a replaceable cartridge installed on an adapter in the centre of the 'vee'. An internal bypass facility permits full flow bypass if the filter is blocked.

Doesn't say exactly what this internal bypass facility is - I bet it is the little protrusion with the hole in the middle that is the cause of the issue in the first place.

Why didn't they just put in a standard screw in oil filter cartridge in the first place would have been so much easier and safer.

Garry