LS7 oil breather system

[unclemark123]

OK, not strictly an Ultima subject, but bear with me as I know alot of you guys run LS7's.

My TVR runs a tuned LS7. I'm looking into the oil breather system as I am suspicious something is not quite right.

The engine has been converted to wet sump. It also has a high pressure high flow oil pump fitted.

Each valve cover has a breather pipe which both T together and feed into a catch can. I note the valley cover has no breather, so it's not an LS7 item.

Heres the problem: the catch tank fills up far too quickly IMO. Also the Engine has the standard TVR oil pressure sensor fitted, but the dash alarms oil pressure when you boot it. I note the oil pressure is always high.

I also note that the engine has a non standard dip stick tube. I have tried different oil levels (within reason) but it does not seem to make a difference.

Scratching my head where to start. Any pointers?

[unclemark123]

If it helps, here is what I have:

[Boosted LS1]

That just looks like an open breather set up to me so it will always push out oil. Have you thought about converting it back to a closed system with a pcv set up? The ls7 valley plate has a pretty good oil separator in it. Your dipstick needs to be the correct item for the sump. If you have an ls3 sump you'll need an ls3 dipstick etc.

[Storer]

How does the oil from the catch tank get back into the engine?

Are you venting the sump area too?

My LS7 has no dipstick (dry sump) but holds between 7 and 8 litres. The amount you will need depends on the size of the sump.

The LS7 has slightly lower oil pressure than my Cerbera 4.5

All you should be getting out of the filter vent is a slight mist that shows a tiny oil stain on the top of the catch tank around the filter vent.


Paul

[samnorthy]

Re the oil pressure alarm, I believe the TVR dash has a high Oil Pressure alarm as well as a low oil pressure alarm.

I had to send my dash off to Paul to get the high alarm set point raised as the LS runs significantly higher OP than the Speed 6.

Can't advice on the oil sump/breather issues as I kept the dry/damp sump set-up on the LS7.

Edited by samnorthy on Wednesday 5th April 07:01

[unclemark123]

Boosted LS1 said:

That just looks like an open breather set up to me so it will always push out oil. Have you thought about converting it back to a closed system with a pcv set up? The ls7 valley plate has a pretty good oil separator in it. Your dipstick needs to be the correct item for the sump. If you have an ls3 sump you'll need an ls3 dipstick etc.

That sounds sensible Boosted, and yes, I think the answer may be to convert back to pcv set up.
The dip stick tube is a flexible braided item, fitted to clear the chassis. Ideally it would have the standard rigid item fitted. As it is, I have no clear idea of the right oil level !

[unclemark123]

Storer said:

How does the oil from the catch tank get back into the engine?

Are you venting the sump area too?

My LS7 has no dipstick (dry sump) but holds between 7 and 8 litres. The amount you will need depends on the size of the sump.

The LS7 has slightly lower oil pressure than my Cerbera 4.5

All you should be getting out of the filter vent is a slight mist that shows a tiny oil stain on the top of the catch tank around the filter vent.


Paul

Hi Paul. When you say are you venting the sump do can you clarify? Is that what the valley breather does? and not the valve cover outlets?

[unclemark123]

samnorthy said:

Re the oil pressure alarm, I believe the TVR dash has a high Oil Pressure alarm as well as a low oil pressure alarm.

I had to send my dash off to Paul to get the high alarm set point raised as the LS runs significantly higher OP than the Speed 6.

Can't advice on the oil sump/breather issues as I kept the dry/damp sump set-up on the LS7.

Edited by samnorthy on Wednesday 5th April 07:01

Ah-ha, thanks Sam. I did suspect the high level alarm needed adjusting, but I was not sure. I need a couple of other bits of calibration, so looks like the dash needs to go to PS.

[845ste]

maybe you have too much oil ... the level is very important: you can break if you have little or too much.
do the exact level and perhaps solve the problem

[Steve_D]

845ste said:

maybe you have too much oil ... the level is very important: you can break if you have little or too much.
do the exact level and perhaps solve the problem

If the sump has been changed then it may be difficult to determine what the correct level is.

Steve

[Storer]

unclemark123 said:

Storer said:

How does the oil from the catch tank get back into the engine?

Are you venting the sump area too?

My LS7 has no dipstick (dry sump) but holds between 7 and 8 litres. The amount you will need depends on the size of the sump.

The LS7 has slightly lower oil pressure than my Cerbera 4.5

All you should be getting out of the filter vent is a slight mist that shows a tiny oil stain on the top of the catch tank around the filter vent.


Paul

Hi Paul. When you say are you venting the sump do can you clarify? Is that what the valley breather does? and not the valve cover outlets?

It is a while since I built my car but I believe I have connected all the breather pipes together and route them to the catch tank.

My LS7 is standard and I have no 'oil ejection' issues.


Paul

[unclemark123]

Steve_D said:

845ste said:

maybe you have too much oil ... the level is very important: you can break if you have little or too much.
do the exact level and perhaps solve the problem

If the sump has been changed then it may be difficult to determine what the correct level is.

Steve

It is indeed difficult to determine the exact level. The engine is wet sump, and the dipstick tube is a flexible item (origin unknown) to clear the chassis.
I have no idea what the correct oil level is!!! (scary I know). I maybe overfilling it by using the marks on the dipstick.

[georg]

Fixing the oil level with a dry bowl in LS7 is not so complicated. I have AS Ls7 engine. KATECH oil pump / high pressure /. In such an engine, about 8 liters of oil is required for proper operation. Pour all the oil out of the system and pour 8 liters of new oil. I start the engine and after heating I put the aluminum strip into the oil tank. So I set its maximum level and at the same time I cut the strip. This cut represents the maximum level. The minimum level after several experiments is the distance from the max level to the lower part of the panel about 2.5 cm
If you do not have a dry bowl then you need to check how much GM recommends oil and even if you have a little increased capacity of the bowl then proceed exactly as above calibrating the cut yourself on the measuring scale.
Good luck
georg