Sump foam...yes or no?

[ChrisEarle]

Hi

The oil gauge on my 1.8 K series Supersport R has started moving down into the red zone (from a reading of 4) whenever I drive it hard. It always recovers back to 4 at idle or when ,I back off the loud pedal..

Any thoughts? Latest advice is that foam in the sum might have disintegrated and blocked return?

Cheers

Chris

[Roadsport06]

Starting point would be the electric sender. Swap it to mechanical and get accurate readings.

If you haven't changed the oil for a while then drop the sump and take out the foam.

[revilla]

Foam or not ... They are very sensitive to oil level. Check it is topped up to the max mark whilst hot and running. You can get this kind of behaviour if it is getting even a bit too low. Personally I run without the foam and have never seen any problems but I'm road only and don't track it. I just don't fancy risking the damage associated with it failing.

[Mort]

I find that when the electric sender goes, the gauge either reads low all the time, or the needle flicks around.  Try disturbing and / or cleaning the contacts on the sender to see if that makes any difference.  It's in a vulnerable place, and is prone to water and grot ingress.

If that changes nothing then what you have described does point to something else, such as low oil or some sort of temporary blockage on the oil pickup.  If the oil level is OK it's worth dropping the sump to have a look as previously suggested.

When was the foam last changed?

[Graham King]

Chris, all good advice above but I'd start off with Revilla's as it's the easiest to do. As Revilla says the k-series are very sensitive to oil level (as little as 1/4 litre can make a big difference). The oil pickup in a k-series is towards the front of the sump so hard acceleration will cause the oil to surge towards the back moving it away from the pickup hence the pressure drops off, lifting off allows it to settle again so the pressure comes back up. You can see the same effect when cornering hard. 

I fitted a mechanical oil gauge a long time ago, it's really straightforward and gives peace of mind that the readings you are seeing are correct. I also removed the sump foam and have seen no detrimental effects. 

I suspect your current problem is oil level being low but fitting the gauge and removing the foam are worthwhile changes as well in my book.

Graham

[Q Catcher]

I used to change the foam as recommended, but have run without foam for quite some time now, and fit Dave Andrews' (DVA) modified sump gasket.

[SM25T]

Foam ... No .... every time.

[L7 FST]

Foam ... Yes .... every time you go on track.

It really does reduce oil surge. Just change it annually and you'll be fine.

I had big problems with surge on track with my VHPD when I removed the foam, following conventional advice. As soon as I put it back In, problem solved immediately....

[SM25T]

Which is odd as the foam is nailed to the underside of the block ..... Not in the oil !

[john milner]

I can't see how sump foam (in a K series at any rate) is going to do much for surge protection. The foam is above a metal plate, a largish sump gasket and way above the sump. The only way I can see the foam reducing surge is if the car was bouncing or airborne. I think the foam is there to reduce the amount of frothing caused by the crank and to filter out a few bubbles from oil that is dripping back to the sump. I would imagine that aerated oil will give low pressure readings.

I have ditched the foam and did the gasket mod not because I had a problem with it but because a lot of others have and I did not want to join them. I also fitted a secondhand Hellier anti-surge baffle which while not great for all must do something positive. I do not track the car or cane it so this all seems to work well for me.

[L7 FST]

Yes I can confirm that without the foam I got serious oil starvation on left hand corners on track, and once I'd put it back in the problem went away completely. I had an Apollo in both instances, of course.  The science may be difficult to explain, but the impact of the change was unequivocal, as confirmed by the (mechanical!) oil gauge...

[john milner]

I am trying visualise how the foam could prevent surge. From memory the sump is about six inches wide and the oil on tickover an inch or so deep. For a low pressure reading surge the oil needs to move away from the pick-up. For this to only happen without foam it would need a very tall wave of oil to the side of the engine that lasted several seconds and when the foam is in place it slows the rate at which the wave can grow. This is just a theory.

 

 

[Seabea23]

The foam issue seems to be full of varying advice, don't we still have contacts with the original Caterham Cars/Rover team who formulated the idea for the sump foam in the first place? 

[Jonathan Kay]

The foam issue seems to be full of varying advice...

Yes. What I'd like to see is all the evidence and opinion in one place, with who is saying what and why. That document doesn't need to be agreed between those with different views; it would just make it easier for us to make up our own minds.

Jonathan

PS: As I've advocated previously a facility for multiauthor wikis would be very helpful, but this issue is so important and so recurrent that we should do it as a one-off. Do we have a volunteer coordinator... or should we try a Google document?

[elie boone]

It's strange that no one ever came up with a metal mesh variant, for instance like the one you find in a cooker extractor.

[Mort]

I had the same idea.  I found a product that might be suitable, but as my foam is changed every year when the oil is changed, and there has never been a problem, I didn't pursue it.

[Bricol]

I seem to recall reading somewhere the foam acts to de-areate the oil - the oil frothed up by crank windage etc (shallow sump in a seven compared to a FWD Rover) hits it and it bursts the bubble so to speak . . .

 

[Julian H]

I don't seem to suffer with oil surge [mech oil gauge] except for hard right hand cornering where pressure drops rapidly to 2bar. Not once that I have observed during acceleration. I don't have foam but do have a have an apollo tank. I tend to keep my oil level between max and 1/2 way down and read it the recommended way when engine is running and hot.

I often wonder if the foam might be there to aide reading the oil level when the engine is hot and running? It might stop the oil splashing all over the place hence dip stick reading is more stable? It might also serve as a filter to help stop the bottom end of the engine sitting in any debris in the [unfiltered] oil when being started.

 

[ChrisEarle]

Thanks to all of you for the advice. Much appreciated.

[Gnockoff]

If Oily says take the foam out, then that was good enough for me. 

[SM25T]

Yup.

[Martin J]

I am glad I don't have to worry about this with the Sigma engine. 

Who wants crispy seaweed in their engine, not me! 

[Gary Stone]

As my SLR was built with it, I like to think there is a reason for that. I've owned my car for 10 years now. Replaced it for the second time this year. Only ever found the old foams to be in perfect condition.

[Gnockoff]

I refer the honourable gentleman to my previous answer.

Although I have never had the pleasure of doing business with Dave Andrews (Oily on here). I am sufficiently aware of his knowledge of K series engines to accept that if he says that the foam is devils spawn then so it is.

[Mort]

I've not had problems with mine either.  Lots of conflicting information.  Some folk experience problems, others don't. 

I seem to recall an earlier thread which gave a possible link between foam degradation and the type of oil used which concluded that using the recommended fully synthetic oil when using the foam was the best option.  

There was also a (much) earlier thread in which the original reasons for including the foam were given - by someone involved in the development IIRC - which were preventing oil surge and aeration caused by the shallow sump, but good luck finding that thread given the search issues on this forum.

You pays your money.........