Why would S2A Oil light comes on when I brake hard?

[65s2a]

My oil light comes on when I brake hard...oil pressure drops to zero (I just fitted a gauge to check it)... oil level is normal, oil pressure when running is 50psi...when idling 25-30 psi...any one got any ideas what would cause this to happen?? Thanks Les

[rick130]

It's called oil surge.

The sump isn't baffled, so when you brake hard (can you actually brake hard in a Series ?? :eek:) the oil surges forward and is uncovering the pickup which cavitates the pump, resulting in zero oil pressure.
This isn't good, and many production race cars of yesteryear 'did' engines from this phenomenon under brakes and hard cornering.

I'd increase the oil level slightly and see if it still does it, if so, drop the sump, maybe the pickup is cracked ?

[Lotz-A-Landies]

Inertia! When you brake hard the oil in the sump continues moving forward until it is all at the front. This allows the oil pickup to suck air which is easier to pump than oil, the oil pressure drops and the light comes on.

Check that you don't have low oil level in the sump and it may be worthwhile to check that the pickup hasn't been bent so it is sitting too high in the sump. This will however require that you remove the sump for the check.

Diana

[JDNSW]

The 2.25 engine has three levels marked - Min, low and high. It should NEVER be operated below Min, but it is allowed to be operated between Min and low, but only on level ground, as they note that oil pump starvation is likely when the vehicle is facing downhill at a steep angle - effectively the same as when braking heavily.

If you are seeing this effect with the oil above low, I would suspect that you may have a problem with the dipstick - perhaps the collar has moved on it or it is the incorrect dipstick, or the tube it goes into has been shortened.

There is a possibility that the effective oil intake is higher than it should be, as Diana suggests.

John

[65s2a]

Thanks for the great feedback...OK, hard-ish braking :) Checking the oil, yep it's just at low (I needed to move to a level spot to check for sure cos my driveway is slight downhill slope) you won't be surprised to know that Hillston leaks oil...I didn't think it was engine oil leaking though. I'll top it up and see if this helps.
I didn't see this covered in the owners manual?? Cheers Les

[JDNSW]

......
I didn't see this covered in the owners manual?? Cheers Les

Page 43 in mine (June 64)

John

[Bigbjorn]

Brakes! You have a 2A with brakes?

"Porco Dio, Porco Madonna", as the maestro of Molsheim, Sr. Ettore would say. "I make my cars to go, not stop."

[Newbs-IIA]

bwhahaha i just got all my brakes overhauled, skimmed drums, new pads, new slave cylinders, sleeved master cylinder I CAN LOCK WHEELS in the dry!!! :D :D :D

And yes I was only thinking yesterday about posting a thread on exactly the same topic as I have the same problem. Will check oil levle again (seems good) although I have a very bad rocket cover leak - is oil pooling on the head next to the rocker cover bad??? :p hahaha

[JDNSW]

....... - is oil pooling on the head next to the rocker cover bad??? :p hahaha

Not necessarily - it helps to reduce rust on the chassis. But you need to keep an eye on the oil level. Almost certainly the rocker cover gasket, easily replaced. Note that the closed nuts on top of the rocker cover will tighten on the end of the studs without applying pressure on the gasket if the rubber washers under the steel washers have compressed and gone hard. Also make sure it is not the oil line to the back of the head is loose - if the union on this comes completely out you will very smartly lose all your oil.

John

[65s2a]

OK so I topped the engine oil up (took 1 litre) and the oil light coming on when I brake hard-ish problem is completely gone...so simple!! :) thanks. Having completely re-built the engine I was hoping it wasn't something I had done wrong (I'm not a mechanic)...I just love it when it keeps on working as intended and the whole vehicle continues to improve my confidence that it's going to remain reliable. I have taken it to work every day (40KM return) and it hasn't let me down but I have yet to take it on a long run or get it off road...this could happen some time soon!! (Some where around Brisbane...not saltwater or sand???) Cheers all.

[Newbs-IIA]

Haha I did the same thing - fixed :p

We should do a trip to Ripley (Binnies rd) near Ipswich or even Mt. Mee

I just did around 300kms highway driving on the weekend so I am pretty confident too. My suspension is still very stiff though. If not you more than welcome to accompany me to DI in Friday arvo

[65s2a]

Good idea. I'm tied up this long weekend but will PM to see if we can set something up. Cheers Les