Web Forum for Singer Cars

Hello !
I wonder if sombady can help me in this matter.
Car is 1952 4AD twin carburettor and restored.
My problem is a huge amount of oil coming
out from the breather tube. The compression
on all cylinders are between 7.5 to 8.5. What is the “correctâ€Â

Rolf,

I have a 1948 Roadster and have had some oil appear from the breather tube, but certanily not as much as you!

I am not an expert in the 1500 engines, but some of the first things that I would check is oil pressure and oil level. From my Pitmans Book of the Singer, the oil pressure for a 1500 engine should be 30-35 PSI when in top gear at 30 MPH.

From what I understand, the breather is on the left side of the engine about midway down from the top. It allows for an equalization of air pressure between the crank/sump and the outside. It is also located in the wall of the channel where the timing chain is located which also serves as a return for oil pumped to the engine's head.

With the propoer pressure, if you remove the breather and run the engine, can you see oil spraying from this hole while the engine is running?

If so if there may be too much oil flowing down this channel and/or splashing from the timing chains this may shoot oil through the breather tube.

You could make a new gasket for the breather attachment point and make the hole smaller. This would still allow air to pass from the engine block through the breather, but provide more of a barrier to any splashed oil.

Rolf: I would echo Paul's thoughts on this. There is an article by Bill Haverly on oil pressure at this site:

http://www.singster.co.uk/mascot%20april%201991.html

but he is more concerned with low oil pressure. Could there be a malfunction of the pressure relief valve or a maladjustment?

Motor trader says compression ratio for twin carb is 7.47 : 1 See article at:

http://www.singercars.com/4ax/motortrader.pdf

Botox, my 1949 roadster with 4AD engine, single carb runs with quite high oil pressure, even when completely warm, at around 40-45 lbs, but no problems as you describe.
Good luck,

Gene

Rolf,

i was chatting with Pillip Avis (Pre-War Registrar and NEWS Editor) and I mentionned your extra oil problem. He mentionned that if you have sufficient blow-by in the pistons, that this may cause excessive crankcase pressurization which may be a cause of your problem.

With Gene's info, check out the compression and if it is way off, then that may be the problem.

Paul

Thanks for your input in this matter. I have measured once again the compression and its in 7.2 to 7.6.. The oilpresssure is 35. I also made a new pipe whit smaller hole for the breather to only 4 mm but still I get out more or less the same amount of oil. Can this kind of problem occur if the timing off the valves is off... Oil in the crankcase/sump is 4 liter
Br
Rolf

Well..after one more check of the timing using "smiley metod" and as in manual..settings are corrrect...this makes me what I notist is that the breahter tube is close to the connector to the feedpipe for oil to the cam..if that is leaking mayby its "spraying the pipe for breather...comments ??
br
Rolf

Rolf,

On the 9 HP engines the oil feed tube on the left side of the front of the engine in the chaincase. Clearances are tight here and if the tube is not secured properly it can wear through if it rubs against the timing chain.

The 1500 engine has a similar layout. So your idea to check that oil feed pipe may be worthwhile. This will require some good eyes, a flashlight and probably a mirror to see from the top of the engine (valve cover removed). Otherwise you may have to remove the cylinder head front cover and possibly the cylinder block front cover to gain access to the feed tube.

If the oil feed tube is damaged or the connection loose, then there may not be a reduction in the oil feed to the head (and valves).

Ouch!

Good luck.

Paul

Rolf,

All the previous suggestions are good. The oil tube could be loose or a hole rubbed in it. Check the end of the breather tube and see how much it puffs. It is hard to tell you what is normal but I would say on a good ringed engine a small amount of blowby is normal. If it feels like a fan blowing on your hand this is excessive. Also the 4AD motor has reverse screw threads on the front & rear crank. You did not state any leakage there. I had a Sunbeam 1600 motor ran great, good power but would leak like a sieve at 3000 rpm out the rear main. Problem... blowby even with the draft tube.
BRG

Connected one meter off waterhose to the brathertube and running the engine on app 3000 rpm i could not feel any large flow from that.
I feeled the flow from small pressure to a small vacuum so it must bee right..no huge blowby.. No leak from other sealings has occured so the problem is more and more as I feel the feed of oil to the cam..Have to take that front cover off an inspect. Well its raining her today and probably also on the weekend so its good time to work on with this red "lady"..
Br
Rolf

Well. After dismantling the engine and replaced rings and controlled the pipe for oil feed to cam I could not find any "faultsâ€Â