|Posted on Sunday, 18 March, 2001 - 03:22 pm: |
MY 1931 Phantom 11 gives an oily smoke out of the exhaust on starting and drawing away from standstill. It has just had a rebore and new pistons and rings, but the problem is still there. The head is original but recently reconditioned,and the exhaust is new.
Where do I start to look for the source of the oil ? All suggestions gratefully received.
|Posted on Sunday, 18 March, 2001 - 03:23 pm: |
Did you use a running in oil to bed the rings? The slow revving phantom motor would take quite a bit of running in. A problem I have found with running in my Austin 7 motor the last time it was rebuilt, was that because it revved low, the bores glazed up again before the rings bedded in. A running in oil may help. How many miles have you done on the engine now? Might be worth while trying to take a longer run at higher speeds to try and bed the rings in, unless the bores have already glazed up, in which circumstances the oil burning is there to stay unless you pull the motor back down.
|Posted on Sunday, 18 March, 2001 - 03:24 pm: |
We had some problems with our PII burning oil. The primary problem was incorrect rings fitted when the bores were done. Fitting the CORRECT rings helped alot. We were also recommended to use a "cheap" oil to run it in (to prevent glazing).
The other thing we have done is to fill in the dished top of the valve spring holder with high-temp silcone to make sort of a rubber washer. This reduced the amount of oil just sitting over the valve seals. There was PLENTY of oil being pumped out of the rocker assembly and the valve seals simply couldn't keep it all out.
|Posted on Sunday, 01 April, 2001 - 04:51 pm: |
Re-where do I start looking for source of oil.
What is needed here is a logical process of diagnosis.
You need to determine whether
A)is it definitly oil smoke(knot fuel).
B)is the oil coming from above(passed valve seals).
C)is the oil coming upwards(passed the rings )
This can be determined by some very simple tests.
Firstly bring engine up to operating temp,with the car stationery hold the engine speed at a constant 2000 rpm for at least 3 mins.Closely watch the exhaust for a constant stream of smoke.
This would strongly suggest oil is coming up- wards passed the rings.
Allow the engine to idle for 5 mins then give it a sharp blip of the throttle and hold engine speed up at about 1500rpm,observe exhaust,if it belches smoke and then clears this indicates valve seal leakage.(repeat this test two or three times).
Remove and read spark plugs(the condition is a direct result of what is going on in the combustion chamber)if the plugs are dry carbon fouled this would indicate oil is coming passed valve seals.
If they are oil (wet) carbon fouled then this would indicate oil is coming passed the rings.
With the plugs still removed look down the plug hole(with the aid of a very small light)and observe piston tops,oil on piston tops is a strong indication of ring problems.Also rotate engine by hand to open inlet valves and see if these are wet with oil,this would indicate oil coming passed valve seals.
If it is decided the oil is coming passed the rings,and the engine has not traveled many miles it may not be to late to try some bedding-in.
The condition required for bedding-in is max B.M.E.P. (brake mean effective pressure) and this happens at the same time as max torque.This is to exert the max pressure behind the rings and force them against the newly honed cylinder bore.
The way to achieve this is to find a nice long
hill and drive up it in forth gear and holding the engine at aprox 1500-2000 rpm or drive at about 25-30mph in forth gear and then accelerate up to 50 mph and repeat.
What is required is LOAD not speed,avoid long periods of constant light throttle driving.The last thing your engine needs is a long high speed drive.
|Posted on Tuesday, 17 April, 2001 - 06:47 pm: |
Ken, The R-R Depot Sheet No Hm 147, 17/3/1930, addresses over-oiling: "When dealing with complaints of overoiling on Phantom II cars, it should be understood that fouling of plugs is much more likely to be caused by 'top overoiling' than by oil passed by the pistons due to excessive bearing clearances etc.
Top overoiling is caused by oil from the rocker mechanism getting past the inlet valve stems due to the induction pipe depression, and results in rapidly sooted plugs.
The following points will aggravate the trouble and should be carefully investigated:
(a) Excessive oil pressure to the rocker mechanism.
(b) Too much oil passed by the drilled plug at the valve end of the rockers.
(c) Inlet valve felt rings in poor condition
With regard to (a) it should be noted that the correct oil pressure to the rocker mechanism is 3 1/2 lbs/sq inch at about 500 rpm. No attempt should be made to reduce this. (b) We have found that this factor has a considerable effect on the tendency to top overoiling, and we recommend in cases of complaint new plugs should be fitted having the hole .015" dia instead of .060" as at present. (c) This is very important and in all cases of top overoiling new felt rings should be fitted as it is found that when these washers have been in service some little time they lose their effectiveness in preventing leakage of oil past the inlet valve stems.
Generally speaking we think it will be found that (b) and (c) together will be effective in overcoming most cases of overoiling."
With my PII (b) proved effective. The holes were filled and re-drilled.