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Paul
Unregistered guest
Posted From: 46.11.122.112
Posted on Saturday, 14 September, 2013 - 01:06 am:   Edit PostDelete PostView Post/Check IP

Hi,
i have a leak coming from the rear of engine, exactly from the crankshaft oil seal. this straight six engine takes 2 wooden dowel as oil seal. can some one tell me if i have to remove the crankshaft completely to change these dowels or just the crank case please?
thanks

(Message approved by david_gore)
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NORMAN GEESON
Unregistered guest
Posted From: 82.6.223.129
Posted on Monday, 16 September, 2013 - 06:27 am:   Edit PostDelete PostView Post/Check IP

Paul

I am afraid you are unlikely to have any luck by trying to change the wooden dowels. These are only secondary seals to the sides of the rear main bearing cap.

The actual crankshaft sealing arrangement is via a reverse scroll on the crankshaft acting within the bore of the main cap and crankcase. This is not a positive sealing arrangement and is usually overcome by excessive crankcase pressure, or overfilling with oil.

Excessive pressure is generated by general engine wear, poor rings and worn/seized pistons etc.

You also need to be aware that if the oil level is kept up to the full mark then the slightest road incline will result in either No.1 or No. 6 con rod contacting the oil. A front nose down position of more than 10 degrees will even have the timing gears running submerged, according to R-R.

In practice you will find the most advantageous situation is to mark the oil dip stick between the half way and full position and use this three quarters mark as the absolute full oil position. Some 50 years ago I was engaged in running these cars across Switzerland and we had to remark all our oil dip sticks, using the aforementioned criteria.

Today I still use a lower oil level dip stick marking on my own car, which I allow to run down to the half way mark if required. This engine has deliberately more piston clearance, and more crankcase compression than usual. Yet in 5000 miles in the last 3 months, running in three countries, returns 750 mile per pint and does not leak excessively from the rear scroll seal.

(Message approved by david_gore)
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 2907
Registered: 4-2003
Posted on Monday, 16 September, 2013 - 04:40 pm:   Edit PostDelete PostView Post/Check IP

Just to supplement Norman's note, the dowels can be easily replaced although as pointed out they are rarely an issue.

With the sump removed, a 20 minute job, the rear main bearing cap can be removed to clear out the old dowel. With the bearing cap refitted, the new dowels are driven in.

RT.

ps: as my R-Type does no tunnel trips trickier than the Sydney Harbour Tunnel, it does not suffer the Gotthard effect that Norman describes. Since 1980 it has had positive valve stem seals, along with more modern pistons and rings than original, so oil consumption and leakage are zero. The level does not drop from the original Full mark at all between changes by more than 1mm.
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Bob uk
Unregistered guest
Posted From: 94.197.122.77
Posted on Saturday, 28 June, 2014 - 11:08 am:   Edit PostDelete PostView Post/Check IP

Gate crasher from sy land

Dip stick marks mean keep oil.somewhere between the marks not keep oil at max

Engines burn oil so there is.extra capacity to allow for his so a good distance can be covered and then topped up.

The driver may want only to go to half way because short trips only the same as petrol

It is fine to run half way

Keep engine breather clean

Would vacuum work

A 4.8 Dawn is my favourite RR

(Message approved by david_gore)
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Randy Roberson
Prolific User
Username: wascator

Post Number: 234
Registered: 5-2009
Posted on Tuesday, 01 July, 2014 - 10:21 pm:   Edit PostDelete PostView Post/Check IP

Some of our guys would keep a little vacuum on their large engines' crankcases to reduce leaks and it did work, but because we feared creating an explosive mixture in the crankcase (air + fuel, you know...) we had to stop it. Some engines even came from their makers with a vacuum arrangement using the intake.
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Bob uk
Unregistered guest
Posted From: 94.197.122.83
Posted on Wednesday, 02 July, 2014 - 07:25 am:   Edit PostDelete PostView Post/Check IP

Use flame traps from Rover V8

They are small tube to tube fitted

I once made a replacement crank case door for a big diesel ship to ssuit a mangled up one the blew off it was 10mm thick it was nearly bent double

The ships engineer said the explosion knocked him over and he felt lucky to be alive

So I understand your concerns

(Message approved by david_gore)

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