Fuel in Oil sump

[MortenHoyseth]

TR6PI – after a month of no usage, and a lot of fiddling prior to that, I was going to start up my TR6 yesterday. As a routine I checked the oil level. Two things were not ideal – (1) the oil level was higher than 1 month back (At least a 1cm over max level) without any oil being added and (2) it smelled strongly of petrol. So my guess is the oil seals in the PI/distributor pedestal is leaking. There is no visible leak from the pedestal itself, so the O-ring between the pedestal and MU should be ok.

Could the fuel-in-oil sump problem be a result of other leaks? Dripping injector pipes shouldn’t be the cause of this, right? I was thinking just to replace the oil and the pedestal seals. Would that make sense?

[Steves_TR6]

I had this problem on an old motorbike recently, caused by leaky float valve in one of the carbs.

 

Dont really see how that much fuel , 1cm over the area of the sump is a lot?!, could drain down.

 

Cant be the injectors for that volume so i agree it must be at the mu.

 

Sorry not to be of more/any help!

 

Steve

[astontr6]

Pedestal Seals need replacing? They go hard with age!

 

Bruce.

[DaveN]

Morten

Just as a precaution before you start the engine remove the plugs and DISCONNECT the coil and spin over the engine just in case an injector or two have leaked into the cylinders!

I had an issue with an open circuit injector filling one cylinder with fuel

[MortenHoyseth]

Thanks guys!

Daven - good tip, I'll be sure to do that.
Steve - yes, it's a lot and the smell of petrol is - how should I put it - significant
I'll try to get a hold of new seals for the MU. It must come from there.

I noticed that the chocke knob what out, thus set for max rich mix, for start-up. So by mistake it was left in this position. Regardless it should not leak down into the sump.

[Peter Cobbold]

Morten, Also check the return pipe from MU to tank is clear, as that prevents high pressure from building up in the space behind the shaft seal. Peter

[DaveN]

+1

Peters advice you should be able to blow through it relatively easily once the return fuel lying in the pipe is blown back into the tank!

If you have trouble blowing through it suspect the short bit of rubber hose accessible behind the l/h rear wheel.

[DaveN]

Here's a simple Guide to replacing the FMU seals:

 

Simple job to do. Just a couple of points to note.

1) remove the dizzy cap and lay to one side.

2) disconnect the rev counter drive.

3) mark the distributor position in relation to the clamp. Use a bit of paint.

4) remove the dizzy......Don't be tempted to rotate the shaft.

5) unbolt the FMU and pull it aft, remove the drive dog for safe keeping. Don't be tempted to rotate the shaft.

6) note the position of the dizzy drive in the pedestal......it is offset!

7) unbolt and remove the pedestal....important.. count the number of paper shim gaskets you remove. As you pull up the pedestal the drive will rotate as a reaction to the skew gear.....make a note of the position it ends up in as the pedestal comes free.

8) remove the bolt and push out the drive shaft.

9) tap out the seals

10) important..... the git seals are installed back to back. Poke a small dowl into the tell tale drain in the bottom of the pedestal. That will help prevent the seal on the FMU end being pushed in to far and blocking the hole.

11) grease or oil the new seals and gently tap into position. Take care not to damage the seal faces.

12) grease or oil the drive shaft... carefully insert it and fit the end cap and bolt..... loctite on the bolt is a good idea! It's only a small bolt so don't strangle it up!

13) referring to item 7 rotate the drive in the pedestal to that final position.

14) clean up the faces.... and again referring to item 7 refit some new gaskets.

15) refit the pedestal and the offset drive should be in the position noted in item 6

16) fit new seal to the FMU some thick grease on the drive dog to hold it in position and refit the FMU.

17) refit the dizzy....ensuring the drive is engaged

Jobs a good un!!

Provided you've not rotated the engine the FMU or the dizzy your back to normal?

Took me just about an hour to do.

Parts required

FMU o ring........149486

2 pedestal seals........145720

End cap seal........nkc101a

Paper shim gaskets to suit.....I bought 6... just in case ...and needed 2.......104939

[MortenHoyseth]

Excellent daven Highly appreciated. Parts ordered.
And I'll check up on the overflow as well.

[Guest ntc]

Here's a simple Guide to replacing the FMU seals:

 

Simple job to do. Just a couple of points to note.

1) remove the dizzy cap and lay to one side.

2) disconnect the rev counter drive.

3) mark the distributor position in relation to the clamp. Use a bit of paint.

4) remove the dizzy......Don't be tempted to rotate the shaft.

5) unbolt the FMU and pull it aft, remove the drive dog for safe keeping. Don't be tempted to rotate the shaft.

6) note the position of the dizzy drive in the pedestal......it is offset!

7) unbolt and remove the pedestal....important.. count the number of paper shim gaskets you remove. As you pull up the pedestal the drive will rotate as a reaction to the skew gear.....make a note of the position it ends up in as the pedestal comes free.

8) remove the bolt and push out the drive shaft.

9) tap out the seals

10) important..... the git seals are installed back to back. Poke a small dowl into the tell tale drain in the bottom of the pedestal. That will help prevent the seal on the FMU end being pushed in to far and blocking the hole.

11) grease or oil the new seals and gently tap into position. Take care not to damage the seal faces.

12) grease or oil the drive shaft... carefully insert it and fit the end cap and bolt..... loctite on the bolt is a good idea! It's only a small bolt so don't strangle it up!

13) referring to item 7 rotate the drive in the pedestal to that final position.

14) clean up the faces.... and again referring to item 7 refit some new gaskets.

15) refit the pedestal and the offset drive should be in the position noted in item 6

16) fit new seal to the FMU some thick grease on the drive dog to hold it in position and refit the FMU.

17) refit the dizzy....ensuring the drive is engaged

Jobs a good un!!

Provided you've not rotated the engine the FMU or the dizzy your back to normal?

Took me just about an hour to do.

Parts required

FMU o ring........149486

2 pedestal seals........145720

End cap seal........nkc101a

Paper shim gaskets to suit.....I bought 6... just in case ...and needed 2.......104939

All good stuff however bring to number1 fire before you start the job.

[Mk2 Chopper]

Just done this, thanks for the tips. 

Can I add a further one:

Having removed distributor with the distributor clamp (so you don't lose the timing) and MU from the pedestal, if you then undo the end cap, and push the drive shaft out, making note of where the gear is so you can insert back the same way.

Then undo the pedestal and lift off leaving the distributor drive in place and in the correct position. 

Gareth

Edited September 3, 2022 by Mk2 Chopper