Lister ST3 rebuild

[bizzard]

The oil pressure pump is a piston pump and it pulses the pressure. Where's the oil squirting out from?

[David Mack]

12 hours ago, RussellBa said:

Basically it is spraying oil and fumes from rocker cover gasket.

 

There are three separate rocker covers. Are they all leaking? Two of mine did after I removed the rocker covers to slacken the injector nuts when bleeding the fuel system. After refitting oil dribbled out when the engine was running. Removed the two leaking covers again, carefully cleaned the matting faces and the gaskets and reassembled. Sorted.

[Tony Brooks]

Once again my ignorance of the ST range is showing but I think the SLs had internal  oil pipes feeding the rocker gear so in view of what @bizzard said if one is squirting towards the poor gasket as described by @David Mack oil might appear to pules out.

 

There is no way I can reconcile exhaust valves operating with pressure pulses in the rocker cover. crankcase pressure does pulse but in response to the power strokes and that is only indirectly related to the valves.

[bizzard]

6 minutes ago, Tony Brooks said:

Once again my ignorance of the ST range is showing but I think the SLs had internal  oil pipes feeding the rocker gear so in view of what @bizzard said if one is squirting towards the poor gasket as described by @David Mack oil might appear to pules out.

 

There is no way I can reconcile exhaust valves operating with pressure pulses in the rocker cover. crankcase pressure does pulse but in response to the power strokes and that is only indirectly related to the valves.

Yes Tony ,oil feed pipes to the rocker shaft the same arrangment really as SL'S, SR'S, coming up internally from the crankcase. 

[Tony Brooks]

Just now, bizzard said:

Yes Tony ,oil feed pipes to the rocker shaft the same arrangment really as SL'S, SR'S, coming up internally from the crankcase. 

Thanks Biz - another bit of learning for me.

[RussellBa]

Thanks again guys for help. They all s seem to be leaking but it's No1 that's actually spraying the oil out at the same time as a puff of smoke from the rocker cover gasket and hits the bulkhead. 2 and 3 not so obvious but must be leaking a fair amount as you can watch a constant pinging of oil off the crankcase oil fill cap but I can't see signs of a drip onto it. The amount of smoke coming off the hot engine looks very dramatic.

[Tracy D'arth]

I can't remember what the crankcase ventilation arrangements are for the ST engines but I bet that it is blocked up and it is crankcase pressure that is forcing oil out of the least effective gaskets, rocker covers, and this oil is running down the finned cylinders and burning off.

 

The bible says that a breather tube is screwed into the top of each cylinder head which connects with the inlet port creating a negative pressure in the crankcase.

 

The great book s here foc,   https://www.winget.co.uk/document/LISTER ST WORKSHOP MANUAL.pdf

 

 

Edited August 24, 2020 by Tracy D'arth

[Tony Brooks]

3 minutes ago, Tracy D'arth said:

I can't remember what the crankcase ventilation arrangements are for the ST engines but I bet that it is blocked up and it is crankcase pressure that is forcing oil out of the least effective gaskets, rocker covers, and this oil is running down the finned cylinders and burning off.

As @bizzard confirms the rocker oil feed is the same as SL and SR then I think the breathers are small upright pipes under the rocker cover. The OP did say he was going to check them. I agree hee is every chance the smoke is oil on the  cylinder fins.

[RussellBa]

Unfortunately I've not been able to get to the boat if weather decent tomorrow I'll make a start. Thanks for all advice you've given me hope that it would turn out to be a relatively simple job.

[RussellBa]

Hi guys d sorry for slow response but was only able to get to the boat today. I checked the breather tubes a and they were all clear. So any ideas as to where to investigate next. One thing I did notice was the out sides of the tubes that screw into the cylinder heads were a little bit gummy with oil and bits of fluff.

[Tony Brooks]

44 minutes ago, RussellBa said:

Hi guys d sorry for slow response but was only able to get to the boat today. I checked the breather tubes a and they were all clear. So any ideas as to where to investigate next. One thing I did notice was the out sides of the tubes that screw into the cylinder heads were a little bit gummy with oil and bits of fluff.

The rocker cover gaskets and if you renew those I suspect that you will have to take one of the tin covers off the side of the engine and run it while you look at the cylinders to see if yo can spot the leak.

[RussellBa]

I'll do that next, hopefully weather will be clear tomorrow. Thanks.

[Tony Brooks]

How much water/oil is there in the engine drip tray / bilge? If its high its possible the flywheel cum fan is throwing it onto the cylinders where it will   boil/burn and the cooling air may well blow some of it up between the cylinder heads.

[Steve56]

57 minutes ago, RussellBa said:

Hi guys d sorry for slow response but was only able to get to the boat today. I checked the breather tubes a and they were all clear. So any ideas as to where to investigate next. One thing I did notice was the out sides of the tubes that screw into the cylinder heads were a little bit gummy with oil and bits of fluff.

By tubes I think you mean the cylinder head and block securing studs. You can see them running down from the heads und into the crankcase. It is not unusual to see these covered in all sorts of muck as they are in the cooling air flow. This could be picked up from anywhere in th engine bay. The one thing I've found over the years when working on these engines, is you know when the boat owner has dogs on board.

[RussellBa]

No I ment the breather tubes when took them out to check clearance the external sides of them had a lot gummy coating. Tony it is possible that the fan had thrown oily water up to burn off and I suspect there has been an unseen leak for a while though I can't say I've noticed much of a drop in oil levels. But it's the puff of smoke and spray of oil from no 1 cylinder that concerns me.

Edited August 29, 2020 by RussellBa

[Tony Brooks]

Anything is possible but what i don't understand is that you have made no mention of the state of the rocker cover gaskets. I can't see how you can get fluff on the breather tubes unless someone has wiped then with fluffy cloth.  If you can see oil squirting out of the rocker cover to head joint the first thing that is be suspect is the rocker cover gasket, the second thing is to check the rocker cover face is not damaged or distorted.

[RussellBa]

To be honest the gasket didn't look in too bad a condition it lifted away in one piece on the leaky side. The fluff looked like a small collection of fibres matted with oil, I suspect possibly drawn into the inlet manifold in the past as it didn't have an air filter element when I first got the boat. I've got 2 sets of cover gaskets so will try resealing to see what happens.

[Tony Brooks]

Put a straight edge (metal rule) along the cover faces and see if there are any gaps along the face.

 

Remember oil gaskets can get compressed so they don't seal any more.

 

Was there much oil on the gasket where it was squashed down, if there was it probably indicates where it was leaking.

 

If the gasket just lifted off it may not have been properly tightened down so make sure the nuts/bolts are not running out of thread like one may be if its a nut on a stud and the stud has come undone in the past and was not properly screwed back in.

[RussellBa]

Thanks for the tip Tony will check tomorrow, thanks again for advice.

[bizzard]

On the port side of the cylinder heads the injector leak off pipes come out through rubber gromets just below the top surface where the rocker cover fits. If the gromets are out of place or knackered oil will leak out from them. They seem to always sweat a little oil from there anyway.

[Tony Brooks]

7 hours ago, bizzard said:

On the port side of the cylinder heads the injector leak off pipes come out through rubber gromets just below the top surface where the rocker cover fits. If the gromets are out of place or knackered oil will leak out from them. They seem to always sweat a little oil from there anyway.

Agreed but I understood from the posts that the leak was coming from between the covers, not from the side. If it is the side your answer is the most likely.

[RussellBa]

An update and I'm a numpty. Went back to the beginning checked oil level again on closer inspection of dipstick I noticed a watery film above the level marks, so withdrew about q/2 a gallon of clear looking oil and let it settle low and behold mostly water, shall drain the crankcase completely tomorrow and refill with fresh oil. The engine bay deeply flooded last year and again during lock down and I didn't think that the water could have gained entrance into the engine. I assume this had been over pressurising the crankcase causing valve cover gasket to leak. Unless someone has a more experienced view. Thanks again for input.

[Tony Brooks]

1 hour ago, RussellBa said:

An update and I'm a numpty. Went back to the beginning checked oil level again on closer inspection of dipstick I noticed a watery film above the level marks, so withdrew about q/2 a gallon of clear looking oil and let it settle low and behold mostly water, shall drain the crankcase completely tomorrow and refill with fresh oil. The engine bay deeply flooded last year and again during lock down and I didn't think that the water could have gained entrance into the engine. I assume this had been over pressurising the crankcase causing valve cover gasket to leak. Unless someone has a more experienced view. Thanks again for input.

 

and then keep a very close eye on the level because those engines are susceptible to internal fuel leaks so the oil gets thinner and the level goes up. Then it starts to seize and/or runaway.

[RussellBa]

Will certainly keep a much closer eye on it in the future. Thanks

[RussellBa]

Hi Tony can you recall the size of the washers on the banjo bolts on the fuel pipes in the engine, I thought it might be worth getting some in just in case.