LW Ram Pump Leaking

[Alan Saunders]

Ever since I owned this 3LW (10 years and 10K+ hours) it weeped a little water from the 'pump body drain' (no. 25, centre bottom below). When it got worse I attached a hose and fed the coolant into a container. Now it is p'ing out but I cannot find any information on the internet to help me to repair/overhaul the pump or find anyone offering to do so or, better, a 'service exchange'.

 

I assume this drain tube should not have a cap-nut as none is shown on the parts diagram, unlike no. 27 (middle, left) the 'delivery chamber drain'. I assume that capping #25 would force coolant into the engine oil sump.

 

 

BTW, this engine is using the 'ram' raw water pump to circulate coolant through a skin tank. When a friend closed both the bypass and restriction water valves several years back water escaped from a hose union rather than the 'safety valve' (no. 30) which may have damaged pump seals.

 

If I cannot effect a DIY repair I would happily drive 120 miles return x2 to get this pump repaired. I am currently near Devizes.

 

Another question, what oil or grease should I use in the 'lubricator', no. 26 (middle, top)? The screw cap on mine (1950) suggests it is a miniature 'greaser' (for 'stern-tube grease'?) but the above diagram shows a 'flip-top' for oil.

 

Thank you to Martyn, Marine Power Services for the LW Marine parts catalogue - I hope you do not object to the above partial copy.

 

Alan

[Timleech]

The pump casting probably already has a bronze sleeve for the pump bore, this will undoubtedly be worn as will be the pump washers/leathers (item 9)

 

You'll need the present sleeve pressed or bored out and a new one made & fitted. Then source some new washers.

The lubricator is for the guide bearing, or crosshead, which is integral with item 2. This may or may not be worn, as may the piston rod.

 

Do not try to close off the drain, you're right in thinking that it is there specfically to let water away before it gets past the piston rod into the oil.

 

If you are stuck I could have a look at it for you, but may be more than 120 miles away (Runcorn), and can't do anything for at least a couple of weeks.

 

Tim

[steamraiser2]

As Tim says this is just an accumulation of general wear of the pump bore and piston washers. Ram pumps are not really the preferred option for tank cooled engines and tend to exhibit more leaks than a centrifugal pump in a tank type circuit.

 

The pump can be reconditioned "but at a cost" Maybe consideration of a standard Gardner centrifugal pump or a Jabsco belt driven one may be worth a moment at this time?

 

Either way it's not going to be quick.

 

Geoff

[bizzard]

If you can remove the seals without damaging them, then as a temporary repair wind a few turns of cotton onto the pistons seals seat groove and replace the seals on top. This will expand the seals a bit, if a few turns of cotton are done at a time quite a good seal fit should be attained. I've done this botch several times over the years, but with rubber or synthetic O rings and lip seals, but not leather seals.

I see the leather seals are fixed on like the old bike pump washers. So perhaps thin shim washers between the washers and seals or behind the seals would squeeze the seals a little and so expand their diameter a touch.

Edited April 24, 2015 by bizzard

[adrianh]

Hello, i have an engineering business in semington nr devizes.

I may be able to help you with seals or machined parts.

pm me for details

[Unmani]

I've recently replaced the ram pump seals on my 3L2 that have been 'weeping' for years. The bore had a few scratches so I honed it out with a flap wheel on a drill as advised by Walshes in manchester (01617877017) who also supplied the new seals. Check the old ones for part numbers as different sizes were fitted. The oiler wasn't always fitted and is to lubricate the piston rod, not the seals.

Edited April 25, 2015 by Unmani

[Alan Saunders]

Thank you all for your excellent advice.

 

I could not understand how a water seal is effected; I imagined there would be a seal where the drive shaft enters the pump. It seems that the only seal is from the tandem washers (no.9) and, unlike a bicycle pump (Bizzard) the pump simply creates positive and negative pressure and there are separate valves (not shown in my diagram) in the pump body. Typical over-engineering from Gardner.

 

I will get two off (no. 9, MA 620), I was confused by the parts catalogue describing them as 'cup washers', hopefully they will be nitrile, not leather! I assume from Tim's reply that the cylinder liner (no. 2) is unobtainable and/or difficult to remove/replace.

 

With a little honing as per Unmani's (Walsh's) advice I hope to make a temporary repair even if it still weeps a little I will be happy.

 

Yes, I would like to have a centrifugal pump, thermostat etc. but this engine also needs an overhaul and there is no access to lift it through the roof. The head could go out via the engine room doors and the block the same way with lifting gear but I doubt the crankcase would fit.

 

Thanks again, Alan

[Timleech]

Thank you all for your excellent advice.

 

I could not understand how a water seal is effected; I imagined there would be a seal where the drive shaft enters the pump. It seems that the only seal is from the tandem washers (no.9) and, unlike a bicycle pump (Bizzard) the pump simply creates positive and negative pressure and there are separate valves (not shown in my diagram) in the pump body. Typical over-engineering from Gardner.

 

I will get two off (no. 9, MA 620), I was confused by the parts catalogue describing them as 'cup washers', hopefully they will be nitrile, not leather! I assume from Tim's reply that the cylinder liner (no. 2) is unobtainable and/or difficult to remove/replace.

 

With a little honing as per Unmani's (Walsh's) advice I hope to make a temporary repair even if it still weeps a little I will be happy.

 

Yes, I would like to have a centrifugal pump, thermostat etc. but this engine also needs an overhaul and there is no access to lift it through the roof. The head could go out via the engine room doors and the block the same way with lifting gear but I doubt the crankcase would fit.

 

Thanks again, Alan

 

Actually the general principle, of a plunger with two separate valves, was pretty much the norm for engine ram pumps. If you want to see over-engineering, study the original RN ram pumps!.

 

The cylinder sleeve is a perfectly straightforward machining job. I've re-lined a few of these in the past, but not for a few years so don't remember how simple it was or wasn't to remove the old sleeve.

 

Tim