Split pipe to oil pressure gauge.

[Karen Lea Rainey]

Just need a bit of advice, my dense plastic pipe that goes from my oil gauge to the sender and oil filter has a small split across the end of the barb which holds the pipe on.

I can cut the pipe at the end of the barb tail and reattach  there is plenty of length of spare pipe, it looks incredibly  tight on to the barb,

Is there a knack or solution to use when refitting the pipe back on once removed.

It is a Lister HRW2 with I think a Borg Warner  gearbox and Jabsco water pump/ oil cooler unit attached.

I dont want to very far to get a repair done for fear of losing a lot of oil and major consequences.

Perhaps you could give me some advice on the best way to reattach the pipe and confirm my thoughts on the gearbox make etc.

Pictures attached.

[BEngo]

To fix the split by shortening the tube, you need to soften the tube to get the barb in.  You can either use a heat gun  or dip the end of the tube in boiling water. This weather 30 minutes on the roof might do!

 

 

Heat the barb as well as the tube, so the barb does not cool the tube.  Work quickly and leave it all to cool as soon as you have the  barb in well.  You can reheat if needed.  Dont forget to put any nut on the right way round  before putting the barb in 

 

The tube is probably nylon and if it has gone hard at the end will be on it's way out generally, so a good idea to put complete renewal on the tuit list.

 

N

[Tony Brooks]

It looks like a Borg Warner with reduction box to me.

 

That pipe looks like clear plastic hose and depending upon type can be hardened by the oil. If I am correct then I am not sure it is the most suitable pipe to use. I would expect copper or hardish black nylon with compression fittings, however you have what you have.

 

Again, If I am correct, you can cut the end off the pipe, put the end in boiling water to soften it and the push it further over the spigot. I would then try to clip it

 

PS in light of Bengo's post, I have never seen nylon tube that is as see through as what you seem to have. The stuff I have seen tends to be translucent white.

Edited July 18, 2022 by Tony Brooks

[Karen Lea Rainey]

Tried with boiling water for 4 or 5 attempts today, I cannot get any stretch in the nylon tube, boil the kettle again and again with no joy, even tried 2 pairs of soft claw molegrips, to give a bit more shove and push and twist.

The nylon tube just will not stretch.

As the boat is 40 years old , I suspect that this could be the original oil pressure nylon tube, could it be that due to age and heat over the years that the tube has now lost all elasticity, therefore would I be better to just replace the tube and be safer/ happier knowing it's not gonna split and lose my oil unbekowingly.

[Tony Brooks]

2 hours ago, Karen Lea Rainey said:

Tried with boiling water for 4 or 5 attempts today, I cannot get any stretch in the nylon tube, boil the kettle again and again with no joy, even tried 2 pairs of soft claw molegrips, to give a bit more shove and push and twist.

The nylon tube just will not stretch.

As the boat is 40 years old , I suspect that this could be the original oil pressure nylon tube, could it be that due to age and heat over the years that the tube has now lost all elasticity, therefore would I be better to just replace the tube and be safer/ happier knowing it's not gonna split and lose my oil unbekowingly.

 

So I was wrong, not plastic.

 

One method of fitting hose barbs into nylon injector leak off pipe was to drill a block of wood to slightly under the OD of the pipe and then cut the block down the middle so that when clamped in a vice with the pipe through the hole the wood gripped the pipe. Pipe in the block with enough sticking out the top to accept the length of the barb. Then soften the end of the exposed pipe but not all the way down and drive the barb into the pipe using a soft hammer/mallet. The only thing is the hose barbs had  afar gentler entry angle compared with yours.

[Tracy D'arth]

More heat, boiling water is not that hot in relation to some thermoplastics.

 

See this chart, much higher temperatures.

 

https://www.rydtooling.com/plastic-melting-temperature-chart/

Edited July 20, 2022 by Tracy D'arth

[Jen-in-Wellies]

3 hours ago, Karen Lea Rainey said:

As the boat is 40 years old , I suspect that this could be the original oil pressure nylon tube, could it be that due to age and heat over the years that the tube has now lost all elasticity, therefore would I be better to just replace the tube and be safer/ happier knowing it's not gonna split and lose my oil unbekowingly.

Replacing the tube seems to be the most sensible thing, considering its possible age and unknown material. Can you find its internal diameter? If you have some twist drills of known size, the shanks can be used to find this. Possibly an imperial size, but the nearest mm should be fine. We can then recommend a suitable hose that is known to be OK for hot engine oil long term.

 

[Alan de Enfield]

53 minutes ago, Tony Brooks said:

 

So I was wrong, not plastic.

 

One method of fitting hose barbs into nylon injector leak off pipe was to drill a block of wood to slightly under the OD of the pipe and then cut the block down the middle so that when clamped in a vice with the pipe through the hole the wood gripped the pipe. Pipe in the block with enough sticking out the top to accept the length of the barb. Then soften the end of the exposed pipe but not all the way down and drive the barb into the pipe using a soft hammer/mallet. The only thing is the hose barbs had  afar gentler entry angle compared with yours.

 

There are two main types of Plastic, Thermoplastic and Thermosetting.

 

If you heat a thermoplastic it softens and you can stretch it over (say) a barbed spigot. (Typically Polypropylene piping)

If you heat a thermosetting material it will do nothing until it starts to melt.

 

Nylon is a Thermosetting plastic.

 

You may be very lucky and get the Nylon to its softening point but you'd have to be quick as it soon goes from soft to molten. Softening point of Nylon 6 / Nylon 6:6 is 220C and melting point is ~265C.

Hot water will do nothing.

 

(23 years as a Product Manger and then Co. Director in the plastics industry)

[Karen Lea Rainey]

I wonder if I could change the barb/screwed thread, I took the joint off today to get a better grip. Surely I can buy the connection with less ball on the end and clamp it on with a circlip.?

[BEngo]

Have to disagree Alan.  Nylon is a thermoplastic. A quick Goog produces no sources which say it is a thermo setting plastic.

 

However, that is academic.  The OP has not got qthe pipe hot enough to soften it.   JEN-IN-WELLIES suggestion is a good one, but it would also be useful to know the outside diameter of the barb  so we can ensure the new piece of tube has enough wall thickness to accept the stretch.

 

The modern favourite for this sort of thing seems to be silicone based tubes.  Personally I prefer copper, with plenty of clips and a few anti-vibration coils.

 

If the pipe has gone hard, and will not soften in boiling water I doubt that it will be made to shrink sufficiently to grip a smaller barb using any sort  hose clip.  (BTW a circlip is a different thing altogether and not useful for fastening hoses onto anything.)

 

Can you get the whole pipe off the engine?  If  so hold it close to a gas flame (a cooker ring  is good) and see if that softens it.

N

Edited July 20, 2022 by BEngo

[ditchcrawler]

Oil Pipe for Mechanical Gauges 3 metres long (holden.co.uk)

[Karen Lea Rainey]

I will call into Streethay tomorrow to see what they have available, oil pipe  or threaded barb etc,,

My guess is I need approx 5 to 6 metres of pipe, the gauge is at waist height on the back of the trad stern with the other gauges, all Smith's gauges for oil pressure, voltage, etc in the standard 52mm sets. It then travels down the inside of the control panel with the throttle cable and gearbox cable, goes under the floor of the boatmans cabin for approx 8 or 9 feet and into the engine room for another 3 feet or so, reckon on approx 16 feet in total.( 5 metres).

It will be a sod to replace the pipe so I'm hopeful we can work around it.

I cut a small circular gasket with metal inside it to fit inside the  threaded  barb today and tightened it up well, knowing the oil pressure is around 45 or 50 lbs I thought that should hold it until properly repaired. Started the engine with no leaks of oil for 20 mins plus running.

Thank you all for your input, i am very grateful  for your knowledge.

 

[Karen Lea Rainey]

Brainwave over night !  What about a small brass olive it's about 3 or 4 mm and do away with the barb and use a compression fitting nut?

[john.k]

It takes a fair while for heat to get through plastic pipe,I suspect not enough time ........wrap a rag around the area,and pour a lot of boiling water very slowly (a trickle) over the rag........usually old plastic is quite brittle when cold ,and there is a chance of it breaking .........i would replace the whole lot with new tube and new brass ends ........the black nylon truck air tube is quite popular for oil or fuel ,and as its for a gauge ,Id go with a very small bore tube,,no more than 1/4"......also the engine end fitting should include a hose break shutoff.

Edited July 21, 2022 by john.k

[BEngo]

3 hours ago, Karen Lea Rainey said:

Brainwave over night !  What about a small brass olive it's about 3 or 4 mm and do away with the barb and use a compression fitting nut?

A compression fitting with a brass olive to fit the pipe will be fine.  Must be a brass olive though.  The copper ones tend to crush plastic pipe without sealing properly.

 

N

[Tony Brooks]

4 hours ago, Karen Lea Rainey said:

Brainwave over night !  What about a small brass olive it's about 3 or 4 mm and do away with the barb and use a compression fitting nut?

 

Look carefully at the fitting with the brass barb in it. I think the brass barb had the aluminium cast around it so it will not be a simple case of compression nut and olive,

 

It seems the  whole aluminium and brass barb assembly is threaded into one of the oil pipes unions on the oil filter but to me the thread looks too fine for BSP. If you can match the thread you might be able to find a suitable male elbow and to compression fitting but I doubt it will be easy unless someone can give you a pointer to possible suppliers.  It might be possible to cut the barb off and get a compression fitting onto the remaining brass stab, but it is a bit "do and hope it works out".

[Chris G]

13 hours ago, Alan de Enfield said:

Nylon is a Thermosetting plastic.

I think you'll find that Nylon is a thermoplastic.

As a aside; my mother was a co-author of a paper (Proceedings of the Royal Society) on the crystal structure of Nylon.

 

[Tony Brooks]

9 minutes ago, Chris G said:

I think you'll find that Nylon is a thermoplastic.

As a aside; my mother was a co-author of a paper (Proceedings of the Royal Society) on the crystal structure of Nylon.

 

 

Either you are correct or the tubes I thought were nylon were not. They softened with heat, admittedly not boiling water but careful application of a small flame from a small gas welding nozzle wafted about the pipe.

 

If it is thermosetting I think it would be difficult to extrude nylon yarn.

Edited July 21, 2022 by Tony Brooks

[john.k]

if the plastic is made too soft by heat,it will collapse like a cooked noodle ...........so there is a happy medium.....................My Leyland truck had the strange fitment of steel tube with flare nut on half,and a bit of plastic tube simply slipped over the other end.............it was Leyland Bathgate,so they probably changed the spec between strikes.................maybe Red Ned did it himself.

[Tony Brooks]

20 minutes ago, john.k said:

if the plastic is made too soft by heat,it will collapse like a cooked noodle ...........so there is a happy medium.

 

Which is why I said "soften the end not all the way down". That analogy seems very apt to me. It needs softening enough to get it to stretch over the barb while leaving enough strength in the rest to resist the force of trying to insert the fitting.

[ditchcrawler]

6 hours ago, Karen Lea Rainey said:

Brainwave over night !  What about a small brass olive it's about 3 or 4 mm and do away with the barb and use a compression fitting nut?

That is how a lot of the kits are made up.

[David Mack]

13 hours ago, Karen Lea Rainey said:

I cut a small circular gasket with metal inside it to fit inside the  threaded  barb today and tightened it up well, knowing the oil pressure is around 45 or 50 lbs I thought that should hold it until properly repaired. Started the engine with no leaks of oil for 20 mins plus running.

On a boat I once owned the oil pressure gauge didn't work. Investigation showed that the plastic pipe was cut a couple of inches from the engine connection, but there was no oil leaking out. Further investigation found that the brass hose fitting had been screwed down onto a piece of lead shot! With the lead shot removed and a new hose kit from my local car spares shop and the gauge was working again.

[Tracy D'arth]

3 hours ago, David Mack said:

On a boat I once owned the oil pressure gauge didn't work. Investigation showed that the plastic pipe was cut a couple of inches from the engine connection, but there was no oil leaking out. Further investigation found that the brass hose fitting had been screwed down onto a piece of lead shot! With the lead shot removed and a new hose kit from my local car spares shop and the gauge was working again.

Standard bad practice to blank off a leaking wheel brake cylinder, lead shot, copper nail or a ball bearing worked wonders as a get you home.

[Karen Lea Rainey]

Sorted now, picked up a brass olive connection, 5/16th I believe from Streethay,

Nick there was very good and quickly sorted the size. Fitted in beautifully.

Engine now runs at tickover around 44 lbs pressure, under load goes upto 60 lbs and then reduces slowly.

Picture of the end piece of the horrible tube, it's incredibly hard, definitely a nylon type tube.

[Karen Lea Rainey]

New connection / brass olive