How To Join Two Tubes (different diameters)

[cb010]

I'm trying to join a tube of inner diameter 10mm with a tube that has an outer diameter of 5mm.

It may be incredibly obvious to some but I planned on using black insulation tape to thicken the smaller diameter tube until it fits tightly into the larger one. It will only be needed to suction oil out of an engine as the tube supplied with the suction kit is too wide to fit into the dipstick pipe.

Can anyone suggest a better way to go about this? I tried to find a valve that would join both hoses, but can't find one with different sized ends.

Any advice appreciated!

[Easternlight]

Unless you can find another piece of tube with the OD 10 and ID 5, then your idea will work.
But I wouldn't stick it any where that you cant get to easily as the oil will probably get to the glue on the tape and soften it, allowing the small bit to fall out quite quickly, more so if the oil is hot!

[voicey]

Type in "hose reducer" into eBay - loads to choose from.

[cb010]

Ahh, hose reducer! Thanks, found some on ebay. I did look for some 5>10 tubing but couldn't find any.

I'll only need to do an oil change like this every couple of years so even if the tape join between the hoses doesn't last long it won't matter too much.

[Charlie1986]

cb010 said:

Ahh, hose reducer! Thanks, found some on ebay. I did look for some 5>10 tubing but couldn't find any.

I'll only need to do an oil change like this every couple of years so even if the tape join between the hoses doesn't last long it won't matter too much.

have you tried hose clips on it? I'm sure you can get a small size

[cb010]

Charlie1986 said:

have you tried hose clips on it? I'm sure you can get a small size

Thanks - hose clips are a good idea, I'll give that a try before buying a hose reducer.

[Charlie1986]

cb010 said:

Thanks - hose clips are a good idea, I'll give that a try before buying a hose reducer.

So what is the actual OD you need to connect? as with the overlap it will more than 10? Or are you putting the 5 in to the 10mm?

http://www.oetiker.com/~/media/Downloads/Technisch...

Have a look at the sizes here and if any will be helpful let me know and i get some out FOC for you. Same with the Worm drives too.

[PaulKemp]

Heat shrink
You can shrink a piece over the small diameter pipe then use large diameter over both 10mm & 5 mm

[Collectingbrass]

You need to transfer the vacuum from the suction kit tube to the dipstick tube and down into sump. Oil being viscous you need to be able to draw it into the extraction tube from below the oil surface - certainly mine works much better when the tip of the tube is right down in the sump.

In your circumstances OP I would not try and join the two pipes as you will loose vaccuum, I'd get a single length of pipe and a bung that is a force fit into the entry into the suction pump, drill a force fit hole through the bung for the pipe and do it that way.

Also, make sure you have an air path back to the sump so you don't end up trying to fight a vacuum down there once the oil starts to flow.

This one has a 5mm pipe so may save you faffing?

http://www.halfords.com/motoring/motorcycling/moto...