Fuel line sizes

[IndigoSteve]

I was planning to change some of my fuel lines today but foolishly started before checking the hoses from the new kit are the same as current.

They weren't - I got 7.5mm fuel hoses and clips that when tightened barely gripped the hose.

I need to get some new hose tomorrow as off on hols for the Easter break.

I'll pop into the automotive shops in Newbury tomorrow but I just wanted to check what I'm looking for. The old hoses say 5 x 3 on them. I assume that's a 5mm outer diameter and a 3mm inner?

I see on some VW sites they sell 6mm. Can I get away with this?

Vehicle. T25 1.9 petrol

Cheers

Steve


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[Oldiebut goodie]

I would buy the hose that fits the pipe that you are putting it on. Measure the pipe outside diameter before you buy anything else and buy hose that has an inside diameter 0.5mm narrower than that. If you just guess it could end up more expensive!
Going by the size that you say is marked it seems very small to me. 7.5mm would be going on 8mm pipe. 3mm onto 3.5mm od pipe doesn't seem correct to me for normal pipes, fuel flow would be extremely constricted. ( I use 3.5mm onto 4mm od pipe for heaters which only use around 0.25 litres per hour)
You will need a petrol guy to help though as someone will have a better idea as to what hoses you have and where on those funny engines.

[bigherb]

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I'll pop into the automotive shops in Newbury tomorrow but I just wanted to check what I'm looking for. The old hoses say 5 x 3 on them. I assume that's a 5mm outer diameter and a 3mm inner?

I see on some VW sites they sell 6mm. Can I get away with this?

That hose is 5mm bore 3mm wall thickness. That's how hose is measured.
We normally use 5.5 or 5.7 bore x 3mm hose. 6mm bore hose won't do as we use a nominally smaller hose to be a tight fit over the 6mm fittings.
Some sellers can confusing state it is 6mm hose although it is actually 5.5/5.7mm bore hose because it fits 6mm fittings, beware they do make a 6mm bore hose which is a loose fit and only relies on the clips to keep it tight which not a good idea.

[IndigoSteve]

Thanks for that. I'll go hunting.


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[Oldiebut goodie]

Some hose is measured, usually pipes though. In most situations the outside diameter is immaterial on hoses in this context. All the hose right to hand behind me, bar one, is marked in the normal way with just the ID.

[Ian and Lins]

Your probably out shopping but it is important to get the right hose. If it's too loose/big then even if you squidge it up tight with a clip it might still have a tiny gap where air can leak IN. This can make a big difference to fuel pumping through as well as introducing air where it shouldn't be.

[IndigoSteve]

Thanks for the reply all. Motorist discount sold me some 5.5mm fuel injection hose which fits snugly and seems to work well


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