Hi,
I own a european specs 1997 Volvo S40 with 395'000 km (manual transmission). As preventive maintenance, I'd like to replace the 24 years old rubber fuel hose that connects the fuel pressure regulator to the fuel return steel line (it still is not leaking and doesn't look cracked but hey...24 years old piece of rubber!).
Volvo doesn't stock this part anymore so I have to look for aftermarket alternatives. One issue is that the original fuel hose runs extremely close to (and even touches) the top of the engine block so it is likely subject to extremely high heat. Basically it runs all along the top of the engine bloc, and touches the casing of the head over roughly 30 cm before being clamped onto the metal fuel return line. Obviously since this is on the return line, this hose is not subject to high pressure but my concern is really about heat resistance.
I've seen that Gates manufactures fuel hoses (3225, see https://www.gatestechzone.com/-/media/files/public-downloads/hose-info-sheets/fuel-hoses/fuel-line-hose-3225/19-gates_3225_flh_en.ashx) that can support up to 125°C (250°F) but I suspect the engine case near the head may run hotter than this. Do you think there is any safety issue running such a hose a long the head of the engine case or would you recommend another type of hose with higher heat resistance (any ref)? Unfortunately, there is no room to route the hose at a distance of the head and I do not know whether Volvo used a regular fuel hose for this portion or if it was a beefed-up version capable of supporting higher temperatures.
Also, the OEM hose is clamped using Oetker clamps. Do you think it is okay to replace these with screw-on style clamps or is this unrecommended for fuel hoses (due to the clamp possibly getting loose with engine vibrations)?
Would be glad to have your view on this question. Thanks!
Aziz
A couple thoughts on possible solutions - 1. you might fit a longer fuel hose with a clamp or bracket to keep it away from the engine block 2. You could get some of the material used to provide heat shielding for exhaust components and make a heat shield for that portion of hose 3. Motorcycles have brake lines with braided steel coverings (to make leaking/burst failure unlikely). This would be less likely to fail, and one would imagine the metal covering would carry heat away from the contact point.
Or, you could do a combination of these things.
Thanks for the suggestions. I'll see if it's possible to fit some bracket maybe but it'll push the hose just over the injectors, which is not ideal either and will require removing the engine cover (which is no big deal). Just for reference, here is a link to a pic of a similar engine. The hose I'd like to replace is the one circled in red.
Since this setup has been running for 24 years and almost 400'000km (and is still running...), I guess it's not a bad design. But I really don't know what type of fuel hose Volvo used on that location and what is its temp rating.