I'm slowly teaching myself some basic mechanics.
Any tips on checking the various rubber hoses in an engine bay?
* Connectors -- check the ends of the hoses are screwed tight?
* Hose condition -- rubber hoses soften with age. Should the hoses be firm to the touch.
* Leaks -- coolant hoses etc. will show leaks. But what about air pipes? Someone suggested listening with a plastic tube.
* Any other tips?
Mike
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Mike, here's my twopenn'orth ...
* Connectors -- check the ends of the hoses are screwed tight?
# Yes, but not overtight as the clips can cut into the hose, especially the 9mm wide ones (13mm not really a problem).
* Hose condition -- rubber hoses soften with age. Should the hoses be firm to the touch.
# On the contrary, hoses often harden with age/temperature. They do go soft though if in long contact with oil. Hose life depends hugely on the original specification and the conditions they operate in. I can't remember replacing the main hoses on my old Triumph (must be at least 15 years ago) and they are still supple and 'rubbery' to the touch, whereas the smaller ones near the exhaust manifold go hard and brittle and are replaced sooner (about every 10 years!).
* Leaks -- coolant hoses etc. will show leaks. But what about air pipes? Someone suggested listening with a plastic tube.
# I have found listening through a plastic tube to be good for hearing air leaks and for detecting exactly where noises are coming from, e.g. to see if bearing noise is coming from the water pump or the alternator.
* Any other tips?
# I use Simoniz 'Back to Black' on my main water hoses and I feel sure that this helps keep them supple, at least on the outside. It also keeps them looking good for those strange people like myself who enjoy having a smart engine bay.
# I would replace any of the old wire-type hose clips with the worm-drive type commonly know as Jubilee clips (look for 'Jubilee' or 'Norma' brand). Wire clips are not very common these days though, so you may not have any.
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I'd agree with Dizzy's list.
I've often been surprised when removing a hose for some reason just how grotty a hose can be inside although looking and feeling fine on the outside.
Ideally I take the opportunity when draining and flushing a cooling system to replace the antifreeze (every 2 years?) of removing all the hoses and checking them. I have noticed jubilee clips seize up, so they can appear tight but in reality are just locked with rust. I always put graphited grease on the threads of new or reused clips, and then wind them in and out before fitting.
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Also beware of some installations where HT leads pass close to rubber hoses. If this is too close, the Corona discharge surrounding the HT lead (worst case is the coil to distributor lead) will leach out the plasticisers in the rubber, making the hose very hard and brittle in this area. If the hose is subject to bending stress (most are), the hose eventually cracks. Very interesting if it is a fuel hose!
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Rubber fuel lines and seals in older diesel cars may eventually corrode if switching to ULSD (or biodiesel) - modern diesel engines contain synthetic rubber components rather than natural rubber in order to deal with this problem. That said, the rubber bits in older diesel engines is probably so vulcanised as to be bombproof by now.
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