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Any advantage to longer oil cooler lines? 22 Nov 2022 11:23 #877078

  • Wookie58
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The longer hose will likely cause a drop in oil pressure where it's needed.  The oil pump has to push more oil with longer lines - and that will cause the oil pump more work and some of these older oil pumps struggle without an oil cooler to start with.
Will it actually cause low pressure or is it more likely and "crucially" that it will take "longer to build pressure" on start up and therefore starve the head and cams during start up - not ideal 
PS: just voicing an opinion and asking a genuine question - not trying to be argumentative (Jeff you know far more about these bikes than I do)

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Last edit: by Wookie58.

Any advantage to longer oil cooler lines? 22 Nov 2022 11:30 #877080

  • Nerdy
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The longer hose will likely cause a drop in oil pressure where it's needed.  The oil pump has to push more oil with longer lines - and that will cause the oil pump more work and some of these older oil pumps struggle without an oil cooler to start with.
 

Thank you for the info. Do you recall if the 440 oil pump historically falls into the "struggle" category? If it does, then I should probably skip the cooler.

The engine has about 21K miles but I haven't had it apart. If a 440 oil pump in good condition can generally handle a cooler, then I'll plan to replace the pump and carry on.
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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Any advantage to longer oil cooler lines? 13 Dec 2022 00:27 #877757

  • Ian_B
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That "around the houses" routing of oil pipes looks like someone shouting "Hey, look at my ultra cool bolt-on oil cooler!". Purely fashion in my personal opinion, a bit like pointing at your left ear with your right hand. I'd be looking for the shortest, most protected route from the block to the cooler, and then tie the lines down properly to stop them fretting.

On the "it takes longer to get oil to the bearings on startup" - this will only happen if the oil coler drains back to the sump when the bike is not running. There's not much of a head difference between the cooler and the sump, and no obvious route for air to get into the cooler, so it will *probbaly* remain oil filled - which means near instant delivery of oil to bearings on startup. May be different after a long stand, or if the system has been opened up, in which case it'll need to refill before delivering a steady oil supply to the bearings.

Oil pumps are gear types, so principally positive displacement pumps. If in good condition, for any given rotation speed, they will pump the same volume, only pressure (eg. due to longer hoses) will increase. This becomes less the case as the pump wears, when it starts to behave more like a centrifugal - more slippage at higher back pressures. The length of the lines will probably hardly be noticed by the oil pump - but I'd still keep them short...

Ian

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Any advantage to longer oil cooler lines? 13 Dec 2022 04:39 #877758

  • hardrockminer
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An oil cooler and long hose attachments will definitely add pressure loss due to friction inside the hoses and fittings.  The impact on the cooling system will depend to some degree on the bike in question.  For example, Z1 engines are low pressure/hi flow systems with gear pumps.  KZ650 engines are higher pressure lower flow systems, so increasing pressure will put more strain on the pump.  

The real question is whether the bike requires a cooler in the first place.  Most vintage bikes are lower (8 or 9 to 1) compression engines with plenty of heat dissipation, so they don't need oil coolers.  Adding one is for style only. 

Higher compression engines (11 or 12 to 1) will create a lot more heat and may need a cooling system to keep the engine in the proper operating range.  If the bike originally came without a cooler I would leave it alone.  But if I was souping up an engine with higher compression I might consider a cooler, particularly if I operated the bike in a hot environment.
I have several restored bikes along with a 2006 Goldwing with a sidecar. My wife has a 2019 Suzuki DR 650 for on and off road.

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Last edit: by hardrockminer.
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