FridgeFreezer Posted July 1, 2018 Share Posted July 1, 2018 Not sure if anyone here can offer solid advice on this - the P38 front cover is a convoluted beastie and it's not documented in RAVE etc. as to exactly what's going on, so with the aid of cable ties I'm taking a guess and hoping someone who knows might chime in. The short version is I want to block off the oil cooler ports - currently on both my lumps I've got a short pipe linking the in & out and that appears to work fine, but it's untidy. Anyway, tracing the oil flow from pump output: PINK goes straight out through the cooler port, a clear passage. YELLOW goes into the outside of the filter housing via a sprung valve that looks a lot like an oil pressure relief valve. ORANGE takes the centre of the filter straight up & into the block, via the oil pressure switch. The mysterious bottom passage (ooo-err) features another pressure-relief valve that looks a lot like it returns "over-pressure" back to the inlet side of the oil pump gears, from the filter input. So, my theory of operation is: The pump sends pressure into the oil cooler, which I'm guessing either has some restriction, a stat, or is just restrictive to cold oil. This returns to the INPUT side of the oil filter, is filtered & passes round the engine. The pump ALSO sends pressure into the spring-valve leading to the filter input directly, so if the flow to the oil cooler is restricted it just goes straight into the filter. From the filter INPUT side, there is a pressure relief valve which regulates the oil pressure for the engine, flowing oil back to the input of the pump (sump pickup). From the filter it's off round the engine and back to the sump. Sound sane so far? Fingers crossed! Anyway, my theory (wot is mine wot I wrote) is that I can block off the two oil cooler ports which should just result in increased flow into the oil filter input side. I don't know whether removing the spring valve would be a reasonable idea or whether it's best not fiddled with (my vote). So - anyone care to point out the glaring errors in my plan? Quote Link to comment Share on other sites More sharing options...
lo-fi Posted July 2, 2018 Share Posted July 2, 2018 I've done just that on my serp engine. Slightly different cover as it's from a disco with a dizzy, but the same pump. Seems to work fine, I get >40 psi hot or cold. My setup runs a remote filter with an oil cooler plumbed in the circuit after the filter and original oil cooler ports blanked. I did try running with an oil cooler on the original lines just to see what would happen, but it made no difference to oil pressure. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 16, 2018 Author Share Posted July 16, 2018 Well having satisfied myself this should work, and that the oil pressure switch is on the "block" side so WILL always give warning if there's low pressure to the engine itself, I bit the bullet and blanked the ports on the Ambulance, and so far so good. The ports are M20 if anyone needs to know. If you get a hydraulic fitting / adapter you may need to shave it down, but blanking plugs seem to fit OK. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 16, 2018 Share Posted July 16, 2018 Useful info for when I fit the serp front on my 4.2. Thanks John. Just a thought though, how sure are you the thread is M20? 1/2" BSP is near as dammit 20mm O.D. but it is a somewhat finer pitch. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 16, 2018 Author Share Posted July 16, 2018 14 minutes ago, mickeyw said: Just a thought though, how sure are you the thread is M20? 1/2" BSP is near as dammit 20mm O.D. but it is a somewhat finer pitch. Definitely not 1/2" BSP. Most automotive stuff generally uses metric these days (as in, for the last 20 years or so...). The fitting is the same as several other things (for example, Freelander oil cooler pipes) all created under the BMW-era using the same style of fitting where the end of the pipe is formed & holds an O-ring, totally different to industrial hydraulics. Also the nice man at the hydraulics shop identified it as M20 and the M20 plug screws in perfectly. Quote Link to comment Share on other sites More sharing options...
neil110 Posted July 16, 2018 Share Posted July 16, 2018 Isn't there a diagram of the oil flow in the later type V8 engines in the Land Rover V8 overhaul manual? The paper version Quote Link to comment Share on other sites More sharing options...
landroversforever Posted July 17, 2018 Share Posted July 17, 2018 Is there a reason for not wanting an oil cooler on there too? Or isn't that necessary with (normal) UK temperatures? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 17, 2018 Author Share Posted July 17, 2018 Neil - not that I've found for the P38-era stuff. Happy to be corrected though! Ross - temperature labels say it doesn't overheat the oil so why add more plumbing etc. to go wrong or get damaged? Also, clearance from the takeoff port to the steering box is "snug" so it's nice to have a plug in there rather than a fitting sticking out: I know it goes against everything most people seem to do with their vehicles (bolt as much extra stuff on as possible) but I'm a big believer of simplifying things as much as possible. Less to go wrong, less weight, easier to fix. Quote Link to comment Share on other sites More sharing options...
lo-fi Posted July 17, 2018 Share Posted July 17, 2018 I found that adding a cooler stopped the oil pressure dropping at lower revs when hot, having originally run without one. Not enough to set the light off, but worryingly low on the gauge. The oil cooler sorted it right out. But I guess you're not going to be using it like a tractor and towing a harrow over deep sand in a manège at 5mph.... Quote Link to comment Share on other sites More sharing options...
dangerous doug Posted July 17, 2018 Share Posted July 17, 2018 I’m glad you looked into this fridge, did the same mod you did and linked to Two ports together but it looks a bit carp and it’s more to get snagged up on like you say. A few few months ago on Facebook the “rover v8 engine appreciation” group were talking about it and apparently tvr blanked the ports from the factory. I diddnt want to act on the word of Facebook experts as I treat everyone on there like an idiot untill proven otherwise but now I’ve seen some more info in it Im off to get some blanking bungs! Quote Link to comment Share on other sites More sharing options...
neil110 Posted July 18, 2018 Share Posted July 18, 2018 (edited) On 7/17/2018 at 1:49 PM, FridgeFreezer said: Neil - not that I've found for the P38-era stuff. Happy to be corrected though! Ross - temperature labels say it doesn't overheat the oil so why add more plumbing etc. to go wrong or get damaged? Also, clearance from the takeoff port to the steering box is "snug" so it's nice to have a plug in there rather than a fitting sticking out: I know it goes against everything most people seem to do with their vehicles (bolt as much extra stuff on as possible) but I'm a big believer of simplifying things as much as possible. Less to go wrong, less weight, easier to fix. Page 28 though it is not the easiest diagram to follow but it does make the point about the oil cooler "if fitted" https://www.usermanuals.tech/d/land-rover-4-0-4-6-v8-engine-overhaul-4th-edition-rover-manual/part3#27 Edited July 18, 2018 by neil110 Quote Link to comment Share on other sites More sharing options...
smallfry Posted July 18, 2018 Share Posted July 18, 2018 Having had lots of vehicles powered by the Rover V8, I have never had an oil cooler fitted, and have never felt it necessary to have one for "normal" use. Not in the UK. Quote Link to comment Share on other sites More sharing options...
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