peter moffatt Posted August 4, 2006 Report Share Posted August 4, 2006 My 5 is still suffering from low oil pressure. I have fitted a new oil pump and the readings are again as follows. On tickover when hot 15/20 lbs psi at 2.200 rpm 40/50 lbs psi. I have rechecked the oil pressure relief valve and it seems okay but I dont know what sort of tension the spring should give. I am using Millers 20/50 grade semi synthetic classic engine oil as recommended by Millers. I have always used Millers in my TRs but I am not sure about the word synthetic it sounds to modern to me. My engine has only covered 5,000 miles since being reconditioned and runs sweet as a nut. I would appreciate any thoughts on this problem. Peter UYM 790F Quote Link to post Share on other sites
marvmul Posted August 4, 2006 Report Share Posted August 4, 2006 If the oil pressure is that low since the rebuild, you ought'nt to be much worried anymore by now. If the low pressure is recent, perhaps your engine has a knackerd oil pump or crank bearings, maybe both things, caused by grid or machine swarf circulating with the oil. I would inspect the oilpump tolerances (o,oo5" between inner and outer rotor?) and the main and big end bearings. Quote Link to post Share on other sites
Richard Crawley Posted August 4, 2006 Report Share Posted August 4, 2006 My 5 is still suffering from low oil pressure. I have fitted a new oil pump and the readings are again as follows.Peter UYM 790F Did you check the clearances on the new oil pump before you fitted it? Some, so called, ‘new’ oil pumps are manufactured to such poor tolerances they are way outside what you can get from a carefully selected secondhand unit! Quote Link to post Share on other sites
marvmul Posted August 5, 2006 Report Share Posted August 5, 2006 I' didn't notice you fitted a new oil pump. Checking the tolerances of the new pump, like Richard is proposing, is the first thing to do I think. Not much can be done if the clearance between inner and outer rotor is too big. The body can be sanded (paper fixed to a flat surface) to get the clearance of the endplate to rotors right. New pumps can have another weak point : the shaft get loose, but then you suddenly have no oil pressure. Quote Link to post Share on other sites
peter moffatt Posted August 5, 2006 Author Report Share Posted August 5, 2006 Hello Marvul & Richard, Thanks for your responses. I checked the tolerances you mentioned and they are well within the limits proscribed. As I said earlier the engine has covered less than 5,000 miles since being reconditioned ie reground crank new pistons etc, and there is definately no crankshaft end float. The problem I think started when I changed the oil and filter in May this year. Having said all that I have just had a word with the oil pump supplier, and he recommends I check the rocker shaft which again is new. These shafts are supposed to have caps in the ends, and having checked my rocker shaft it has no cappings. I have ordered another shaft and hopefully that is the answer to my problems. I will keep you informed. Cheers Peter UYM 790F Quote Link to post Share on other sites
Bald Rick Posted August 5, 2006 Report Share Posted August 5, 2006 (edited) Hi Peter Chris Witor does an uprated/blueprinted oil pump for about £65, I've bought one to fit in the engine I'm rebuilding. It may be worth talking to him - http://www.chriswitor.com Also, Do you have fitted one of the auxilliary oil feeds to the top of the head (can you do this on a five?) it can lower the oil pressure quite a bit. On mine it lowered the pressure by about 10-15psi. It is now about the same as yours. Tony Edited August 5, 2006 by mollyqotz Quote Link to post Share on other sites
Guest ron Posted August 8, 2006 Report Share Posted August 8, 2006 Hi Peter Have you checked the accuracy of the oil pressure gauge? Ron Quote Link to post Share on other sites
peter moffatt Posted August 8, 2006 Author Report Share Posted August 8, 2006 Thanks for your input. I an inclined to go with my original rocker shaft supplier in that the rocker shaft bought when I reconditioned the engine has no caps in the end of the shaft ,and I could be losing a significant amount of oil pressure for that reason. A new shaft is on order and I will let you know the outcome when fitted. Thanks Peter UYM 790F Quote Link to post Share on other sites
peter moffatt Posted August 10, 2006 Author Report Share Posted August 10, 2006 I have fitted a new rocker shaft this being one with the ends capped off. The oil pressure is still very low. On speaking to a TR supplier he says that the spin off oil filter I have fitted can drop the oil pressure quite substantially. Is he right?. I am getting desperate now.Will fitting the old type oil filter cure the problem I must say I am rather sceptical. Also I have checked the oil pipe to the guage and it is clear no obstructions, and also fitted another oil guage. The saga goes on. Regards Peter UYM 790F Quote Link to post Share on other sites
Guest harry dent Posted August 11, 2006 Report Share Posted August 11, 2006 A mate of mine had the same problem and it was down to the spin on filter housing.He changed it to the new design which is spring loaded with a more positive seal.Bearing in mind the old designed unit was ok when first fitted and clocked up a few thousand miles till it failed. Harry. Quote Link to post Share on other sites
spiro Posted August 11, 2006 Report Share Posted August 11, 2006 15/20psi on tick over and about 50psi at 2500rpm, I Wouldn't say that's bad. I'don't think you'll find that much better on others 6 cylinder TRs. My TR6 has done 4000 miles since rebuild and has a similar figure plus it has an oil cooler fitted. I've spoken to others and its not that much in it. I'd be happy with that. depends how much you expect really Quote Link to post Share on other sites
Tom Fremont Posted August 11, 2006 Report Share Posted August 11, 2006 A few years back Racetorations told me to expect 70 psi @ 70 mph, not specifying whether or not O/D were present. Mine drops to about 60-65 psi at this speed, in O/D, after about 30+ miles, but no oil cooler is fitted. It drops to 15 psi at idle ( tickover ) speed of ~650 rpm / 20 psi @ 750 rpm, then 50 psi @ 2000 rpm. It will achieve 80+ psi when revved to 4000 rpm or so - all these while hot. The motor has 67000 miles on a rebuild and a spin-on oil filter ( Harry: what on earth is " spring-loaded " on the latest version ). I have verified the oil pressure gauge against a Snap-On gauge: dead on accurate. Note that the needle should rest on zero with motor off; the oil line attachment nut will allow some deviation upon tightening. My oil pump has the minimum practical clearance: 0.0015" between rotor/vane and 0.001" between rotor/housing ( when fitted ). My TR250 Owner's Handbook states "...45-65 psi @ 2000 rpm when hot " Like some others I tend to worry overmuch about oil pressure. I'm thinking to add a cooler. Does anyone know how this will affect pressure ( I'm concerned it will drop due to the added resistance to flow ) Quote Link to post Share on other sites
spiro Posted August 11, 2006 Report Share Posted August 11, 2006 Tom I get the same readings as you say and its has like I said before an oil cooler fitted with a stat in line, so I think you should be ok Quote Link to post Share on other sites
Guest Wyn Posted August 11, 2006 Report Share Posted August 11, 2006 Tom, I've seen no difference in oil pressure readings now I've fitted an oil cooler with thermostat compared to the readings before. Greatest change to oil pressure readings I've noticed is different kind of oils. I had an oil change at a local car garage using modern oils (not sure which) a couple of years ago and the guage was showing far lower pressure, I'm back to Penrite 20/50 now and old readings returned also. We can get a bit paranoid about oil pressure I think (with my limited knowledge!) Tom, I've seen no difference in oil pressure readings now I've fitted an oil cooler with thermostat compared to the readings before. Greatest change to oil pressure readings I've noticed is different kind of oils. I had an oil change at a local car garage using modern oils (not sure which) a couple of years ago and the guage was showing far lower pressure, I'm back to Penrite 20/50 now and old readings returned also. We can get a bit paranoid about oil pressure I think (with my limited knowledge!) Wyn Sorry! Quote Link to post Share on other sites
DaveR Posted August 12, 2006 Report Share Posted August 12, 2006 If you increase the revs up to around 3500 rpm the hot oil pressure should be 55 to 60 lbs psi for an engine in good condition. If the pressure does not increase then check the oil pressure relief valve is seating correctly and replace the valve spring. As interest if you maintain a steady speed on a motorway the pressure will reduce by 5 to 10 lbs psi after a short distance because the oil is heating up and thinning out, hence the need for an oil cooler Just my thoughts. On tickover when hot 15/20 lbs psi at 2.200 rpm 40/50 lbs psi. Peter UYM 790F Quote Link to post Share on other sites
peter moffatt Posted August 12, 2006 Author Report Share Posted August 12, 2006 Thankyou for all your replies to my oil pressure problems. On Monday next week I am taking the 5 to an engineer rebuild specialist he has an accurate oil pressure guage & has offered to check the oil pressure independently from the dash guage. I get the feeling that the iol pressure is not very far from being okay at 2.2200 rpm but rather low on tickover. I will keep you posted. Peter UYM 790F Quote Link to post Share on other sites
rob wilsher Posted August 17, 2006 Report Share Posted August 17, 2006 Hi Peter, I have had similar oil pressure anxieties with my 6. On cold start up I get 70-80 at 2000 rpm (50-60 idling) At running temp I get 50 ish at 2000 rpm and about 15 idling. I have an oil cooler with temp stat, spin on filter and use Penrite oil. Engine runs sweet as a nut with the occasional belch of oil burn smoke from the rear on start up, which I am pretty sure is down to oil seeping down the valve guides (considering fitting oil seals-mixed opinions on this) I'm interested to follow your findings through. Cheers Rob Quote Link to post Share on other sites
peter moffatt Posted August 18, 2006 Author Report Share Posted August 18, 2006 Thankyou for all your replies to my oil pressure problems. I had the oil pressure checked with an independant guage and the readings are the same as the dash guage so it cancels out a faulty dash guage. At the present time I get 15/20 lbs psi at tickover when hot and 50/60 lbs psi at 2,200/2,2,500 rpm which I think is still to low. However we are reaching the end of the Summer season now, and I will nurse the 5 for a few weeks, and will consider ordering an uprated oil pump to fit during the Winter. Cheers Peter UYM 790F Quote Link to post Share on other sites
spiro Posted August 18, 2006 Report Share Posted August 18, 2006 Hi Pete I think me personally its all ok, If read back through the oil pressure reading from the others on this you'll find they all about the same. I don't know what reading you are hoping for, ( to high can be just as bad as to low) I don't think you will improve on what you are getting even with a new pump. Cheers Spiro Quote Link to post Share on other sites
unclepete Posted August 23, 2006 Report Share Posted August 23, 2006 Pete Is the Oil Filter housing the purolator type? If so, on the top there is a big nut with a screw in the middle. loosen the nut and unscrew the oil pressure regulator - remove - strip down and clean - replace and run engine till warm - adjust oil pressure to 70psi at 2000rpm(check?) and nip up nut - job done - had one with a little bit of muck under the spring loaded ball bearing! If it isn't a purolator type just ignore me!!! Unc Quote Link to post Share on other sites
DaveR Posted August 23, 2006 Report Share Posted August 23, 2006 Peter, having lived with this family of engines, 6 Cylinder and the SC 4 Cylinder, for over 40 years your oil pressure sound ok to me. Quote Link to post Share on other sites
Red 6 Posted August 24, 2006 Report Share Posted August 24, 2006 Peter, I have just re-picked up this thread. The oil pressure you describe is normal for a 6 cylinder engine ie 15-20 at tickover when hot and 50-60 at 2500, in fact the pressuure is excellent! If the pressure was higher certain oil seals would leak. If you remember our conversation i explained that the oil presssure is governed by the spring and plunger under the big nut. At the time you thought the pump was suspect. My suggestion was to put in a 2nd spring in i.e 2 springs at once, this would prevent the plunger releasing the pressure and if the oil pump was working would push the pressure reading off the scale! ie it would prove that the pump was capable of pumping. My reccomendation is still to pop an extra spring in and see what happens. In the past i have seen low pressure caused by an old weakened spring and the temporary fix is to stretch the spring until the desired pressure is achieved. Of course it could be somthing else Tom. Quote Link to post Share on other sites
peter moffatt Posted August 24, 2006 Author Report Share Posted August 24, 2006 Tom thanks for your input. I have tried various springs in the relief valve to no avail. I am still convinced the problem is caused by the repro oil pump. During the Winter I shall fit an upmarket oil pump. Cheers Peter. Quote Link to post Share on other sites
Paul Hogan Posted August 26, 2006 Report Share Posted August 26, 2006 Interesting stuff this about oil pressure on 6 pot engines. I also tend to think we worry about oil pressure too much. If you have pressure then its ok. If you haven't got it your up SH*t creek and looking at a rebuild. My own 6 pot was rebulit with a new oil pump and cooler and all tolerances were checked well within limits but would it produce a decent head of pressure? No, it struggled to make 40- 50psi and on tickover it barely registered on the guage. Naturally I was quite worried about this as it was an expensive and all for intents, a brand new engine. It should have been putting out something like 80psi @ 2000 rpm and 40 psi at idle. I too checked the oil pump and the PRV. Nothing. We changed the spring in the PRV with only a very slight improvement and changed the guage. Still nothing. All this time the car was running hot with the temp guage running high. After about 3000 miles I just happened to be looking at the oil guage and noticed it had suddenly shot up to 80psi! Even more surprisingly, at the same time the temp guage went down to the centre of the guage and it has run 'normal' ever since! All i can presume is that an oil way in the block had got some gunge in it even though the crank and engine block had been scrupulously cleaned and assembled. We all know that oil and water don't mix but as for the drop in water temp I can only think that the oil must have been running hotter than it should be and this increased the tempreature of the water flowing through the block. I don't run an oil stat by the way so perhaps the fault lay in the cooler iteslf or from the spin off adaptor which were off the shelf items. (If anyone has any ideas on this then I would be glad to hear them.) On the plus side, there is no sign of damage to the crank or bearings and the car now behaves as if nothing had happened. However, the real point of my own tale is that some oil pressure is better than none at all. 80psi at 2000 rpm might be regarded as normal but 50psi is ok too as your not going to do any damage to the engine. hope this helps. hogie. Quote Link to post Share on other sites
jdbinnington Posted August 28, 2006 Report Share Posted August 28, 2006 peter, those pressures are NOT low. the recorded pressure is simply the resistance to forward oil flow. If you want high oil pressure put gearbox oil in the sump, the pressure will be high but the flow low (and hence the lubrication) the lubricity of an oil in a plain bearing is INDEPENDANT of the supply presssure, it all rests on the film strenght between the journal and the shell. yes knackered engines have low oil pressure, ie less than 5 lbs at hot idle (oil press light comes on) and 20-25 lbs at 3-4000 rpm repeat 50 lbs squinch hot at 2500 rpm is exactly where it should be with oil from 0-30 to 20-50 have you thought about taking out health insurance? you probably won't need that either... spikius maximus lateralis Quote Link to post Share on other sites
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