stag chris Posted July 5, 2022 Share Posted July 5, 2022 I have a 1976 stag with a rebuilt eng oil presure is fine on start up but presure drops to 0ps when eng gets up to working temp any ideas thanks CHRIS Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted July 5, 2022 Share Posted July 5, 2022 0psi at idle, or everywhere? What are the actual numbers when cold and what oil is in it? Mechanical gauge or electrical? Assuming it’s not a measurement issue it sounds like excessive clearances either within the oil pump or crank to bearing shells, especially main bearings. The oil thins down when hot and slips through the gaps easier, dropping the pressure. Nick Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 5, 2022 Share Posted July 5, 2022 Also, what oil do you use? There are some pretty poor oils out there and excessive thinning when hot is a common issue. Quote Link to comment Share on other sites More sharing options...
stag chris Posted July 5, 2022 Author Share Posted July 5, 2022 exopro 20w-50 classic mineral Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 5, 2022 Share Posted July 5, 2022 Well, I'm not familiar with that make at all. Their web site makes all the usual meaningless claims for it, but the data sheet doesn't even mention the "high zinc content" they claim. It also gives viscosity figures that look decidedly runny when hot, to my inexpert eye. It might be worth you trying something like Penrite 20W60 - I find that's one of the better oils for Triumph engines. Also, answer Nick's questions, as he generally knows what he's talking about. Quote Link to comment Share on other sites More sharing options...
stag chris Posted July 6, 2022 Author Share Posted July 6, 2022 thanks i have ordered some just have to wait for it to come Quote Link to comment Share on other sites More sharing options...
Martins Stag Posted July 6, 2022 Share Posted July 6, 2022 I would bow to Rob and Nick expertise but I would hope that any 20/50 engine oil would have some pressure at working temp and not zero? I would try a second gauge first just to check before you look further. I also use a 20/60 oil 1 Quote Link to comment Share on other sites More sharing options...
pete jackson Posted July 6, 2022 Share Posted July 6, 2022 I once tried that Classic brand of oil once in my 2000 and after my first run after the oil change the oil light came on first at idle then it would flicker at low speed in traffic. Needless to say I change the oil to 20/50 and never had another issue with the oil light after that. Quote Link to comment Share on other sites More sharing options...
glang Posted July 6, 2022 Share Posted July 6, 2022 Know nothing about Stags but must have some sort of oil pressure relief valve so is it worth checking its not stuck open? Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 6, 2022 Share Posted July 6, 2022 (edited) 3 hours ago, Martins Stag said: I would hope that any 20/50 engine oil would have some pressure at working temp and not zero Yes, but given how accurate most oil pressure gauges aren't... We had one on a Herald, which admittedly had a fairly worn engine and low pressure, which would read a good 30PSI negative at idle! That was one of Nick's comments and he asked what sort of gauge too. Edited July 6, 2022 by RobPearce Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted July 6, 2022 Share Posted July 6, 2022 6 hours ago, Martins Stag said: I would hope that any 20/50 engine oil would have some pressure at working temp and not zero? Well absolutely. Me too. Though it was never revealed whether that is 0 psi at idle or 0 psi everywhere. If the latter, I’m not sure I’d be wasting more oil on it without making some checks on gauge accuracy. 5 hours ago, glang said: Know nothing about Stags but must have some sort of oil pressure relief valve so is it worth checking its not stuck open? Yeah, except that is sort of ruled out by it having oil pressure when cold…. I suppose the valve may not be seating properly. It’s in the pump body which is external so reasonably easy to check. Quote Link to comment Share on other sites More sharing options...
glang Posted July 7, 2022 Share Posted July 7, 2022 Precisely, if not seating 100% will leak oil which is ok cold but excessive when hot... Quote Link to comment Share on other sites More sharing options...
stag chris Posted July 11, 2022 Author Share Posted July 11, 2022 I have put penrite oil 40/70 in I have oil presure 50lbs from coid down to 15lbs at 1000rpm when hot not as good as I use to be have but better than it was Quote Link to comment Share on other sites More sharing options...
Andy Farmer Posted February 11 Share Posted February 11 Hello, my first posting on here as a Stag owner and am hoping the fonts of all knowledge can help. I have 2 MG's also but this is my first Triumph classic. So a few weeks ago I bought a 1973, 3ltr V8 Triumph Stag (Triumph engine) from a company who deal with all things classic cars. Judging by the amount of history that came with the car, the previous owner (sadly now passed away) really did look after it with all receipts, MOT's and a full service history. The company I bought it from serviced and MOT'd the car before delivering it to me. Time and work constraints prevented me from taking it for a drive immediately but last Sunday I said to myself, "nice day so why not go for a spin". Something in me though told me to check the water and oil levels before setting off and I'm glad I did. The dip stick was bone dry and although I had run the engine just after delivery and it run fine, there was no sign of any oil. Reluctantly, I turned on the engine and it started fine and ran well so I switched it off after a couple of minutes. I checked the dip stick again thinking oil would be present, but it was dry. I got under the car and could see a new oil filter had been fitted and there was no sign of any oil leak. I contacted the seller and he told me he has 2 long term mechanics and both thought the other one had filled it with oil but actually, neither of them did !! Her apologised and offered to refund a small sum for the error which I accepted. I had a new bottle of Castrol GTX 15W-40 on the shelf so topped up the engine as I feared more damage would be done if I didn't. Oil pressure on re-start was very low and if I'm reading the gauge correctly, shows about 25lb per square inch but then gets to about 48lb per square inch as the engine warms but then drops again and doesn't really rise again. It may well be that the GTX 15W-40 is the wrong oil for this engine (guidance please) but having done some research, I've bought some Heritage 20W-50 and whilst I enjoy watching Fuzz Townshend on the TV, I was not influenced by him as such but more by the notion this oil would be better for a classic car engine. I plan to drain the engine of the GTX oil, replace the new oil filter with another, and basically do another oil change myself as I'll know it's been done !! My question then is, would the GTX oil cause the low oil pressure and fluctuation in pressure when the engine is warm or would damage have been done on the occasions when the engine was run "dry" ?There must have been some oil present otherwise the engine would have been very "tappy" but in fairness, it started well and run well and smooth for the times the engine was run in my workshop. No sign of any blue smoke from the exhaust either and no signs of overheating. My second question is do you think the replacement 20W-50 oil will improve the oil pressure or are these Triumph engines just prone to low oil pressure ? Thanks and sorry if I rattled on a bit !! Quote Link to comment Share on other sites More sharing options...
Rubce Posted February 11 Share Posted February 11 (edited) Hi. 20:50 oil is required in a Stag V8. The 15:40 you initially added is simply too thin. I suggest you drop the whole lot out, replace the filter and refill only with 20:50. The pressure will improve with the thicker oil. Pressure at cold should be around 40 to 50psi and that will drop to 25 to 30psi when the engine is properly hot and the oil is nice and warm. With regards to the company you bought it from, they sound unprofessional. If it was me I would be thinking what else did they miss on the service! But that's probably just me. Enjoy your new acquisition Regards Bruce (Stag owner for 18 years) Edited February 11 by Rubce 1 Quote Link to comment Share on other sites More sharing options...
glang Posted February 11 Share Posted February 11 Is your oil pressure warning light working? Ive changed mine to a very bright LED bulb... Generally oil pressure is highest when the oil is cold and new then drops as both of these factors change. The other thing that affects oil pressure is the state of the engine. As the crankshaft bearings and/or oil pump wear their clearances increase so leakage makes system pressure drop. Finally oil pressure gauges are also known as 'worry gauges' exactly because they can induce excessive concern😁 They can be quite inaccurate so really youre looking for change in the reading to indicate a problem... Quote Link to comment Share on other sites More sharing options...
Andy Farmer Posted February 11 Share Posted February 11 2 hours ago, Rubce said: Hi. 20:50 oil is required in a Stag V8. The 15:40 you initially added is simply too thin. I suggest you drop the whole lot out, replace the filter and refill only with 20:50. The pressure will improve with the thicker oil. Pressure at cold should be around 40 to 50psi and that will drop to 25 to 30psi when the engine is properly hot and the oil is nice and warm. With regards to the company you bought it from, they sound unprofessional. If it was me I would be thinking what else did they miss on the service! But that's probably just me. Enjoy your new acquisition Regards Bruce (Stag owner for 18 years) Thanks for the feedback. I do plan to do a full oil and filter change now I have the 20:50 oil and I was already asking myself, what else did the seller not do as part of the agreement so will be checking other aspects too, such as brakes. The company I bought it from appeared to be reputable and indeed the owner, on the subject of lack of oil in the engine, told me quote "the mechanics have been with me for over 35 years and would be most unlike them". Well the fact is, they both screwed up and the company owner screwed up too for not checking. I'll do the oil change this week hopoefully. 2 Quote Link to comment Share on other sites More sharing options...
Vader Posted February 11 Share Posted February 11 Your pressure sounds fine. My stag is just under 50 psi when cold and driving and 25 psi hot idle. you may see you pressure increase with 20/50. Too much pressure isn’t good tho as that may suggest a blockage. Yours sounds fine. Quote Link to comment Share on other sites More sharing options...
Andy Farmer Posted February 11 Share Posted February 11 10 hours ago, Rubce said: Hi. 20:50 oil is required in a Stag V8. The 15:40 you initially added is simply too thin. I suggest you drop the whole lot out, replace the filter and refill only with 20:50. The pressure will improve with the thicker oil. Pressure at cold should be around 40 to 50psi and that will drop to 25 to 30psi when the engine is properly hot and the oil is nice and warm. With regards to the company you bought it from, they sound unprofessional. If it was me I would be thinking what else did they miss on the service! But that's probably just me. Enjoy your new acquisition Regards Bruce (Stag owner for 18 years) Thanks for the feedback. I do plan to do a full oil and filter change now I have the 20:50 oil and I was already asking myself, what else did the seller not do as part of the agreement so will be checking other aspects too, such as brakes. The company I bought it from appeared to be reputable and indeed the owner, on the subject of lack of oil in the engine, told me quote "the mechanics have been with me for over 35 years and would be most unlike them". Well the fact is, they both screwed up and the company owner screwed up too for not checking. I'll do the oil change this week hopefully. Quote Link to comment Share on other sites More sharing options...
Andy Farmer Posted February 11 Share Posted February 11 This may sound daft but for the life of me I cannot find how much oil is supposed to be put in this engine. Any pointers would be much appreciated. Quote Link to comment Share on other sites More sharing options...
Rubce Posted February 11 Share Posted February 11 Thw V8 takes about 4.5 litres. Fill it to the marks on the dipstick. 1 Quote Link to comment Share on other sites More sharing options...
Andy Farmer Posted February 12 Share Posted February 12 Thanks for the help so far, much appreciated. Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted February 12 Share Posted February 12 Might be an idea to cut the old oil filter in have when off the engine and have a good look at what is inside it? Try and cut it without leaving swarf as this will skew the findings. Valvoline VR1 or Classic Oils 20/50 are good oils. Quote Link to comment Share on other sites More sharing options...
Slimboyfat Posted February 14 Share Posted February 14 We bought in a Stag once from a local chap. He had given up on it because not long after a service from a reputable classic car specialist it quickly lost oil pressure. It turned out they had done a through job of cleaning out the oil filter housing, including disassembling it, but in the reassembly they had put the bypass valve the wrong end of the filter. A crank grind later, and a correctly orientated oil filter arrangement it had fantastic pressure. Quote Link to comment Share on other sites More sharing options...
glang Posted February 14 Share Posted February 14 Amazing, seems some people dont know what the oil pressure warning light is for! Quote Link to comment Share on other sites More sharing options...
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