Berty Posted July 17, 2019 Report Share Posted July 17, 2019 Hopefully someone can advise. I have read up on this and the suggestions range from "don't worry about it" to "rebuild the engine"! Herald 13/60 When starting from cold the idle oil pressure is around 30 PSI, which seems to be about correct. As the engine gets hotter the idle oil pressure drops. Eventually reaching 0 PSI if stuck in traffic. At 3000 revs it's always 35+ PSI whether hot or cold, it's only the PSI at idle that changes. The car is not losing oil and runs fine. I have recently changed the oil which has made no difference. I am using "Comma CLA20505L 5L 20W/50 Classic Motor Oil" (this was recommended somewhere, but can't remember where). So my first thought is the oil itself, getting too thin when hot. Any recommendations? Second thought would be the oil pump, but I'd rather not change that if it doesn't need it. Are these symptoms a problem anyway? Thanks in advance. Link to comment Share on other sites More sharing options...
Clive Posted July 17, 2019 Report Share Posted July 17, 2019 1. Check if the oil pressure gauge is accurate. To be honest, it sounds like it probably is, but worth checking, or try(beg/borrow/steal) another and see if it behaves the same. 2. I would be examining the pressure relief valve. I would expect more pressure when cold, but Dodgy off spring or damaged seat may help explain things. 3. The oil is "ok" when new but needs changing at 3k max miles. There are better oils available. 4. Oil filter. People have had issues with the current oil filters, quality is patchy. I know of one that caused pressure issues. 5. Could be bearings and or oil pump. When did you notice the issue? Is it always the same, or didn't happen after an oil/filter change? Does the oil pressure green lamp come on? That is about 7psi. 1 Link to comment Share on other sites More sharing options...
Berty Posted July 17, 2019 Author Report Share Posted July 17, 2019 Thanks for getting back to me Clive. I noticed this at the end of last season, it may have been like it since I got the car 3 years ago - not sure. Earlier this year I did a basic service and changed the oil filter and oil. Thought this may have alleviated the issue as the pressure seemed fine - but I hadn't worked out that it was only when hot that the problem appears. So the oil change and oil filter change made no difference. Probably only done around 200 miles since then. The oil pressure light does not come on (could have sworn this was orange though). I will do another test today, but the problem seems consistent. Sounds like the oil pressure relief valve may need a service...... Link to comment Share on other sites More sharing options...
NonMember Posted July 17, 2019 Report Share Posted July 17, 2019 I'd echo Clive's comments. When I had a 13/60 the oil pressure gauge would read negative pressure when hot - which is clearly meaningless so it was obviously out of calibration. It's worth a check. I also had a Vitesse that I fitted a gauge to because the oil light started coming on and I replaced all the big end bearings to no avail... only to realise the switch was duff. If it's a moderately high mileage engine and isn't making any nasty noises, try using a better oil. Penrite's 20/60 is good for such engines and will last longer - about 6K miles as per the book. When I used Comma oil in one of mine, it gave good pressure for about a hundred miles then went thin! Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2019 Report Share Posted July 17, 2019 I had a similar problem with oil pressure readings last year. Ok til warm then low reading/warning light. Replaced both pressure warning light sensor and oil pressure releif valve and all now fine. It was running on Wilko 20/50 oil but now replaced with Classic Oils Heritage 20/50 and running nicely at the moment. The last time I made a comment about something running well, it failed the next week!! 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 17, 2019 Report Share Posted July 17, 2019 and the spec is 40 to 60 psi at 2000 rpm all engines . if it shows 0 on gauge the oil light should have come on around 6psi , dont worry about the colour many have wrong bulb in wrong holder i would have said orange for oil red for charge and green for indicators , blue main beam but its easy to mix them around . i wouldalso suggest whip the relief valve out and check its clean and .......seated Pete Link to comment Share on other sites More sharing options...
poppyman Posted July 17, 2019 Report Share Posted July 17, 2019 13 minutes ago, Badwolf said: I had a similar problem with oil pressure readings last year. Ok til warm then low reading/warning light. Replaced both pressure warning light sensor and oil pressure releif valve and all now fine. It was running on Wilko 20/50 oil but now replaced with Classic Oils Heritage 20/50 and running nicely at the moment. The last time I made a comment about something running well, it failed the next week!! I have heard similar problems with Wilko 20/50 Badwolf, but do you know they do two types? One is the standard 20/50 the other is "classic" 20/50 a couple of quid dearer. I have used the latter with no problem. Which did you use? Tony. 1 Link to comment Share on other sites More sharing options...
JohnD Posted July 17, 2019 Report Share Posted July 17, 2019 I don't think that 30psi when cold is OK at all! Should be at least twice that, and as even a good multigrade oil gets 'thinner', less viscous, as it warms up, the pressure for the same flow of oil from the pump will fall. That it 'only' registers 30psi cold when means that the bearings are worn and allowing oil to flow more easily through them. No amount of new oil, filters will make any difference. It just could be the oil pressure relief valve is stuck open, or more open than it should be. That operates because the oil pump is a full-flow type, running relative to engine speed. At high revs, much more oil than the engine can consume is pushed towards it, so the valve opens to avoid blowing anything up. Same at cold starting. So may be worth taking that out and inspecting it, making sure there is a wear mark, all around the valve rim, and that the spring is not broken. But the definitive fix has to be new bearings. Can be done, lying under the car with the sump off and old oil dripping in your face, but the ultimate faff. Better take out the engine and rebuild it, as the crank might need a regrind by now. Who knows until you take it out? Again, using a micrometer from under the car is possible but shall we say fiddly? John 2 1 Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2019 Report Share Posted July 17, 2019 Tony - It was the Wilko 'classic' that I used. Wanted a sort of flushing oil after the car had been laid up, before putting in something fairly decent. Ended up getting 4 'gallons' of Classic Oils Hertage at a discount and free carriage on a fleabay sitewide discount day so very reasonable price in the end. Should see me and probably tbe car to the end of our days!! 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 17, 2019 Report Share Posted July 17, 2019 we changed the crank on the Vit6 In car....does it get heavy or what !!!! however ... certainly do the easy cheap first , but its no use tickling an elephant with a feather if its not simple . Johns right . Pete Link to comment Share on other sites More sharing options...
Clive Posted July 17, 2019 Report Share Posted July 17, 2019 What concerns/baffles me is the max pressure being 35psi hot or cold. Even with knackered bearings pressure is higher when cold. Link to comment Share on other sites More sharing options...
JohnD Posted July 17, 2019 Report Share Posted July 17, 2019 Reread, Clive. "As the engine gets hotter the idle oil pressure drops. Eventually reaching 0 PSI if stuck in traffic. " The OE oil pump has a large capacity that increases as revs do. Hence the need for the relief valve. JOhn Link to comment Share on other sites More sharing options...
Clive Posted July 17, 2019 Report Share Posted July 17, 2019 John, suggest you read the first post.... When starting from cold the idle oil pressure is around 30 PSI, which seems to be about correct. As the engine gets hotter the idle oil pressure drops. Eventually reaching 0 PSI if stuck in traffic. At 3000 revs it's always 35+ PSI whether hot or cold, it's only the PSI at idle that changes. Link to comment Share on other sites More sharing options...
Berty Posted July 17, 2019 Author Report Share Posted July 17, 2019 Thanks everyone for your input. Very Helpful. I will recondition the relief valve - I'll get a new spring and piston. I have certainly not replaced these and I don't know if they were done when the engine was rebuilt some time in the 90s. I'll see if that gets the pressure up. If it does then I'll change the oil if it doesn't stay up. Otherwise I will be getting some work done over the winter and will add bearings to the list..... I will report back...... Link to comment Share on other sites More sharing options...
daverclasper Posted July 17, 2019 Report Share Posted July 17, 2019 Hi. Just out of interest. If an oil light comes on/goes off at around 7 PSI, and a gauge confirms this. Is that an indication that the gauge is likely to be accurate at the higher pressures?. Cheers, Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 17, 2019 Report Share Posted July 17, 2019 er yes , there again possibly not we had a gauge calibration rig, went in the skip when everything closed down , being clever afterwards i should have secreted it away , as did loads of what could be useful now apart from space .to keep it all. Pete you can make a rig off tube to attach to a tyre inflator or even the tyre valve blow the tyre to 30psi then connect the oil gauge should read the same Link to comment Share on other sites More sharing options...
johny Posted July 17, 2019 Report Share Posted July 17, 2019 Berty I would save your money for the other bits you might need because as long as the relief valve isnt damaged and closes fully it wont be the cause of the low pressure. A stronger spring just increases the max pressure reached ie at high revs and not the idle pressure which is your problem. Its almost certainly down to worn bearings and pump (dont think youve said how many miles your engine has done) however a high running temperature especially in traffic will exacerbate the problem as the oil thins even more. If this is the case be careful to minimise driving it under those conditions as you run the risk of a bearing failing (they can deteriorate quite quickly) and damaging the crank which will then require a regrind as well as new bearings. My Vitesse had just the same symptoms after about 70k miles from new but I caught it in time and only had to replace the bearings and pump (only!) to restore great oil pressure. Link to comment Share on other sites More sharing options...
Clive Posted July 17, 2019 Report Share Posted July 17, 2019 I think pulling the org is sensible (and easy/free) and have a quick look. You can put a washer or 2 behind the spring to increase pressure,free what happens. But does the oil bought come on (it should before you start the engine)? If it comes n then, but not when running, even at indicated zero pressure, I would suspect the oil pressure gauge. Maybe get along to a meeting and see if you can borrow one? Or check you gauge on somebody else's car? See if that is the issue, otherwise you could try stuff to fix a problem that does not exist. 1 Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2019 Report Share Posted July 17, 2019 Further to Clive's post this may be worth a look. It offered me a little help when I had problems. It may not solve your problems but it is interesting... http://tr6.danielsonfamily.org/RaisingOilPressure.htm Link to comment Share on other sites More sharing options...
JohnD Posted July 17, 2019 Report Share Posted July 17, 2019 4 hours ago, clive said: John, suggest you read the first post.... When starting from cold the idle oil pressure is around 30 PSI, which seems to be about correct. As the engine gets hotter the idle oil pressure drops. Eventually reaching 0 PSI if stuck in traffic. At 3000 revs it's always 35+ PSI whether hot or cold, it's only the PSI at idle that changes. Clive, read mine. Link to comment Share on other sites More sharing options...
Gully Posted July 17, 2019 Report Share Posted July 17, 2019 58 minutes ago, clive said: But does the oil bought come on (it should before you start the engine)? If it comes n then, but not when running, even at indicated zero pressure, I would suspect the oil pressure gauge. Maybe get along to a meeting and see if you can borrow one? Or check you gauge on somebody else's car? See if that is the issue, otherwise you could try stuff to fix a problem that does not exist. Agreed - need to establish if there is a problem with oil pressure before trying to cure it. They're not called worry gauges for nothing! Gully Link to comment Share on other sites More sharing options...
johny Posted July 17, 2019 Report Share Posted July 17, 2019 And above all, let us know what you find so we all learn🤗 1 Link to comment Share on other sites More sharing options...
hugh Posted July 21, 2019 Report Share Posted July 21, 2019 Have to say I agree with Johnd your bearings are well worn, and if bad enough to virtually no oil pressure when warm, the crank will need a rgrind Link to comment Share on other sites More sharing options...
SpitFire6 Posted July 21, 2019 Report Share Posted July 21, 2019 Hi, Hi, Calibrate your oi pressure gauge first. Explained in a previous post. if your hot oil pressure is 40+ at 2k or maybe 3K hot then OK. No harm in checking PRV. Do not add washers unless the cheap spring is shot. Do not try 20W60 in the engine unless you are selling to a dealer. Dump the crap Comma oil. It will last a couple of K if your lucky. Much better 20W50 oils out there. Oil pump would be next easy thing to check with feeler gauges. If you do have to change bearings & pump; suggest you avoid 20W50 if you do not want a repeat. LOL. Cheers, Iain 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 21, 2019 Report Share Posted July 21, 2019 Ian you say there's better 20/50 then say avoid 20/50 Think youve got my typing gremlins Pete Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now