Anglefire Posted May 28, 2018 Report Share Posted May 28, 2018 I have a real weird issue with my oil pressure on start up. Which I think I've worked out what is happening. Basically, I start the engine and the oil light goes out almost straight away. The pressure gauge builds up, then falls, then builds up, then might fall again, then builds up and sits at 90psi ish. Then as it warms up drops back to 50psi ish - even hotter and it drops another 10psi or so. The lower the oil level, the more times its seems to oscillate. I think what is happening, is that the pump basically is pulling the oil out of the sump quicker than its dropping back in - until its warm enough. I've had a look at the dipstick tube to see if the marks are in the right place and compared it to the engine I took out. Current engine on the right, old engine the left. Current engine tube length 30mm or 1 3/8" Old tube length 1 1/4" So given the marks on the old and new are about the same in the engine, any ideas why the oil return is slow? Assuming that the oil level is actually correct in both cases! The old engine came out of a Dolly, the new one is a Spitfire engine. I am going to change the oil anyway soon and put Millers 20/50 in which might get done next weekend unless I get some time one evening this week. Link to comment Share on other sites More sharing options...
yorkshire_spam Posted May 28, 2018 Report Share Posted May 28, 2018 I wonder if the relief "plunger" is sticking? Rather than it being an issue of the pump sucking the sump dry? Link to comment Share on other sites More sharing options...
Anglefire Posted May 28, 2018 Author Report Share Posted May 28, 2018 Doesn't seem to be. But never say never! Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 29, 2018 Report Share Posted May 29, 2018 With a sump capacity of 4.5 litres and guess the oil, gallery and crank take about 0.5 ltr then doubt its sucking from a empty sump There more than enough to keep the strainer in oil, unless theres a crack in the suction tube I would look more at the prv and its seating and the filter Pete Link to comment Share on other sites More sharing options...
yorkshire_spam Posted May 29, 2018 Report Share Posted May 29, 2018 Is it sucking the sides in on the filter? Ahhh no, pump then filter, so it won't... ignore me. Link to comment Share on other sites More sharing options...
Anglefire Posted May 30, 2018 Author Report Share Posted May 30, 2018 21 hours ago, Pete Lewis said: With a sump capacity of 4.5 litres and guess the oil, gallery and crank take about 0.5 ltr then doubt its sucking from a empty sump There more than enough to keep the strainer in oil, unless theres a crack in the suction tube I would look more at the prv and its seating and the filter Pete Oil pump is new. So hopefully that it’s it. The level only needs to go below the level of the intake. And was a lot worse when the level was down to the minimum mark. Once topped up was ok. Prv is new - but I’ve not inspected the seat. Might need a cut down drill .. Link to comment Share on other sites More sharing options...
NonMember Posted May 30, 2018 Report Share Posted May 30, 2018 But as has been said, the oil pickup should be below the dipstick minimum mark, and the oil capacity between marks is much more than the expected capacity of the upper part of the engine. If your theory is correct, then you've got a serious problem with failure to drain back from the working parts to the sump. I'm not quite sure how that could be. Link to comment Share on other sites More sharing options...
Anglefire Posted May 30, 2018 Author Report Share Posted May 30, 2018 No, I haven’t either. Im going to drop the oil at the weekend and fit a new filter and look at the prv again. Going to fit the 3/4 adapter and a suitable filter. The one @rogerguzzi suggested on the other post is about £2.70 from eurocarparts with the current discount and they have an outlet right by the office. So will get one or two in Link to comment Share on other sites More sharing options...
Anglefire Posted May 30, 2018 Author Report Share Posted May 30, 2018 Especially given the longest drop is from the rocker cover and that is normal looking. Link to comment Share on other sites More sharing options...
Anglefire Posted May 31, 2018 Author Report Share Posted May 31, 2018 It does look like PRV - looking at the video's I took a few minutes ago. You can see the valve (I assume!) either opening or closing! The choke stuck on the one carb so was running rough and only about 500rpm! Second time I started it, it was ok (ish!) Link to comment Share on other sites More sharing options...
Anglefire Posted June 2, 2018 Author Report Share Posted June 2, 2018 Changed the PRV this morning as well as changing the oil (did the prv first) and the pressure didn’t drop like before. I’ll still reserve judgement until I’ve been out properly though. Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 2, 2018 Report Share Posted June 2, 2018 Mark, What is that rhythmic clanking noise about 20 seconds in on the first vid, 10 seconds in on the second? Doug Link to comment Share on other sites More sharing options...
Anglefire Posted June 2, 2018 Author Report Share Posted June 2, 2018 I think that was me tapping the rev counter to make it work - it sticks until you tap it. 1 Link to comment Share on other sites More sharing options...
Anglefire Posted June 17, 2018 Author Report Share Posted June 17, 2018 I decided to have another look at my pressure this morning - as I have changed the oil, I thought I would see if I could work out how much went in. As I used a new can I poured out the remaining oil into my topup jug (Nice green quart Castrol one) - and it went way past the quart mark and was about to spill and there was still some more in the can So I poured half what was left back into the can to leave me with about 0.5ltr and poured that into the engine (Bearing in mind the dipstick was showing full already. So its now showing well full on the dipstick But started it up - still getting the initial 50psi after a couple of seconds to then fall back before rising to 80-90 and staying there until it warms up - so I think unless it blows up before then I'll strip it down next winter and see what the issue is. (though I'm trying to sort a shorten drill bit to clean the PRV seat in the meantime too) But after a few miles with the engine hot (oil may not be fully hot to be fair) but it did look a better pressure. Its also running alot better now I have the manifold leak sorted - does actually idle below 1000rpm. Need to twiddle some more as the needle is now, in theory too lean for the exhaust etc. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2018 Report Share Posted June 17, 2018 I dont think there is a problem its just the time it takes to refill the gallery Have fun drive it dont get paranoid about triumf oil psi Pete 1 Link to comment Share on other sites More sharing options...
Anglefire Posted June 17, 2018 Author Report Share Posted June 17, 2018 When I say fall back, the oil light comes back on again. And when hot the oil pressure drops to 30psi at 2000rpm - which is a bit low according to the specs. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 18, 2018 Report Share Posted June 18, 2018 Guess thats aplan, 30 is low , this drop off after initial start might take some finding The prv and gallery zone is a good start. Worn shells would give more loss when hot but doesnt explain the start up blip. Pete Link to comment Share on other sites More sharing options...
Badwolf Posted June 19, 2018 Report Share Posted June 19, 2018 Still not got around to checking my prv (see thread elsewhere), can I remove it without making a mess, without draining the oil? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 19, 2018 Report Share Posted June 19, 2018 you might get a cup full from the gallery when you remove the valve body hex nut. but no need to drain anything Pete Link to comment Share on other sites More sharing options...
Badwolf Posted June 19, 2018 Report Share Posted June 19, 2018 Ok Pete thanks. Hopefully a quicker job than I expected. When I extract the valve, how will I know if it is the cause of my warning light? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 19, 2018 Report Share Posted June 19, 2018 if the spring is intact and the simple plunger is clean and the seat inside the plunger sits on is clean assume its OK most oil light problems are due to switch failures not the PRV but worth a 10min look see. have you changed the switch ?? Pete Link to comment Share on other sites More sharing options...
Anglefire Posted June 19, 2018 Author Report Share Posted June 19, 2018 I’d be interested in seeing how you can see the seat. I’ve got a usb camera but when I used it last time it was about as much use as a chocolate teapot. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 19, 2018 Report Share Posted June 19, 2018 just mind you don't get your pinky stuck in the hole or its A E to get the engine removed Ha ! 1 Link to comment Share on other sites More sharing options...
Badwolf Posted June 19, 2018 Report Share Posted June 19, 2018 Not changed the switch but hopefully going out this evening for a more controlled checkup. It is so long since I had a problem, I thought that the green light was the alternator... until I got home and checked the book!! Never thought to check the oil pressure guage and not been out since. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 19, 2018 Report Share Posted June 19, 2018 wont be the first car to have the right bulb in the wrong holder in no particular order Pete Link to comment Share on other sites More sharing options...
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