AlanG Posted July 17, 2014 Report Share Posted July 17, 2014 The oil pressure has always fluctuated when hot. This was particularly noticeable driving along the A1 last weekend. Cruising at 3200rpm the pressure would be at 70psi for a while and then suddenly drop to 50psi. Minutes later it would recover to 70psi. I have replaced the pressure relief ball and spring with no effect. Anyone any ideas what maybe causing this? Alan. Quote Link to post Share on other sites
Ashley James Posted July 17, 2014 Report Share Posted July 17, 2014 I wonder if that's the valve opening and closing and if screwing the adjuster down 1/2 to 1 turn mightn't keep the pressure up when the engine is good and hot. Quote Link to post Share on other sites
Shrappers Posted August 6, 2014 Report Share Posted August 6, 2014 I have had exactly the same 'problem' with my 4A but after 11 years and n thousands miles later I've given up worrying too much about it. All I do is back off on the revs for a while, wait for things to cool down a bit and then resume cruising at my standard 3,000 rpm when normal service is resumed. I can tell you that screwing down the oil pressure adjuster had little effect on my machine. It merely caused the same thing to happen but 10psi higher! I wonder if a new oil pump might be the answer because I am beginning to run out of ideas. Quote Link to post Share on other sites
Ade-TR4 Posted August 7, 2014 Report Share Posted August 7, 2014 Have you tried bleeding the oil pressure gauge line? There may be air trapped in there. Ade Quote Link to post Share on other sites
RogerH Posted August 7, 2014 Report Share Posted August 7, 2014 I don;t think air in the gauge pipe would cause this problem (they probably all have to some degree). In fact I would think it would have the opposite effect as it would act like a spring and keep things stable for a while. have you got enough oil in the sump? Is you dipstick too long? Roger Quote Link to post Share on other sites
AlanG Posted August 8, 2014 Author Report Share Posted August 8, 2014 Strappers This isn't a heat problem. I don't back off and let the oil cool. The fluctuations repeatedly occur at steady rpm's. Roger Oil is up to the mark and the dipstick looks correct but you never know. Could somebody tell me the length it should be please. Alan. Quote Link to post Share on other sites
MikeF Posted August 8, 2014 Report Share Posted August 8, 2014 (edited) Mine did this. I fixed it by bleeding the feed pipe from the engine to gauge. Essentially cranking the engine in short pulses with the pipe off gauge and a lead removed from coil. This expelled a whole load of tar like sludge and stuff from the pipe which I did until it ran out clean. Be careful when removing the gauge and pipe from gauge as it will spurt and dribble all over the place, have plenty of pigmat or cloths around the place as well as a container to collect the sludge/oil.can As Roger said the air acts like a spring, but my reasoning was different: if you ping a spring it vibrates, so I thought the explanation w/effect would be similar to old central heating systems with trapped gas which make hammering effects. Mike Edited August 8, 2014 by MikeF Quote Link to post Share on other sites
Ashley James Posted August 9, 2014 Report Share Posted August 9, 2014 I have had exactly the same 'problem' with my 4A but after 11 years and n thousands miles later I've given up worrying too much about it. All I do is back off on the revs for a while, wait for things to cool down a bit and then resume cruising at my standard 3,000 rpm when normal service is resumed. I can tell you that screwing down the oil pressure adjuster had little effect on my machine. It merely caused the same thing to happen but 10psi higher! I wonder if a new oil pump might be the answer because I am beginning to run out of ideas. That's what I'd expect to happen. I think your oil is thinning with heat and leaking past the release valve, so adjusting it to do the same at 10 psi higher is probably the solution. Quote Link to post Share on other sites
billg Posted August 11, 2014 Report Share Posted August 11, 2014 I had a similar short incident on the A1 my TR3 A normal shows 50 psi at 3000 and 185C But dramatically fell to 20psi for 15 mins so slowed up and stopped to put the hood up. After that it returned to 50psi. For the rest of the journey . We were hammering up the road at 65mph in a heavily load car though. Will wait and see as this is the first time in 4000 miles this has happened Bill G @ NB Quote Link to post Share on other sites
richardix Posted September 4, 2014 Report Share Posted September 4, 2014 I have a litte bit the same problem. when the motor is on temperature, the oil pressure meter indicaties 70 psi at 2200 rpm. When I drive for a while 70 mph (at 3000 rpm) the oil pressure drops to 50-60 psi. Driving 60 mph and the pressure meter indicates 70 psi. So fluctuating and somewhere between 2700 and 3000 rpm a dip in the pressure. So I used the screw to increase the pressure. that helpen nothing. Just a few psi when the engine was cold. so hopefully you have more ideas regards richard Quote Link to post Share on other sites
Ashley James Posted September 7, 2014 Report Share Posted September 7, 2014 FWIW Pete Cox told me to replace the relief valve spring if the gauge did odd things. Quote Link to post Share on other sites
SpitFireSIX Posted January 11, 2015 Report Share Posted January 11, 2015 Have you tried bleeding the oil pressure gauge line? There may be air trapped in there. Ade Hi, I am in the searching this site for an answer to my question and saw this statement and thought I better comment. Air in the pressure gauge line will have NO effect on the static gauge reading. It is a myth. Sorry. If the engine pressure is dynamically fluctuating then air would cause it to read the average. A blockage or sticking pointer more likely. Back to the search. Cheers, Iain. Quote Link to post Share on other sites
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