cliff.b
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Posts posted by cliff.b
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20 minutes ago, johny said:
yes we want a definite fix as it may come back to bite again but trouble is if Chris runs a new wire we will never know if the problem was an earth fault or induced current😭
I agree, but what can he do to prove one way or the other 🤔
Can only try various things and gather evidence, I guess.
Maybe a test led connected to +12v and a trailing wire on the other terminal which he can waggle around the engine bay while looking closely for flickering 🙂
Actually, any of us could do that test ourselves lol
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5 minutes ago, Pete Lewis said:
surely this is simple remove the LED fit the correct Bulb and see what you get
that eliminates stray LED illumination back to the basics
Pete
I think this has got past the point of fixing it now and into the realms of trying to understand why it's doing it lol
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If you have a smart phone there are plenty of free GPS based speedometer apps. I'm using digiHud at the moment which lets you save average speed, max speed, distance covered etc.
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40 minutes ago, johny said:
But surely even with an induced voltage you still need a circuit - this problem occurs even if the wire from the light is disconnected at the pressure switch....
I was thinking that one side of the LED is connected to +12v and the engine end is just effectively a length of wire. If a voltage is induced in that wire which is different to 12v, there would be a voltage difference across the LED & a miniscule current may briefly flow through it, perhaps enough to make it flicker.
It's only a theory and some further testing will hopefully show if it "holds water" or not.
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17 minutes ago, NonMember said:
It may not be the HT leads you need to worry about. The LED only needs a tiny voltage, so what matters is whether you can induce a few milliamps of current for a moment. Running parallel to the coil supply wire could do that, as long as there's enough capacitance to pump it into. I'm not really sure how much that would need to be.
Exactly my thinking. There may not be a fault here at all.
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Thinking further about the possibility of an induced voltage making an LED flicker, the oil pressure switch is pretty close to the distributor, how near does the wire pass near any HT leads?
Might be worth disconnecting the wire and moving it well away from the engine and doing another road test (making sure the free end can't ground on anything as that might become confusing lol)
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7 minutes ago, Chris A said:
Yes. All instrument and warning bulbs are LED except the red ign. light, and have been for quite some time. The LED for the oil pressure warning was changed a few weeks ago for a brighter one. When I swapped the bulb for another the other day it too was a LED but the less bright version. Maybe I should do a bulb swap and put in a filament version and see if there is a change. The short could have been there for ages but I never spotted it with the less powerful LED. You have to bear in mind the car is a convertible and is driven with the roof down all the time hence the reason for wanting bright warning lights to be visible in the sunny conditions Normandy is famous for.😎
I'll do a bulb swap tomorrow if I can get time free for the car.
I have ordered some wire, correct colours, and a few other bits and pieces to make the postage worthwhile
Is it, my wife is bi-polar. One day with the penguins, the next with the polar bears.
Aha, didn't realise the oil pressure light was already an LED. If barely flickering it could be due to an extremely small current or possibly even an induced voltage from something else. If this has happened since a newer/brighter LED has been fitted then I suspect there might not be a fault at all, just more sensitive or as you suggest, now visible. If you were to put a filament bulb back in then it may not do it at all.
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3 minutes ago, Colin said:
Thanks chaps.
All good suggestions!
Non-Member, if by "the feed to the gauge is usually not", you mean the nut right on the back of the gauge, certainly mine is not - it is much smaller.
Cheers All.
Now - how to find such a union . . . 🤔
If you use eBay there are lots of different combinations of adapters. Found different m & f combinations from 1/8 NPT to M14x 1.5, M16x1.5 & M10x1.0
Just searched on oil pressure gauge adapters
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1 minute ago, NonMember said:
I think the T-piece is 1/8 NPT but the feed to the gauge is usually not. I suspect on modern gauges it's a metric fine but who knows what on an older one. The male-male adapter is supposed to be a thread converter to match it.
That makes sense. So what thread is a modern metric car sender? I have looked on eBay & most say M14 X 1.5. Poss worth a try
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mintylamb.co.uk
Should provide some answers about speeds in any gear for our cars using various parameters, like tyre size, diff etc 👍
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I thought they were usually the same thread as the oil pressure sender, whatever that is 🤔
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24 minutes ago, NonMember said:
Is it? I'm pretty sure the air box inlets on my 1500 Spitfire (completely standard engine, albeit in the wrong car) are the same size as the carbs.
The internal diameter of each metal inlet stub on my airbox is 1.25". Obviously the plastic pipe is slightly bigger as it needs to fit over it.
So in total, I think that gives a combined inlet area of about 2.45 sq inches whereas 2 X 1.5" would be about 3.5 sq inches area.
But do both carbs ever demand maximum flow at the same time🤔
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On 06/06/2022 at 17:00, Chris A said:
At that point it was still connected. I did think of stopping and disconnecting it but knowing my luck a neighbour would have driven past just as the bonnet was up, the reputation of British engineering would have been lost forever!
As I have mentioned the fault is there even when the pressure switch is disconnected.
It is erratic, after 'fiddling' under the dash it seemed to have been cured but within a couple of hundred metres it was back again.
I'm going to have a VERY close inspection of the mess of wires under the dash next. As we all know to do that is "less than easy" and my back has to be having a good day or else I risk being stuck . .Picking strawberries & raspberries in the garden for over 2hours this pm did me in.
It will NOT win, a draw is possible though 😠
Just a thought, do you have any led bulbs?
I am presuming that if you are getting a slight flicker then the current through any short is low, but it may still be enough to make an led come on brightly, thus aiding fault finding when wiggling stuff about.
Obviously, polarity would have to be considered.
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While on this subject, as the diameter of the filter box inlet pipes appears to be less than that of my HS4 carbs, why would this not "strangle" them.
I'm sure there's a good explanation but it's bugging me that I don't know what it is lol
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25 minutes ago, PeteH said:
Not like some of the "locals" then, You can hear the Base from Miles away!. Surprised they are not all deaf/do-lally. One local "sport" has a Subaru with a 4" pipe, and a sound sytem that would grace a Festival.
Pete
Yes, we have a few of those round here as well 😒
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5 minutes ago, PeteH said:
The "old adage" used to be "Turn the (radio)Volume" up?.
Pete
Hmm, I rarely put the radio on as I can't hear it over the exhaust noise.
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18 minutes ago, Pete Lewis said:
i chased the shocker spindle for weeks until we did a jump on and bounce it
with there's that squeak
Pete
If it gets louder then I will probably find it. If it doesn't then I should probably ignore it 🙂
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1 minute ago, Pete Lewis said:
one more .....disc pad chatter
does the noise stop if you are light on the brakes ???
Pete
I've had that before and I could tell it was coming from the front wheel area.
I can't pinpoint where this new noise is coming from at all and it is intermittent.
Doesn't seem to be road speed dependant, but I can't hear it when driving faster as it isn't loud enough. I will have to try coasting down a slope with the engine off, which may eliminate quite a few things if it is still happening.
My feeling though is a suspension noise of some sort. It doesn't sound like it's caused by something turning.
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I had exactly this problem last year when I first got my Spitfire. I had replaced bad fuel lines and the car had been standing for a year, so it could well be the dreaded rubber slivers or sticking for some other reason.
Took top off float chambers at side of road, removed floats, cleaned float pivots, valves & valve seats with petrol, reassembled and tested by blowing gently into fuel inlet pipe while moving float. When float down, I couldn't blow through so reasoned it was now working which proved to be the case. I have covered 4000 miles since then and it has been ok ever since 🤞
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46 minutes ago, Colin Lindsay said:
Yes. Touching on paranoia! My GT6 used to 'tinkle' when rolled back and forward, a light metallic jangling but no idea of what it was.
(My own Herald is suspiciously quiet at present, no squeaks, no rattles, no tinkling, what's wrong?)
You usually find that when the noises stop, something has dropped off.
It's not so much the noise as not knowing what's causing it.
When I first got the car it was making lots of different noises and as I worked on the car and found the causes it was usually due to something quite worrying. Loose nuts & bolts, missing nuts & bolts, things fitted incorrectly etc. So now if I hear something, I'm concerned that there's something I've missed.
Maybe I should just drive faster so I can't hear anything 🤔
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Am I being unrealistic striving for no unexpected noises, rattles, creaks etc 🤔
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Sun out so under car and exhaust bracket tightened. Also found next joint rearwards was leaking so sorted that out as well. Annoying tinkling noise now gone and exhaust (a bit) quieter.
Which means now I can hear another noise 😟. More like a squeak this time and I would guess suspension related.
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11 minutes ago, Piglet said:
All my previous Spitfires had chrome K&N filters on but Lora doesn't, She has that enclosed box thing with paper filters inside. I'd like to fit K&Ns instead but I'm wondering what all the tubing that goes around the standard box actually does and should it be removed or left in situ?
Alex
Do you mean the two "corrugated" pipes that go to the front of the car or some other pipework 🤔
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6 minutes ago, Chris A said:
Got one! Somewhere in the bottom of my 'tools I never use' box. Solder? I think there might be a bit there as well.
My first check will be to follow the route of the wire ( especially behind the dashboard in the mess there!) and loom to look for any obvious damage causing the short circuit. If the loom/wire is rubbing on something it could cause more trouble in the future so better to be safe than sorry. Second step, make a completely new length of wire from the bulb holder to pressure sensor as I'm convinced it is along this section that there is a problem.
Sounds like a plan 👍
Oil pressure warning light
in Engine
Posted
Ok, I felt compelled to carry out a bit of testing on my own car.
I connected one lead of my meter to the +ve terminal of the battery and the other to a random spare length of wire, connected to nothing. The meter showed a background reading of about 0.005v
I then started the engine and the meter was reading 0.3v to 0.5v depending where I placed the wire (near HT leads was highest) and how fast the engine was running.
I then connected an led bulb (12v but not a car one) across the meter terminals, so I now had an led connected by one terminal to the battery, the other terminal to a loose piece of wire and a meter across it which was now showing about 0.05v
I started the engine again, repeated my wire waggling and was now seeing up to nearly 6v on the meter. The led did not flicker that I could see, but clearly there is a potential difference here and the behaviour may be down to the individual led behaviour.
Interested in thoughts/explanations🤔