Temp, Oil and Ammeter Guages

[all mod cons]

Hi there,
Thanks to all who gave advice on how to connect my ammeter in previous threads. It's all in and working now.
I have three more questions, one about the ammeter, one about the temperature guage and one about an oil pressure guage. Ther car is a 1965 Herald 1200...

1) The ammeter is in and now shows a current drop when I turn on the lights, push the brake pedal or indicate etc. However when the engine is running (idling and even driving), with none of the electrics turned on, it still reads zero. I would expect a postive reading to show that the dynamo / regulator are giving charge to the battery.
Am I right? do I need to start looking into the dynamo / regulator? I have suspected them for some time now as the red ingniton light was always very dimly lit - giving me the idea that the engine was not charging.

2) I've also fitted a temp guage. Purely because my replacement engine came with a sensor built into the thermostat housing (the old engine didn't have this). I connected one side of this to the guage and the other side of the guage to to one of the 4 white wires that are attached to the voltage regulator fixed on toe the back of the speedo/fuel guage.
I get a reading. It slowly increases but I've found that even with the engine idling it creeps across to the max 'H' reading. Even when driving (at night so not hot) the guage gets to 3/4 of the way across the scale and then creeps up to max when I get to lights or a junction. Is this normal behaviour or should I maybe suspect/replace the sensor?

3) Finally, I also bought an oil pressure guage which came with a short length of metal pipe on the back. Is it possible to connect this up to a Herald 1200 engine. If so how do I connect it?

Thanks in advance for any help or experience anyone can give on any of these questions.
Richard.    

[herald948]

Richard, it would be worth double-checking the output of the dynamo. Are you finding the battery runs down a lot?

With the temp. gauge, it's possible you have the wrong sender -- or gauge -- for a voltage-stabilised circuit. Or the sender has failed, which is sadly rather common.

Oil pressure gauges are easy enough to hook up, using the same place the warning light sender goes. Many of us like to put in a "T" fitting so that both gauge and warning light still function. (I know, belt and suspenders....)

[all mod cons]

Thanks Andy,
Yes, I'm planning on testing the dynamo output at the weekend - as per the Haynes manual. I've got a spare that came with a replacement engine I put in so I can do some swapping and testing.

I think I'll order a replacement sender unit first then for the temp guage.

I'm interested in the 'T' piece idea you mentioned. Where can you buy them from?
Also can you buy the pipe that needs to run from the T piece to the guage as the pipe that came with the guage is far too short.

[Nick Moore]

Hi Richard,
Temperature gauges usually have a specific sender they're calibrated to work with. If you just connect your new gauge to a sensor already in the thermostat housing, chances are it's resistance curve (changes with temperature) isn't correct for your gauge.

Most oil pressure gauges have a brass nut sealing a plastic or copper pipe with a gland. Does yours? A photo might help here.

A place I've bought temperature senders and oil gauge fittings from is Holden.co.uk. Doubtless there are others, and most cities have gauge specialists who can measure threads, resistances and fittings over the counter.

Nick

[all mod cons]

What a great website. I'd never seen that one before. I've mailed them to see if they do the T piece and pipe I need, also a temp sender.
Will keep you posted.
Thanks,
Richard  

[Freebird]

Hi

This is a suitable pipe for the oil pressure gauge. The guy selling it can also supply an 1/8" BSP adaptor to go in the side of the T piece below.

http://cgi.ebay.co.uk/OIL-PRESSURE-PIPE_W0QQitemZ310041515215QQihZ021QQcategoryZ72205QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

And this is a suitable T piece

http://cgi.ebay.co.uk/OIL-PRESSURE-GAUGE-PIPE-T-PIECE-LMA010_W0QQitemZ310042304695QQihZ021QQcategoryZ72205QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

You take the oil pressure light switch out of the block just under the distributor and replace it with the T piece ensuring the side hole faces towards the bulkhead. Use PTFE tape or liquid pipe sealant on all threads.
Next re-fit the sender into the open end of the T piece.
Then fit the 1/8 BSP adaptor to the side of the T piece - facing the bulkhead.
The flexible pipe goes on this adaptor next.
The other end of the flexible pipe connects to the gauge inside the car, so you will need to find or make a suitable hole in the bulkhead. I went through the tunnel cover as it's easy to drill through. Use a grommet to ensure the pipe can't rub against the side of the hole - if it wears through there will be a right old mess.

I have this setup in my vitesse. I must add I have no connection with the supplier of the parts.

Hope this helps

Glen

Glen..

[all mod cons]

Hi Glen,
Thanks for the Ebay links.
So I need three things: The T peice,a 1/8 inch BSP adapter and the pipe?

When you did yours did you use buy a pipe with Flat ends, cone ends or one of each?
Also, the seller says the pipe is 6ft long. Is that the one to use as it seems a bit long.
I'll just wait to hear back from you and then make a purchase. My brother wants to do the same on his Vitesse so you should be asking the Ebay chap for commision!
Richard.    

[Freebird]

Hi Richard

Yes, 3 things exactly as you say. I have seen T pieces with a male termination in the side to take the pipe, eliminating the adaptor, but couldn't find a suitsable one when I did mine.

You need one flat end for the gauge, the other end needs to match the 1/8" adaptor, (which he also supplies so knows what to give you). The 1/8BSP end of the adaptor goes into the T piece, the other end needs to match the pipe. It doesn't matter whether they are flat or cones as long as the adaptor and pipe are the same. I hope that makes sence.

The pipe he sent me had two flat ends. The adaptor therefore had one flat end with 1/8"BSP at the other end. The flat ends are sealed with a tiddly fibre washer - be careful not to loose them.

The pipe is quite long, my gauge is in a centre consol that I made myself. The excess pipe is inside the consol, it natuaraly coils up, so doesn't take up too much room. You could shorten it, but need to ensure you get an oil tight seal at 60PSI or so when replacing the brass end. I didn't need to try.

I don't need commission, just pleased to be able to help.

Glen

[all mod cons]

Thanks again Glen,
I've been in touch with the eBay chap and he's sending me the required bits.

Richard.

[Deleted User]

Hi Richard, I've seen a two engines fail because of oil pressure gauge line leaking and letting all the oil escape. Both were Mini's, perhaps enough said... Both cases it was worn top stabiliser bushes allowing the engine to rock about enough to work-harden the copper oil gauge (factory fitted) pipe until it cracked.

Moral of the story... coil up the pipe around a beer bottle about 3-4 times and put the coils between the engine and body so that any vibration is taken up by the springyness of the coils, rather than flexing the pipe. Also use rubber-faced clips everywhere so it can't chafe or bend in normal use. The more modern/cheapy gauges use a thin plastic pipe which is better for flex-cracking problems but really can't handle any heat at all.

Personally I'd rather have a reasonable quality electronic gauge which has a sender unit in the tee and a wire to the gauge.

Andy.

[mikeyb]

I had a plastic pipe burst on Mk3 Spit a few years back - I was late going somewhere and had been caning her hard down the A12.  I turned onto the M25, just came off the roundabout onto the clockwise slip, when the back drifted out.  

Bugger, puncture I thought.  Pulled into the side of the road,  looked at each wheel in turn - all had air.  Then I saw the oil running out from under the car!  I had actually skidded on my own oil slick!!  

The timing couldn't have been better - a minute earlier, I eas belting down the A12, a minute later I would have been belting down the M25!

[Spitfire2500]

Just one point re the ammeter -- if it's correctly wired it will only indicate the charging current (or discharging) current of the battery i.e. with the engine on it will only read the current required to charge the battery NOT the current required to run whatever electrical items are switched on.

So if the battery is in good condition and had a full charge when you started the car after a short while you should be getting a zero current reading (once the dynamo has "topped up" the battery charge used to start the car).

The fact that's it's reading zero probably indicates that the dynamo is OK. If the dynamo wasn't working with the engine on the battery would discharge so you would get a negative reading (i.e. no difference between engine off and engine on).

Still worth checking the dynamo though just to be sure.

[all mod cons]

Andy and mikeyb - some very good points re the oil pipe. I've ordered the bits now for a flexible pipe so I'll start off with that. May consider an elctronic sender later.

Bill,
I've still possibly got some issues with the ammeter so could I take you up on your comments......
I hadn't realised it shows the current required to charge the battery rather than the output of the dynamo. As I said in my first post and you picked up in your response, it never seems to show a positive reading, but happily indicates anything elctrical being turned on with a negative reading.

Suspecting the dynamo, at the weekend I followed all the test procedures in the Haynes manual. The dynamo itself (terminals connected and then a voltmeter between the wire connecting the terminals and the yoke) gives a healthy reading of around 15 - 16 volts.
I then checked the wiring back to the control box terminals D and F and got the same results, proving the wiring back to the box is ok.
I did the Haynes manual tests on the regulator and got the voltmeter steadying at about 2000rpm as per the instructions.
Then finally I tested the cut-out. I found that the cut-outs closed at  13.1 volts (within limits), but I must say that I noticed they didn't spring back immediately once I reduced the engine speed. The book didn't mention anything about this so I'm not sure if this is normal behaviour. Any idea?

So all in all the tests seemed to work fine. This, coupled with fact that the red ignition light goes out when you rev the car makes me wonder if everyjting is ok. It was just the fact that I've never had a positive reading on the ammeter, together with the fact that the battery let me down a couple of times last year after driving with the lights on, that made me doubt things.

Tonight I placed a voltmeter across the battery and registered 12.8 V (note that I do use one of those permanently connected trickle chargers - so it should be quite healthy). On starting the engine and reving it the voltage remained at roughly 12.8V. When I put on the lights, heater fan etc the voltage dropped (and the ammeter showed negative) but even reving the engine it never showed and increase on the voltmeter.
Should it show an increae in voltage if it is correctly charging the battery?

I guess I'm really after a definitive test to prove that the battery is being charged. Until I can get prove this I'm wary of driving at night and getting taken home by the AA again!. Please let me know if you can think of any other test to prove I'm charging the battery successfully.

Richard.
        

[mikeyb]

all_mod_cons wrote:

Andy and mikeyb - some very good points re the oil pipe.          

to be fair, I used a old pipe from an indeterminate source (prob scrapyard!) - it def failed due to over pressure, however if you buy something designed for the job you will prob be ok.  Worth enquiring what it's pressure rating is though.

[all mod cons]

Thanks Glen and all who helped with the oil pressure guage questions. All fitted and working now.

Anyone got anymore ideas on my charging / not charging issue? I'm just looking for a way to be sure that the battery is being charged. See my last post for all the details and tests so far.

Richard.    

[Freebird]

That's OK mate, it's what the forum is for. Brilliant is it not?

What oil pressure do you get hot at 3000rpm and at idle?

Glen.

[all mod cons]

I don't have a tachometer fitted (yet), but at idle I think it was around 60 lb / sqr ft. I haven't taken it out on the road since I fitted the guage so I can't tell you what it reads under load.

I may look into fitting a tacho next. Think it might be an interesting addition as I'll then have all the guages needed to monitor the engine.
Is yours a factory fitted one or aftermarket?

[Freebird]

My car is a Vitesse, these all had factory fitted tachos driven by a cable from the distributor.

If you are going to fit an aftermarket one, you will need an electronic version as your dizzy won't have the take off for a cable. Easy to wire up, search this forum if you need help.

[all mod cons]

Hello again,

Back to the charging issue.... I drove the car for the first time at night tonight.
Without the sunlight / daylight on the dashboard - ie in pitch balck it showed up the at the ignitiion warning light was coming on very faintly. I guess  this shows what I suspected - that the battery is not being charged. Of course this light has not been noticable during the day.
As I drove the lights started to get dimmer, but I made it home ok.

As per my previous posts in this thread, the dynamo seems to be putting out the correct voltage. Do you agree that I should now suspect the regulator/cutout and maybe consider replacing the control box.
Thanks.  

[piman]

Hello AMC,

if the voltage you get is correct then it would seem the regulator is doing it's job.
The charging or otherwise of the battery depends on sufficient current from the dynamo to both charge the battery and satisfy the car's electrical load. The first check is always the condition and tension of the fan belt. If the voltage is correct at no load, i.e. no lights, wipers fan etc but drops off under load I would then look at the brushes?

Alec

[Deleted User]

It is quite normal for the indicator light to glow dimly on older cars, particularly if the ignition switch contacts are a bit worn. this is because the light goes out when the voltage is the same at both ends (battery via ignition switch and output 'D' terminal of generator) of the wire- therefore no current can flow = no light. As the voltage at each end of the wire is slightly different due to various resistances in the wiring loom, there is always a small current flow and this is what we see as the dim glow. Most older cars you find the bulb is not clear any more, a brown shiny coating is on the inside of the glass caused by operating a lamp at low output for long periods.



That shows your gen is doing something, I'd also guess that either the fanbelt is loose or the brushes are a bit tired. I had to make an emergency repair to one of my brush springs on the Zephyr out of a ballpen spring. Come to think of it, 4 years later it's still in there.

[all mod cons]

Andy and Alec, thanks for the info and diagram. I'd always wondered how that ignition light worked.
I assumed that because the voltage across the dynamo was 15 - 16 volts, it was healthy.
I'll now check the belt tension - I'm sure it's fine - and then the brushes in the dynamo after doing the load test you described.
Richard.  

[Deleted User]

Hi Richard,

No worries ;-) Voltage 15-16v at the dynamo terminal can indicate that the points aren't closing in the regulator. if you ping the wire clip off the reg box and increase the engine speed from slow idle to say 1500 you should see the cutin relay close. if it doesn't close, try pressing it closed (its the one with the thick wire and without the setscrew on the contacts) and the engine rpm may drop a little as it starts charging. Be careful here, if there is a regulator problem the points may not open when the engine returns to idle but you can pull them open easily. The points should close and reopen as the throttle is blipped off idle, but never stay either open or closed.



If the battery is low you will also see a few white sparks coming off the other relay contact points (the one with the setscrew) when the engine is revved above about 2000rpm. This is the current limiting regulator working correctly.

[all mod cons]

Hi Andy,
The bit in your post saying 'The points should close and reopen as the throttle is blipped off idle, but never stay either open or closed', is interesting......
I already carried out some tests on the control box - see previous post which I've copied in below.
The contacts didn't spring back immediately - so this could be the fault?

I've also just found out that a friend is going to lend me spare dynamo which he thinks is in good working order. I may try that out if I can get it today - just to see if it makes any difference. Although I'm fairly sure mines is ok what with giving out 15 - 16V.




Suspecting the dynamo, at the weekend I followed all the test procedures in the Haynes manual. The dynamo itself (terminals connected and then a voltmeter between the wire connecting the terminals and the yoke) gives a healthy reading of around 15 - 16 volts.
I then checked the wiring back to the control box terminals D and F and got the same results, proving the wiring back to the box is ok.
I did the Haynes manual tests on the regulator and got the voltmeter steadying at about 2000rpm as per the instructions.
Then finally I tested the cut-out. I found that the cut-outs closed at  13.1 volts (within limits), but I must say that I noticed they didn't spring back immediately once I reduced the engine speed. The book didn't mention anything about this so I'm not sure if this is normal behaviour. Any idea?

Richard

[all mod cons]

Hi again Andy, just another quick update....
I swapped the dynamos today and found that the replacement dynamo caused the red light to stay on all the time. So, I reckon that unit is faulty and think that this has now proved my dynamo is working ok. I've swapped back of course.
I'll try your tests with the control box tomorrow, but I'm sure that's where the fault lies.... unless I have a faulty ameter (as this never reads positive).