checking guages

[jtparr]

after just posting the last note about car not starting seems a bit daft posting this but I was going to do it anyway tonight

I want to check my oil fuel guage and fuel guage, which means I probably want to check sender units ?

I wondered if there is a correct liquid to clean these sender units with and is there anything particularly obvious to look for when inspecting them

thanks

Jonathan

 

[bones]

I'm not sure I understand Johnathan do you just want to clean the sender or are your clocks misreading or not working. If you want to clean the sender contacts wet and dry paper should remove any corrosion, then just spray with 'Damp Start' or something that promotes electrical conductivity, that's all you can do. If the clocks are a problem don't open them up unless you know what you are doing, they are to hard to come by at affordable rates to mess with. Unless they are clearly dead (check first) leave them alone. This might help too
http://www.pelicanparts.com/techarticles/Mult_gauge_repair/mult_gauge_repair.htm

 

[jtparr]

bones

sorry, to be specific there are 2 issues, since I had the car in its 12K service recently
firstly the oil guage is behaving differently to before the service, it is quite docile until the car warms up and then bounces around frantically whilst driving at reasonable speed, unlike before the change, it realy bounces up and down under hardish acceleration
second one is the fuel guage which seems to drop unevenly, takes its time from full to 3/4 full, but once i get down to 1/2 to 1/4 it drops in bigger jumps

so i want to check what i believe is called the senders (is this correct terminology?), the guages i am not wanting to investigate

thanks
jonathan

 

[bones]

You don't say whether you mean oil pressure, temperature or level. The sender for the pressure is located immeadiately to the right of the main engine fan. It's a small brass cylinder with two electrical contacts on, the upper contact is the oil pressure sender - green/white wire - and the lower is the oil temperature sender- black/green wire. The oil level sender is attached to the oil tank in the rear of the right rear wheel arch. It is possible to remove the single - I think - contact but it's tricky. The petrol level gauge sender is on the fuel tank. Before you start messing with that do this. If you think your car has probably never had an electrical overhaul since new buy yourself a complete set of the correctly rated fuses for front and rear fuse boxes and clean as many terminals as you can get to including grounds to the chassis. Use a small wire brush or weapon of choice and finish off with a suitable electrical contact maker spray or jelly.
The gauges should work like this:-
1. Pressure gauge should read about 0-1 bar at idle with a hot engine, then for every thousand rpm approx 1 bar, it should fluctuate rapidly in sympathy with the revs you are using i.e. if you are driving at 5,000rpm the needle will be at the top of the gauge, immeadiately you brake and loose revs the gauge will drop to match those lower revs.
2. Temperature , well mine just sits about 8 '0' clock unless it's a very hot day and I'm caning the engine.
3. Oil level will read highest with the car at tickover as soon as you pull away this should drop into the red sector and stay there. If it is fluctuating then it could be you have a touch too much oil in there which can happen after a service. If it's not causing a problem keep an eye on the oil level and with the engine hot on level ground and with the engine running the oil should ideally be midway between the two markers. For fuses check your ratings before ordering.
http://www.vehicle-wiring-products.co.uk/

 

[SJW BASIRE]

If your level gauge is fluctuating more it is probably because your oil tank is not full to the top of the dipstick but around half to two thirds.Some people say you shouldn't run with the oil tank full but I like to keep mine up to the mark,especially since the time my oil cooler burst and I had to make it to the next petrol station to buy 2 gallons of cheapo oil to get home with..I think that some garages might save on a couple of litres of oil because of this fact!

 

[bones]

God Steven that's an amazing incident , I've never heard of that before. Porsche specified the original 911 engine to be capable of running on just 4 litres of oil, so with 10-11 litres in there, 12-13 in the sportos then we are clearly swimming in the luxury of loads of oil, which I imagine is how your engine survived. The 'some people' are Porsche by the way, the oil should be filled to midway between the oil dipstick marks, if you are driving fast on a very hot day or anywhere under load you run the risk of the oil expanding so much it finds it's way out of the air box and anywhere else it can get out of , messy and potentially disastrous - don't overfill!

 

[jtparr]

on saturday I attemped to resolve the oil level issue by inspecting the oil sender unit, which is the problem

firstly sprayed WD-40 around the unit to soften up the crud and oil, and then with an old tooth brush eased off the muck.
Repeated sprays of the WD-40, and clean rags worked wonders but the 5 tiny threades have 5 pathetic alloy washers (at least on mine) that were distorted around the threads
I managed to gradually ease each of these off, only to realise that the sender was impossible to get off (since then I have read Wayne Dempseys 101 project book and realise it is a tricky task that perhaps I have to rey again)

I cleaned what i could and re-fitted, cleaning the contacts as best I could

Bizzare thing was that after re-assembly on the Monday morning, driving to work the oil level guage told me I had a lot less oil than before.......weird

Monday evening, starting the car up in the office car park the oil guage told me I had no oil at all !!!!, so I drove home slowly watching the temperature guage

Got home, engine wonderfuly warmed up, dipstick reading halfway between empty and full

Conclusion, get another sender unit ????

any advice welcomed, also who would be the best person to buy a new unit from

this weekend i will try the fuel guage department..................

jonathan

 

[bones]

Hi J forget buying another sender unit it won't solve anything. Don't rely on the oil level gauge it's just a guide and don't look at it till the oil is properly warmed up . At start up temperature it will read low. Once hot and with the car stationery it will read higher than before, oil expands when hot. I removed and completely refurbished my oil tank even with the tank off the car the sender was a fiddly bugger to remove and install.

 

[bones]

As a scholar I notice the PCGB forum software has censored an everyday typically Northern English expression used in my post above. By way of explanation I should point out that the word begins with B ends in ER and has UGG in the middle!

 

[geoff Ives]

firstly the oil guage is behaving differently to before the service, it is quite docile until the car warms up and then bounces around frantically whilst driving at reasonable speed, unlike before the change, it realy bounces up and down under hardish acceleration

If the wire from your sender to the guage is earthing it will do just as you describe. This couls easily happen under acceleration. The advantage of the guage is non existant as you MUST use the correct procedure and check at the dip stick. My oil level guage has been playing up for years and I might get around to sorting it out one day, or maybe not.
_____________________________________________________________________
Geoff Ives. Classic & Heritage Group Secretary.

 

[jtparr]

geoff
when you say "earthing" do you mean it is a bad earth conection somewhere, so i should check earth leads, sorry electrics is not my strong point

thanks
Jonathan

 

[SJW BASIRE]

Monday evening, starting the car up in the office car park the oil guage told me I had no oil at all !!!!, so I drove home slowly watching the temperature guage

Got home, engine wonderfuly warmed up, dipstick reading halfway between empty and full
[/quote]
Bones thinks I am wrong but I still reckon that if your oil level is at half full on the dipstick when the engine is warm and idling then you need to put some more in! If you increase the level to a milli-tad under the top mark it will stop all this gauge fluctuation.I find that cruising at about 3000rpm the level gauge is comfortably in the 1/3-1/2 region and when you stop at the lights it slowly creeps back up to the full mark.This is because you have 2 oil pumps in your engine which work at different outputs;a normal lubrication pump and a scavenge pump to pump the engine oil back to the tank.

 

[Guest]

Bones is correct.

The level on an SC (and a 3.2 Carrera), should be half way between the two marks, with hot engine at idle, on level ground.

Any more, and you run the risk of burning off the excess - or it dumps itself over odd parts of the engine, which then smells too much of hot oil. In my case, it seems to be picked up by the heater, so hot oil smell in the cabin.