Jump to content


Photo

Dash Vibrating


  • Please log in to reply
4 replies to this topic

#1 maystro

maystro

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 253 posts
  • Location: Townsville

Posted 04 August 2021 - 09:55 AM

Hi Mokers,

 

After fitting a new engine and replacing all the engine mounts and stabiliser bushes with firmer neoprene parts I am now experiencing some very bad vibrations coming from the dash/speedo compartment.  So much so that I noticed today the oil light and brake fail light come on when it vibrates the most.  

 

I have two questions.  

 

Does the brake fail and the oil pressure switch wire have a common wire that might be earthing out in the speedo compartment or some other common connection?  

 

Secondly how do I stop the rattling in my speedo compartment area?  If I put pressure on the box which holds the speedo, the rattling stops.  Everything is tightened up and nothing is loose that I can see.

 

Thanks

 

Brad

 

 



#2 Spider

Spider

    Moved Into The Garage

  • Admin
  • PipPipPipPipPipPipPipPipPipPipPip
  • 12,274 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 04 August 2021 - 09:41 PM

Hi Brad,

 

Bear with me here, it's a little convoluted in explanation. The Brake Fail Lamp has a Test Function that works off the Oil Pressure Switch via a Diode (The Diode is essentially a one way valve for electricity). It's configured such that when the Key is on and the engine's not running (or there's no Oil Pressure :ohno: ) the Brake Fail Lamp also comes on, but if you have an actual 'Brake Failure' only the Brake Fail Lamp comes on. The Circuit has a +ve to the Lamps and then Earths out via the Oil and Brake Fail Switches to bring the lamps On.
 

Often though, the Diode is missing with the 2 wires plugged together or it's blown (they go closed circuit when that happens, letting the current flow both ways), so both Lamps come on with the Failure of either Oil Pressure or the Brakes. Check to see if you still have yours, it's in the wiring loom, just past the washer bottle, it's a black cylinder, about 1/2" in diameter and 1-1/2" long, wires connected in each end. One way to test is is the firstly check both lamps come on with the Key On, and the engine not running. Then disconnect the Oil Pressure Switch (White / Brown wire) and the Lamps should go out. Then short the Black / White & Black wires that go to the Fail Switch (on the side of the Master Cylinder) and only the Fail Lamp should come on. It's also possible from the vibration you're describing here, that the Diode (for what ever reason) is shorted and there's a connection occurring in the Brake Fail Switch, since that's basically sitting on the end of the engine steady.

 

With the Vibration, I'd say almost certainly it'll be the Poly Engine Steady Bushes, they are quite hard. For a Road going vehicle, I'd always fit Rubber in here. It doesn't look as good I know, but it does work much better as a vibration insulator. For what ever it's work, I run standard rubbers in out off road Mokes and they seem to last very well.



#3 maystro

maystro

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 253 posts
  • Location: Townsville

Posted 05 August 2021 - 09:10 AM

Hi Spider,

 

I wish I had read your post before I started fiddling with things.

 

Yesterday I wacked the speedo compartment near the brake fail light and now that light never comes on.  I'm guessing I just killed a 40 year old bulb.  So I can't properly do your test method but the green oil light goes off as soon as I disconnect the white brown wire going to the oils sender switch. 

 

I also checked, I do have that diode which is covered in a little hard plastic tube.  I wandered what that was?  

 

I'm thinking something is a amiss or cross wired in the speedo compartment area because now the heater switch doesn't work either which is right next door to the brake fail bulb.  I actually noticed when I turn the heater switch on, the ignition light dims?

 

I know I have oil pressure because yesterday when I was in my fiddling mood, stupid me decided to connect up my spark plug compression gauge to the oil sender outlet just by the rubber plunger because I didn't have the correct fittings and wow,  what a mess.  I reckon nearly a litre of oil spewed out of that miss fitting guage in the space of 2 seconds.  The guage also showed 50 psi on fast idle.  Probably the last reading that guage will ever show, at least it will never go rusty ;-)

 

Another question which is how I got into this oily mess.  

 

I fitted 2 SAAS electric guages. One for water temp and one for oil pressure.   The new oil pressure guage has never worked.  Well it does but the needle does a full 360 sweep as far as it goes.  

 

Is their a specific Mini oil pressure sender unit I need?

 

Thanks

 

Brad


Edited by maystro, 05 August 2021 - 09:14 AM.


#4 Spider

Spider

    Moved Into The Garage

  • Admin
  • PipPipPipPipPipPipPipPipPipPipPip
  • 12,274 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 05 August 2021 - 06:38 PM

Hehehehehehehe,,,,,,,, that's somewhat ingenious think - using the compression gauge for checking the Oil Pressure. No, it won't rust !

 

By the sounds of things, you may at some point do well to take the Speedo Housing off and check all the connectors back there, perhaps even disconnect them - one by one - and clean them up. With the age of your Moke and that I'm pretty sure this hasn't been apart since leaving the factory, it's highly likely that some corrosion has set in. I gotta say, it's definitely not one of the most fun jobs, working in behind there.

 

It does sound odd for the Oil Pressure Gauge to behave in such a way. It appears the current range of these gauges read up to 140 PSI. I would think the sender that's supplied with it would match the gauge. Ordinarily, I wouldn't expect to see more than 80 PSI when hot and maybe 100 - 110 for a short time when cold, well within the range of that gauge. I'd suggest getting in touch with SAAS;-

 

[email protected]

 

I wonder if they have included a sender for a boost gauge here ?

 

Their Instructions and coff coff Trouble Shooting Guide, you can find here;-

 

https://www.shopsaas...sureFitting.pdf

 

but I would think that would have been supplied with the gauge.

 

A few checks you can do here;-

 

Check there is a good earth connection to the sender and also the green wire has a good secure connection all the way to the gauge. If this circuit becomes open circuit (a break in it), it will do as you describe.
 

If that checks out then disconnect the wiring from the sender unit. Check with a Meter it has between 11 and 15 ohms. Start the Engine and with warm oil, it should be around 75 - 85 ohms, cold oil around 90 - 100 ohms (unplug the gauge before doing this)

 

If that checks out, pop in to your local Jaycar store and grab one of these;-

 

https://www.jaycar.c...1c-a9a7f60948cf

 

Connect the middle terminal to Earth and one of the side terminals to the Green Wire (that runs to the gauge). Turning the shaft you should be able to have the gauge do a full sweep from zero to full scale and beyond.

 

These tests at least will help narrow down if it's the gauge, wiring or sender that's at issue here.

 

 

 



#5 maystro

maystro

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 253 posts
  • Location: Townsville

Posted 10 August 2021 - 05:41 AM

Hi Chris,

 

You weren't wrong about it being another lovely place to work behind the dash.  It's pretty tight in their to unscrew the speedo cable just to gain access.  Anyway it gave me a chance to install my new choke cable which I had been putting off.  

 

I couldn't really see anything to obvious a miss behind their other than 40 years of dirt and grime which I gave a clean up.  The brake fail globe is blown which I wasn't too fussed about since I don't even have that sender wire hooked up to my brake master cylinder.  However I didn't realise I must have damaged the right hand indicator bulb on the speedo untill I had put everything back together.  Are those bulbs still available?  I was thinking of just buying a brand new Smiths speedo till I saw the price, I'm hoping the bulbs are still available.  

 

Anyway back to the oil pressure gauge.  I put the multimeter on the sender and I got 5ohm with the motor off and 110 ohm with warm oil.  

 

I then tried the 500ohm Potentiometer on the gauge and the needle would only swing up to 22 psi so I'm guessing the gauge is stuffed.  Curiously the same 22 psi where the needle reads before I start the motor then does the full sweep once she is running.  

 

I'm thinking of just going simpler and old school and getting a mechanical oil pressure gauge.  Less wires to run too.  

 

Thanks

 

Brad






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares