Patrol 4x4 - Nissan Patrol Forum banner
1 - 5 of 5 Posts

Premium Member
2016 CRD wagon
Joined
1,630 Posts
Discussion Starter · #1 ·
Hi MQ/MK gurus

Can someone tell me what the sensors pictured below are for and how they work (if known)?
These are all at the front of the motor.

Automotive tire Motor vehicle Gas Plumbing Rim


And

Motor vehicle Automotive fuel system Automotive tire Gas Auto part


Both have 2 wires. The top one goes into the thermostat housing...... but there is already a separate temp guage sendor just near it.

I'm wondering if the second is a tacho signal??

TIA
 
  • Like
Reactions: Scout2mike

Rust is just natural weight reduction.
1986 SD33T SWB
Joined
11,093 Posts
The sender on the front timing cover is the tacho sender - its a magnetic pickup or hall affect sensor from memory.
I'd guess the best way to test it would be with a multimeter on ohms and spin the engine over, or remove it and pass some metal close to the front of it. Use a thick gasket when you reinstall or reuse the old gasket if its okay, it needs that thickness to set the depth of the sender to the timing gear.

The sensor of the thermostat housing is coolant temp for the glow plug controller. It is supposed to let the plugs glow longer with a cold engine, and turn them off quicker with a warm engine.
Nissan's electrical documentation in the 80s was patchy at best, so they don't really give much in the way of what sensors and senders should produce what values.
 
  • Like
Reactions: trev zd30

Premium Member
2016 CRD wagon
Joined
1,630 Posts
Discussion Starter · #3 ·
The sender on the front timing cover is the tacho sender - its a magnetic pickup or hall affect sensor from memory.
I'd guess the best way to test it would be with a multimeter on ohms and spin the engine over, or remove it and pass some metal close to the front of it. Use a thick gasket when you reinstall or reuse the old gasket if its okay, it needs that thickness to set the depth of the sender to the timing gear.

The sensor of the thermostat housing is coolant temp for the glow plug controller. It is supposed to let the plugs glow longer with a cold engine, and turn them off quicker with a warm engine.
Nissan's electrical documentation in the 80s was patchy at best, so they don't really give much in the way of what sensors and senders should produce what values.
Thanks James. Very much appreciated!

I plan on a simple momentary switch to operated glow plugs for now so no worries about that coolant sensor.

With regard to tacho, do you know how the L28 sensed rpm? Did they use a similar system or was it sensed from the distributor or other ignition components?

I've had a look through the wiring schemes you linked in a different post. One thing I'm having trouble is identifying colours for wiring which would make life just a bit easier. Any hints or is that info difficult to come by?

Cheers
 

Premium Member
2016 CRD wagon
Joined
1,630 Posts
Discussion Starter · #4 ·
@james008
You've got me curious now.........
If the sensor is on the front of the sd33t for the tacho, where is the tacho pickup on a NA sd33?
 

Rust is just natural weight reduction.
1986 SD33T SWB
Joined
11,093 Posts
Thanks James. Very much appreciated!

I plan on a simple momentary switch to operated glow plugs for now so no worries about that coolant sensor.

With regard to tacho, do you know how the L28 sensed rpm? Did they use a similar system or was it sensed from the distributor or other ignition components?

I've had a look through the wiring schemes you linked in a different post. One thing I'm having trouble is identifying colours for wiring which would make life just a bit easier. Any hints or is that info difficult to come by?

Cheers
No worries mate.

A momentary button is simple way of doing it, IH Scouts used them from the factory, and a pull cable as an engine shut off on SD powered Scouts.
It may be worth looking into a 555 timer or timer relay if you or the young bloke were so inclined.

From memory the L28 tacho pickup was in the dizzy or triggered from the coil.

There should be this little table at the bottom RHS of the last image of the wiring diagram that shows colours and connectors.
534619


@james008
You've got me curious now.........
If the sensor is on the front of the sd33t for the tacho, where is the tacho pickup on a NA sd33?
Early SD33s didn't have tachos or the boss in the timing cover. They got them a bit later on with other MKs though in the same spot.
There is another very similar looking boss on the timing cover but just behind the harmonic balancer. No idea what its for, some marine or commercial application probably.
 
  • Like
Reactions: trev zd30
1 - 5 of 5 Posts
Top