Coolant woes. '89 2.1 digifant, no coolant temp indicator.

[pastyman]

I've been having a few coolant issues recently. I'm slowly getting to the bottom of it all, but I have some questions that I need answered by the more electronically adept!!!

My bently manual shows that I should have a Coolant Level Control Unit in slot 3 of the fuse\relay board. I haven't. Can anyone with a similar van confirm that they have or haven't got such a unit in place?

Secondly, does anyone know how to test the coolant temperature level gauge sender and circuit. I put a voltmeter across the two wires that go to the sensor and with the ignition on got 2v across it. 2v seemed like a weird amount to me. Anyone with any clues?

Thirdly I have a coolant leak. This seems to result in the expansion tank emptying without dragging any coolant from the reservoir tank. Is this expected? If so why?????

Thanks in advance!

[pastyman]

Can't believe that's my first post on the new forum! I used to be all over the old one!

[pastyman]

Here is an electrical schematic from bently. ANyone know what the numbers where I have put red highlights mean?

What does that coolant low level control sensor unit do? I don't have one!

Answers greatfully recieved....!


http://jamiebowen249.fotopic.net/p32512024.html

[tonytech]

Right....
I'm away from the van just now, so Ill check the fuseboard tommorrow.

The lines at the top of the diagramm are wires within the fusebox and go over the pages, the Numbers enable you to follow a track over several pages.

The cooolant level sensor sits in the expansion tank ( not the top up tank behind the No plate) and flashes the red LED when coolant is low.

Coolant temp sender is a resistive device. Set your meter to Ohms disconnect any wireing and connect meter accross sensor. Bently have some graphs that give resistance at temperatures. I'll interpret them for you if you like (Bently in van tonight)

Coolant should move from tank to tank , Is the expansion tank sealed properly??

T

[Mocki]

Hi ya stranger!

Is the header tank cap in good fettle, if it is, take a looksee if the header tank is craked at the top where the cap goes on...... sounds like cracked top syndrome to me.....

[pastyman]

Thanks Tony.

I have recently replaced my coolant level sensor (seal was leaking) and put a new cap on the expansion tank, so the expansion tank should be sound, but obviously if the coolant is leaking out (I think from the seal between the thermostat housing and the engine body) then air can get into the system. I guess this pressure equalisation is what is stopping the movement of fluid from the reservoir tank.

The temp sender is resistive and I did get some ohm readings from it. It seemed OK. However I didn't find the charts you refer to in Bently! The readings I was refering to was for the voltage across the wires that connect to the sensor, not the sensor itself. Obviously the change in resisance is used to produce a change in current when a voltage is put across the sensor. As far as I can see from the electrical schematics this voltage should be the full 12v of the battery, however, with the ignition on I was only getting 2v at the wires, i.e. there would have only been 2v across the temp sender.

Will be interested to hear if you have a Coolant Level Control Unit in position 3 in the fuse/relay box!

Thanks again for your help Tony.

[pastyman]

Will have a check there tonight.

Spent lastnight replacing the O ring between the thermostat housing and the engine body. Looked like it was leaking a bit. Seemed better this morning, as I have been able to smell hot coolant after a good journey recently, and couldn't when I got to work this morning.

How are you? What van's are you running at the moment? Still got the big white camper?

Anyone looked to see if they have a Coolant Level Control Unit in slot 3 of the fuse\relay board? I could really do with getting one if it's supposed to be there!