Saved by the bell (light)

[Roverdrive]

Driving up the M6, towing a tin tent, the P gasket decided to let go on my 300tdi.

Luckily I had previously fitted the header tank level mod, and was able to pull over, add water, and get to a service station. I threw some rad weld in and hoped for the best as we were on our way to the lakes for a weeks holiday. We got there and back with no further issues.

No damage seems to have been caused to the engine, and all is well once the system was flushed and the gasket was replaced.

My set up uses a normal relay with an "87A" terminal fed from an ignition live supply, and is connected to the redundant 24v light on the dashboard.

If you haven't already fitted the level monitor to the header tank, I highly recommend you add it to you "round tuit" list, as it saved my much needed holiday!

Mike

[mmgemini]

May I second everything you've said about a coolant loss sensor. They are a MUST on any 300Tdi engine.

Well done Mike for seeing the light,

[landroversforever]

Are they as critical on a 200?

[AMB]

Are they as critical on a 200?

Apparently not - more height in the system. But always a good idea.

[mmgemini]

The big problem with the 300Tdi apart from the header tank too low, is the height of the water pump on the 300.

Have a look. The level in the header tank is BELOW the height of the thermostat.

Any coolant loss on the 300 results in a dry water pump. Unless you have a coolant loss sensor on a 300, then by the time the Land Rover water gauge moves, the engine is damaged.

The 200 water pump isn't as high up the block

This is a useful post

http://forum.difflock.com/viewtopic.php?t=10972&highlight=300tdi+collant+level+switch

[Roverdrive]

mmgemini

Cheers for the link up post. I know this has been done to death now, but wanted to flag it up for people who may have missed the original. I was surprised to read in the link that "A series resistor of 680ohm is built-in making direct interface with a relay difficult."

I didn't remember having that issue with my relay system, so have just been out and double checked, and the terminals read 0.8 ohm closed circuit, so maybe I have a different cap? It certainly explains why you needed the electronic system.

I have used a Lucas relay SRB500 part number 21939836.

I think the level float is from a Range Rover, but would have to check back to verify that.

Cheers

Mike

[mmgemini]

My level float is from a Range Rover.

[Roverdrive]

I have double checked and mine is also a Range Rover unit.

I can't remember if it came in a blue box though!

I don't think it did, as it still works, and certainly saved the day.

I like the idea of a test button for the light, so will have to incorporate that in the future.

At the moment, I check the operation every time I check the fluids under the bonnet.

[mmgemini]

The first one I fitted came from a scrap Range Rover. That was the one Tim used to try everything out.

It lasted about three weeks and failed. The water corroded something in the unit. So far since that date I've not had any problems.

Just to add

Anybody with a 300Tdi needs a coolant check system fitting

[Roverdrive]

_mmgemini

_{Just to update}

_{I fitted another system on to a friends 300tdi Hi Cap today, and the sender unit was an Allmakes one. This too was either open circuit or <0.6 ohms resistance.}

_{Seems that the aftermarket ones available do not have the internal resistance of the ones you were using.}

_{After my tales of woe, he is more than happy to see the light too!}

_{Wiring his dash we found that the central unused light indicated temperature, possibly for a gearbox??}

_{This is what he decided to go for, and makes more sense than my 24v one!}

_Mike

[mmgemini]

Mike

Have you a link for that Allmakes one please

MIKE

[Roverdrive]

Mike

I don't have a link but got it from Alan at Overlandrs in Litherland, as it was his 110 I was fitting it to!

It was from the Allmakes Premium Range, PRC7295.

2 year warrenty.

Also we used a Durite relay this time which only has the four terminals rather than five. ( ie does not have the terminal 87 just the 87A)

Durite part number 0-727-02

Hope this helps

Mike

[mmgemini]

That's interesting as we couldn't get anything to work to get the light to come on. Get a light to go out though.

I do have, somewhere the wiring diagram for my sensor.

[GW8IZR]

For what its worth, I have a brand new Allmakes cap here.

It is a simple on/off switch with no series resistance.

Cursory investigation suggests it is a reed switch with a magnetic actuator on the float.

This means it should be pretty reliable (suitable for the application) but there are a couple of precautions.

It probably isn't the most reliable switch for high current or inductive loads.

Don't try to switch too much current and if you switch a magnetic ( normal automotive ) relay you definitely ought to use a quenching diode across the coil.

HTH

[western]

in the link to difflock that mmgemini posted above, you'll find my 200tdi low coolant warning system & diagram, I also used a genuine lr rrc sensor cap & Tim's interface module.

[GW8IZR]

I think if I was going to do this I'd use the relay that tests the brake fluid warning cap wiring to do the same function for the coolant cap wiring.

[jbs]

I use one of these: http://www.ebay.co.uk/itm/Low-Coolant-Level-Alarm-12V-/170927068334?pt=UK_Sound_Vision_Other&hash=item27cc0c14ae

Combined with the RRC grey sensor type cap-this does say Land Rover on it too, I cut the two little ring terminals off and attached two female spade connectors in they're place-no relays and quite straight forward too

John

[Roverdrive]

GW8IZR

Cheers for the advice on that. Will look in to the diode.

The system has been on for a year or so already, but always willing to improve.

Will have a look at the wiring diagram for the test facility when I get home.

JBS

THat is an interesting link. Would probably have gone for that if I hadn't already fitted something.

[Markoteal]

JBS - just to clarify -is the system you highlighted hooked up to one of these? (with the adaptions you flagged re adding the spade connectors)

http://www.ebay.co.uk/itm/111340595177?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Just want to check I don't need anything else (except a good car sparky friend to wire it in for me!)

Since reading this post I keep dreaming about running dry!

[Roverdrive]

Markoteal

Sorry for encouraging paranoia....

Actually, no I am not!

It saved me a blown engine.

[mmgemini]

I use one of these: http://www.ebay.co.uk/itm/Low-Coolant-Level-Alarm-12V-/170927068334?pt=UK_Sound_Vision_Other&hash=item27cc0c14ae

Combined with the RRC grey sensor type cap-this does say Land Rover on it too, I cut the two little ring terminals off and attached two female spade connectors in they're place-no relays and quite straight forward too

John

Looking at the link. It appears you have to drill the header tank to fit this. Is that right. How would that work on an aluminium header tank ?

[cookie64]

ive got a genuine lr range rover cap fitted but havnt got round to the wiring yet, my only problem is that the bottom of the float has broken off!! it was brand new so i wonder if my engine runs too hot anyway

[AMB]

Looking at the link. It appears you have to drill the header tank to fit this. Is that right. How would that work on an aluminium header tank ?

- it wouldn't without insulating at least one of the terminals from the tank, probably both. You may be able to drill a large enough hole to hold an insulating bush and screw through that, but I have serious reservations about breaching the integrity of my cooling system by drilling holes in it. You may get to test whether the system works for real as a direct result of fitting this.

I can't see any obvious reason why the circuit shouldn't work using the RRC sensor cap, This senses whether water is present through conductivity. Once the water level drops below the top sensor the circuit is broken - as per the sensor cap. Only question is whether 680 ohms lies within the design parameters for the alarm circuit.

[Markoteal]

Yes - agree re not planning to drill my header tank - I think the coolant sensor wiring on ebay is designed for a different car (Mitsubishi) where screwing maybe required - for the landy, by changing to female spades, I believe these slip over the two male spades on top of the Range Rover float cap and then its "just a case" of getting some juice into the circuit and getting the alarm light positioned somewhere obvious in/around the dash.

Well that was my plan!

And I do thank you RoverDrive for making me paranoid - I'll thank you one day!

Right back to my "to do list" - a big tin of Waxoyl awaits me this weekend mi thinks! Where did I put those old overalls?

[jbs]

Looking at the link. It appears you have to drill the header tank to fit this. Is that right. How would that work on an aluminium header tank ?

Mike,Sorry for the late reply-I've been working onboard again, I didn't drill the header tank at all, I cut the two ring terminals off of the wiring that you would attach by the two self tappers and replaced them with two female spade connectors and then attached them to the RRC expansion cap, This works just as good as the original set up using two self tappers

John