Coolant Level Sensor Ideas.

Someone asked me about this and I reckon it's a good idea, but how?

Certainly makes sense to have one. We are all aware of the catastrophic engine failure (just means very quick, very final) potential of the cambelt snapping, but a coolant burst on the motorway would/could have the same effect as well. At the moment, you'd get the coolant temperature gauge flying up to max and then down to nothing, as the sensor became surrounded by air, instead of water. You could easily miss that on a motorway or assume that the gauge had packed up on you. I suppose as Pumas get even older then this idea becomes even more pressing as plastics and rubber sure don't like getting old.

I do know a bit about engines, but not car engines, so if any of the following sounds like nonsense, then it probably is, but that's why I'm asking for your ideas here.

Here's what I've come up with so far - there are loads of coolant level sensors (float type, capacitance, etc.) out there for other vehicles, brand new for under a tenner as well. But how would you know where to fit them on the expansion tank? Plus, those sensors are designed to be attached to the ECU. Plus, would a sensor in the expansion tank even detect a burst HCV connection quickly enough before harm was done or even a top hose? I gave up this idea at this point.

So, even if it's nonsense, here's what I thought - pumped liquids are always under a pressure, however slight, so use a pressure sensor for this. The psi ratings for oil pressure sensors are miles too high for this, but fuel pressure sensors aren't. I've calculated that the water would be at around 3psi and you can get adjustable (2 -7 psi) fuel sensors without difficulty. A 'T' connection into the positive flow side of the pipe leading to the HCV, a wire through the firewall leading to a big dash light and bypass the ECU. Start up, light comes on (due to no pressure) few seconds later it goes off, but will come on if there is a pressure loss anywhere in the coolant system. Total cost - under £30 the lot.



Your ideas?

Hi Frank
I think having a coolant level sensor is a brilliant idea as well. Don't some French cars have one on the expansion tank?
Barry

tuonokid said:

[post]346017[/post] Hi Frank
I think having a coolant level sensor is a brilliant idea as well. Don't some French cars have one on the expansion tank?

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Hi Barry,
I'm glad you think it's a good idea. I thought perhaps some of the guys who put their cars on the track here might already be doing something like this?

As you say, some French cars have them and many German cars too, judging by what's for sale. In theory, you could use one of those sensors or even the entire expansion tank if you knew for sure it was the same size. These sensors do not connect to gauges, but are just on/off switches, so you don't need the ECU to interpret the results and so can bypass all of that and go to a warning light instead. But...that route seems very hit and miss to me, unless someone already knows what sensor, what height from the top, etc. Even then, your HCV side could blow up on you and you'd be none the wiser, until maybe too late.

Therefore, I need the opinions of people that know these engines.

Hi Frank
I think using one of the other makes expansion tanks with a big warning light on the dash would be simplest and best but are there any scrapyards left that you can wander around to find one?
Barry

tuonokid said:

[post]346034[/post] Hi Frank
I think using one of the other makes expansion tanks with a big warning light on the dash would be simplest and best but are there any scrapyards left that you can wander around to find one?
Barry

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To be honest, I had assumed that this stuff would already exist and that the track guys would be using it. I mean, look at the money they spend on those engines and, silicone hoses or not, they're going to risk all that for the sake of a coolant level sensor? But, I can't find it. There's a kit for the MGF to stop it blowing head gaskets, but that's £130 and a bit amateurish.

Not sure about the idea of a substitute expansion tank, original one might have a head pressure based on its size and capacity that would be upset by slapping one on from another motor.

I'm thinking along the lines now of a new float-type sensor for a BMW or Mercedes i.e. sensor already purpose made for a coolant system; into the side of the existing tank. Then, to save lying upside down routing new wires and dash lights, use the leads/connector off the washer bottle water level sensor (leaving the sensor in place!) and make up a short flylead to connect that to the new sensor (which again is just an on/off sensor). No new wires or lights needed and just remember to top up your washer bottle by yourself.

I see what you're trying to achieve - however in my opinion engine damage from high coolant temps or loss of it doesn't happen instantly.

Over the years I've had loss of coolant many times on different engines, I've been as high as 130 degrees C several times without a consequential problem later (not intentionally but some of the times due to sensors failing and not me no realising)

It perhaps is slightly more of an issue on a fully alloy engine. I've only really had experience of cast iron blocks and aluminium heads. The head can warp and the head gasket fails if you're unlucky with loss of coolant.

With regards to header tank size etc. It's not entirely important IMO, it is exactly that, just a header. Remember the header tank is the same size for the 1.4, 1.6 and 1.7. Both Errol and I still use the same tank for our duratec turbo and FRS engines without a problem.

In the winter if a hose failed, you would lose the heater inside the car first and it would become cold very quickly. That's enough time to realise something's wrong and pull over? I think summer is the most dangerous time. I'm not sure how the standard coolant sensor works but both my Omex and Stack gauge (stack gauge sensor seems far more sensitive) go up very fast when surrounded by air and the temp doesn't drop on them.

If you were concerned enough to modify something I think fitting a level sensor into the existing tank is a good idea. I also think that a pressure switch or even a pressure gauge (you can get fuel pressure gauges with a range from 1-15 psi) is also a good idea as you can have it standalone. This should tell you when the engine gets too hot also, I think the header tank cap blows at about 1 bar/ 14.5 psi.

Alternatively, is it just easier to become more aware of the potential problem and the possible signals. So many of us just drive cars and that is it and can take for granted reliability of them especially in certain areas. Isn't there enough instrumentation on the Puma to have a glance at to prompt you to pull over? It's a bit easier for me to say as I'm mechanically minded and I'm always aware of the clocks and gauges in front of me. Maybe that's why you don't find much concerning this on track cars? It could be worse - the Mk1 Focus RS doesn't even have a water temp gauge. The only way you'd know is if you have the heaters on and I think it may have a warning light!

Thanks for your feedback, especially about being able to use an alternative expansion tank or modifying an existing one.

I see what you're trying to achieve - however in my opinion engine damage from high coolant temps or loss of it doesn't happen instantly.

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But, based on real life experience, it does happen. Years back, 50 miles down a motorway at night, noticed coolant temp gauge on zero, decided not to assume faulty sensor, hard shoulder, HGV's thundering past at over a ton just 3 feet away.......hire car for 2 weeks, head skimmed, new head gasket, etc, etc on mine (luckily all covered by the special insurance I had on it). Car was never quite the same after that. So yeah, it happens.

Since I started this thread, I've done a proof of concept on a mate's motor and the fuel pressure sensor idea works. I also found out a bizarre fact (that may or may not apply to Pumas) - some ECUs initially assume a false positive on max coolant temps and reset the gauge back to the middle!

You modify your motor for performance, I modify mine so I never have to rely on luck. For less than £30, this one is a no brainer and when the new HCV goes on, then I'll be fitting a variable psi fuel pressure sensor at the same time, using a T piece, once I've sourced the right one. Plus, a massive dash light.

Here you go Frank
http://www.carbuildersolutions.com/uk/float-switch
Barry

tuonokid said:

[post]346691[/post] Here you go Frank
http://www.carbuildersolutions.com/uk/float-switch
Barry

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Thanks, Barry, I knew you'd come good. :grin: ...and what a find that site is, it's like an Aladdins cave in there!

You have a kit car you become a frequent customer
Europa's a good one as well.
Barry

Frank said:

You modify your motor for performance, I modify mine so I never have to rely on luck.

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I modify for performance and reliability, which can be seen in the products and materials used to build my conversion. I don't rely on luck either, I have enough feedback to tell me if something's wrong quite quickly.

The pressure sensor is a good idea for more standard Pumas, even for track Pumas. For me, I'll be upgrading to different engine management in the future to help.

If you do install one let us know how you get on with how it works. Is there any way to test it?

well, uhm, punching through your coolant hose should do the trick of testing, I'd say.....

True!! Or you'd have to undo a hose clamp or spring clip.

Or use an empty washing up liquid bottle with a tube attached to suck up water from the expansion tank. Easy really.
Barry

Without sounding facetious, the massive amount of steam suddenly appearing from under the bonnet would be a pretty good indicator of a blown coolant hose, or anything that would similarly cause a rapid overheat.

TGPlayer1 said:

[post]346811[/post] Without sounding facetious, the massive amount of steam suddenly appearing from under the bonnet would be a pretty good indicator of a blown coolant hose

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On an already stationary car at the side of the road or one in slow moving traffic, sure. When was the last time you saw that actually happen on a fast moving car, Tom, especially with a bottom hose burst?

We have an electronic sensor and dash warning light to tell us if the fluid in the washer bottle is too low, but not the same for the more vital coolant system and should instead rely on 1960's type tell-tale signs of cold heaters, possible wisps of steam and flickering gauges? It is not logical.

Seems I forgot to do an update on this one.

Did this ages ago and it's pretty quick and simple.

#1. Purchase a ready made float type coolant level sensor from, er, Barry's link above. It cost around 14 quid.

#2. Clamp off expansion tank pipes.

#3. Drain expansion tank with wine making syphon pump or similar.

#4. Find flat bit of tank (near the cap) about an inch (2.54 cm) below normal coolant level and drill suitable sized hole.

#5. Flush out expansion tank with hose to get rid of swarf and re-drain.

#6. Fit level sensor.

#7. Remove washer bottle level sensor connector and aim it in an engine bay direction.

#8. Using spade connectors, wire, etc connect that connector to your new coolant level sensor.

#9. Test, refill tank and you're done.

I figured that knowing the level of my washer bottle fluid was not as important as instantly knowing the level in the expansion tank. Plus, it was easier than farting about with new wiring through the firewall, rolling around upside down under the dashboard, etc.

If you were really bothered, you could put red plastic on the binnacle where the washer light is, but, I didn't. If you were really, really, really bothered you could throw in a buzzer into the equation as well if you wanted to. I tend not to miss lights coming on, so didn't bother doing that either.

Not many things can write an engine off, but running without oil or water sure can and the above has closed off the glaring loophole of not knowing about the latter and then not stopping damn quick.