The study of a radiator

[Avocet]

Mine does exactly that.

The fuel gauge is likewise an interpreted value, based on two level sensors, and present mpg. Park the car, and it will show one level, then restart the car later, it will show a lower level whilst running cold, then as the engine warms, and mpg improves, it will rise.

Yeah, although I haven't seen one with two level sensors? We have no end of fun when we modify cars for wheelchair access, because we usually have to make our own fuel tank - typically wider but not as tall, so we can lower the floor for the wheelchair. That plays havoc with the original fuel sender, as you might imagine! The ones we work with, tend to have one conventional float sensor, with the float roughly in the middle of the tank, so that it doesn't change level too much when the car is parked on a slope.

When the ignition is switched on, it takes an instantaneous reading from the float and feeds that t the computer that calculates fuel level, remaining range, etc, and sends that signal to the fuel gauge. From then on, it ignores the reading from the float in the tank, and just counts injector pulses, then calculates what's been used, and tells the gauge to display that. It's surprisingly accurate too! However, it's not completely accurate, so each time the ignition is turned on again, it takes another spot reading (before the car has had a chance to move and slosh the fuel around in the tank) and then corrects the gauge reading (if necessary).

Unlike the "managed" temperature gauge, I can, at least see a few small advantages to having a "managed" fuel reading. For a start, you can have the tank any weird shape you like, but still have a pretty linear fuel gauge movement, just by tweaking the software. Secondly, you don't get that annoying 20 miles or so when the low fuel warning light can't make up its mind whether it's on or off! The light is told to come on when the calculated fuel level drops below the arbitrary limit set by the manufacturer, and stays on, until refilled, so it doesn't matter what you do with acceleration, braking or cornering, the light is either on or off.

 

[Harry Bloomfield]

Yeah, although I haven't seen one with two level sensors?

It's a saddle shaped tank, so it needs to measure the level in both sides, when it drops below the hump. It uses a fancy venturi system, to transfer from one side, to the in tank pump side.

The light is told to come on when the calculated fuel level drops below the arbitrary limit set by the manufacturer, and stays on, until refilled, so it doesn't matter what you do with acceleration, braking or cornering, the light is either on or off.

I never usually run it that low that the light comes on, but... If the level is low-ish, when I park up, when I switch on, it can come on, then a few hundred yards down the road it goes off. It claims to warn when you have <50 miles of range, and is obviously linked to the fuel gauge software, deciding the mpg consumption. It has two pumps, the in tank, and a second under bonnet pump. If the ITP fails, the venturi stops, and if the level drops below 1/4 tank, the car stops. Until that point, the UBP can cope.

A trick is to regularly remove the filler cap, switch on the ignition, then stick an ear to the filler to listen to ensure the ITP is running. It only runs for a few seconds, after the ignition is turned on.

 

[Avocet]

It's a saddle shaped tank, so it needs to measure the level in both sides, when it drops below the hump. It uses a fancy venturi system, to transfer from one side, to the in tank pump side.


I never usually run it that low that the light comes on, but... If the level is low-ish, when I park up, when I switch on, it can come on, then a few hundred yards down the road it goes off. It claims to warn when you have <50 miles of range, and is obviously linked to the fuel gauge software, deciding the mpg consumption. It has two pumps, the in tank, and a second under bonnet pump. If the ITP fails, the venturi stops, and if the level drops below 1/4 tank, the car stops. Until that point, the UBP can cope.

A trick is to regularly remove the filler cap, switch on the ignition, then stick an ear to the filler to listen to ensure the ITP is running. It only runs for a few seconds, after the ignition is turned on.

Ah! OK that makes sense. Mrs. Avocet used to have an old Nissan X-Trail with a similar arrangement, although that only had one fuel sender in one half of the tank, and a little internal transfer pump that used to just suck fuel out of the other half of the tank and chuck it into the half with the sender and pump assembly in it! The pumps would fail periodically and the owners would think their cars had suddenly become very thirsty because they'd read empty when there was still a load of fuel left in the other half of the tank!

 

[DiyNutJob]

No, nothing else changed. Took out leaky old radiator, fitted new one, refilled and bled system, job done. It's just a crap radiator. I have since found and bought an original, and I might replace the Nissen one this summer if the weather gets hot - in which case, I'll happily post you the old Nissen one to tie to your bumper and use as a fender for playing bumper cars, if you like!

What is interesting, is that my son has the 2 litre version of the same car, (mine's the three litre), which also has a Nissen radiator fitted and the matrix looks about the same thickness as mine, so I suspect the corner-cutting scumbags have just used the same matrix for all versions of my car, and only changed the end tanks.

Your son had no problems, I have no problems, that leaves you as the odd one out. My 3L runs fine with a radiator that is 40-50% lighter/thinner. It also ran fine with 40-50% of the coolant missing. Your overheating is most likely to do with your messing up. Through carelessness, you probably plugged up the plumbing somewhere. Mixing of incompatible coolants could gel up and cause a restriction. The other possibility is your engine internal mechanical resistance is too high and generating excessive heat. Use of the wrong oil could contribute to that. I would suspect your using thick oil to reduce leaks or something.

 

[Harry Bloomfield]

What is interesting, is that my son has the 2 litre version of the same car, (mine's the three litre), which also has a Nissen radiator fitted and the matrix looks about the same thickness as mine, so I suspect the corner-cutting scumbags have just used the same matrix for all versions of my car, and only changed the end tanks.

My diesel, is very thermally efficient, and they used the same radiator for, petrol 2L, and I understand the 4.6L. The diesels problem is one of it produces hardly any waste heat.

 

[Avocet]

Your son had no problems, I have no problems, that leaves you as the odd one out. My 3L runs fine with a radiator that is 40-50% lighter/thinner. It also ran fine with 40-50% of the coolant missing. Your overheating is most likely to do with your messing up. Through carelessness, you probably plugged up the plumbing somewhere. Mixing of incompatible coolants could gel up and cause a restriction. The other possibility is your engine internal mechanical resistance is too high and generating excessive heat. Use of the wrong oil could contribute to that. I would suspect your using thick oil to reduce leaks or something.

Yes... that'll probably be it...

Thank you for your well-informed and insightful comments, as ever. I promise I shall give them all due regard...

By the way, where did I say my son's car had no problems with cooling?

 

[Avocet]

My diesel, is very thermally efficient, and they used the same radiator for, petrol 2L, and I understand the 4.6L. The diesels problem is one of it produces hardly any waste heat.

Yes, diesels are a fair bit better than petrols in that respect. Both my and my son's cars are petrol (and "old" petrol at that)! They're also quite high power output engines (for their time and type) and neither of us, (shall we say), "spare the horses"!

 

[Harry Bloomfield]

Yes, diesels are a fair bit better than petrols in that respect. Both my and my son's cars are petrol (and "old" petrol at that)! They're also quite high power output engines (for their time and type) and neither of us, (shall we say), "spare the horses"!

The down-side, is that it needs to burn diesel, in a diesel burning boiler system, just to help get the cooling system warm enough to provide cabin heat.