Bongo Fury

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mikeonb4c wrote:

Driver+Passengers wrote:Totally off topic for this thread, but +1 for monitoring pressure first (and level/temp, if so desired).

Out of interest, what warning pattern would you expect to see as coolant level drops due to a pinhole leak in a hose, or maybe poor circulation due to blocked rad, failing water pump etc? Would it be easy for the average owner to understand and act on?

My understanding and educated guesswork is as follows...

As coolant level drops due to a pinhole leak in a hose (over time, typically many days/weeks) there will be less coolant to expand and the typical running pressure when the engine is up to temp will be lower. I'm currently trying to quantify this somewhat by varying the initial/cold coolant level in my tank.

Air settled in the head/matrices would thermally expand, causing pressure rise, high-level coolant alarm to trigger and temperature increase.

Poor flow will result in increased temperatures and an increase in temp/pressure will be observed. If localised boiling occurs around the exhaust ports, you would observe a spike in pressure, and a high coolant alarm would likely react, too. Only then after coolant expulsion would the low level alarm trigger.

Catastrophic failure of a hose would dump all pressure, trigger low level alarm and shortly give rise to temp alarm.

With a leaky gasket or cracked head, pressure and temperature may increase unduly with load, or even no load. Only after coolant expulsion will a low level alarm trigger. High level alarm would help in this case. Alternatively, level may drop and you're back to the same symptoms as a pin-hole leak.

Alarming on coolant pressure conditions requires rise/fall alarms, not just absolute thresholds, implying R&D, untested kit, etc... Monitoring pressure is not "install and forget". Low level (and high level) coolant alarms are much easier for the average owner to understand and act on. Also, pressure is unlikely to tell you on start up if the header tank is empty, this is where low level alarm definitely wins out.

I believe there is going to be a delay in almost every situation before a low coolant alarm triggers. Similarly, as has been well thrashed over the years, the position of a temperature sensor on the head is going to give readings that mean different slightly things. Typically, all rely on heat transfer through metal and so there will again be a delay.

That's why, with the exception of a cold start with an empty header, I rely on pressure to tell me what's what. I have not yet installed a low (or high) coolant alarm. I haven't even replaced my digital temp gauge(s), though I have modified the dash gauge. My alarm conditions for pressure are still immature (<2psi, >15psi, >3psi/s, <-3psi/s).

I'd be happy to stand corrected on any of this.

The exception to the low coolant alarm being subject to inevitable delay would be if the leakage occured while the vehicle was not running, e.g. overnight (and you didn't see the puddle).

A low coolant alarm would avoid the galling experience of unknowingly cooking the engine slowly. For what it costs to install, it is surely a must.

However, a high coolant alarm would be a very useful addition. Fortunately, I haven't yet experienced a boiling Bongo but I once had a Hillman Imp which gave the appearance of boiling but in fact was blowing gases into the cooling system and raising the water pressure/level to the extent that the cap was blowing off coolant. If this happened in the Bongo the header tank level would rise and trigger such an alarm and draw the driver's attention to the fault condition. An experienced driver would realise that it was not neccessarily overheating but something else was amiss.

Time for a new generation of combined alarm with two tones?

Frank

Diplomat wrote:The exception to the low coolant alarm being subject to inevitable delay would be if the leakage occured while the vehicle was not running, e.g. overnight (and you didn't see the puddle).

Yes, alarming when "starting on empty" is a major feature of the LCA. For everything else, I claim it's possible to detect trouble sooner, though I don't discount or contest the value of an LCA or LCA/TM combo - that's always been the right way to go.

Diplomat wrote: Fortunately, I haven't yet experienced a boiling Bongo but I once had a Hillman Imp which gave the appearance of boiling but in fact was blowing gases into the cooling system and raising the water pressure/level to the extent that the cap was blowing off coolant. If this happened in the Bongo the header tank level would rise and trigger such an alarm and draw the driver's attention to the fault condition.

This is precisely what my van was doing. Though discontinued, I wonder if Haydn/Jo would consider a group buy on the forum to achieve the minimum order quantity from their suppliers for another batch of HCA add-ons...? I've never had one, but I see the loss of the HCA from the market as a pity.

Thanks D+P, a really good and simple explanation. How funny Frank, the only car I ever cooked a head on was my first car.............a Hillman Imp (the old alloy head didn't much like being mistreated I recall).

I think the LCA is simple to fit and understand, and takes care of the most important stuff for most people: don't drive if you're losing coolant. But there's no doubt that for the more savvy owner, and to cover misperformance of the engine and cooling system, monitoring temperature and pressure can provide much better early warning than an LCA alone. I have a TM2 ready to fit over winter, but the pressure stuff will need a user-friendly front end (as you say) before I could cope with what's its saying whilst keeping my eye on the road ahead (priority uno!)

I agree with every point you make, Mike.

As for the "front end", one 3 digit LED display, two or three LEDs and a buzzer - that's as far as I want to go. None of this touchscreen LCD nonsense.

http://www.igmaynard.co.uk/bongo/forum/ ... lant+alarm.

both haydn and others did try .

I can appreciate the difficulties involved in getting folk to commit before an order can be placed from the supplier - consensus is there that detecting a high coolant level is "a good thing", though.

http://en.wikipedia.org/wiki/Thermal_expansion wrote:Expansion in liquids

This section requires expansion. (August 2010)

...

Cheers, Mel.

The Great Pretender wrote:Have you managed to take pressure readings at the head and tank simultaneously? If so do they differ?

No, the closest I'll get to the head at the moment is the bleed hose sensor - I've got one made up but no cable for it.

PM sent.

The Great Pretender wrote:I think, and it is only an opinion that there is a differential between pressure in the head and tank that needs exploring.

During reliable operation, or as an indicator of a fault?

Driver+Passengers wrote:

The Great Pretender wrote:I think, and it is only an opinion that there is a differential between pressure in the head and tank that needs exploring.

During reliable operation, or as an indicator of a fault?

During reliable operation.

I'll post a graph over the weekend.

I know Steve and others have drawn schematics and layouts for the coolant system - I just wanted to draw my own to get my head around it, too. Here it is. Please let me know if I've got anything wrong.



Pity I don't have a license for Flowmaster V7 Automotive.