BXProject

[docchevron132]

Ok, last couple of days I've noticed the running temp of the TD has risena few degree's.
Didn't take that much notice since the guages aren't known for accuracy, and I've been running with the heater on so figured maybe it was just tipping the thermostat in and out like, it's not a hot running engine unlike the last one.

Anyhow, today when I got to work I thought I could smell the faint whiff of anti-freeze, so I popped the bonnet and had a grope of the rad (hot) and the top hose, also hot, but had NO pressure in it at all. It was running just under 90 deg (yes I've already forgotten the ALT code for deg), fan not in, but I could take the coolant cap off and there was no hiss, no release of pressure, no nothing.
Cant find a leak, the water level is fine, haven't touched it since that engine went in a few thousand miles back.
Now, I've arsed around with a fair few cars in my time, but I've never had one up to temp that doesn't have some pressure in the system.
Oh, the rad cap is fine aswell.
Am I just looking for trouble that isn't there? OR should I be concerned?

[mat_the_cat]

I can help you with the ALT + 248!

But the real problem is a bit of a mystery...the only thing that springs to mind is that the system is no longer sealed - but in that case surely you'd lose water! Unless there's a problem with the header tank above the water level, would have thought it would have to be pretty obvious to prevent pressure build up though.

[Philhod]

It's defo not pressuring up. Why I will have to think about for a bit, but history tells me it is the cap.
Only a run of about 15 miles will cause water loss, if the pressure loss is gradual.

The other thing that I can remember giving those symptoms is that ex fuel heater plastic thingy at the back of the motor. When it first cracks, the water loss is almost none, you only see any water as it progresses and then only if it's on a surface that will show it and again only if you look there.

[jayw]

The system will only pressurise if the water's getting hot and creating steam, it's the steam that creates the pressure which is then moderated by the thermostat and limited by the pressure relief on the cap.

I'd say that as the weather has become noticeably colder in the last few days, you're ambient coolant temp has dropped accordingly (to around the 'stats temp) and there's nothing to worry about!

Don't worry, be happy >> insert whistling smiley<<

[Way2go]

Good call! The purpose of the pressure cap is to raise the temperature point at which the water boils. So without it water boils at standard temperature which you would see evidence of, ergo the water is not heating up as it was. Either influence of the colder weather or the themostat has failed open, possibly both.

[Philhod]

What the fuck was all that about If you've got steam in there you have real problems Jay.That's the whole point of having a pressurised system, you don't get steam....hopefully!!
As the water gets hot it expands into a system with NO air in it, thereby increasing the pressure within the system to between .7 and 1.1 bar, controlled by the cap for ultimate pressure and the thermostat for flow. Raising 1bar raises the boiling point 10° (approx).

However.Steam, or more correctly water vapour, occasionally,does occur around the cylinder head. The surrounding water is of course above the natural boiling point, so doesn't allow the vapour to re condense. As vapour has literally no thermal efficiency this allows the surrounding metals temp to spike, with obvious consequences over time.

The whole point of this is that we used to use a waterless coolant in big industrial diesels
(cummins 500 HP). I wondered if anyone else has heard of this and where it might be available, as not only was it trouble free, but as it allowed us to raise the cut in temp of the fans and therefore the running temp of the engine, but it cut the fuel used by about 5%.

[docchevron132]

Cummins...mmmmmmmmmmmmmm

if I take the cap off then there is some steam emitting, just like I'd expect any engine to.
Oddly enough, since I've now been a tad paranoid about it, every time I've runt he engine I've checked the pressure as soon as I stop.
Today, I've used the car a fair bit, and all day it's had no pressure in it at all.
Until the drive home from work just now. Less than I'd expect, but some pressure non the less.
The stat is new and seems to be working normally. Temp goes up to just under 90 on the guage, stat opens and you can watch the temp drop off on the guage back to about 75 °.
Still no loss of water at all, but I have noticed if I stick my foot down the temp rises very quickly towards 90°, never past it, but it didn't do this before..
Given the lack of coolant loss I'm not shitting it, and taking Jays approach to not worrying about it, for now.. I'm thinking maybe trundling round as I usually do the stats maybe shutting off a tad and the temps rising when I boot it because the stat is partially closed, then it's opening again and pulling the temp back?
Dunno, either way, it aint losing water so I think it's ok..
Time to get the valver fixed though, just in case!

[Philhod]

Is this the motor that you fried twice to and from Vanny's last year.??

Just a thought. The new stat may just be opening earlier and be very temp reactive.

If no coolant ensues why bother.

[Bx Bandit]

Air lock my dear Wotson? I wouldn't of thought the coolant would cool sufficiently quickly to close the stat sufficiently quickly to cause any noticeable drop in temp that quickly (although I guess the night air when you drive home is pretty cool now....)

Give it a hard run and lift the header cap

[Way2go]

Not sure where you were trying to go with that post Phil. Waterless coolant? Not going to go there for BX's are we?

What the fuck was all that about If you've got steam in there you have real problems Jay.That's the whole point of having a pressurised system, you don't get steam....hopefully!!
As the water gets hot it expands into a system with NO air in it, thereby increasing the pressure within the system to between .7 and 1.1 bar, controlled by the cap for ultimate pressure and the thermostat for flow. Raising 1bar raises the boiling point 10° (approx).

As I said, the purpose of the pressure cap is to increase the temperature point at which the water will boil.

But how can there be NO air above in the system as you say because if that was so, then the pressure cap can not efficiently regulate pressure. There would then only be initially volumetric expansion and no pressure build up and a vaccuum above the water when it volumetrically contracted. Likely result would be damage, without the air buffer.

Also when the thermostat fails open then the system will take a long time to get up towards temperature and in my experience when this has happened it never reaches the normal working temperature. The old aneroid thermostats were notorious for this as they always failed open and people would run like this for quite a while. Modern stats normally fail closed though as far as I am aware and you are aware something has to be done quickly.

[mat_the_cat]

Modern stats normally fail closed though as far as I am aware and you are aware something has to be done quickly.

That's what I always understood too (the wax rather than bellows type), but I've had 4 thermostats give problems of cool running unless stationary, none failing shut! They hadn't failed open, as they were closed when removed but I suspected they were opening significantly earlier than they should. Cured with new 'stats anyway, afterwards they sat at a constant level on the gauge whatever the load/speed/air temperature.

[docchevron132]

Is this the motor that you fried twice to and from Vanny's last year.??

no no, that engine died, this is engine number 4. Known good.
No air lock, change of rad cap, no coolant loss.
Still the occassional whiff of coolant though...

[charlie]

hmmmmmmmmmmm interesting



just leave it with me mate and i'll fix it for u





[stud]

[Philhod]

Still the occassional whiff of coolant though..

Heater matrix minute leak evaporating off immediately???????.

But how can there be NO air above in the system

I didn't say there wasn't any AIR above the water, that's what the expansion tank/tube is for.

I said there should be no steam IN the system or you will contract the issues I described.
In an efficient system, working properly, steam should never occur as the water, at increased pressure, never boils, or shouldn't, even 10 to 15% above it's natural boiling point.
The stuff I referred to, was a greeny yellow "liquid" with no water in it. It had a much higher boiling point, didn't freeze and with much better cooling dynamics.
As I said, it allowed the engine to run about 10% hotter and produced a good 5% better fuel economy.
We also used it in some 400 HP Crossley engines as well Doc.

If you remember I posted ages ago about Nuclear heat exchangers. These raise the pressure of the water by around 30 bar, taking the water up to about 400° without boiling. That has to be fully sealed as any "steam" would be rather irradiated.

[Fish_Botherer]

Whiff of coolant inside the car? Been using the heater for first time in a while? I Know I'm being pretty unsubtle and unoriginal here

Heater matrix minute leak evaporating off immediately???????.

and that it doesn't explain hot running...

[docchevron132]

no no, not IN the car, but under bonnet, occassionally I catch a whiff if I have the window down..
But then, it still hasn't used a drop of coolant, none, at all...

I'll keep an eye on things for now and see how it goes.

[Fish_Botherer]

Not a lot else to do, really ... any nicks or scratches on the expansion tank top to defeat the cap seal?

After idly thinking in terms of dye in the coolant to detect leaks I just had a daft idea for detecting hard-to-find leakage. An inert dye that'd be visible in road grime/oil doesn't exist to the best of my knowledge - which is by no means exhaustive.

I've been fish-bothering with a float at night lately which has been jury-rigged to have a glow-stick attached to it. I've no idea what goes into the glow sticks - they're a rigid stick smaller than a small matchstick activated by bending the plastic it's encapsulated in to break the stick and start whatever chemical reaction goes on. Once activated, the stick becomes both luminous for 24-36 hours and liquid.

Anyone know what goes into them?

[Way2go]

Once activated, the stick becomes both luminous for 24-36 hours and liquid.

Anyone know what goes into them?

Here you go:

http://science.howstuffworks.com/innova ... -stick.htm

[docchevron132]

well, , turns out it is the rad cap..
I'll replace the fucker tomorrow, although it did over 400 miles today without issue.
Thats the second new component I've had fail in as many weeks.
They dont make things like what they used to.

[Philhod]

See end of first line 3rd post, this thread




smug bastard