Coolant issue.

[mikelamb]

Hi All,

I will try and explain My issue the best I can.
I have recently Had the head replaced on the Bongo.
I have a slight worry even though the van is running really well and much lower on the temp gauge.
My coolant alarm keeps coming on about every fortnight. I top up with coolant and its fine for about the same lenght of time. At first I was very cautious, but have now noticed that the alarm will stop after driving for a few miles. ( I guess thats down to the water expanding?)
After the van had cooled today I used a thick cable tie to dip the expansion tank and found the level to be above the lower sensor screw on the tank. Despite this the alarm still stays on when the van is started.
The other thing I have noticed is that when I open the cap on the expansion tank there is a good bit of pressure in it. This is after the bongo has been on stop all day.
I guess a trip back to the garage is needed, but just wanted your thoughts on this please.
I should add that the mechanic is experienced with bongos.

Thanks for your help,
Mike.

[mikelamb]

Am I not making much sense? 29 views but no comments usually means I'm talking rubbish again!

[munroman]

Hi, the coolant alarm will sound when the level falls below the upper screw, it sounds as if the alarm is working as it should, so definitely get it back for a check up!

[westonwarrior]

Hi, the coolant alarm will sound when the level falls below the upper screw, it sounds as if the alarm is working as it should, so definitely get it back for a check up!

Depends on wether its set up with a high-low sensor or a low sensor and earth?

you are correct if its the latter but if its the former then the coolant should not be touching the higher sensor

[haydn callow]

The fact that the level in the tank is above the LOWER sensor screw is irrelevant.
It's the top screw that matters....as soon as the level drops below the top screw ...the alarm will sound,
(we don't even have a bottom screw anymore)
You are losing coolant from somewhere.
Could be the tank cap or a leak.....
You must get it fixed asap..
the coolant alarm is doing it's job and warning you..
The loss of coolant can only get worse.

[New Forest Terrier]

Not too clear from your post if the Bongo is actually loosing coolant or the alarm is just coming on with an adequate coolant level.

On mine the screw holding the sensor occasionally works loose and I get a chirrup from the alarm. No coolant is ever needed and the remedy is to tighten the screw holding the sensor. Mine has never needed a coolant top up in the two years I have owned it so the problem is entirely a false alarm. Far better to get an occasional one of those than an overheat.

If it is actually losing coolant, you need to find the problem before it gets worse.

[missfixit70]

Get them to pressure test for hose leaks etc & check the strength of coolant, the alarm picks this up if it's not right.
If you use something to dip the header tank it should be at 20mm from the bottom vertically, a lollystick or something wooden gives an accuratedip as it soaks the wood.
Have you topped it up at all? Or just left the level as it is?

[dreamwarrioruk]

might be an idea to get some of the coolant dye so you can see if you have a visual leak or get the system pressure tested. we have a small leak that ive found since doing a pressure test on the system, we were loosing about 25ml of coolant over 3 months and glad ive found it. how much are you topping up with and how often. sometimes the leaks can only be found when its warm and up to pressure.best checked at night with a flashlight to see if you can find any misting from a leak.
it could be internal tho, we had a turbo water seal go which we couldnt see visually.

[mikelamb]

Thanks. I fill the header tank too about half full. This is over the top screw. After about a week the alarm starts to sound and I have to put about 1/2 a pint in to get it back to that level. But if I then continue without topping up it does not seem to lose anymore water, but the alarm sounds as it should. I thought perhaps it was overfull with Me and the excess was coming out through the overflow pipe. (hoped!) I will get back in touch with the garage and see if He can find something. I will let you know how I get on.
Mike.

[missfixit70]

How many times have you topped it up? Are you just using water? If so you're gradually diluting the coolant, not a good idea.
Make sure you know what coolant is in there so you can top it up with that without mixing incompatible coolants, but if you're topping it above a dipped 20mm it'll probably keep blowing it out, but it sounds to me like you may have a leak, pressure test ( & uv dye if you haven't got red coolant in there, this shows up under uv anyway) is the way to go. Get it back to the garage & get it checked asap.

[mister munkey]

If you're topping it up with water it may cause the alarm to be more senstive as the coolant strength becomes weaker.

I had a prolonged weep for over a year, using about a cupful a week. Sticking plain water in bought the level up but made the alarm chirp for much longer on a cold start.

[lindeelu]

will try and explain My issue the best I can.
I have recently Had the head replaced on the Bongo.
I have a slight worry even though the van is running really well and much lower on the temp gauge.
My coolant alarm keeps coming on about every fortnight. I top up with coolant and its fine for about the same lenght of time. At first I was very cautious, but have now noticed that the alarm will stop after driving for a few miles. ( I guess thats down to the water expanding?)
After the van had cooled today I used a thick cable tie to dip the expansion tank and found the level to be above the lower sensor screw on the tank. Despite this the alarm still stays on when the van is started.
The other thing I have noticed is that when I open the cap on the expansion tank there is a good bit of pressure in it. This is after the bongo has been on stop all day.I guess a trip back to the garage is needed, but just wanted your thoughts on this please.
I should add that the mechanic is experienced with bongos.

Two things stand out here.
1/. The coolant is dropping below the top (active) sensor screw, causing the alarm to activate.
2/. There is pressure in the system after the engine has been stopped all day & is presumably cold.

Not a good look as the system is being slightly pressurised and probably forcing coolant out of the tank overflow during normal running.
I would get the coolant tested for exhaust gases before doing anything else as I suspect a tiny head gasket leak
into the water jacket.

[missfixit70]

I don't get the pressure still being there after it being parked all day & cold as being indicative of head gasket failure? where is this pressure coming from on a cold engine?

[Alacrity]

I can't see how it can have a leak if it is holding pressure over a long period? I had the smallest of weeps on one of the numerous small hose's & the only reason I knew I had a leak it that it wouldn't hold pressure in the expansion tank. Surely if it holds pressure then the system must be sealed? The worry then is where is the water going? The first thought is head but if that has been done where else? Tranny oil cooler?

[mikelamb]

Good evening all,

Just called at the garage and He is having the van back soon.
To answer a couple of your questions, It holds pressure in the system all day. I parked it up in work this morning at 7 and returned at 18:00 and there was pressure in the tank.
I am using a mix of coolant and water to top up with.
A pressure test is on the cards, So Lets see what that shows.
I must say the van is running much cooler than it has since I bought her, but I guess thats nothing to go by.

Mike.