Slight coolant loss

[thepickles]

Hi all,

I have noticed that the fluid level in the coolant tank is going down about 10mm a week I have checked all over , with no obvious signs of leaks

any ideas??

Cheers
Steve

[widdowson2008]

How many miles do you cover per week to get the 10mm loss?
Reason for asking is as follows:
If you do enough to get the temperature up to normal, then it could be something as simple as the expansion tank cap needs replacing cos it's not allowing the system to get to correct pressure. Look for any tell-tale marks around the expansion tank?

Pumps can (and do) leak, but this is not quite so easy to get to and spot. Pump leaks will drip onto the undertray and get absorbed in the felt and not drip onto your drive.

Hoses and clips are also suspect.

Can you get a pressure test done? It will tell you if the system is holding the 1.1 bar and hopefully the leak spot will become more apparent.

[Diplomat]

Inspect the top of the radiator where there is a plastic to metal interface. Any leak will show up after a run. To make absolutely sure, run a finger under the edge and check for droplets.

Frank

[Northern Bongolow]

Hi all,

I have noticed that the fluid level in the coolant tank is going down about 10mm a week I have checked all over , with no obvious signs of leaks

any ideas??

Cheers
Steve

how many weeks? just one, or several.
with the lower ambient temps at this time of year its normal to experience a small loss, this isnt actually a loss at all, it is just the fixed amount of coolant in the system contracting further than it does in summer.
if its just once, then top it up to the level marked on the tank, an check regularly till your happy. if its more than once you have a leak. as steve says get a garage to do a pressure test,not a vac test.the leak should show itself.

[Driver+Passengers]

Obligatory warning - you probably already know...

If for any reason you do have a slight leak and it develops further or persists, you risk damaging the engine. If the coolant level drops out of the header tank at all, the result is air in the system and you will need to bleed it correctly. Just know that one option is DO NOT DRIVE until you get it located and sorted.

Now you know.

(PS do you have a low coolant alarm fitted?)

[bigdaddycain]

A 1cm drop per week sounds like a leak to me...

Theoretically, if the system is "leak free" then NO coolant drop should be experienced, however after 7years+ of ownership of my bongo, mine had always (on average) needed maybe half a cupfull of coolant every six months or so to bring the level back up to the FULL mark.

My bongo has no leaks.

The coolant contraction theory is an interesting one... But would an ambient temp change really drop the level in the header by 1cm?

Another question.... If you hadn't topped up the level each week, would the level drop yet another 1 cm each and every week? i.e If you didn't top up the level for 5 weeks, would the level be 5cm lower than full?

[borntobag]

I had a coolant loss that was very illusive last year, the crimped seam where the plastic and metal components join at the top of the radiator was the culprit.

I looked for the leak for ages and it wasn’t until we used the bongo to go shopping I found it as I normally park up and go to work or in the house and don’t see her it till the next day.
On our return from shopping I noticed a small puddle about A4 size at the front on the floor.

I popped the bonnet and saw a very small amount of fluid/droplets on the top of the radiator, but no obvious leaking point. I drove her home and parked up and waited, after 3-4 minutes I could hear a hiss and then saw a very fine spray coming from the top of the radiator.

My theory is that when she is running at normal temp all is fine as the heat expands the joint in the radiator and keeps its integrity but when she cools the components contract and the pressure in the system is relieved through this weak spot. Then when she is parked up either all day or over night the little amount of fluid that has escaped evaporates leaving no signs of a leak apart from a drop in the tank.

If this is your problem forget rad weld and stuff like that and get a replacement radiator.
Best thing I ever bought? a low coolant alarm.
If you haven’t got one, get one.

Good luck

[thepickles]

Thanks for all the replys,
I had a new rad last year and yes have a coolant alarm, with work etc not had time to check bongo once up to temperature, that will be the weekend. I have checked whilst cold and did have some spilling when I took the rad cap off like the system was under pressure this resulted in a 10mm loss in the header tank, but I don't what that means I will check at the weekend when the van has been run.
Cheers
Steve

[wonkanoby]

unless you plan on bleeding it dont ever touch the rad cap

[Diplomat]

I had a coolant loss that was very illusive last year, the crimped seam where the plastic and metal components join at the top of the radiator was the culprit.
...
My theory is that when she is running at normal temp all is fine as the heat expands the joint in the radiator and keeps its integrity but when she cools the components contract and the pressure in the system is relieved through this weak spot. Then when she is parked up either all day or over night the little amount of fluid that has escaped evaporates leaving no signs of a leak apart from a drop in the tank.

I have to tell you , borntobag, that this join is quite capable of leaking when hot!

Coolant can squirt out or appear as a fine mist. The giveaway that is happening is the smell detectable by a well trained nose. I know all the motoring smells from coolant, through wiring, to burnt out selenium rectifiers (not to be confused with catalytic converters).

It is feasible for the hot coolant level to rise in the header tank even if there is a slight leak. When it cools the level will then drop below the normal mark, further and further with each heating/cooling cycle.

I have taken advantage of the suction whick occurs on cooling by applying epoxy to the radiator joint. Some will get sucked in as the radiator cools, giving a better bond than simply 'painting' it on.

I have found a 'Swiss Roll' type epoxy mix putty which combines to make a coppery brown colour and is far more heat resistant than most but unfortunately I can't find the packing with its name on it!


Frank

[borntobag]

Frank, i dont doubt it at all, just pointing out what happened to me as something else to look for.
We all know its vital to keep the integrity of Bongos cooling system intact and any info/pointers helping to do that are certainly welcome by me.
I have replaced most of the cooling system on mine, hoses, rad, pump, thermostat and the rear matrix and it is quiet alarming how many junctions, joints and hose clips there are, all potential weak spots that could cause coolant loss.

The best tip I can offer to anyone who hasnt is to fit an LCA and a Mason alarm or similar and above all if there is any loss of coolant at all DONT drive it until its sorted.

I learnt the hard way and it cost me over £1200, when £60 quids worth of alarms and bit more knowledge of the standard temp gauge limitations (if the needle goes to hot its too late) would have saved alot of hassle and expense.
Or as my old employers work moto stated "quo certior eo tutior" roughly translated "the more fully informed the safer"

[helen&tony]

Hi Frank...
There are lots of epoxy putties on the market...if it is in a cardboard box containing 2 hard-ish round rods of material, then it's "milliput"...probably one of the best...two types...and the more rapid variety can even repair a split pipe under water...
Devcon do another one...and Devcon products are stupendous...
You'll find Milliput in model shops, and Devcon in the better class Hardware stores!
Cheers
Helen

[Diplomat]

Hi Frank...
There are lots of epoxy putties on the market...if it is in a cardboard box containing 2 hard-ish round rods of material, then it's "milliput"...probably one of the best...two types...and the more rapid variety can even repair a split pipe under water...
Devcon do another one...and Devcon products are stupendous...
You'll find Milliput in model shops, and Devcon in the better class Hardware stores!
Cheers
Helen

Hi Helen

None of those names ring a bell, unfortunately.

This came as a single two ingredient 'sausage' rather like A Swiss Roll or Liquorice Allsort wrapped in a tatty, easily torn, acetate sleeve and sold on a cardboard outer box. It might have been Isopon or Plastic Padding. The most noticeable thing being the unusual colour of the resultant mix.

So far it has not deteriorated in the same way that the more liquid derived mixes have done.

Hopefully, I have not thrown away the outer box. Merely mislaid it!

Until such time as I find myself near somebody I can trust to fit a new rad and do an entire cooling system overhaul, and I mean entire, the leak proofing is keeping me on the road. Unfortunately, none of the garages that people recommend on the forum are anywhere near me and I no longer have the enthusiasm, eyesight, suppleness and knuckle skin to do major repairs, especially ones involving fluids.

Frank

[helen&tony]

Hi Frank...
I know EXACTLY the one you mean...2 strips, one blue, and one white in a blister-pack....I had some, and sadly nowhere near as strong and reliable as Milliput...I can't remember the name of the one in question...old age ...but i'll bet you can get Milliput on e-bay...you won't be at all disappointed!...For plastic, I've found a superb prodict C/O. our English plumber...he got it from America....again, now in UK off e-bay....it's simply UNBELIEVABLY effective...sadly, most adequate adhesives are not available here...the most hi-tech stuff available is cyano. but the stuff you get here is WAAY better than UK stuff...it REALLY would stick someone to a lavvy seat
Cheers
Helen