Coolantgate

Tin.tin · Tuesday at 5:04 PM

Hi Gents

Having an issue with coolant level dropping over 4-5 days, topping up around 250ml. Temp staying where it should be however & car runs as normal.

Had the car pressure tested at renotec as well as a local specialist. Both have reported no visible leaks, only a bit of coolant residue around thermostat housing flange & a bit around pipe from back of water pump.

Had thermostat done & flange vapour blasted not too long ago so that area was spotless initially.

Now seeing a new bit of residue around it, not a lot though. Which is odd considering no leaks from pressure test.

Im scratching my head as this a bit outside my comfort zone & both garages can’t say 100% what it is so a bit lost.

Any advice/recommendations would be greatly appreciated

Cheers

Louis · Tuesday at 6:12 PM

What jubilees are they? Only use JCS Higrips.

Check the heater matrix too and for any damp floors inside the car

dann2707 · Tuesday at 9:07 PM

Personally wouldn't be using a jubilee clip at all on something that gets hot and expands and contracts. You need a constant tension clip on there imo.
I can't see it being the root cause but it's clearly leaking from there.

Aaron.. · Tuesday at 9:47 PM

dann2707 said:
Personally wouldn't be using a jubilee clip at all on something that gets hot and expands and contracts. You need a constant tension clip on there imo.
I can't see it being the root cause but it's clearly leaking from there.

Here was me thinking there are just different types of jubilee clips.

I wonder if this is why my boat absolutely pisses coolant and sea water

Oh well.

JamesBryan · Tuesday at 10:01 PM

250ml every 4-5 days is a fair bit.

When they did the pressure test and couldn't see any leaks, did it hold pressure?

If it's holding pressure then it can only really be burning it.

Tin.tin · Tuesday at 10:40 PM

JamesBryan said:
250ml every 4-5 days is a fair bit.

When they did the pressure test and couldn't see any leaks, did it hold pressure?

If it's holding pressure then it can only really be burning it.

Yeah not seen it like that before. Forgot to ask if it's holding pressure. Local specialist cleaned the area said check back in 3 days, will ask when I go back in.

Tin.tin · Tuesday at 10:52 PM

Louis said:
What jubilees are they? Only use JCS Higrips.

Check the heater matrix too and for any damp floors inside the car

Think it is JCS if im not mistaken had it done at AWM.

Nice one will have a look but honestly above my level of knowledge. Have it booked in again for August hopefully it doesn't blow up in the meantime

Louis · Tuesday at 11:20 PM

Just touch the floor near the centre console. You're skilled enough to feel if something is moist im sure

E30kev · Tuesday at 11:21 PM

Might be worth replacing the coolant cap to rule it out too.
I had a similar experience with an e36 328i which was losing a small amount of coolant every few weeks and no visible leaks.
Had it pressure tested and it all held fine, the advice I was given was to change the cap which solved the problem.
It must have been relieving pressure early and slowly boiling the coolant off.

Tin.tin · Tuesday at 11:37 PM

Louis said:
Just touch the floor near the centre console. You're skilled enough to feel if something is moist im sure

Should some transferable skill for the task

Tin.tin · Tuesday at 11:48 PM

E30kev said:
Might be worth replacing the coolant cap to rule it out too.
I had a similar experience with an e36 328i which was losing a small amount of coolant every few weeks and no visible leaks.
Had it pressure tested and it all held fine, the advice I was given was to change the cap which solved the problem.
It must have been relieving pressure early and slowly boiling the coolant off.

Oddly enough fit a new cap recently, may try the old one on as it was still ok just looked a bit shabby. Good shout though man.

Did you have any coolant residue around the cap/tank?

JamesBryan · 2026-07-08T00:03:31+0100

Put the heaters on a warm heat, do you smell a sweet scent? That would be an indication of the heater matrix.

E30kev · 2026-07-08T00:05:57+0100

Tin.tin said:
Oddly enough fit a new cap recently, may try the old one on as it was still ok just looked a bit shabby. Good shout though man.

Did you have any coolant residue around the cap/tank?

Just a very small amount below the cap and down the side of the expansion tank.

Brigsy · 2026-07-08T06:14:49+0100

Jubilee fine if its tight. The oem constant tension clamps arent perfect and let by when stood. Common to see a bit of fur in the stat area especially on occasional used cars as it does not evaporate with daily use.

As above 250ml is a fair bit. Id pressure test again and borescope the heater box to see if any traces of coolant leaking. I had all this carry on with the kangoo and left cooling system pressured up at 1bar for a couple of hours and it was the heater core.

If your worried about h/g, pull the spark plugs whilst the cooling system is pressured up and borescope. Highly unlikely any h/g issues unless running poorly or misfiring from cold etc, usually obvious when looking at plugs if any coolant has been in a cylinder.

Tin.tin · 2026-07-08T08:42:48+0100

JamesBryan said:
Put the heaters on a warm heat, do you smell a sweet scent? That would be an indication of the heater matrix.

Will try this today cheers !

Tin.tin · 2026-07-08T08:59:32+0100

Brigsy said:
Jubilee fine if its tight. The oem constant tension clamps arent perfect and let by when stood. Common to see a bit of fur in the stat area especially on occasional used cars as it does not evaporate with daily use.

As above 250ml is a fair bit. Id pressure test again and borescope the heater box to see if any traces of coolant leaking. I had all this carry on with the kangoo and left cooling system pressured up at 1bar for a couple of hours and it was the heater core.

If your worried about h/g, pull the spark plugs whilst the cooling system is pressured up and borescope. Highly unlikely any h/g issues unless running poorly or misfiring from cold etc, usually obvious when looking at plugs if any coolant has been in a cylinder.

Cheers Brigsy. Yeah it’s a fair amount tbh thankfully caught it early. Engines been pretty good sometimes can go a while without opening bonnet but decided randomly to open it while at Tesco to find it on min, horror.

Not too worried about h/g atm it’s been running as usual no misfire, smoke or oil cap sludge; more so heater matrix heard that’s not the easiest job. Is it not always obvious from coolant in cabin if that?

Brigsy · 2026-07-08T18:52:06+0100

Yep should get a whiff of coolant inside cab if heater is leaking, can borescope the lower vents in heater box to see if any crystallised coolant deposits

Yarp · 2026-07-08T20:11:37+0100

You can get UV dye you can add to the coolant and can then use a UV light to see if you can spot where it’s coming from.

As above though, I had issues with mine with a s**t aftermarket cap for the coolant bottle. Issues went with the old original back in.

Brigsy · 2026-07-08T21:38:59+0100

Ive also had the faulty cap causing no pressure/coolant to spill out. The quality of them for megane and clio is terrible.

Search

Search

Coolantgate

Tin.tin

Louis

I Love Ed Sheeran

dann2707

Aaron..

JamesBryan

Tin.tin

Tin.tin

Louis

I Love Ed Sheeran

E30kev

Tin.tin

Tin.tin

JamesBryan

E30kev

Brigsy

Tin.tin

Tin.tin

Brigsy

Yarp

Brigsy

Similar threads