Coolant loss issue

Gremlin · Aug 8, 2018

Hi guys.

I have a 2003 golf. I had been loosing coolant on an irregular basis fo a while. Like for 2 years it would lose 200ml every 4 months, then I had a hose go. That could have contributed. I eventually realized the tank or cap was faulty. I replaced both. Seemed fine then again randomly lost all the coolant in the reservoir. I haven't seen any of the tell tale signs of a blown headgasket but that's where I am thinking this might be going and am taking it in tomorrow to get checked.
I am wondering though, if I'm lucky and it's not the head gasket. Can the ac cause issues. I ask because yesterday I drove 600+kms with the ac on (been brutally hot here in the maritimes) and halfway through the trip I had to pull over, light came on, and fill up the bulb. It was empty. Finished my trip and topped it up this am. Today, I checked the fans and one is not working. So just to see, I drove 300kms back without ac....it was brutal. And no coolant loss. I have looked everywhere and see no leaks. And I am sure it blew out the relief on the bulb as there was coolant all around it. My girl has never overheated, it has 490,000kms on it and o just had the waterpump and timing belt done.

Could the fan not running with the ac on heat it up enough to not overheat but build excessive pressure and relieve it via the build and cap? It is totally random, when it loses coolant. The only common denominator is the ac. New compressor 2 year ago.

Fingers crossed it's not the head, but thoughts anyone???

Genesis · Aug 8, 2018

It IS harder for the cooling system to reject heat with the A/C on, as the air goes through the condenser first before the radiator.

Enough to do this? Probably not, IF the coolant is properly balanced (e.g. 50/50 coolant and distilled water), absent other issues. But if there are other issues... (e.g. partially plugged radiator, etc)

Gremlin · Aug 8, 2018

Figured it couldn't be a sufficient enough reason but hoping till I find out tomorrow. Shes got alot of kms so likely is the head.

Tdijarhead · Aug 8, 2018

Check the coolant temperature sensor right over top of the transmission, that O ring is know to leak on occasion.

WildChild80 · Aug 8, 2018

The fans do nothing while you're going down the road, they are to maintain cooling when stationary.

I'd get a pressure tester and pressurize the system and put it on ramps or on a lift and see if you can see anything and leave it for an hour and see if you loose pressure.

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Gremlin · Aug 9, 2018

So checked it for CO in the coolant. None. Guy said it doesn't look like the gasket is bad. So random when it loses fluid.

Genesis · Aug 9, 2018

Get a UV light and look around. Coolant residue will glow under black light.

A POSSIBILITY, but not a high probability one, is the EGR cooler. They have a history of failure in the PD engines, but not in the ALH vehicles.

If the leak is to the outside (and not being ejected out the exhaust) a black light should point you in the right direction.

Genesis · Aug 9, 2018

Get a UV light and look around. Coolant residue will glow under black light.

A POSSIBILITY, but not a high probability one, is the EGR cooler. They have a history of failure in the PD engines, but not in the ALH vehicles.

If the leak is to the outside (and not being ejected out the exhaust) a black light should point you in the right direction.

KrashDH · Aug 9, 2018

I had coolant loss for about a year that I didn't know where it was going. I had crawled under the car and thought I was leaking oil because there was brownish-black gunk coming down the front, but I just thought I had a bad seal job on my hybrid oil pan.

I cleaned everthything off and checked again the next day, and saw coolant dripping, and it was coming down the front of the oil pan (clean coolant). Started digging and it was VERY hard to see, but it was coming from the hard line that houses the T-stat. I would check that seal for starters

BobnOH · Aug 9, 2018

Gremlin said:
................. My girl has never overheated,,,,,,,,,,,,,,,,,,,

Well the answer to that would be a complete different forum.
Seriously though, sounds like you have a hard to find leak. Blown head gasket will port combustion gas to the cooling system, leaving sign, sometimes even blowing out the coolant bottle.
And make time to get those fans fixed, that condition will eat your AC system.

KrashDH · Aug 9, 2018

BobnOH said:
sometimes even blowing out the coolant bottle.
.

As well you'd be able to see some bubbling or "boiling" in the bottle as well

Gremlin · Aug 9, 2018

Thanks guys! I ordered the fan this am and will not use ac until that's installed.
I am definitely going to give it a real good cleaning (as I do have a slight oil leak, been that way since I purchased at 200,000kms) and see what I can. No wet carpet at all so dont think it would be the heater core.
I am also wondering, I have an old cap for the bulb. Was thinking of drilling a hole, tapping a thread and install a air fitting. Using my little pig, set it at 15psi and pressurize the system to help see a leak. Do you think that might work?
Really appreciate all your advice and input. It is a phantom leak. Drove over 300kms today, mix of highway and town and didn't loose a drop. Seems like it's all going quickly at once. Gonna drive me nuts till I find it.

BobnOH · Aug 9, 2018

Yes, if you can do it with a hot engine, the thermostat should be open. Heater on hot, TB top cover off. Don't know how much pressure.

Gremlin · Aug 9, 2018

Ok. TB cover? Sorry, not up on all the acronyms. And should I have the blower on or just at full heat setting? Thanks!!

KrashDH · Aug 9, 2018

Gremlin said:
Ok. TB cover? Sorry, not up on all the acronyms. And should I have the blower on or just at full heat setting? Thanks!!

TB = timing belt

Gremlin · Aug 9, 2018

KrashDH said:
TB = timing belt

Thanks. Duh, should have got that.

Gremlin · Aug 21, 2018

So had a hose go on Friday morning, small one the the online block heater was put in. It was a crack that just spurted and let go. Fixed it and haven't had any loss of coolant, fingers crossed.
But I replaced the small fan, still not working, swapped out the thermo switch, still not working. Is the fan module the next logical step? Fuses, connections all look good.

And.....thanks to reading some threads in here. I've had a weird, random knocking from under the hood for quite some time, it's gotten louder. Goes away when I depress the clutch. It's at the garage for a clutch kit tomorrow. I think I dodged a bullet on that one. 494,000kms and clutch never done so I'd say that's a pretty good run!!!

Elliot · Aug 21, 2018

the water pipe (coolant pipe) it has several hoses that connect to it it seals into the motor with an o-ring the pipe itself or the o-ring is a fairly common cause of very slow leaks that is hard to locate take a kook.

Gremlin · Aug 27, 2018

Ok. This is driving me crazy. So had it for a drive on a hilly hwy, bout 2hr drive, and it blew out coolant via the expansion tank again. Seems to only happen on extremely hilly highways where she is working harder. The top hose is super hot and the bottom hose is maybe luke warm. I ordered a thermostat just in case. It's never overheated but is always running on the high side of the 90 mark. Anyone got any other ideas???? Head gasket checked out ok, no co in coolant. Seriously driving me mad. And, I replaced the thermo switch and the small fan and the small fan still wont come on. I'm about to loose it (had to replace the clutch last week).
Any ideas...any???

Genesis · Aug 27, 2018

Plugged radiator? Ever have the wrong coolant in it?

Gremlin · Aug 27, 2018

No. Always had proper coolant, rad was just replaced less than a year agao and just had the timing belt done, with a new water pump.
I'm suspecting a faulty thermostat. Its warm by the thermostat (hose is) but fairly cool by the rad. Like it feels way too cool even if the rad was cooling down the fluid...shouldn't it still be fairly warm. My mechanic, who actually hasn't felt the pipe, said no, it should be cool to the touch if the thermostat is working correctly. I think it would still be fairly warm, just not as hot as the top hose. Perhaps its slightly overheating and building pressure? Not registering on the guage as overheating but something is not right.
Also the small fan not running, module?

Genesis · Aug 27, 2018

Entirely possible -- diesels have bypass thermostats (including these cars) so a thermostat that fails CLOSED (mostly or entirely) will result in almost-no flow through the radiator yet it will be recirculated through the block.

Gremlin · Aug 27, 2018

Genesis said:
Entirely possible -- diesels have bypass thermostats (including these cars) so a thermostat that fails CLOSED (mostly or entirely) will result in almost-no flow through the radiator yet it will be recirculated through the block.

In theory If the thermostat is opening properly how warm should that lower pipe get that comes from the block to the lower rad. Once it gets to normal operating temps in theory that thermostat should be open? And the lower hose close to the rad warm? Hot? Cold?

WildChild80 · Aug 27, 2018

Check your temp sensor too, it may not be reading accurately

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Genesis · Aug 27, 2018

Gremlin said:
In theory If the thermostat is opening properly how warm should that lower pipe get that comes from the block to the lower rad. Once it gets to normal operating temps in theory that thermostat should be open? And the lower hose close to the rad warm? Hot? Cold?

It's not that simple.

The thermostat modulates the coolant flow through the radiator so as to maintain a nearly-constant coolant temperature in the block. Once the thermostat starts to open the differential across the radiator will decrease (as it opens more and more flow occurs) and increase (as it closes down some) in response to engine load. There's only about a 10F difference between the opening temperature and fully open for a properly-working thermostat and as such temperature stability of the coolant irrespective of load should, as long as you're within the cooling system's capacity, not vary by more than that.

If the temperature changes materially (more than 10F or thereabouts) above the opening point it's because you either are beyond or dangerously close to being beyond the cooling capacity of the system (in other words you're putting more heat into the coolant than the system can reject to the atmosphere) and at that point you WILL overheat -- it is just a matter of time. Fully open is fully open -- there's no more cooling capacity remaining once the thermostat is open all the way.

So with the car not moving it doesn't tell you much unless it's hotter than hades out, you're putting a fair bit of load on the engine (e.g. full-load on the AC with the cabin at 100F that it's trying to cool) and everything is fully warmed up (at which point your fans are probably running on high too due to the thermoswitch closing!) Diesels, at idle, reject notoriously little waste heat which is why in the winter time while stopped (e.g. for a train, etc) you can actually see the temperature of the coolant drop to the point that the gauge starts to head for the cold peg and the heater no longer produces anything in the cabin!

Gremlin · Aug 27, 2018

Genesis said:
It's not that simple.

The thermostat modulates the coolant flow through the radiator so as to maintain a nearly-constant coolant temperature in the block. Once the thermostat starts to open the differential across the radiator will decrease (as it opens more and more flow occurs) and increase (as it closes down some) in response to engine load. There's only about a 10F difference between the opening temperature and fully open for a properly-working thermostat and as such temperature stability of the coolant irrespective of load should, as long as you're within the cooling system's capacity, not vary by more than that.

If the temperature changes materially (more than 10F or thereabouts) above the opening point it's because you either are beyond or dangerously close to being beyond the cooling capacity of the system (in other words you're putting more heat into the coolant than the system can reject to the atmosphere) and at that point you WILL overheat -- it is just a matter of time. Fully open is fully open -- there's no more cooling capacity remaining once the thermostat is open all the way.

So with the car not moving it doesn't tell you much unless it's hotter than hades out, you're putting a fair bit of load on the engine (e.g. full-load on the AC with the cabin at 100F that it's trying to cool) and everything is fully warmed up (at which point your fans are probably running on high too due to the thermoswitch closing!) Diesels, at idle, reject notoriously little waste heat which is why in the winter time while stopped (e.g. for a train, etc) you can actually see the temperature of the coolant drop to the point that the gauge starts to head for the cold peg and the heater no longer produces anything in the cabin!

That makes total sense. Thank you. Since there is over 150k plus on this stat I'm going to replace it regardless. Good preventative measures never hurt.

Do you have any other ideas why it might be overpressurizing? No co in the coolant. New rad. When I squeeze the top hose or bottom hose under pressure or not I can hear sloshing up in the pipe that circulates from the water pump, which is also new less than10k ago.

Other issue is the small cooling fan. I replaced it, then the thermo switch and just came in from switching out a fan control module. Still no joy! Fuses all looked good.

Any input into either issue...interrelated or not be so appreciated.

wonneber · Sep 1, 2018

Gremlin said:
No. Always had proper coolant, rad was just replaced less than a year agao and just had the timing belt done, with a new water pump.

Did the problem start after the belt change?
Who did it for you?
Did they change the water pump and what brand was it?
Did it have a metal impeller?
Where were -all- the parts purchased?
I'm thinking maybe the impeller is free spinning.
I believe you can check it through the thermostat hole.

Powder Hound · Sep 2, 2018

Which fuses did you check? For the rad fans, it is the 1st green (30 amp) on the top of the battery. That is, looking from the front, of the 3 green fuses on the right side, it is the leftmost one.

If the fuse appears OK, pull it out and push it back in. Test it while it is out. I just had one that appeared OK, but on pulling it out the fuse block itself showed signs of arcing and failure on that one fuse.

Good luck,

PH

Coolant loss issue

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