Cooling System misbehaving again!

andycadabra · Post by **andycadabra** » Thu Mar 08, 2012 2:20 am

Best thing I can do is this list of symptoms - any thoughts would be appreciated...
1. High-pitched continuous canary song coming from engine compartment mostly when engine is cold. Can often be stopped by decelerating or changing gear - waterpump or slipping belt?
2. Frequent coolant top-ups needed - no visible large leaks, and no bubbling to suggest blown head gasket.
3. Low coolant level warning light coming on fairly randomly, often going out after after 5 minutes or so.
4. Heater heating normally when the engine is cold then blowing cold air when it's warm.
5. Radiator fan coming on during normal driving on a cool day (especially annoying when cold because heater not working!)
6. Noticeable air pressure remaining in cooling system even after the engine has been idle for 12 hours or more.

Caffiend · Post by **Caffiend** » Thu Mar 08, 2012 8:08 am

Sounds silly, and I'm certainly no expert - but recent losses of coolant with no apparent leaks and random lighting up of the coolant light on my Xsara were due to a faulty pressure cap - have you tried replacing that?

Mickey taker · Post by **Mickey taker** » Thu Mar 08, 2012 8:31 am

I would suggest tighten belt, check rad cap, back flush system, change thermostat, refill and bleed all air out of the system,

Also check theres no oil in the water or water in oil to confirm head gasket is ok

andycadabra · Post by **andycadabra** » Fri Mar 09, 2012 3:26 pm

Thanks for the replies - interesting that neither of you have mentioned the waterpump, as, bearing in mind the symptoms, with my limited knowledge I would have thought it has the ability to 1. leak water and 2. fail to pump coolant around the system properly 3. make a noise when failing, though not sure a very high pitched one?

Caffiend - I haven't tried replacing it, but I've been monitoring the cooling system for a while and haven't noticed any evidence of coolant exiting via the pressure cap - in fact I've been surprised that the cap seems to have not yielded to the large amounts of pressure that have been building up, and remaining a day or so. When you mentioned the coolant light on your Xsara, do you mean a low coolant level light or an overheating light?

Mickey taker - which belt to tighten though? - I could try tightening the alternator belt, but this wouldn't have much effect on the cooling system. The waterpump is on the timing chain belt, isn't accessible, and I assume can't be adjusted anyway. How could I check the rad cap?
Not sure how to do a backflush, but after a little research, do I understand that this means connecting the radiator feed from the thermostat to the radiator outlet instead of the inlet, and doing something similar with the heater radiator- are those hoses accessible?
Does the fact that the thermostat is opening to allow coolant to the radiator mean it's working ok? It was replaced 15,000 miles ago, and the waterpump about 25,000 miles ago.

JayW · Post by **JayW** » Fri Mar 09, 2012 4:12 pm

As it notably decreases when you lower the revs i'd suggest your Canary is the axuilliary belt slipping. This could be for a number of reasons:

1. High drain on the alternator possibly related to a poor battery (but only when lights etc on)
2. Worn or loose belt.

Or, more related to your issues:

If the water pump is failing/failed you could have a small leak which will drip into the timing case and onto the bottom pulley, this can in turn make it's way onto the aux belt pulley causing it to slip.

It's been a while since i've done a pump on one of these but i'm pretty sure they're fitted with a leak-out journal (a small hole in the housing which drips water when the inner bearing seal is compromised through failure) so that could be your culprit along with simple gasket failure. As water drips out it's going to be replaced by air and so pressurise the system.

Equally, the plastic impellers easily disintegrate and the metal ones rust through time.

It would certainly seem the most (if not worst case scenario) likely culprit with all your symptoms.

The only way to be sure and avoid serious failure would be to whip it all out and do a pump/cambelt change.

andycadabra · Post by **andycadabra** » Sat Mar 31, 2012 7:13 pm

Apologies for the radio silence on my part - I've been away, and had more important things to do, however the problem is getting worse so need to do something.
Thanks for your input, JayW, regarding the waterpump. However I can't find any evidence of water leaking from it, though coolant is leaking out via the radiator cap, and sometimes a small crack in the moulded spout on the left-hand side of the radiator, probably due to it taking a knock while being couriered, which I've been trying to live with.

I think the radiator cap is only doing its job because there's a lot of pressure building up, and now some bubbles in the expansion tank suggesting a compression leak, which is a pain because it's only 18 months since I had a new cylinder head and gasket. No trace of water in the oil though, (although there wasn't last time either). Last time I failed to fix the compression leak with K-seal or Steel seal, but I'll flush the radiator, and try K-seal, as the bubbles aren't yet as big as last time.

Even when the engine is hot, the radiator is very cool in the middle and top, although warm each side and at the bottom - I think it might be pretty bunged up with lime scale due to the many substantial water top ups, bar's leaks, and K-seal I used to try and fix the radiator leak. I don't know if the radiator is so blocked that it's preventing water from circulating, and that's forcing the water to boil in the engine side?.
And another thing, the lesser of the overheating lights came on once and I was late for something important so kept driving for 5 minutes albeit with the heater on full - probably not a good idea!
Am I right in thinking that more pressure builds up in a cooling system when air gets into it, than if it was full of water?

The noise is now not so bad, maybe because the weather is warmer - I think its belt chirp from the alternator belt.

B-Hive · Post by **B-Hive** » Sun Apr 01, 2012 7:32 am

FWIW the symptoms sound like air in the system being drawn in (venturi like) from a slow leak in the system.....also don't overlook the possibility of two/three separate issues... apparently the harmonic balancer/main crankshaft pulley can cause canary like noises if tired..(maybe due to coolant being dripped on it and flicked away..

Any way just a thought!!

electrokid · Post by **electrokid** » Sun Apr 01, 2012 11:05 pm

pretty bunged up with lime scale due to the many substantial water top ups,

I know you have some problems there that need a lot of topping up - but actually filling up with tapwater is the quickest way to damage the engine to the point where it needs a lot of topping up...

When you've found the problem and fixed it - fill with antifreeze (which contains an inhibitor to prevent the kind of corrosion that causes water leaks) and distilled or de-ionised water - never tapwater.

andycadabra · Post by **andycadabra** » Wed Apr 04, 2012 3:02 pm

Interesting theory, 2BX, about the venturi effect. I assumed that with such high pressure in the system, air could only be blown out, do you think there is low-pressure somewhere in the system where air could be sucked in?
Electrokid - I take your point! I've had cooling system problems for the best part of 10 years now, and would have spent a fortune if I'd been topping up with distilled water, but once I reach the point of solving them I'll do as you say!

Well I'm getting closer to solving the problem.
I took the radiator out and ran the hose through it, took the thermostat out and did the same with the engine (surprising amount of black grit came out- I think this might be a mixture of limescale and oil that I mistakenly put in the system a couple of years back).
Checked the thermostat, and intended to run it for the moment without the thermostat, but this seemed impossible as the rubber gasket on the outside of the thermostat doesn't seem to work unless the thermostat is there.
Incidentally, the seating (on which the rubber gasket sits) on the engine side of the thermostat housing seems to be non-existent at the very top, and this has caused the rubber gasket to become distorted. Has anyone else noticed this - I can't imagine it would have been designed as such - could it have corroded?

Anyway having washed out all the bars leaks and K-seal from before, the radiator now has more small leaks than the incurable one I knew about, and I managed to source a new one from a fellow member, in the spare parts thread, which should arrive tomorrow.
On the bright side, the heater now seems to be working normally, and the radiator is now getting hot in the middle, the bubbling in the expansion tank is just occasional, and there is no buildup of pressure in the cooling system (although this could be due to the small radiator leaks). I'll report back once the new radiator is fitted.
I also tightened up the alternator belt which has stopped the chirping.

electrokid · Post by **electrokid** » Wed Apr 04, 2012 9:52 pm

and would have spent a fortune if I'd been topping up with distilled water,

Your point taken too Sir

You seem to be getting there at last - hope the new rad makes the difference. If I'm going to be in your neck of the woods I'll PM you - sometimes 2 brains are better than one - even if one of them is mine

andycadabra · Post by **andycadabra** » Sat Apr 07, 2012 2:09 pm

Electrokid - Thanks for that kind offer, that would be great!- sometimes think I'm the only BX left in London!.

The new radiator has arrived and been fitted. Testing the cooling system up to temperature led to the radiator cap allowing a trickle of coolant out from the hole at the top of the reservoir. This was happening most of the time once it got hot and it is especially annoying since I can see it dripping right onto the exposed end of the clutch cable! (I think there is supposed to be a little rubber pipe that carries it somewhere innocuous) Is this ever normal? I suppose the radiator cap could be faulty (is it possible to get it tested?) But my fear is that it's just doing its job and that there is a compression leak which is causing undue pressure to buildup in the cooling system again. About half the time there is no bubbling in the reservoir whatsoever, so I had hoped that the few bubbles were trapped air escaping.
Anyway, the latest problem is that the end of the spout on the thermostat housing cover has broken. It got very gently knocked while I was testing the system and the high pressure blew the hose off with the end of the spout containing the flange inside the pipe. When I picked it out it broke readily - it had obviously become very brittle. This has left me with about 15 mm of pipe to fix the hose to, so in order to prevent it being blown off again I've had to loosen one of the hose is at the top of the radiator to allow excess pressure to escape. I'm thinking of either glueing the hose to the spout with epoxy resin or using the silicone gasket sealant I used for the thermostat housing, together with attaching the hose clip to the thermostat housing with wire! Alternatively I can use my K-seal in an attempt to fix the compression leak and ease the pressure on the system.

Oilyspanner · Post by **Oilyspanner** » Sat Apr 07, 2012 6:49 pm

I think I have seen an alloy thermostat housing in the pile, will investigate tomorrow.
Stewart

andycadabra · Post by **andycadabra** » Sat Apr 07, 2012 7:41 pm

Oilyspanner - Thanks for offering to look, but I don't think there's anything seriously wrong with the alloy thermostat housing, it's the plastic cover/outlet which I would need.
I may have just done a good repair, so might not even need that - I glued the hose to what's left of the outlet and using a combination of cable ties and wire, the hose is now attached to each of the nuts at the base of the terminals which are mounted on the thermostat.
I'll run it up to temperature tomorrow and see what happens..

andycadabra · Post by **andycadabra** » Mon Apr 09, 2012 2:04 pm

The high-class bodge job seems to be holding, but there's still a fairly constant trickle from the radiator cap when the engine gets hot. A breakdown guy thought it might be water pump failure which was allowing the water in the engine to overheat (not that any of the warning lights were on) rather than be pumped through the radiator quick enough to be cooled.

There seems not to be anyway of knowing if the water pump is faulty, but thinking about it I had the idea that a car could be left at tickover, and a timing could be taken between the time hot water starts entering the radiator on the right, and the time the heat spreads to the left side to exit the radiator. Any excessive time taken would presumably indicate waterpump failure.
Does this seem like a good test?. Would anyone with a healthy TD be willing to participate in in a little benchmarking?

Post by **mat_fenwick** » Mon Apr 09, 2012 7:46 pm

andycadabra wrote:But my fear is that it's just doing its job and that there is a compression leak which is causing undue pressure to buildup in the cooling system again.

I have to say that would be my fear also. I once changed the HG on a ZX, only to have pressurisation occur within a few days. The head had been skimmed and pressure tested, so I was fairly confident that was OK. It's possible the block was cracked, but we never found out as I just replaced the engine with a known good runner.

If you crack open the expansion bottle cap say 30 seconds to a minute after a cold start, is there any hiss?