Some help please. My 1990 Citroen BX TGD, ie the 1905cc normally aspirated diesel, recently required the hose leading to the heater matrix replacing as it was leaking coolant through it. The repair has been effected and the coolant level has stabilised for several days and hundreds of miles in the coolant expansion bottle at the recommended level.
Last night the low level coolant warning light came on after the car had been standing for 2 hours after use in congested town traffic. Coolant had been expelled through the overflow hole at the top of the expansion bottle.
This morning with the engine cold over night, I removed the pressure cap on the expansion bottle and saw the bottle completely empty. I have, of course, completely refilled it to the recommended level but am baffled as to why all the coolant should have been expelled from the expansion bottle after many miles of travel after the initial repair. There are, moreover, no signs of cross contamination of coolant and oil in the coolant and no indication of any other leak.
One other thing, in a journey I made yesterday of 100 miles in the countryside, I noticed the engine seemd a bit sluggish on acceleration. The engine has clocked 156,000 miles.
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Andrew, Don't run the engine any more till you have read and done this.
Posted it in lieu of David W in case he is grappling with the Astra cam belt still.
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Posted by David Woollard on June 3, 2001, 4:38 am , in reply to "Re: Possible faults.
Chris,
Years ago cooling systems were simple and filling them just meant pouring in cooolant to the rad and a few minutes running would self-bleed any small air residue. My 1970 diesel tractor is like this, big old radiator mounted higher than all the other waterways, no complicated narrow hose runs curving over the engine - no problems.
But like many other modern cars the BX can be a real problem to fill and bleed. Models with the cap on the radiator are the worse as there is almost no head of water when filling, even those with the expansion tank aren't much better.
So my method is......
First locate all the bleed points on your particular engine. These may include one on the radiator opposite the filler cap, two on the thermostat housing, one on the small hose that leaves the thermostat housing, one on the metal heater feed pipe just behind the camshaft cover, one on the heater hose just to the rear of the engine, one on a small hose running just behind the radiator. I do not want to be specific to a particular model/year as I have seen cars with odd combinations of the normal set-up, just carefully look for them all.
With the engine cool remove the filler cap and fabricate some sort of header tank that will give about an extra 300mm head of water. Mine is very simple. It is a large plastic funnel for filling up tractor fuel that has a nozzle about the same size as the filler hole and holds 3 litres of coolant. I cut the nozzle at a point so that the taper just goes into the radiator/expansion tank filler hole and a firm push will keep it wedged there. I have seen loads of other clever solutions to this with little tanks held on a stand and filler hoses that connect to a modified radiator cap boss, I used mine because it was lying about at the time and has worked OK for 7 years now.
Now top up the system with coolant and allow the funnel/header tank to fill about 2/3rds. Bleed each coolant bleed point in turn until bubble-free coolant is seen. Close them all firmly. Start the engine and allow it to run at a fast idle until the thermostat opens and the radiator becomes fully hot. During this period you should see loads of small bubbles appear in the funnel/header tank, and as the thermostat opens a huge amount of air often bubbles up. Now stop the engine and bleed each point in turn again. Use great care as the coolant will be scalding. Top up the funnel as needed during this to keep it about 2/3rds full at all times. Close all bleed points finally and re-start the engine. Allow it to run for up to another five minutes for all the remaining small air bubbles to bleed off. When you are happy stop the engine and remove the funnel. Put the radiator cap back on with the coolant still right to the top (ie overfilled by cold standards). Allow the car to cool completely then check the level and add/remove coolant as needed. Give the car two days normal use then check the level again when completely cold. Again add/remove to get the level spot on. Only now consider this an accurate level to monitor from.
Why is this bleeding crucial to the BX? Well the thermostat and coolant temperature warning sensors (and fan switch on P.405 A/C models) are in a position that is easily left air-locked if this procedure isn't properly carried out. And these do not work properly in air, only if the water is in contact with them. So it is possible after a water loss, and re-filling without bleeding, for the engine to go above the thermostat opening temperature without it allowing coolant to the radiator. Then because the temperature senders are also in the air lock they don't indicate a problem. Result engine cooks and the head gasket/head are damaged.
Many BX (diesel in particular) head gasket problems follow a simple loss of water incident after a few days. It is my belief this is often due to the problem of bleeding the system rather than the initial fault damaging the head.
Well hope that essay helps, come back guys with any arguments!
David
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Thanks Stuart, have you an indexing system on the laptop or a good memory?
Andrew take great care to have a look at this properly following the method of mine Stuart posted above.
Worse case sequence of events......
Some small coolant loss....repaired and topped up without bleeding....thermostat doesn't operate due to air lock....car boils again.....topped up without bleeding.....boils again and so on.....all the time cooking the head gasket.....finally realise head gasket blown....get this changed....find head is warped.....skim head to find that valve seats then need re-cutting for correct recess.
It all gets badly out of hand, hope we've caught yours in time.
Come back with any queries.
David
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"have you an indexing system on the laptop or a good memory?"
Must have a good memory. I realised that Andrew is in a potentially risky situation, maybe its too late already I hope not. I remembered your funnel method and searched on the word funnel.
Actually the first search gave just one result about the Blackwall Tunnel, referred to in the post as (pardon me) the Tucking Funnel, as I forget to reset from last 30 days, wish I had a quid for everytime thats happened, so then on second search Bob's your Dad's bruv.
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my citroen bx has been doing the same but i think its too late for my car, as it has sludge in the oil filler cap, so i think the head gasket has given up, also its been losing coolant but i dont know where from, and also the car has been very reluctant to start, keep going, etc. and it sometimes is VERY slow to pull off from junctions. can anybody tell me what it could be????
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Scrap it and buy a Lada. LOL
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