pressure in radiator & stop & ! lights flicking on

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dunx.wantok
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pressure in radiator & stop & ! lights flicking on

Post by dunx.wantok » Sun Aug 06, 2006 7:52 am

I have just bought my first ever BX, a 1991 1.9 TGD Estate. I have loved them for a long time, and finally plucked up the courage to buy my first one. It has a couple of issues I want to get solved before I do many miles in it.

First, the coolant system. The temperature lights are not coming on, but if you release the radiator cap when the engine is warm (even a fair while after it has stopped running) there is a large amount of pressure in the system. The level looks okay when checked when cold, but dissappears from the top of the radiator when hot. So much so that last night, after it had been sat for half an hour, the coolant level light came on. Releasing the pressure from the system (carefully) thru the radiator cap made the light go off. Apart from this sthe system seems fine. The fan cuts in, the radiator is hot all over... any ideas?

Second is the lights on the dash. the red ! light and stop light stay on when the engine is fired up, until the car has reached its normal height. Then they stay off, except occaisionally when I stop at lights, or have the engine on tick over. Again, suggestions appreciated.

By the way, is it normal to spend most of your BX owning life explaining to normal car owners how cool they are?

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Post by jeremy » Sun Aug 06, 2006 8:18 am

Sounds like a head gasket problem is causing the water loss and pressurisation. Could be a cracked head but they are unusual and often seal as soon as the engine warms a little.

The warning light may be due to a weak accumulator. It can be easilytested by getting the car to normal height and turning the engine off after it has settled. Now sit in the boot - and the car should sink and rise again after 30 seconds. If it does not the accumulator sphere has probably failed.

Once the hydraulic system light has gone out it should never come on again until the engine is turned off.

Basic check - is there enough LHM - this should be checked with the car on MAX HEIGHT - the copper disc should be between the lines. This means at normal height the float should be jammed against the top of the indicator. Too low a level will allow the light to flash on as the LHM sloshes around.

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Post by DavidRutherford » Sun Aug 06, 2006 9:26 am

I concur that it does sound like the beginnings of head gasket failure.

To test:

Make sure the cooling system is both full, and cold. Start the engine and allow it to idle for about a minute.

Now turn off the engine, and immediately undo the cooling system pressure cap.

Was there any pressure build up? There shouldn't have been. If there was, then your Head gasket is on it's way. Sorry!
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Post by AndersDK » Sun Aug 06, 2006 11:17 am

Opposite the dooming advice above :

It is PERFECTLY normal to have pressure in the cooling system when the engine is still warm. Even when it has cooled down there would be a small hiss on opening the cap.

I bet that if both Jeremy & David use their own advice on their own cars - they will be scared to death :lol:

Just to sort of balancing out :wink:

And yes - I've spent most of my BX owning life explaining and excusing why I still drive a BX - and why I dont buy a Ford or VW.
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dunx.wantok
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Post by dunx.wantok » Sun Aug 06, 2006 12:09 pm

in response to Jeremy's test for hydraulics: it returns to height if the engine is running, but not if the engine is stopped

in response to DavidRutherford's test for head gasket: there was an ever so slight pressure build up when I released the cap after just one minute of running on a cold engine.

How high should the water level in the radiator be when it is cold, anyway?

And thanks to AndersDK. I guess the only way to find out will be to run it and see. That is about all I can afford to do anyway. I have to do a 300 mile round trip next weekend. I guess that will shed more light on the subject!

Thanks for all your thoughts so far.

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Post by AndersDK » Sun Aug 06, 2006 12:22 pm

As the coolant will expand when hot - any surplus coolant filled in will be expelled when engine heats up. A frightening sight for the not so experienced car owner :shock:

Once the engine has cooled down (i.e. is literally cold) - the coolant has retracted to a smaller volume - leaving the needed expansion space empty in the filler neck. This would be approx 4-6" down to the coolant level - not far from the low level sensor - which has 2 small gauge wires attached.

If the h/g blows up - the consequence is that the coolant system is pressurised and the fluid is expelled. This in turn causes the engine to overheat as the there is no fluid to transport the heat to the radiator.
Unless in real bad cases - it is commonly possible to limp home having lots of water onboard for frequent topping up.

But the overheat warning lamps are to be obeyed. At first glimps - turn off engine - refill cooling system - and idle engine (for cooling) to have any chance saving the h/g.
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Post by DavidRutherford » Sun Aug 06, 2006 12:43 pm

dunx.wantok wrote:there was an ever so slight pressure build up when I released the cap after just one minute of running on a cold engine.
Which indicates to me that you have an ever so slight headgasket failure. One minute of running shouldn't pressurise the cooling system at all.

But. The good news is that it didn't spit coolant out all over the place, so the gasket isn't completely gone. On top of that, the XUD9 head gasket fails very slowly and progressively. You will no doubt find it takes 5k-10k miles for it to fail completely, with you getting less and less distance between each coolant fill-up.

You may also find that a light right foot prolongs the gasket life. It's obviously also good for fuel economy. When the H/G was failing in one of my 405D's, I was getting well over 55 mpg due to driving so gently. Lasted another 8K before it was really really gone.
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Post by Stewart (oily!) » Sun Aug 06, 2006 12:59 pm

You can maybe buy a little time by not putting the rad cap on fully, at least that will stop too much pressure building up and blowing all the water out, it will also protect the waterpump seals, heater matrix etc from damage. and of course carry plenty of water for topping up on your long trip.
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Post by ed4ferrets » Sun Aug 06, 2006 3:54 pm

My BX had the same symptoms waterwise for quite a few k and I was convinced the hg was on it's way :cry:, there was pressure in the rad the following day even.

The rad was relatively new having been replaced for mot a year ago when she had overheated during emissions test.

Anyway I tried a proprietary radflush and lo and behold the end of the problem......... :shock:

It may have been a blockage in the engine waterways or something as the car had stood with coolant in for around 3 years before I got it :roll:

I don't pretend to understand why it worked for me but it may be worth a try for you :wink:
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Post by jeremy » Sun Aug 06, 2006 4:15 pm

I should think your 1.9D is much the same as our ZX 1.9D - in which case the header is at the off side of the radiator and the level settles about 4 inches down, and stays there.

If your car will only rise on the 'Boot' test if the engine is running its likely that the accumulator sphere is flat. £19 or so from GSF or EuroCarParts.

After replacement the ticking interval should drop to 30 seconds or more. If it does not it may be the non-return valve is not sealing properly. This can be re-seated at no cost - but the exercise is pointless if the accumulator is flat.

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Post by dunx.wantok » Sun Aug 06, 2006 5:36 pm

I took it for a spin this afternoon, doing over 100 miles through some small twisty, hilly lanes and over some fast, flat A roads. Approximately half way round I stopped for a couple hours walk, and checked the radiator. The radiator cap and top two inches of the radiator were cool, the rest of the system was hot. A slight twist of the cap did show there was pressure to be released, but I tightened the cap straight back up.

After being parked for two hours the whole system was warm. When I got home the sytem was hot all thru, and hissing slightly from the escape hole just below the radiator cap.

No over heating lights came on at all. (on the subject of the rear hydraulics, at times there was constant ticking from the back).

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dunx.wantok
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Post by dunx.wantok » Mon Aug 07, 2006 7:42 am

I may as well flush the coolant system this week while I wait for the head gasket to blow then, as the water does look a little on the rust coloured side. My (limited) mechanical skills, however, have pretty much been gained around air cooled two stroke motorcycles, so if anyone can talk me thru it, I would be grateful. I have heard about such things as air blocks, and the like, so would prefer to have advice before starting. Thanks.

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Post by dunx.wantok » Mon Aug 07, 2006 1:56 pm

just found the DIY articles on the web, saying how to do this. Any ideas where I find the drain points and bleed valves on a 1.9 diesel (NOT turbo)? Thanks.