leaking coolant through radiator cap

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oladiti
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leaking coolant through radiator cap

Post by oladiti »

Hi All,
I have a leaking coolant/antifreeze from the radiator cap,
spraying the diesel pump and dripping onto the alternator,
Its a brand new radiator but with old cover? known to be good.
Anyone please help (bx 19 diesel non turbo)
Checks so far : main top pipe from radiator to thermostat housing
is very hot and very tight ( I assume th'stat is not opening!!!)
Also iv carried out basic bleeding of air from the system! Thanks
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Re: leaking coolant through radiator cap

Post by Kitch »

If the thermostat wasn't opening, the rad wouldn't be that hot. It could be a dodgey rad cap.
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Re: leaking coolant through radiator cap

Post by Philip Chidlow »

Is the system pressurising - with gasses in the coolant? ie with the rad cap off (careful!) does the coolant bubble and fizz when the engine's running? This would indicate likely head gasket failure... Hope not though!
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Re: leaking coolant through radiator cap

Post by citronut »

as Kitch says if the top hose is hot/very the thermostat has opened,

sounds to me you have either got a lot of air traped in the system or the head gasket has failed,

to check for the later, with the engine stone cold, remove the rad cap and have an assistant crank the engine over whilst you watch the coolant in the rad, if it erupts or there are lots of bubbles this is a sign the head gasket has failed,

if the coolant is calm, then run the engine up to temperature till the rad fan/s cut in then back out, now very gently open the rad cap, be very very careful as the coolant might/will be under pressure and very hot,

if the coolant erupts now, let it settle then remove the bung in the top left corner of the rad, top up the coolant till it comes out of the bung point and stops sinking, refit the bung and open the other bleed valves, and continue filling the rad till coolant comes out of these,
if it does not come out of these start the engine and run till you get coolant out of them, now refit/close the bleed valves and continue running the engine till the fan/s cut in and back out, now once again open the rad cap with the same causion as before,

if it still erupts i would be fairly sure the head gasket has died

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Re: leaking coolant through radiator cap

Post by Kitch »

Easy way to test for HGF is to just start the engine cold, run it for 40-50secs, then knock it off, then undo the cap. If it expels coolant then yeah, it's goosed.

If the cap had failed however, it will still pressurise to a point, but overheat more quickly. At normal running temp it'll be kicking coolant out everywhere and generally getting the hump. A cap is a few quid, and a failed one can kill an engine.
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oladiti
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Re: leaking coolant through radiator cap

Post by oladiti »

Thanks, Kitch, Malcolm and Phillip, for your prompt response and help.
I will carry out the checks suggested and Keep you posted.
regards
ollie
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Re: leaking coolant through radiator cap

Post by rutter123 »

Maybe your radiator is blocked Has the coolant been changed regular Is there sludge in the bottom of the radiator? How are you bleeding the system With the bleed screw by the thermostat housing? Thete is also a bleed screw on the top of the radiator. It sounds as tho only the top of the engine is getting water, take out the thermostat and test it in the kettle.
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Re: leaking coolant through radiator cap

Post by citronut »

rutter123 wrote: take out the thermostat and test it in the kettle.
Mr Rutter
the OP says the top rad hose is getting very hot and pressurising, so i think the thermostat is open/oppening

regards malcolm
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Re: leaking coolant through radiator cap

Post by Tim Leech »

I think the td I've recently acquired is spitting coolant out of the overflow in the expansion tank which makes me worry about headgaskets...
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Re: leaking coolant through radiator cap

Post by Philip Chidlow »

Mm. I'd worry too - best get it checked asap
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Re: leaking coolant through radiator cap

Post by Tim Leech »

It was done this year but it's worth getting it checked, I understand the radiator was leaking for a while and may have run low on water which may have popped the gasket. I'll let Barry have a look.
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Re: leaking coolant through radiator cap

Post by Jaba »

Tim its easy to overfill the TD. The tank only needs to be 1/4 full, if there is more than this the surplus is ejected just below the rad cap.
If you look in the header tank there is a sort of bar at the bottom. The water level when cold should not go over the top of this.
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Re: leaking coolant through radiator cap

Post by Thread Bear »

I am in the habit of stripping the coolant out of old cars, removing the thermostat and flushing/backflushing the system. You would be amazed at the crud that some cars carry. Its a good summer job and the car can be run on clean water for a while to prove that it will behave itself, before refilling with antifreeze mix. Two BX here, TD and 1.6, would have died if driven hard as they were. The 1.6 was known about as it had had little use on short trips, latterly. I got about a cup of solids out. My belief that using its last bit of MOT to drive down the M6/M5 would kill it was probably correct. It came by bloodwagon. Its a false economy to not flush if there seems to be a problem.

The TD rad as a bad design as it has poor flow in part of it. Also its very hard to flush that same area. So just because the top is hot, do not assume its working, until or unless, you can feel heat all over and near the same temperature level, in good time. I have an otherwise perfect rad bunged up, awaiting my making a tool to fit on the hose to fire a jet at right angles into the galleries blocked. It might work, and since these are becoming unobtainium, worth a try.

I have found that mixing the caps, where they appear to fit, is not always satisfactory between radiator manufacturers. Alarm bells ring when you find plumbers tape round bleed caps. Several cars have had home made heater bleed off screws. Fortunately my scrap yard provided enough choice to resolve those issues. Even having the correct assembly, I have had to replace O rings, and discard main one radiator cap as it failed to pressurize, allowing an 'invisible' leak that took sometime to identify.
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Re: leaking coolant through radiator cap

Post by Tim Leech »

I've ordered a new rad cap and the radiators brand new, it's loosing water somewhere as the low water lamp comes on regularly....I put 1.5 litres in Sunday but that did brim the tank, I can't see any leaks but the cars running ok and doesn't seem to be smoking and the heaters hot.

I'll keep an eye on it.
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Re: leaking coolant through radiator cap

Post by oladiti »

So far I have carried out the 50 seconds test, there was pressure built-up, with a hisss! sound when cap was open, but no eruption.

I then went on to run the engine with cap off, slight bubbles soon clear away and water remain stable for about a minute and then!
the water level slowly rises up to the little safety hole on radiator neck, I mob this off with a rag and pop back the cover and went on to try and run car up to running temperature to encourage the fan to cut-in, but before that temperature could be reached the water/coolant started flowing out of the cap.

Switched ignition off and left car for about 2 hours, Upon my return, I decided to open the cap with a rag, even though the radiator had sufficiently cooled down, turned the cap slowly the water erupted on to my face.

Also one other thing I noticed was that only the top part of the radiator that is getting hot

Tomorrow 19/5/15 I will be conducting a chemical test at my local garage.
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