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  #1  
Old 06-30-2016, 03:59 AM
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Cooling System Help Please!!

Hi All,

I did have a very small leak on my radiator which I kept at bay with a bars leak tablet. Finally it gave up on monday and blew completely. Luckily I was close to help and didn't redline the temp gauge. It probably went up to about 3/4. I got a tow truck to the garage and a new radiator was fitted.

When I spoke to the guy (I know him well) he said that he was having difficulty getting hot air out of the blowers and maybe there was the dreaded HG damage.

The engine is running sweet as a nut. I drove it the 2 miles home and during that drive I did start to get warm air but the temp gauge was fluctuating with the fan so I got a lift to work.

I did some reading on the forums and decided to check for air when I got home. The expansion tank was full, the rad was full but when I opened the bleed screw I put over 2 litres of coolant into the system and burped it. I have used the car for a few days and everything was fine. Temp gauge was rock solid in the middle with no issues.

This morning I noticed a small misfire and the temp gauge started to drop and the car cut out (luckily I was next to a pull in and stopped immediately). I checked the rad and it had lost a little bit but the expansion tank was full and when I opened the bleed screw I had to add coolant again???

There's no dripping coolant or white smoke from the exhaust so I can figure what's happening. If I take off the radiator cap and turn the car over the level in the neck rises so it appears to be pumping and when the bleed screw is opened I see movement in the fluid there also so I'm pretty stumped unless there's a blockage somewhere.

Any tips what to check next as I'm going to change the thermostat next to see if that cures it.

Cheers

Paul.

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  #2  
Old 06-30-2016, 08:43 AM
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Re: Cooling System Help Please!!

Most of the time the problem is trapped air in the cooling system. I always squeeze the upper rad hose during the filling to get a bit of movement in the coolant to help to get rid of eventual trapped air. During the filling its very important that the bleed screw is removed, so that trapped air can escape. There can still be some air trapped, but that should move itself towards the radiator and escape to the overflow reservoir during the next heat-up cycles. If you still have air in the upper radiator hose after a few heat-up/cool down cycles and the level in the overflow reservoir doesn´t change, then there must be a leak.
Did you check the engine oil as well for evidence of coolant?
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  #3  
Old 06-30-2016, 09:11 AM
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Re: Cooling System Help Please!!

Hi Frank,

Thanks for the reply. I checked again lunchtime and had a small funnel in the bleed hole and topped it off and let some more bubbles out with the engine running.

I checked oil and expansion tank and there's no sign of contamination at the moment.

Is there a possibility that the water pump maybe on it's way out and not circulating at it's full capacity or are they generally an on / off type of failure mode?

Many thanks,

Paul.
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Old 06-30-2016, 11:38 AM
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Re: Cooling System Help Please!!

Just another thought after reading more. I think the Filler cap may be bad as I don't think that coolant is being drawn in when cooling down either.

My cap is the strange 20lb rated which is difficult to get hold of in the UK (52079778AA).

Would I cause any damage if I put on a 18lb rated one as these are the more common ones????

Thanks,

Paul.
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Old 07-01-2016, 02:51 PM
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Re: Cooling System Help Please!!

When I'm not wrong is the original cap on my jeep an 18 PSI one.
A bad radiator cap can prevent the buildup of the required pressure, probably also the return of the coolant from the overflow reservoir back to the radiator when cooling down. Or there is some internal leak which prevents the coolant from returning. I would just put a new 18 PSI cap on it and see how it goes. Did you check if the upper radiator hose becomes hard during the heat-up cycle?
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Old 07-04-2016, 03:31 AM
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Re: Cooling System Help Please!!

Hi Frank,

I've ordered the 20/21lb cap from Germany and it should be here soon as well as a thermostat.

The upper hose does get hard when it's warming up and retains the pressure when the engine is switched off.

Fingers crossed this is something simple as I stopped pretty quickly after the radiator let go.

Many thanks,

Paul.
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Old 07-04-2016, 12:59 PM
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Re: Cooling System Help Please!!

I doubt you have a problem with the head gasket. If you have pressure leaking from the engine to the cooling system that pressure would continuously build up until somethign let go in your cooling system. It would not simply add some air to the cooling system and stop there.
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  #8  
Old 07-05-2016, 04:36 AM
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Re: Cooling System Help Please!!

Cheers for that MD,

I'll try and get the air in the expansion tank tested for exhaust gases to confirm but I've got my fingers crossed it's not the HG !!!!

Many thanks,

Paul.
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Old 07-08-2016, 07:05 AM
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Re: Cooling System Help Please!!

Just got my new rad cap from Germany.

From what I recall, the coolant return valve on my existing one had little or no spring tension but this new one does and it feels a lot firmer on the main spring.

Fingers crossed we'll get there as it drives fine and there's still no cross contamination.

I know it's a new radiator but I think I'll give it another flush through and change the stat when it arrives from Rockauto.

Regards

Paul.
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Old 07-08-2016, 09:47 AM
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Re: Cooling System Help Please!!

My old cap was faulty so I replaced it lunchtime.

Still getting pressure though
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Old 07-08-2016, 09:55 AM
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Re: Cooling System Help Please!!

You are getting pressure where?
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  #12  
Old 07-08-2016, 10:02 AM
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Re: Cooling System Help Please!!

There's still some bubbles getting into the expansion tank.

I haven't got the new thermostat yet either so I won't flush the system until I get that.

Don't know what else I can try as I haven't managed to get the expansion tank sniff tested yet.

Thanks

Paul.
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