T

tsangpa

New Member
Hi there,

I've searched back and forth on coolant and HG threads but still unsure whether to get my disco to a garage to test the HG.

Its a v reg TD5 with 140K on the clock. It looses about 150 - 250ml of coolant every 200 - 300 miles. I can't see any obvious leaks. After a long run on popping the bonnet I can hear a hissing from the expansion tank cap. I recently replaced the cap with a genuine LR cap and still get coolant loss.

The system remains under pressure overnight. In the morning when I check the coolant level its about 4 inches below the cold level, then when I release the expansion tank cap pressure comes out and the level goes up to an inch or so below the cold level marker.

So I fear it may be the HG or a cracked head. If I get it tested and the HG replaced will they be able to tell if the head is cracked - as I don't want to replace the HG only to find out that I have the same problem and then have to get the head replaced.

Ian
 
I assume you have looked at the oil filler for mayo and the coolant for oily film?

Have you checked the radiator for cold spots!

Have you checked your fans viscous coupling?
 
tsangpa said:
Hi there,

I've searched back and forth on coolant and HG threads but still unsure whether to get my disco to a garage to test the HG.

Its a v reg TD5 with 140K on the clock. It looses about 150 - 250ml of coolant every 200 - 300 miles. I can't see any obvious leaks. After a long run on popping the bonnet I can hear a hissing from the expansion tank cap. I recently replaced the cap with a genuine LR cap and still get coolant loss.

The system remains under pressure overnight. In the morning when I check the coolant level its about 4 inches below the cold level, then when I release the expansion tank cap pressure comes out and the level goes up to an inch or so below the cold level marker.

So I fear it may be the HG or a cracked head. If I get it tested and the HG replaced will they be able to tell if the head is cracked - as I don't want to replace the HG only to find out that I have the same problem and then have to get the head replaced.

Ian
Click to expand...

Hi Ian just a quick question, with the engine warmed up and running do you get normal hot air from the heater - or is it cold air?


Have you tried bleeding the cooling system?
 
Last edited:
tsangpa said:
Hi there,

I've searched back and forth on coolant and HG threads but still unsure whether to get my disco to a garage to test the HG.

Its a v reg TD5 with 140K on the clock. It looses about 150 - 250ml of coolant every 200 - 300 miles. I can't see any obvious leaks. After a long run on popping the bonnet I can hear a hissing from the expansion tank cap. I recently replaced the cap with a genuine LR cap and still get coolant loss.

The system remains under pressure overnight. In the morning when I check the coolant level its about 4 inches below the cold level, then when I release the expansion tank cap pressure comes out and the level goes up to an inch or so below the cold level marker.

So I fear it may be the HG or a cracked head. If I get it tested and the HG replaced will they be able to tell if the head is cracked - as I don't want to replace the HG only to find out that I have the same problem and then have to get the head replaced.

Ian
Click to expand...

Hi There

I had the same problem on my TD5 I spend age’s looking for the problem :mad:
I went back to the dealer 4 times with it and he didn’t know what was up:confused: and told me it would be ok a week later I broke down on the side of the motor way after the water temp went into the red :mad:I pulled over to fined I had no water in the system MR AA towed it back to the dealer
The engine was striped down to reveal head gasket had gone on the 5th cylinder water way. :eek:

I was lucky to have the work done under warranty :D

 
Yep - checked the oil filler - clean as a whistle and the coolant is nice and clear pink - no bubbles on the return. I was getting some water leaking from the expansion tank cap, so I replaced it, but still have coolant loss and still get the hissing from the cap. I was thinking that it sounded like the system was over pressurised, which made me think maybe the HG had gone after reading lots of HG and coolant posts. I'll check the other things you suggested though.

Thanks
 
tsangpa said:
Yep - checked the oil filler - clean as a whistle and the coolant is nice and clear pink - no bubbles on the return. I was getting some water leaking from the expansion tank cap, so I replaced it, but still have coolant loss and still get the hissing from the cap. I was thinking that it sounded like the system was over pressurised, which made me think maybe the HG had gone after reading lots of HG and coolant posts. I'll check the other things you suggested though.

Thanks
Click to expand...

We have the same problem with our Discovery. I had the cooling system pressure tested and they found a leak on the thermostat housing. This was replaced but it is still loosing coolant slightly and I can see it gathering on the thermostat housing again, so I guess it is coming from somewhere above.
 
OK bit more info. I've bled the system and don't get too many bubbles coming out. The fan seems fine, but the radiators aren't hot at all - the hoses are hot, but the radiators are cool to the touch. Also there's quite a bulge that I've just noticed in the top hose.
 
tsangpa said:
OK bit more info. I've bled the system and don't get too many bubbles coming out. The fan seems fine, but the radiators aren't hot at all - the hoses are hot, but the radiators are cool to the touch. Also there's quite a bulge that I've just noticed in the top hose.
Click to expand...

Hi
That bulge will be pressure from your head gasket , You need to get you head gasket done that’s the problem
 
Could the bulge be caused by a blocked radiator and would that cause the over pressurising - I'm guessing that if the systems under too much pressure the coolant loss could be due to steam escaping from the expansion tank cap.

Or would the cause of the over pressuring always be the head gasket?

I've ordered some block test fluid, but having said that the tests can be clear despite a HG fail.

The top hose gets hot so I am guessing that means that the water pump and the thermostat are both working ok.

Just probably clutching at straws as I've read a lot of posts on HG failures and I want to avoid a huge bill if at all possible.
 
I think you should shop around and get some prices for head gasket replacement I would also use some one that has done this job before avoid back street garage this is a big job as a lot of parts need to come out before they get at the head. When my gasket was done I went to the work shop where the head was skimmed as I had a mate that worked there, he said it would have cost £300 for the skimming I would also check that they put new washer and o rings in for the injectors on the rebuild
 
This was My disco when the work was done:(
 

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What concerns me the most is that I get the HG replaced and they find the head is cracked - I can't afford that too. Are there any specific things that might indicate a cracked head?? It doesn't overheat, there's never been any problem with hot air coming through the heaters and it doesn't lose a massive amount of water. So I'm hoping if it comes to the HG replacement I won't have to replace the head too.
 
I had the same concerns and I asked similar questions:confused:, the answers I had was if the head was cracked it would not hold pressure and you would see water leaking out. Please don’t quote me on that as this was information I was told by the chap who fixed it.
I would say all your symptoms are the same as I had, you could try and have it sniff tested but when I had it done it didn’t work because it was on the water side the gasket problem was. I would fined a diesel engine specialist and ask there advice, I would do that as they may have done one and might have the best advice for you, a back street garage will only want the work and they might not know what they are doing
 
Thanks - after a quick google search there's a couple of decent sounding garages to check, so hopefully I'll find a cure that won't cost the earth. I'll post again when I have some more answers.
 
Well it is a HG failure - it's in the garage in bits at the moment - hopefully Monday should see it repaired and back to health, just in time for the next problem.......
 
I suspect my TD5 has the same problem, very slight coolant loss but if left standing for a few days its a bit steamy when first started. What did it cost to get your HG replaced and head skimmed etc?

Cheers.
 
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