blocked radiator??

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tsangpa

New Member
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62
Today I replaced the thermostat on my TD5 (1999) to try and cure a radiator problem. The radiator is always cold to the touch - only hot near the top pipe connection, so after reading a couple of threads it sounded like a failed thermostat. Thermostat changed and still the same problem. Am I right in thinking its a blocked radiator or is there another more likely candidate? Also any hints and tips regarding changing the radiator?

Thanks
Ian
 
A bit more info - the top hose is hot and the radiator fins around this area are hot, but the bottom hose is cold. Would this be indicating a blown water pump or a blocked radiator? Any ideas?
 
Could be either.....

Don't know about Td5's but can you not remove the stat, disconnect the top hose and turn the engine over (when cold......obviously) to check the pump?
 
Could be either.....

Don't know about Td5's but can you not remove the stat, disconnect the top hose and turn the engine over (when cold......obviously) to check the pump?


Unfortunately no you can't. The stat on a TD5 is semi-permanently plumbed in, in the bowels of the motor unlike the stat on a TDI where it's easily available.
 
A bit more info - the top hose is hot and the radiator fins around this area are hot, but the bottom hose is cold. Would this be indicating a blown water pump or a blocked radiator? Any ideas?


I would say it's almost certainly a blocked rad. You could try flushing it but the likelyhood is that you'll need a new one.

The trouble is that you have to take everything apart again to get the rad out to give it a thorough flush, then you put it back and maybe the problem is still there. Your car has been running for about 13 yrs now so maybe it's time to treat it to a new rad.


I get mine for £100+vat from Paddocks and they are fine. Just be VERY careful when screwing in the the screws which retain the plastic frame on top of the rad. I did one once where the screws pierced into the waterway - BOLLOCKS!!!!!

Also take care of the small plastic spigot on the rhs as you look in the engine bay - they break off really easily - DOUBLE BOLLOCKS !!!!!!
 
Can you see the water circulating in the expansion tank? You should be able to see a constant flow that will speed up with engine revs?

Also is the hose after the pump getting hot?

Sounds like a rad but I would be tempted to do both, for the cost and ease of a water pump why not?
 
I would say it's almost certainly a blocked rad. You could try flushing it but the likelyhood is that you'll need a new one.

The trouble is that you have to take everything apart again to get the rad out to give it a thorough flush, then you put it back and maybe the problem is still there. Your car has been running for about 13 yrs now so maybe it's time to treat it to a new rad.


I get mine for £100+vat from Paddocks and they are fine. Just be VERY careful when screwing in the the screws which retain the plastic frame on top of the rad. I did one once where the screws pierced into the waterway - BOLLOCKS!!!!!

Also take care of the small plastic spigot on the rhs as you look in the engine bay - they break off really easily - DOUBLE BOLLOCKS !!!!!!

Agreed but change the pump at the same time.
Flushing the rad works sometimes but it's hard to get a decent flow going on a back flush when the rads insitu but you could try a local rad repair firm as they would probably be willing to blast some de scaling sh1te through and pressure test afterwards but at the end of the day a new rad is the way to go.
 
I would say it's almost certainly a blocked rad. You could try flushing it but the likelyhood is that you'll need a new one.

The trouble is that you have to take everything apart again to get the rad out to give it a thorough flush, then you put it back and maybe the problem is still there. Your car has been running for about 13 yrs now so maybe it's time to treat it to a new rad.


I get mine for £100+vat from Paddocks and they are fine. Just be VERY careful when screwing in the the screws which retain the plastic frame on top of the rad. I did one once where the screws pierced into the waterway - BOLLOCKS!!!!!

Also take care of the small plastic spigot on the rhs as you look in the engine bay - they break off really easily - DOUBLE BOLLOCKS !!!!!!

If you do happen to pierce the waterway with those screws is there anyway of fixing it
 
I'm in two minds about changing the rad now. I had hoped that it was a simple faulty thermostat, but it seems that it is likely to be the HG. Don't want the expense of changing out the rad and pump to then still have to change the HG.
 
I'm in two minds about changing the rad now. I had hoped that it was a simple faulty thermostat, but it seems that it is likely to be the HG. Don't want the expense of changing out the rad and pump to then still have to change the HG.


What makes you say that?
 
I've looked at quite a few posts on HG failures on the TD5 and it seems to have the symptoms. Overpressurised system, some loss of coolant over time with no signs of external leak, bulge in the top hose near where it connects to the engine, and no water circulating through the radiator. The only other thing that shares the cold radiator symptom seemed to be knackered thermostats. So with fingers crossed I changed the thermostat, but no joy, still a cold radiator. So it looks most likely HG failure. The only other possible would be a blocked radiator, but thinking about it, it seems logical that a blocked radiator would usually be partly blocked, so you'd get hot and cold patches. Seems odd to have an entirely blocked radiator, so it seems more likely HG failure, which apparently is quite common on early TD5's what with the head being fixed with lovely wobbly plastic bolts rather than metal ones :-(
 
I've looked at quite a few posts on HG failures on the TD5 and it seems to have the symptoms. Overpressurised system, some loss of coolant over time with no signs of external leak, bulge in the top hose near where it connects to the engine, and no water circulating through the radiator. The only other thing that shares the cold radiator symptom seemed to be knackered thermostats. So with fingers crossed I changed the thermostat, but no joy, still a cold radiator. So it looks most likely HG failure. The only other possible would be a blocked radiator, but thinking about it, it seems logical that a blocked radiator would usually be partly blocked, so you'd get hot and cold patches. Seems odd to have an entirely blocked radiator, so it seems more likely HG failure, which apparently is quite common on early TD5's what with the head being fixed with lovely wobbly plastic bolts rather than metal ones :-(

Get it to a garage and ask for a chemical block test, this will tell you if its a headgasket and will cost about £20 to do which is alot cheaper than removing it and finding out it wasnt that...

Oh and good luck, fingers crossed, touch wood and hope its ok ;)
 
I've looked at quite a few posts on HG failures on the TD5 and it seems to have the symptoms. Overpressurised system, some loss of coolant over time with no signs of external leak, bulge in the top hose near where it connects to the engine, and no water circulating through the radiator. The only other thing that shares the cold radiator symptom seemed to be knackered thermostats. So with fingers crossed I changed the thermostat, but no joy, still a cold radiator. So it looks most likely HG failure. The only other possible would be a blocked radiator, but thinking about it, it seems logical that a blocked radiator would usually be partly blocked, so you'd get hot and cold patches. Seems odd to have an entirely blocked radiator, so it seems more likely HG failure, which apparently is quite common on early TD5's what with the head being fixed with lovely wobbly plastic bolts rather than metal ones :-(


Sorry mate but I don't agree with your logic at all.

When a head gasket goes, the common symptoms are:

1. Over -pressurising of hoses;

2. Blowing bubbles in the header tank related to engine revs;

3. Loss of power;

4. Fault codes relating to an over heat. If car has aircon - forced start of aircon fan;

5. Mayonnaise in the top of the engine;

6. Oil skin in the coolant


But NOT a cold rad.

When a rad is blocked with sediment, hot coolant goes in the top right of rad but cannot pass along the cooling waterways, so hot coolant comes out of the rad, uncoolled.

It's your car off course, but if it were mine I would be changing the rad tout de suite.
 
Not my logic Biglad, just the experience of quite a few people who've posted on the forum. Several posts about people who've had HG failure without overheating, mayo etc. Apparently the TD5 is notorious for failed HG and can still pass compression tests and sniffer tests with a failed HG. I can understand the blocked rad logic, but surely there would be some parts that weren't blocked so some water would flow through it?
 
Not my logic Biglad, just the experience of quite a few people who've posted on the forum. Several posts about people who've had HG failure without overheating, mayo etc. Apparently the TD5 is notorious for failed HG and can still pass compression tests and sniffer tests with a failed HG. I can understand the blocked rad logic, but surely there would be some parts that weren't blocked so some water would flow through it?

If there is any interaction between combustion and cooling it will show up in a sniffer test, dont assume hg so quickly, it could be as simple as the waterpump
 
Not my logic Biglad, just the experience of quite a few people who've posted on the forum. Several posts about people who've had HG failure without overheating, mayo etc. Apparently the TD5 is notorious for failed HG and can still pass compression tests and sniffer tests with a failed HG. I can understand the blocked rad logic, but surely there would be some parts that weren't blocked so some water would flow through it?

Perhaps I didn't explain myself clearly. Coolant will still flow through the rad, from top to bottom, instead of sideways, consequently little or no cooling effect. In other words the coolant is straight in - straight out of the rad.
 
So the coolant would flow in through the top pipe and out through the bottom pipe, it just wouldn't go through the fins?? So the rad would be cold, but the pipes would be hot?
 
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