Hi All

Been a little while since i last posted on here, probably because the Fabia has been running so well (serviced it today).

Sorry for the long post, but would really appreciate some knowledgable assistance.

Reason for the post is the GF's golf (Y-reg, 1.9tdi) - have had a number of problems recently and wanted to get some 2nd opinions on here. So the story goes..........

Bought it off my bro, 178k miles on clock so got the timing belt down at local vw/audi garage, whilst they were in there we agreed for them to change out the water pump as well.

GF got the car back and then a little while later when i was driving it noticed temp gauge fluctuating (going down slightly when sedate driving), poor mpg and taking a long time to get up to temp. Also noticed that rad out-pipe pretty cold.

Back to garage - they replaced temp sensor which fixed gauge issue, but still had the cold exit pipe from rad.

At this point i suggested it seemed a coincidence that this had happened after the pump change and that maybe the lack of circulation and temp sensor issue etc... could be a faulty or incorrectly installed pump. I was told that this was very very unlikely and not the problem.

Back to garage - they replaced the thermostat as they were convinced that this would be the cause. Still had the cold rad exit pipe issue on test drive and then they put some flush detergent stuff in coolant and told us to see if that clears what they suspected to be a crud-upped rad.

Back to garage - still cold rad exit pipe, so they replaced rad as they were now convinced that this was the cause.

I decided it would be useful to get the old rad back and asked them to leave this in the car, checked it today and flows absolutely fine with no evidence of sludge, crud or anything else.

When car is hot the rad exit pipe is still cold!!!

Getting really annoyed now as I have repeatedly suggested the coincidence to all this happening after they changed the water pump, now they have changed a number of things at our cost with no sign of fixing the problem. What is worse is that they gave the car back to my GF without saying there was a prob (as if a garage would replace a rad and not road test to check entry and exit hoses where hot!)

Going to call them on monday and cleary request that they go back in and check the water pump (guess they have been avoiding this due to time required and hassle etc...), as I can't think of anything else that it could now be. Will also be asking them to do this FOC considering how much we have now spent on replacing a perfectly good thermostat and rad.

Anyone got any ideas of what the cause could be?? Any things to check or ask the garage to do??

Cheers very much in advance

Andy

Has g12 coolant and blue coolant been mixed at any point? I.e. is there now blue coolant in the system when before there was red? It's generally easy enough to see the flow of coolant from the pump at the expansion tank once the car has warmed up and the thermostat opened (at least on mine, no experience of diesels). It flows out of the small hose at the top. This may be easier to see with the expansion cap removed but be careful that the coolant doesn't spew out etc.

Edited 6 November, 201015 yr by anewman

A PD diesel engine is a really efficient prime mover and produces relatively little waste heat. At this time of the year, unless the engine is working hard, I would expect the thermostat to remain closed - the cab heater will provide sufficient cooling for the engine. The radiator will therefore not heat up.

I suspect everything is operating correctly.

rotodiesel.

/\ i read something along those lines last night im sure i did

cold side will stay cold

Has g12 coolant and blue coolant been mixed at any point? I.e. is there now blue coolant in the system when before there was red? It's generally easy enough to see the flow of coolant from the pump at the expansion tank once the car has warmed up and the thermostat opened (at least on mine, no experience of diesels). It flows out of the small hose at the top. This may be easier to see with the expansion cap removed but be careful that the coolant doesn't spew out etc.

Pretty sure it has only ever had G12 coolant in it and they have replaced it twice recently with G12 as well. I doubt it is caused by any dodgy reaction as not been mixing anything up.

No flow visible at expansion tank, but do get the system over-pressurising and spitting coolant out the blow-off valve on the expansion tank, am guessing this is due to the fact that it is running so hot as no circulation, but seems a little strange that the pressure would not force it more round the system. i.e. struggle to believe that a non-functioning pump would create a pressure block.

A PD diesel engine is a really efficient prime mover and produces relatively little waste heat. At this time of the year, unless the engine is working hard, I would expect the thermostat to remain closed - the cab heater will provide sufficient cooling for the engine. The radiator will therefore not heat up.

I suspect everything is operating correctly.

rotodiesel.

OK, but the hose to the rad is roasting hot (after motorway run) and the exit pipe is completely cold. Thats not an engine being efficient surely, that is water not being circulated through the rad??

OK, but the hose to the rad is roasting hot (after motorway run) and the exit pipe is completely cold. Thats not an engine being efficient surely, that is water not being circulated through the rad??

What sort of distance are you doing before checking? as to be honest i agree with the statement above, they just dont get that hot, maybe leave the car idling untill the rad fans cut in (obv keep an eye on the coolant guage) and then chack the coolant pipe ?

Agree, if the bottom hose isnt very hot then surely the rad is doing its job, thats the idea isnt it?

If the water pump wasnt working it would be over heating straight away.

OK, not disputing all the above, but after 20mile motorway run....

engine roasting hot

coolant expansion tank pinking with the sound of pressure in coolant system

rad entry hose too hot to hold on to

rad exit hose completely stone cold, no residual heat at all which should be left after it flowing through the rad

rad is now new (although old one seems to flow fine), thermostat is new, temp sensor is new, coolant is new and good level

Andy.

OK, not disputing all the above, but after 20mile motorway run....

engine roasting hot

coolant expansion tank pinking with the sound of pressure in coolant system

rad entry hose too hot to hold on to

rad exit hose completely stone cold, no residual heat at all which should be left after it flowing through the rad

rad is now new (although old one seems to flow fine), thermostat is new, temp sensor is new, coolant is new and good level

Andy.

Try what i said, might be able to help you a bit more then, a 20 mile run in this low ambient temp will probs not be enough to open the stat at all

Try what i said, might be able to help you a bit more then, a 20 mile run in this low ambient temp will probs not be enough to open the stat at all

Took it for a hard run today to make sure that my judgement of 'hot enough' was definitely right!

Pulled up after some hard driving and had coolant running out from the front of the car - this is the coolant spitting out the overflow of the expansion tank and running down inside the front wing.

The fact that it is doing this suggests the engine is defo up to temp!!

Inlet rad hose was roasting hot, exit hose was still stone cold.

There is no doubt that the thermostat is open as heat is conducting along the coolant to the top of the rad, it just seems to have no flow and is therefore not getting circulated through the rad.

I can only now conclude that this must surely be a badly installed or faulty water pump??

Andy

Took it for a hard run today to make sure that my judgement of 'hot enough' was definitely right!

Pulled up after some hard driving and had coolant running out from the front of the car - this is the coolant spitting out the overflow of the expansion tank and running down inside the front wing.

The fact that it is doing this suggests the engine is defo up to temp!!

Inlet rad hose was roasting hot, exit hose was still stone cold.

There is no doubt that the thermostat is open as heat is conducting along the coolant to the top of the rad, it just seems to have no flow and is therefore not getting circulated through the rad.

I can only now conclude that this must surely be a badly installed or faulty water pump??

Andy

Badly installed water pump would still work but just leak, could either be a severe airlock, or head gasket failure (which is uncommon but still likely) in any case you need to take it back to whoever did the work and deffo stop driving it if it is getting as hot as you say

air lock is a good call

What is the temp guage doing?

Does it reach normal, stay there until the pressure cap blows and then shoots into the red?

Does it climb slowly into the red?

What is the temp guage doing?

Does it reach normal, stay there until the pressure cap blows and then shoots into the red?

Does it climb slowly into the red?

All in the original post my friend ; )

All in the original post my friend ; )

The only reference I can find in the original post to the temp guage is that it was "fluctuating (going down slightly when sedate driving)" and "they replaced temp sensor which fixed gauge issue". I assume fixed means that it reaches 90, hence the question.

If water impeller at rear of water-pump is not turning, would certainly not help circulation it is supposed to.

Thermostat, electric fans and every other sensor etc are doing their job but cannot substitute water pump operation failure.

A water pump impeller shaft seized/broken or shaft detached from impeller would give your symptoms.

There would not necessarily be a visible leak, to pinpoint this problem, so could go unnoticed.

I assume the temperature gauge just keeps climbing up into it's highest point?

Leaving header/water fill-up cap off and heaters turned onto hot position would get rid of any air that my have been trapped in system,

but again would rely on water-pump moving water around system, in the first place.

Suggest with my above long input water-pump assumption has got to be eliminated after everything else has failed.

Edited 10 November, 201015 yr by giandougl

By way of an update and to answer a few of the q's.....

Temp gauge goes to 90, smack in the middle, stays there (since temp sensor has been replaced)

Now that there are low ambient temps I can only get the car to throw coolant out the expansion tank overflow (and down inside the wing) when the car has been driven hard and engine is hot.

So this is NOT a case of thermostat not opening because (the PD engine has good temp efficiency and ambient temps are low at the moment) - the entry pipe to new rad will be roasting hot (I assume due to heat conducting along the coolant rather than flow) and the exit hose from rad is stone cold.

Took the top hose of the coolant expansion tank tonight, pointed it back into the tank with cap removed, then revved the engine to check the coolant flow existed and increased pressure as engine revs rose - all flowed ok and increased when revved!!

Not sure if flow was high/low/good/bad as don't have the previous condition to compare to.

Still have a noise coming from the top of engine/water pump area - had been assuming that this was confirmation that the pump had failed (sheared shaft/slipping wheel/stuck impeller etc...) but the pump seems to be creating flow. Not sure if this is just some 'bedding-in' as the garage put it or whether it is something completely unrelated.

Loosing the will to live with this now!!

Options for possible causes as I see it are:

1. Water pump problem or ill-fitting leading to very low flow

2. Something has been dislodged or a foreign body entered coolant circuit on pump change that has caused a restriction in the system between pump and rad

3. Head gasket - what would symptoms be though?, as not loosing oil and no sign of oil in water

4. Something else that will be incredibly simple and obvious to us all when I find out!!

Help!!

Andy

Edited 9 November, 201015 yr by A Woodster

This will tell you if the HG has gone (if you can bear to read it ALL IN CAPITALS!)

reviews.ebay.co.uk/HOW-TO-TEST-FOR-A-FAILED-HEAD-GASKET_W0QQugidZ10000000001891247

FWIW, the return flow to the expansion tank is barely a trickle at the best of times, so the fact you can see anything at all is probably a good sign. I'm beginning to think the advice to take it back to the garage is best, but maybe on the way there you could wrap up warm, and drive there with the heater on 'cold', just to be sure it's not simply losing all the heat into the cabin as has been suggested?

By way of an update and to answer a few of the q's.....

Temp gauge goes to 90, smack in the middle, stays there (since temp sensor has been replaced)

Now that there are low ambient temps I can only get the car to throw coolant out the expansion tank overflow (and down inside the wing) when the car has been driven hard and engine is hot.

So this is NOT a case of thermostat not opening because (the PD engine has good temp efficiency and ambient temps are low at the moment) - the entry pipe to new rad will be roasting hot (I assume due to heat conducting along the coolant rather than flow) and the exit hose from rad is stone cold.

Took the top hose of the coolant expansion tank tonight, pointed it back into the tank with cap removed, then revved the engine to check the coolant flow existed and increased pressure as engine revs rose - all flowed ok and increased when revved!!

Not sure if flow was high/low/good/bad as don't have the previous condition to compare to.

Still have a noise coming from the top of engine/water pump area - had been assuming that this was confirmation that the pump had failed (sheared shaft/slipping wheel/stuck impeller etc...) but the pump seems to be creating flow. Not sure if this is just some 'bedding-in' as the garage put it or whether it is something completely unrelated.

Loosing the will to live with this now!!

Options for possible causes as I see it are:

1. Water pump problem or ill-fitting leading to very low flow

2. Something has been dislodged or a foreign body entered coolant circuit on pump change that has caused a restriction in the system between pump and rad

3. Head gasket - what would symptoms be though?, as not loosing oil and no sign of oil in water

4. Something else that will be incredibly simple and obvious to us all when I find out!!

Help!!

Andy

I've seen several of these cars with your symptoms turn out to be a bad HG.

In most cases, the guage stays rock solid at 90 until the system overpressurises and coolant escapes through the pressure cap. The temperature guage doesn't creep up slowly as the load increases. The problem is usually worst when trying to make progress on busy A roads.

It is a good idea to change the pressure cap in case this is the problem. The coolant will boil and blow off if there is a loss of pressure.

I've seen several of these cars with your symptoms turn out to be a bad HG.

In most cases, the guage stays rock solid at 90 until the system overpressurises and coolant escapes through the pressure cap. The temperature guage doesn't creep up slowly as the load increases. The problem is usually worst when trying to make progress on busy A roads.

It is a good idea to change the pressure cap in case this is the problem. The coolant will boil and blow off if there is a loss of pressure.

I understand the over-pressurizing symptom with HG failure, but have no oil in water (or vice versa) and even if the HG had failed surely it would not impact so significantly on the coolant flow through the rad??

Cheers

Andy

I understand the over-pressurizing symptom with HG failure, but have no oil in water (or vice versa) and even if the HG had failed surely it would not impact so significantly on the coolant flow through the rad??

Cheers

Andy

There are many ways the HGs can fail. You can get a coolant leak to the outside, exhaust to coolant or oil to coolant.

Exhaust to coolant can stop coolant circulation. Sometimes it will force all the coolant out of the reservoir and when you take the cap off, like magic it's back

Sniff test will rule that in or out, if there's any doubt after the 'roadside' tests I linked to earlier. I was worried about HG failure a while back, as there was still pressure in the system even after the car had sat over the weekend. Swapping the expansion tank cap with my wife's showed it to be the cap that was at fault, though!