Coolant query

M

MKZ4000

Active member
I recently had a coolant flush and change and noticed the coolant has been dropping.

I've only driven it twice since and topped up the coolant.

I was just wondering if the coolant expansion tank is meant to have a hole in the top where the coolant flows out of back into the rad? see pic attached. Thanks in advance

IMG_0534.JPG
 
Is it losing coolant or has the level just settled because it wasn't bled properly ? How old is the car ? Check the expansion tank, radiator, water pump, thermostat housing and o-ring on temperature sensor for leaks. :thumbsup:
 
Mine seemed to keep needing topping up before I changed the coolant myself, bleeding it properly twice (N52). Spot on since :thumbsup:
 
Thanks for the replies.

Its a 3.0 2003 MY.

I've not had much opportunity to drive it lately but it seems to be staying at the same level after a 2nd top up. I'll keep an eye on it and check those areas suggested for leaks.

The garage was going to change the thermostat as it was throwing up an error code even though the car isn't overheating. They didn't change it in the end as they said the bolts were seized. I think they would have noticed a coolant leak there. I have read the expansion tanks are a common area to crack but I can't see anything.
 
Could be something as simple as the radiator cap. The O rings go flat and start to leak so it won’t hold pressure.
 
MKZ4000 said:
They didn't change it in the end as they said the bolts were seized.
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That's pretty poor if you ask me, they're the 'professionals' it just sounds like laziness. What happens when/if the thermostat fails? Scrap the car because of seized bolts? Take it back and make them sweat :poke: lol
 
TBH i thought that myself as we are talking about a proper garage. Their reasoning was that I never brought the car in with an overheating issue and they thought changing the thermostat was worthwhile due to an error code thrown up. (I brought the car in for a full service including coolant change)

When they found the bolts were seized they decided not to carry on as the labour costs could mount up and mentioned the head might need to come off if they end up breaking (? I didn't really understand that part) They also said I would have some warning if the thermostat failed as the temp gauge would rise - it always stays bang in the middle.
 
MKZ4000 said:
TBH i thought that myself as we are talking about a proper garage. Their reasoning was that I never brought the car in with an overheating issue and they thought changing the thermostat was worthwhile due to an error code thrown up. (I brought the car in for a full service including coolant change)

When they found the bolts were seized they decided not to carry on as the labour costs could mount up and mentioned the head might need to come off if they end up breaking (? I didn't really understand that part) They also said I would have some warning if the thermostat failed as the temp gauge would rise - it always stays bang in the middle.
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I thought that might be the case, the cost would outweigh the benefit. If the bolts break off in the head it may have to be removed to get access to drill them out and helicoil.
 
MKZ4000 said:
Thanks for the replies.

Its a 3.0 2003 MY.

I've not had much opportunity to drive it lately but it seems to be staying at the same level after a 2nd top up. I'll keep an eye on it and check those areas suggested for leaks.

The garage was going to change the thermostat as it was throwing up an error code even though the car isn't overheating. They didn't change it in the end as they said the bolts were seized. I think they would have noticed a coolant leak there. I have read the expansion tanks are a common area to crack but I can't see anything.
Click to expand...

This smells fishy to me. My car is '03 and I've just recently replaced my thermostat and water pump without any problems. This is the Wahler thermostat I fitted. It is secured by 4 x bolts as shown. 20181219_143706.jpg
The right hand one is a 13mm bolt shared with the engine hanger bracket and torqued to 24Nm. The other 3 x bolts are 10mm and only 10Nm. They are only holding a piece of plastic on and each bolt hole has a metal liner anyway. As I say mine is a 2003 car and all 4 bolts undid easily.
Sounds like your garage has a case of CBA to me :(
 
Thanks for your replies and I've been googling the thermostat replacement.

I know they bought the thermostat/housing but returned it because 2 of the bolts were seized. What are the chances of having to take the head off if the bolts were to snap? Would they not be able to be removed by drilling out or welding to them?

I'm no mechanic but is it easy for me to access the thermostat housing and spray WD40 in the bolts? Hopefully over a few months that might unseize them. I could then take to a different garage to replace the thermostat. There is no immediate concern as the engine is running sweetly and not overheating but it would be a kick in the teeth if the head needed to come off to replace a thermostat. I guess thats worse case
 
MKZ4000 said:
Thanks for your replies and I've been googling the thermostat replacement.

I know they bought the thermostat/housing but returned it because 2 of the bolts were seized. What are the chances of having to take the head off if the bolts were to snap? Would they not be able to be removed by drilling out or welding to them?

I'm no mechanic but is it easy for me to access the thermostat housing and spray WD40 in the bolts? Hopefully over a few months that might unseize them. I could then take to a different garage to replace the thermostat. There is no immediate concern as the engine is running sweetly and not overheating but it would be a kick in the teeth if the head needed to come off to replace a thermostat. I guess thats worse case
Click to expand...

I doubt the head would need to come off IF the bolts broke. There's not much room but I seriously doubt it. I think you'll be wasting your time with WD40 as the bolts are through the plastic thermostat and into the alloy head restricting any oil penetration.
Here's a photo I took of my thermostat location on the cylinder head and a cylinder head diagram with the thermostat location and 4 x bolt holes.20181219_233748.jpg
20181219_234421.jpg

I'd be tempted to just leave the thermostat alone but keep an eye on it. As the saying goes 'if it ain't broke, don't fix it !' :thumbsup:
 
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