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3.0 HDi has had a coolant burst episode

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Fri Jul 12 2019, 01:53am
Joined: Jul 12 2019
Member No: #3981
Location: SF
Hello everyone, it's my first post here

I've been guided here by a virtual friend from our local Citroen community. I still don't own a C6 but I'm keeping an eye since a year and actively searching for about a month.

I went to see a 3.0 HDi and took it to a mechanic I trust beyond myself who takes care of our French cars since 20 years. He concluded the car has been taken care of generally well, BUT there were traces of hot coolant on the degassing tank and the coolant cap has been replaced. Probably a head/gasket problem was leading to increased pressure in the cooling system, what's worse is that the cap has a valve and the fact it's replaced made him presume that there's been a previous attempt at just replacing the cap hoping its valve is defective, which only prolonged the actual problem.

According to him at the best scenario a successful repair has been done, at a more probable a repair has been done which we'll see how successful is (he said head/gasket work on these engines is very specific and with low long-term success rate even in official Citroen services). In short, he sad if I'm prepared for the worst case, which would be a full engine replace, to go for the car - which of course I'm not considering the price.

I searched long across the forum but managed to find only threads regarding thermostat housing failures and coolant lever sensors not being fitted at manufacture, but nothing regarding this problem. I currently drive a Peugeot which also suffered from the exact same problem, raising pressure due to head fault (but mine was corroded due to previous owner using wrong type of coolant).

Does anybody have any experience he might share on this with me, I'll be very grateful!
Fri Jul 12 2019, 03:09pm
Joined: Jul 17 2012
Member No: #954
Location: Bergen
A very optimistic theory : Just a slight overfill (the "max" mark) may push some coolant out and leave white traces. Fill to the first mark, not "max" and see if the white marks still appears. This is the case with my 3.0 after Citroen changed to new coolant.
1 User said Thank You to Tjensen for this Post :
 gkirkov (Today)
Fri Jul 12 2019, 09:04pm
Joined: Jul 12 2019
Member No: #3981
Location: SF
That would indeed sound great if they hadn't recently replaced the cap... The photos with which the car is being sold show the original cap. I saw it 7000 km after the photos with a replaced cap... So they must also have lost it, which kind of minimizes the chances.

Would someone who has had high pressure issues or other engine head and gasket issues join?
Tue Jul 16 2019, 08:05am
Joined: Apr 20 2010
Member No: #94
Location: Belfast

I had the thermostat housing fail on my 2.7 HDI C6. The car then overheated and head gaskets failed. The car was repaired at considerable cost by a Citroen dealership. The repair held for about 14 months and then failed again causing major damage. I then cut my losses and sold the car for scrap value. The cheapest lesson in life is to learn from another's mistake. I would be inclined to walk away if there is any doubt about the car.

1 User said Thank You to Leo for this Post :
 gkirkov (Today)
Tue Jul 16 2019, 08:26pm
Joined: Jul 12 2019
Member No: #3981
Location: SF
Hi Leo, thanks for your reply

What were the symptoms of the first and second failure and how were they different? I'm trying to figure out what exactly has happened in my case...

I definitely am very cautious about this eventual purchase - the reason I'm still considering is only because my mechanic assured me that this is not an uncommon problem and considering all aspects, I don't have much better chances of getting a better C6 abroad (this would mean he won't be able to inspect it and this car is OK except this).

Your story confirms what he told me that head repairs are with suspicious success even at Citroen dealers...

I see our Citroen dealership offers 3 kinds of engine replacements - a new engine (without accessories), whose price is as much of the price of the car, and a "Recycled" engine, the price of which is about half of the vehicle price. So I'm thinking about buying it and having in mind I'll probably have to replace the whole engine, be it with a recycled one (for which I surely will have to negotiate for a huge discount with the seller).

Has someone replaced an engine with a recycled engine from Citroen? I wonder what exactly does that mean, is it just a used but OK engine, or it's a repaired one...

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