Corsa D: Gunk in Coolant

Engine, Exhaust, Drivetrain, ECU
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devon556
Posts: 124
Joined: Tue Dec 04, 2018 9:19 pm

Corsa D: Gunk in Coolant

Post by devon556 » Wed Jan 08, 2020 9:16 pm

Hey all

So I used to own a 2007 Corsa D which I then passed down to my mum.

Since I bought it back in 2016 there has always been a mayo gunk in the coolant tank. In 2017 I took it to Vauxhall as the heater motor had burn out and they claimed it head gasket was going, even though the car had a good service history, and had been maintained by them for 18 months beforehand. On speaking with a relative who has been an engineering for 30 years, we did a check and found it was basically old coolant.

After an argument with the Vauxhall manager, I took it back to them for a coolant change, they claimed to have flushed out all the muck in the tank and replaced the coolant, and to be fair it was fairly clean, but the header tank was stained. After a few drives (mainly long distance motorway driving) I checked it regularly and saw a small amount of what looked like residue left in the system.

However, my mum has only been doing short journeys with the car, and the muck has gone back to how it was in 2017, which I am guessing is condensation. There is no loss of power, nothing unusual under the oil filler cap, and no problem with getting hot air from the fan, to be honest its actually warmer than my 2015 Corsa SE.

I'm seriously considering draining the coolant myself, changing the header tank, flushing the entire system with a pressure washer and changing the coolant. I'm wondering on what other people think is best, From what i've heard the "D"s do seem to have this as a common problem.
2015 Corsa SE 1.4 90PS Automatic.

TheGeorge
Posts: 90
Joined: Tue Apr 25, 2017 6:26 am

Re: Corsa D: Gunk in Coolant

Post by TheGeorge » Thu Jan 09, 2020 8:18 am

I'd be hesitant to do a 'high pressure' water wash. If too high you may damage some seals.
Also if you don't use demineralized water for the wash, you have to flush the cooling circuit with demineralized water 2-3 times before introducing coolant, to dilute/remove the salts from the pressure wash (otherwise they'll precipitate in the circuit, causing more issues).

It's entirely possible that the first coolant change left a few deposits, that later were unsettled. In this case 1 more coolant change should remove them almost completely.
Corsa E - 1.4T
MY 2016

Rickardo
Posts: 388
Joined: Thu Jan 26, 2017 1:23 pm

Re: Corsa D: Gunk in Coolant

Post by Rickardo » Thu Jan 09, 2020 1:37 pm

Googling around suggests you should check and possibly replace the oil cooler as oil is getting into the coolant system

devon556
Posts: 124
Joined: Tue Dec 04, 2018 9:19 pm

Re: Corsa D: Gunk in Coolant

Post by devon556 » Thu Jan 09, 2020 7:41 pm

TheGeorge wrote:
Thu Jan 09, 2020 8:18 am
I'd be hesitant to do a 'high pressure' water wash. If too high you may damage some seals.
Also if you don't use demineralized water for the wash, you have to flush the cooling circuit with demineralized water 2-3 times before introducing coolant, to dilute/remove the salts from the pressure wash (otherwise they'll precipitate in the circuit, causing more issues).

It's entirely possible that the first coolant change left a few deposits, that later were unsettled. In this case 1 more coolant change should remove them almost completely.
How high a pressure would you recommend? Do you think it might be better to drain the current gunk, change the header tank, fill with demin water, run the engine for 5 mins, then shut down, and drain it, then repeat filling it, running it and draining it once more then fill with coolant?
2015 Corsa SE 1.4 90PS Automatic.

devon556
Posts: 124
Joined: Tue Dec 04, 2018 9:19 pm

Re: Corsa D: Gunk in Coolant

Post by devon556 » Thu Jan 09, 2020 7:44 pm

Rickardo wrote:
Thu Jan 09, 2020 1:37 pm
Googling around suggests you should check and possibly replace the oil cooler as oil is getting into the coolant system
But surely if the oil cooler was leaking, there would be a greater oil consumption? It had it's service last April and hasn't required any top ups.

I suppose if necessary it could be removed to check it, but then i'd have to drain perfectly good oil.
2015 Corsa SE 1.4 90PS Automatic.

TheGeorge
Posts: 90
Joined: Tue Apr 25, 2017 6:26 am

Re: Corsa D: Gunk in Coolant

Post by TheGeorge » Fri Jan 10, 2020 10:10 am

devon556 wrote:
Thu Jan 09, 2020 7:41 pm

How high a pressure would you recommend? Do you think it might be better to drain the current gunk, change the header tank, fill with demin water, run the engine for 5 mins, then shut down, and drain it, then repeat filling it, running it and draining it once more then fill with coolant?
The demin flushing 2-3x would be the best, and least risky procedure, to get all the gunk out (just be careful when replenishing to the final coolant, to take out all the air in the system -> may take a few days for ALL the air to make it's way to the expansion vessel so keep the level under observation, and check the final coolant density after a week or so of daily driving to be sure there were no water pockets left to dilute it (i.e. in the cabin heater core or somewhere else)).

Gunk can come from various sources, including oil contamination, degrading plastics in the cooling circuit (if so, they will crack and leak soon™), corrosion products due to very old coolant or past top-ups with incompatible coolant.

A good drain/flush with demin water can eliminate the last 2 gunk sources. A (gentile, manual) squeeze check on a few plastic/rubber connections around the radiator can tell if the connections are degraded (think thin cracks when squeezing rubber, or clear rubbery plastics feeling 'stiff' and easily going off-color at the squeeze area). If there is still significant accumulation of gunk after a few weeks following the flushes, then oil leaks can be investigated further.


A quick check for oil leaks would be to see if there is cappuccino foam around the dipstick and/or oil cap, after running the engine a few minutes (some oil <--> water leaks are 2-way, depending on oil and water systems pressure profiles at various times).

If oil is still clear, and gunk still accumulates at a significant rate, then indeed it can be oil -> water contamination. It doesn't take too much oil to form an emulsion in the water, so significant oil level changes can be hard to detect. In this case, maybe is best to refer to a specialized garage to see how to proceed further.
Corsa E - 1.4T
MY 2016

Rickardo
Posts: 388
Joined: Thu Jan 26, 2017 1:23 pm

Re: Corsa D: Gunk in Coolant

Post by Rickardo » Fri Jan 10, 2020 1:30 pm

devon556 wrote:
Thu Jan 09, 2020 7:44 pm
Rickardo wrote:
Thu Jan 09, 2020 1:37 pm
Googling around suggests you should check and possibly replace the oil cooler as oil is getting into the coolant system
But surely if the oil cooler was leaking, there would be a greater oil consumption? It had it's service last April and hasn't required any top ups.

I suppose if necessary it could be removed to check it, but then i'd have to drain perfectly good oil.
Not necessarily as the gunk is building up over time

Would deffo start there rather than flushing as you did this before and it returned so you have a problem

You can always reuse the oil

devon556
Posts: 124
Joined: Tue Dec 04, 2018 9:19 pm

Re: Corsa D: Gunk in Coolant

Post by devon556 » Sat Jan 11, 2020 6:55 pm

Rickardo wrote:
Fri Jan 10, 2020 1:30 pm
devon556 wrote:
Thu Jan 09, 2020 7:44 pm
Rickardo wrote:
Thu Jan 09, 2020 1:37 pm
Googling around suggests you should check and possibly replace the oil cooler as oil is getting into the coolant system
But surely if the oil cooler was leaking, there would be a greater oil consumption? It had it's service last April and hasn't required any top ups.

I suppose if necessary it could be removed to check it, but then i'd have to drain perfectly good oil.
Not necessarily as the gunk is building up over time

Would deffo start there rather than flushing as you did this before and it returned so you have a problem

You can always reuse the oil

I don't think it's come back more that it's in all the lines and radiator etc. Since it was flushed in 2017, the car has done less than 5k miles.

I will keep in mind about the oiler cooler, but I think il probably drain the coolant, change the header tank, maybe some of the lines encase they are perishing, flush ti with deionised water a few then top up the coolant. Looking around If I get the coolant and deionised water from Halfords, the job's going to cost less than £30. Where as to buy a new oil cooler is £100-150, plus new Dexos 2 oil, plus the filter, and then finding the time do such a big job or send it to Vauxhall to have it done, your looking at £200 minimum probably more.

Besides if it does happen again with new header tank and lines, you can tick off a lot more possible issues.
2015 Corsa SE 1.4 90PS Automatic.

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