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VT Commodore - Brown Sludge, in overflow tank reservoir.

Bronson3

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I've got this brown sludge in the bottom of my coolant overflow tank where the dipstick is, since I've owned the car.

I flushed the radiator and refilled it, but it's still there and really bothers me... I've heard that it can be from mixing coolants and seeing as I didn't flush the heater core, it's probably made the problem worse. (but no obvious change, it does look better since my flush of the radiator about 5 months ago when I got the car)

I can flush a radiator and all that, but my main question is how to flush the heater core. I've done some research and they say don't use chemicals, don't use compressed air, don't use high water pressure, etc. But my problem is that I don't know where/which hose I'm meant to be flushing through or disconnect either.

Does anyone else have a VT comoddore that'd be willing to take a couple photos for me to help out. My car doesn't overheat or anything, it's running perfectly, but I don't like the fact that it's there and could be slowly creating more problems for me in the future and more problems = more $$$

Thanks Guys.
Bronson.
 

dirty hands

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if it aint broke dont fix it

thats normal most holdens have that brown gunk

mine has been brown for years and been no problem

i would no do anything to the heater core ..cleaning it make cause a leak
 

commodore665

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I've got this brown sludge in the bottom of my coolant overflow tank where the dipstick is, since I've owned the car.

I flushed the radiator and refilled it, but it's still there and really bothers me... I've heard that it can be from mixing coolants and seeing as I didn't flush the heater core, it's probably made the problem worse. (but no obvious change, it does look better since my flush of the radiator about 5 months ago when I got the car)

I can flush a radiator and all that, but my main question is how to flush the heater core. I've done some research and they say don't use chemicals, don't use compressed air, don't use high water pressure, etc. But my problem is that I don't know where/which hose I'm meant to be flushing through or disconnect either.

Does anyone else have a VT comoddore that'd be willing to take a couple photos for me to help out. My car doesn't overheat or anything, it's running perfectly, but I don't like the fact that it's there and could be slowly creating more problems for me in the future and more problems = more $$$

Thanks Guys.
Bronson.
Hey Bronson , if it's only the over flow tank it's fine , if the radiator fluid ( check when the car is cool ) is not like a chocolate thick shake its OK , and welcome to the forum also .
 

lout

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have a look at your radiator cap
if you have an oily residue like vaseline
you probably have worn lim gaskets
if you use the holden pellets you will get a brown residue
if it is pinkish trans coolant pipes in radiator may be coroded
my money is on lim gaskets
 

lignum1966

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I got that after a mechanic at work told me to put the waxy pellet thing in after a cooling system flush - and flushing the system with mukowt didn't seem to get rid of it !
 

Nut Kracker

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If the radiator's coolant is ok, then as said above, don't worry.
People drain and flush their radiators, but seem to forget about the recovery tank.
Mainly, because it's either in a prick of a spot to get to, they forget about it, or don't bother.
And over the years, it's bound to build up some gunk.
 

billythakid

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Start the car and turn full lock right turn off and get under the passenger wheel arch and undo the three screws , drop out overflow bottle . Rinse bottle out up side down with hose , refit and refill . 10 min job
Check the overflow hose for splits/ cracks while its out
 

BlackoutSteve

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If a V6, my money is on the intake manifold gaskets as these will allow the mixing of oil and coolant when they fail.
Get your cooling system pressure checked.
See how much pressure it holds and for how long.
Roughly, at 20psi it should not lose more than 2 ~psi over 2 mins.

Easiest check right now would be to check the torque of the intake manifold bolts..
If they are not tight, it's very likely the gasket has perished and "relaxed" -removing the bolts' preload.
If the bolts are lose, torquing them now may stop or reduce the sludge you are seeing, but it also means that replacing the gaskets is imminent.

Don't go gang-busters on them, they only need about 20ft/lbs.. :)
 

Bronson3

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Thank you all so much for your help I might just empty the overflow, clean out the reservoir and fill her back up, could be a possibility that it's only in there, I replaced my cap when I did a flush 4 months ago so I guess there is really no point in flushing it again and buying more coolant :)

Cheers everyone.
 

Bronson3

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If a V6, my money is on the intake manifold gaskets as these will allow the mixing of oil and coolant when they fail.
Get your cooling system pressure checked.
See how much pressure it holds and for how long.
Roughly, at 20psi it should not lose more than 2 ~psi over 2 mins.

Easiest check right now would be to check the torque of the intake manifold bolts..
If they are not tight, it's very likely the gasket has perished and "relaxed" -removing the bolts' preload.
If the bolts are lose, torquing them now may stop or reduce the sludge you are seeing, but it also means that replacing the gaskets is imminent.

Don't go gang-busters on them, they only need about 20ft/lbs.. :)
Very insightful response always appreciate new suggestions, thanks!
 
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