Brown coolant

[DSYKES5500 22]

Hi all,

 

When I bought my 205 a few months ago, the coolant was brown.  I thought no problem as I would be replacing the entire pipework with BM stuff as well as replacing the rotten pipe under the wheel arch with the stainless version.  I flushed out the engine, the heater matrix, took off and cleaned out the coolant reservoir and fitted a new radiator, thermostat and got the thermostat housing off and cleaned it to look like new.  I knew that the engine and heater matrix would be coated inside with the brown stuff so I used a 50/50 mix of coolant for about 100 miles before it was flushed again when a new cambelt and water pump were fitted.  After about 100 miles the new coolant is brown again.

 

My questions are:

 

Is the coolant turning brown because of the previous deposits breaking up?

Is there anything else in the system that is steel and rusting to cause it to turn brown?

Is there anything I can add to the coolant to remove the brown deposits in the system faster?

Is brown coolant bad for the engine even though it's a 50/50 mix?

 

Thanks!

 

Dan

[Tom Fenton 1,542]

It’s probably crap in the block, very difficult to clean it all out short of stripping the engine. As long as it’s coolant to the correct mixture then there’s not much more you can do.

[DSYKES5500 22]

Thanks Tom, I'll try and do a flush every 6 months.

[Thijs_Rallye 87 4 Cars]

There are cooling system cleaning agents. I've had good results with Forté cooling system flush after tons of mayonaise because of a failed head gasket. Add it to the coolant and drive around with it for a day or two. Then drain the coolant, fill the system with water run the engine a bit, drain, fill with water run the engine, drain and fill with your coolant of choice. Garden hose directly on the heater matrix helps lots as well. 

[Ozymandis 97]

In the past I have put some food grade citric acid crystals in, then run it  a bit, drained, re-crystalled and re-filled a few times and eventually it came out clear.

All the flushes I  tried just got oily contamination out not the rusty crap. YMMV 

If you used a concentrated solution, I dont think You would do much good to a marginally corroded wet liner engines sealing arrangements.

To get the brown crap out of things like the stat housing ,header tank etc, a load of skin crawling allergy inducing washing powder in them and into a hot dishwasher works wonders. I once had some pre-war  dampers re-built and they daubed black paint on them, a soak in brake fluid and the dishwasher treatment got it all off.

[SootySport 23]

If you are using the the new ‘OAT’ type coolant it will go brown. Did the same with my Redtop engine, think the coolant reacts with cast iron in the block for which it it not intended.  You need the blue glyco-ethylene  coolant like Bluecol or Comma.  As for flushing out, food grade citric-acid works well. Run the car for a couple of days, flush with water then refill with glycolic-etheylence based coolant.

I also de-rust steel and iron based metal car parts in citric acid dissolved with water in a bucket, that works well.

[Ozymandis 97]

Bernie, OAT doesnt go brown with cast iron if its clean to start with, and it doesnt react in any way with cast iron.

Its safe on and intended for all common metals apart from SnPb soft solder. So General Motors boffins say.

 

I have four iron blocked, alloy headed engines with alloy/plastic radiators and 50% OAT, 50% Yorkshire tap water stays clean and the original red colour long term ie 5 years between changes.

 

My iron blocked, alloy headed,  copper/brass radiatored ones all use ethylene glycol and stay the original blue, I do change it every 2 years though and keep the concentration 50% anti freeze, 50% Yorkshire tap water

 

I use OAT in everything that hasnt a copper/brass radiator or heater matrix. Never had any problems with leaks or corrossion since it first came into general use.

[SootySport 23]

I’ve cleaned and reFilled my Redtop engine 3 times in as many years with the OAT coolant and it still ends up brown after about a month. Can’t think of anything else that’s causes discolouration, hoses are silicone, rad and head are alloy, header bottle is a standard polythene jobby.  Any other idea why?

[welshpug 1,661]

how brown/what kind of brown is it?

 

 

[SootySport 23]

On 11/30/2019 at 11:44 AM, welshpug said:

how brown/what kind of brown is it?

 

 

That’s a tricky one to describe, I would say the colour of dried out peat, I’ve just had another go at flushing it all out so can’t photo it.

 One other possible cause is the head gasket on its way out, it has overheated on the last 2 trackdays but compression test ok, no loss of power, no oil in the coolant and vice versa.
Just had a test kit delivered yesterday so that’s my next thing to try.

Edited December 1, 2019 by SootySport

[SootySport 23]

Done a head gasket test today and it seems it is leaking a bit.

[welshpug 1,661]

that in itself wouldn't make the coolant brown however if the cooling system hasn't been kept up to scratch with the appropriate mix of corrosion inhibitors then the gasket and fire rings can rot away, as we,ll as corrosion/sludge build up in the far end of the block behind the liners at the transmission end from the mix of dissimilar metals, but mostly the cast ferrous liners   (if this is an alloy XU engine}

[SootySport 23]

It’s a Vauxhall Redtop, alloy head and cast block. I’ve decided the engine is coming out anyway, some oil leaks to sort out as well. I’ll revert back to the original Bluecol coolant after a thorough block clean.

[Ozymandis 97]

Sounds like the coolant wasnt up to strength previously, OAT is fine in an iron block.

 

I think You probably had a manky cooling system to start with, I saw a nissan last week the head gasket was literally rusted away to holes, due to a tiny radiator leak and constant topping up with water, weakening the anti corrossion addiitives strength.

 

If You think about it ally blocks have ferrous liners/bores and if OAT was the problem then they would all fail with corrossion ,brown contamination etc.

Nowt wrong with bluecol, but its 2 yr life, I prefer OAT for the longer life.

 

I have an MGB block in bits, thats been bluecol`ed since my Mrs bought it new in 1981, all the passageways around the rear cylinder are solid with brown crap, I had to get a long series 10mm drill and drill out the crap through the drain plug at the back of the block to get a flow. It has a complete history of me changing the coolant every 2 years and had not a trace of brown in the coolant yet was still crapped up to buggery.

 

[Telf 224 2 Cars]

If you have a look at my engine build thread you can see the amount of crap that collects around the water jacket, around about page 3 or 4 ... The block in question was scrap due to corrosion between the liners/block and probably hadn't been maintained with the correct coolant. I can imagine that the gunk I found is what causes your coolant to discolour. 

 

Worth noting on my rebuilt engine that's now done about 3000 miles the coolant is still bright blue( yep I've currently got a leak !)

[Telf 224 2 Cars]

Found the pics. 

[SootySport 23]

38 minutes ago, Telf said:

Found the pics. 

Must have been a struggle removing those liners

[Telf 224 2 Cars]

Actually no they came out ok. The interface between liner and block was completely wrecked though. Had to scrap the block