After a couple of days of nonstop driving around Lochaber my engine started running hot, so I had a look at the coolant. It seems to be brown and sludgey (if that's a word!). Am I right in saying that's not good, and I should probably head to a garage for a coolant change? If so, is that normally a quick cheap procedure or is it more complicated?
I'm not a mechanically minded person so don't suggest I do it myself!
sounds like you've got oil in it.. which could mean your head gasket's gone. that's a big job!
When you say big do you mean £££ or just time consuming? The engine has done 194k miles so far, I hope this isn't the end.
If it is oil in the coolant and if it isn't a blown head gasket then its an even bigger job. A blown head gasket will also drive combustion gasses into he cooling system thus driving coolant through the release valve in the coolant filler cap. After a significant amount of coolant has been lost the engine will then destroy itself.
Lifting the head and replacing the gasket is not too big a job unless the cylinder head has been distorted or otherwise damaged.
Before the doom mongers have you totally depressed, is the sludge a rust colour? If the car is old it may just need a flush out and new coolant. Is the sludge that you can see oily? Also have a look at the oil, has the level dropped and is there any sign of water in the oil? Further, overheating can be caused by the electric fan not operating, either due to the switch failing, or the fan itself.
A further question, what make model and age is the car, some are much more prone to head gasket failure than others.
As Nimbus says,if the sludge is brown it probably just need flushing and refilling,BUT,if the sludge is a creamy colour then it`s probably the head gasket.I had the problem 10 years ago(Nissan Sunny).The sump was full of an emulsion of oil and water and it cost £350 including a total rebuild of the top of the engine.
I hope for your sake it`s simpler than that.
Cheers
Dave NRIPN
If it wasn't for bad luck, I wouldn't have no luck at all - Albert King
Blues is a healer - John Lee Hooker
my flickr
The important thing is whether the "water" is just a rusty brown colour or whether there's evidence of "emulsion" (oil trying to mix with water and creating a white sludge which often sticks around the area of the filler cap). If it's the former, then the cooling system just needs flushed out and filled with new coolant, a simple and cheap job which the likes of your local quick-fit will do for you if you don't feel confident in doing it yourself. If it's the latter however, then be prepared for a hefty repair bill if the cylinder head gasket needs replacing (the gasket itself is dirt cheap but it's the labour time required to fit it that's expensive!)
BigWill
P.S. NEVER put just "ordinary water" into your cooling system, make sure it is properly mixed (usually 50:50 with water) "coolant" which will make the engine run cooler, protect it from frost and stop the buildup of rust and crud inside the cooling system.
I'm sailing like a driftwood on a windy bay.
Will is right.The important thing is whether the "water" is just a rusty brown colour or whether there's evidence of "emulsion" (oil trying to mix with water and creating a white sludge which often sticks around the area of the filler cap). If it's the former, then the cooling system just needs flushed out and filled with new coolant, a simple and cheap job which the likes of your local quick-fit will do for you if you don't feel confident in doing it yourself. If it's the latter however, then be prepared for a hefty repair bill if the cylinder head gasket needs replacing (the gasket itself is dirt cheap but it's the labour time required to fit it that's expensive!)
BigWill
P.S. NEVER put just "ordinary water" into your cooling system, make sure it is properly mixed (usually 50:50 with water) "coolant" which will make the engine run cooler, protect it from frost and stop the buildup of rust and crud inside the cooling system.
Take a quick sniff at the inside of the filler cap. If it's the head gasket then there probably will be a smell of petrol/oil/fumes. This test isn't infallible but if the smell is strong and unmistakable then it's a very good indicator.
MickLL
A little word of hope here. If a head gasket has gone there will be a sudden and severe loss of cooling water into the oil which will turn into something resembling Seven Island Dressing. There may be accompanying clouds of steam!
The oil will NOT migrate into the water because the coolant is under pressure and when the gasket goes the pressure increased quite significantly. In really serious cases an engine can seize up or the cylinder head can warp past further use.
Coolant when it has reached the end of it's life WILL NOT act as a coolant, it becomes highly inefficient and the engine will tend to overheat. The radiator matrix will become blocked, hence your problem.
What you describe as a brown slugy mix may not be a serious problem, all that may need doing is a good flush out, preferable with back pressure flushing to clean out all the sludge which will contain a high proportion of rust from inside the engine. This sludge may be preventing the circulatory pump from working as well which will add to your difficulties.
A garage will be able to do it for you in about an hour or two and as to the the cost, well, how long is a bit of string? Budget for a couple of hours work plus new antifreeze. Max about £100 - £120
Used to do engine flushing as a DIY job, bet there's some environmental law now that says dirty engine water has to be collected and taken to be 'recycled'
I didn't say that there would be oil in the coolant. I said there may be a smell. I suggest that you google 'failed head gasket symptoms' or similar. Every link will include not only the possibility that I described but also the possibility of emulsification of the coolant.The oil will NOT migrate into the water because the coolant is under pressure
Here is just one example from thousands,
MickLL
I would hope that the oil is under pressure too. However the reason that oil will not migrate into the coolant is that the most usual failure mode of a head gasket is not between oil and coolant but between coolant and combustion, resulting in a loss of coolant into the combustion chamber and clouds of steam from the exhaust. Alternatively the gasket can fail between coolant and oil return which dumps coolant into the unpressurised side of the lubrication system.
The oil will NOT migrate into the water because the coolant is under pressure
Yes the oil will be under pressure but only in the moving parts. (Crankshaft, camshaft and possibly valve gear depending on the design of the motor etc.) The oil in the sump will be at atmospheric levels.I would hope that the oil is under pressure too. However the reason that oil will not migrate into the coolant is that the most usual failure mode of a head gasket is not between oil and coolant but between coolant and combustion, resulting in a loss of coolant into the combustion chamber and clouds of steam from the exhaust. Alternatively the gasket can fail between coolant and oil return which dumps coolant into the unpressurised side of the lubrication system.
The oil will NOT migrate into the water because the coolant is under pressure
For heavens sake, this chap (the original poster) was only asking advice and quite frankly he has been given some crap advice preaching doom and despair when all is probably needed is a well overdue coolant change. I do not wish to get into any argument over the innermost why's and wherefores of the internal combustion engine.
Thanks for the advice. I need to get out and check it again now I know what to look for. Fingers crossed...
I thought the check you should make is the condition of the engine oil. If it has emulsified with the coolant it will look like mayonnaise.
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