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[Webby the Bear]

Afternoon fellas, one trusts you're all well.

So. My diff leaks from the pinion seal. My autobox leaks from the rear seal. I have a small engine oil leak. And i have a coolant leak.

Took mrs' car to mot. . . advisories... oil leak. coolant leak.

Mrs' dad had his mot few weeks back and i had a goosey gander at the advisories. guess what... oil leak 

TB has an oil leak he cant even find!!! 

in all the above cases (apart from TB's as thats unknown to me) there's leaks but no real noticeable loss of fluid. so i simply keep my eye on them and topped up.

so my question is. unless its a severe leak where youre going through a litre of lost juice a day, or its a cam cover leak affecting ignition components for example.... why do we bother to try and fix them?

Have you a leak? (still talking car fluids STEMO, not your bladder weakness  ) do you just keep it topped up? or are you anal and want it fixed?

Discuss.

[05omegav6]

Liquid leaks affect the pressure of the system, thereby having a negative effect on the efficiency of the system.

In the case of cooling systems...
At normal atmospheric pressure, plain water boils at 100°C.
At normal atmospheric pressure, 50/50 coolant boils at about 105°C.
In a sealed cooling system at 1.5-2 times atmospheric pressure, 50/50 coolant boils at around125°C.

You'll note that most thermostats open at 85-90°C, and if driven hard/stuck in traffic on a warm day the temperature gauge might hit 100°C. With a leak, the system won't pressurise and the coolant will soon boil off, resulting in a wrecked engine. The water pump creates flow rather than pressure per se, the pressure simply being the result of fluid expansion due to temperature increase within a closed system

With oil leaks, where they are has a bearing on their significance. This is because although the engine is fluid tight, the oil system is effectively an open system (unlike the closed cooling system). So a cam cover leak, whilst messy, annoying and potentially coil pack killing... is mechanically no big deal, whereas a leak from the crank seals or oil cooler is much more significant as the oil in these places is under considerable pressure. The nearer the leak is to the pump, the higher the pressure and the more significant the problem/consequences

Gearbox and diff leaks ideally need sorting, as over time the levels will drop, accelerating wear. The rubber mounts and propshaft dampers will also perish and fail if they become soaked in oil.

Remember, if fluid is getting out, then generally speaking air is getting in. And as you'll probably ask... the reason oil cooler failure lets oil into the coolant and not the other way round... the oil is at a higher pressure than the coolant as it is fed from the oil pump. You'll only get water in the oil if the oil pressure drops below the water pressure...

That should be as clear as an expansion tank after the oil cooler has broken

[Webby the Bear]

That is absolutely clear Al.

So why in the real world doesnt this happen?

Sure, the guy who leaves his engine oil leak and doesnt top up will eventually seize his engine as it runs out of oil. But pretty much everyone i know (and a few listed in first post) top up as necesary and no harm is done.... other than external parts that get caked in oil and feel as you quite rightly mentioned

[Webby the Bear]

Just to add, dont mean that last part to sound condescending (i cant even spell it lol). just commenting on what i actually see

[05omegav6]

That is absolutely clear Al.

So why in the real world doesnt this happen?

Sure, the guy who leaves his engine oil leak and doesnt top up will eventually seize his engine as it runs out of oil. But pretty much everyone i know (and a few listed in first post) top up as necesary and no harm is done.... other than external parts that get caked in oil and feel as you quite rightly mentioned

On a scale of 10, 10 being the highest level of mechanical aptitude and 1 being unaware that the car has an opening bonnet...

Most people here will be somewhere between 3 and 10, averaging around 6-7... however, in the general population that average would be alot nearer 2-3...

[omega3000]

They all leak .... look at my block paving 

[Webby the Bear]

That is very true lol

Ok lets look at a specific example that i can give you...

When my pistons and my valves decided to shake hands i rebuilt with all new seals. however in my naievity i re-used the dowty washers on the coolant bridge. after running round for couple of months i noticed car was losing the amount between 'full' and the 'check coolant level' warning (however much that is) every 2 weeks or so.

this to me was far too much of a loss. thus i looked in to it. found the leaky washers and replaced them. job jobbed.

however, other than a coolant leak there were no symptoms. car drove at bang on 85oC on the motorway and up to 90oC in traffic brought down by the fans when needed.

how come with this loss and obvious ''open wound'' didnt the car overheat due to reaching its boiling point earlier due to the lack of pressure?

see what i mean?

[05omegav6]

Because it was only a slight weep, and the rest of the cooling system was performing well... a blocked rad or weak waterpump would have highlighted the problem far sooner, and don't forget, the temp sensors live next on the coolant bridge, ie next to the leak, and the temp was at least 15°C lower than the boiling point of correctly mixed coolant, so would never boil off... the leak was a minor pressure release, hence taking a while to find

[chrisgixer]

Oil leaks are one thing.

Real world..... All combustion engines consume oil through the breather system at the very least. This is why the plenum is/should be oily internally. So day to day use with no oil leaks WILL see the oil level drop. The only question is how much.

Hopefully not enough to run the sump dry by the time the owner next checks the level. Assuming the owner bothers to top up of course.


....if i understand your question correctly?

[chrisgixer]

To add to that, check control is very handy on the omega with an oil level sensor as well as oil pressure. Something else to add to the list of must haves for the "omega replacement"

[Webby the Bear]

Exactly what i'm thinking boys and thanks Al for your thoughts on that.

Exactly my point chris. if i look at my oil one day and its full. a week later its on low i know ive got a problem.

if i have a slight oil leak (e.g. i find a little dripping off the subframe) and only a very slight loss im not going to be too concerned. me being quite anal id look in to it asnd try and fix it but like steve says ''they all do that sir'' 

[Webby the Bear]

I'm thinking a poll as to who's leaking and who isnt. never set up a poll before.....

[chrisgixer]

They do all leak, there's no doubting that.

All easily repairable though.

[Webby the Bear]

They do all leak, there's no doubting that.

All easily repairable though.

Easily repairable (most) and a bugger to find sometimes. step up TB 

Thing is though they must be designed to withstand leaks otherwise, as i said before, most of the nation would come to a halt. innit lol

[chrisgixer]

If the groomer had more time I'm sure he'd of sorted the dip stick leak by now.


I haven't had an engine yet that didn't leak somewhere, however slight. Even looked at a new vxr insignia that had a weeping turbo. ..."oh really sir, I don't know anything about that" ....no shit