Hi all,
I've been having overheating issues for a while now. I thought the gauge was faulty so I fitted a mechanical gauge. Went for a spin last night and the temp gauge stayed around 75 which I thought was ok. When left to idle it would get up to around 100 but hitting the accelerator would make it drop heaps (below 80). Checked there were no leaks in the cooling system when it was warm and all looked ok. Checked the radiator this morning to find the radiator was down approx 1l (below the baffles) and the water in the expansion tank had not moved. I looked under the rocker cover to find it dripping with water and a bit of mayo forming under the cover. I have had the radiator and the expansion tank checked and replaced all caps (flat cap and expansion tank cap). Any ideas??? Why is there water in the expansion tank but not in the radiator?? At my wits end with this ....... Pls help. (I'm thinking cracked head. Head gasket was replaced 2yrs ago/ 300km ago)

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Justin

water dripping from inside the rocker cover is a pretty clear sign... but it shouldn't be a crack

got water residue/mayo/creamy oil on the dipstick?

If temp is going down when you accelerate but climing up on idle; I would chek if the fan installed on a correct way, then water pump impallers as a starting point. also check the cap is it the correct lenght.

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Since light travels faster than sound, people appear bright until you hear them speak

running around 80 to 90 degrees is fine. Don't trust any guages, go buy yourself a $20 electronic thermometer from Dicksmith, start ebngine cold with cap off, and place thermometer in to check if the temp on the gauge is reading same as the thermometer or not.

Next, check that you have the right cap for your radiator. There are 2 types, one with a shallow neck and one with a deep neck, you need to buy the right cap for your radiator.

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Lillee - 1969 Morris Mini K

I'm no expert, but it looks like the water lines may be breaking into the cylinders. If this happens, the exhaust can get into the radiator (which would explain why the level is dropping without the expansion tank taking it up) and the coolant can get into the engine (which would explain the mayo).

A compression test should show this, but you might need one of those exhaust-fume-detector-thingies that check if the exhaust is getting into the coolant.

So yeah, it could be a cracked head. But your head may just need tightening again if it's after only 300km. Or it could be the head gasket wasn't installed properly.

Not sucking back from the expansion tank. Check all hose joints for signs of a coolant leak (it will leak coolant out when running and suck air back in when you stop). Sometimes moisture in the rocker cover builds up if it only does short runs. Check the dipstick for a level or colour change. A good radiator place can pump your system up to check for leaks, check your gauge against their infrared thermometer and test for combustion gases in the coolant. It might not be as drastic as you think.

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Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

Thanks for the quick responses
It has very clean KMX but it does look a bit milky/opaque (it's hard to tell). I have had this issue for a while but the oil is only just becoming very slightly milky now.
yep - fan is the right way around and the caps are correct.
The dipstick has changed (i think). Can this be from short driving??

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Justin

Leaky hoses can be very hard to spot sometimes, they only leak while it's hot and your driving, as soon as you stop it stops and the evidence evaporates. A visit to a radiator shop will put your mind at ease and give you an answer eitherway.

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Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

Head Gasket.

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i concur

Looking at it again - it's only a tiny bit of mayo under the cover, and the oil looks OK under proper light. (looks clean)

Thinking it might be a leaky bypass hose (stupid thing) which was replaced when the head gasket was redone - I will recheck the clamps. Also thinking of the thermostat housing as this has the engine steady and a gasket glued either side with the permatex anaerobic red goo.
I just used a standard head gasket and used copper spray on it (it has not been retorqued) but I am swaying away from a gasket issue.

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Justin

you need to find out where the water went before you start fixing things

how long did it take to lose that 1l of water? sounds like a short drive, then overnight... that's a lot to lose. Or did it really lose 1l? the normal fill level is about 20mm below the neck, it'll usually spew any more than that out under expansion.

But where did the water go?
How long did it take to lose it?
Did you let the engine run with the bonnet open so you could see it?



either of those will keep leaking with the engine off - when they leak, they really keep leaking. You'll also have signs of coolant or rust where it's dripping, and a probably puddle on the floor.



of course you're swaying away from it, but don't rule it out - you could be dicking around with 100's of things but ignoring the bleeding obvious.

thread revival........

OK - So I have checked the thermostat and removed to test (and left it out as a temporary thing).
Re torqued the head to 45lbs. Checked water pump, etc.

Ran engine with the cap off for 10-15mins to warm up. Got to around 75-80 on the digital thermometer and all was OK at idle but when I hit the accelerator pedal the water went down and stayed down - hit the accelerator again and more water went. I let it cool down and the water was low.

I pulled the plugs to check for water in the cylinders. The plugs were clean (no signs of corrosion). i left the plugs out and turned it over a few times and nothing came out of the cylinders (no water).

I have left it to sit and still have to top it up ( only a little bit) but I can't see where water is leaking. Water is not leaking into the cylinder as it would be full of water. I don't think it's leaking into the exhaust as it would push this out on startup/whilst running.
Checked all connections/radiator/welsh plugs (at the front), even the heater but no signs of a leak.


Got me stumped! Any thoughts???

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Justin

I put a new head gasket on a mate's Cooper S recently, was same symptoms as yours. Had done ~2000 miles.
The water was getting down the pushrod holes and into the oil.
New gasket, retorqued again hot and all is good.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Just going out on a tangent here...

But it sounds like all you're seeing is the purging of air from the system after working on it.

Especially your last post where :



If you've let water out of the system & refill, there's air-pockets where the water wont get to until you rev it, which forces the water in and the air out = water drops at rad.

Or is there history of lost coolant I don't know about?

Cheers

Jacob

ps. don't run without a thermostat or blanking sleeve, else it mucks up the water flow terribly.

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'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project