1.4 mpi cooling system engine overheated for no reasons

[Alexandru]

Hi guys,

 

The terms are the following:

 

- a flawless 70miles trip with a brief stop of less than 25 minutes (with the engine turned off);

- I left, I drove about 1 mile or so the coolant temp raised to max in less than 15 seconds and the red warning + buzzer came on;

- with the bonnet up and engine running, both radiator fans working at full speed, but no heat coming from them;

- engine turned off -  radiator was cold cold;

- the pipe coming or going to the interior heater matrix, can't tell which one for sure, the one that gets into the thermostat was hot, the one going to the radiator was cold;

- I blamed a faulty sensor so I turned on the engine. In less than 2-3 minutes which took me to investigate the problem. the coolant needle was back to the middle, so I blamed again a faulty temp sensor;

- while going uphill for about 2 miles, I was hearing some clanking noises coming from the engine bay, not constant, couldn't find a patern though; - I blamed a faulty water pump;

- I got to a stoplight. Since I was driving with both front windows down to detect anything that might go wrong (the coolant needle still in the middle position) it started to smell funny, as the engine was overheating. I turned off the engine for a half a minute (till green) and tried to start it. First time, it started but it died like in no time, so I tried again. It went ok, a bit low on power .. can't say how low because it's a 50kW engine so it's meant to be slow and lazy;

- I got off that stoplight, over the intersection and found a parking lot within 100 feet;

- I turned off the engine, got the bonnet up and the first thing that came into my mind was to check the oil. There was steam coming through the oil filling hole, coolant was pretty high in the expansion bottle and the dipstick was showing ... well, it wasn't showing too much.

 

If the water pump would be faulty, shouldn't it be bleeding and loosing coolant ? If the thermostat would be blocked on closed position, shouldn't it be blowing hot air in the car? 

Edited 6 March, 2016 by Alexandru

[sepulchrave]

Head gasket. That is all.

[Alexandru]

I burned or got all my oil in the coolant and this is why it overheated ? Makes sense. The oil sensor should be doing it's job though and tell me I have a low oil level. 

Edited 6 March, 2016 by Alexandru

[sepulchrave]

It could be waterpump failure that triggered the head gasket failure, I'd definitely check.

[Tech1e]

I burned or got all my oil in the coolant and this is why it overheated ? Makes sense. The oil sensor should be doing it's job though and tell me I have a low oil level.

You won't have an oil level sensor on an MPi

[Alexandru]

That's only an oil pressure sensor? If so, how in the world it did still had oil pressure?

[Breezy_Pete]

You don't need much oil in the sump to keep oil pressure OK. Just enough to cover the pick-up head continuously.

[Alexandru]

Well .. if the internal damage is too high due to running the engine with low oil I will swap it. This little ****** did it's job, 130.000 on the clock, who knows if it's genuine, no fsh, it's a 2000 car so I'm thinking more of a 190.000 miles. ATZ is not that bulletproof as they say after all, but right after before it died, it was still able to do 95mph on the motorway..so it went away with dignity. I have to pay my respects to it. 

Edited 7 March, 2016 by Alexandru

[Breezy_Pete]

I reckon it will be OK.

[LB123]

I had a head gasket fail one month ago on a Fabia 1.4 MPI. Dumped the water into the oil. Car got so hot it melted the oil filler plug and some of the plastic engine cover! Carefully repaired with a head skim and have done 1000 miles since and all well.

They are tough old engines!

Edited 7 March, 2016 by LB123

[Alexandru]

update: The car was towed. I had to turn on the engine to get it on the platform (so she's still a runner), but before that I checked the oil level. It was in the middle with no sludge or any signs of coolant. I'm lost..all my speculations are gone now. 

 

Later edit: the engine has been running for about 10 feet, to move the car out of the parking lot, the towing truck actually pulled the car on its flatbed. 

Edited 7 March, 2016 by Alexandru

[sepulchrave]

update: The car was towed. I had to turn on the engine to get it on the platform (so she's still a runner), but before that I checked the oil level. It was in the middle with no sludge or any signs of coolant. I'm lost..all my speculations are gone now. 

 

You tend to see oil in the coolant when a head gasket fails, this is because the oil is at a much higher pressure than the coolant when the engine is running. Conversely coolant in the oil generally only happens if a liner seal fails or coolant is drawn into a cylinder by vacuum while the engine is stopped.

 

You still need to check that the water pump impeller hasn't separated from the shaft causing the overheating in the first place.

[Alexandru]

Today I haven't checked the coolant *YET*, but last night it had the same color, smell and texture as usually. I have one more hypothesis. For the last couple of weeks I was suspecting an open thermostat. The temp was going up to the middle only when really stuck in traffic, otherwise it was somewhere at 10.30 o'clock. Could it be possible to have got  somehow fuel in the oil due to running it with a higher than usual fuel/air mixture ? Could this have been causing the oil to degrade that much in a such short time and the engine to overheat due to abnormal friction between it's internals?

 

I will check the water pump and replace it if required, of course. I'm more concerned about the damage on the {cam,crank}shaft, bearings, pistons and what any other thing could have been affected by the excessive heat and lack of lubrication in about 2 uphill miles with some load in the boot and 3 in the car.

Edited 7 March, 2016 by Alexandru

[Breezy_Pete]

You tend to see oil in the coolant when a head gasket fails, this is because the oil is at a much higher pressure than the coolant when the engine is running. Conversely coolant in the oil generally only happens if a liner seal fails or coolant is drawn into a cylinder by vacuum while the engine is stopped.

 

You still need to check that the water pump impeller hasn't separated from the shaft causing the overheating in the first place.

 

But that high pressure oil is highly localised within the gasket, at precisely one hole where the oil goes up into the head, so you have to have the seal at that one hole fail for oil at higher pressure than coolant to infiltrate the cooling system, no?

 

Picture of upside-down ATZ gasket with HP oilway ringed in red:

 

[Alexandru]

 

Got her to the shop, now looking for what caused all this circus. It's going to take a while.

[Breezy_Pete]

If you take the lid off the expansion tank, start the engine and give it a few revs, you should see a trickle of coolant running into the tank high up. If you don't, the water pump probably isn't doing anything useful.

[Alexandru]

I should get her up to 90 degrees to be able to spot something in the expansion tank ?

 

 October the 2nd, 2014: broken oil switch wire, buzzer + warning light on when going over ~2000rpms. I was too scared to drive it to the shop so I had her towed. I was suspecting a bad oil pump at that time.

 

Maybe I should got used to some kind of failure schedule ?   

Edited 7 March, 2016 by Alexandru

[sepulchrave]

But that high pressure oil is highly localised within the gasket, at precisely one hole where the oil goes up into the head, so you have to have the seal at that one hole fail for oil at higher pressure than coolant to infiltrate the cooling system, no?

 

Yes, but a head gasket failure caused by overheating would mean a warped head and your red-ringed oilway will be the very first thing to fail in such a situation due to the large pressure differential between the oil and the coolant. Most wet liner head gasket failures occur this way, see any French engine for further proof, the fire rings will often fail as well subsequently.

Paradoxically the worst thing Alex could have done was to stop the engine when it overheated thereby shutting off coolant circulation, better to let it tick over with the fans running full blast until the temperature stabilised.

[Breezy_Pete]

I should get her up to 90 degrees to be able to spot something in the expansion tank ?

 

[snip]

 

No, you should see it from cold.

[Breezy_Pete]

Yes, but a head gasket failure caused by overheating would mean a warped head and your red-ringed oilway will be the very first thing to fail in such a situation due to the large pressure differential between the oil and the coolant. Most wet liner head gasket failures occur this way, see any French engine for further proof, the fire rings will often fail as well subsequently.

Paradoxically the worst thing Alex could have done was to stop the engine when it overheated thereby shutting off coolant circulation, better to let it tick over with the fans running full blast until the temperature stabilised

Maybe, but Alex doesn't seem to have oil in the coolant, as I read it? (He thought he must have due to the apparent oil level lowering, but didn't, is that right Alex?)

[Torbo]

I am thinking of the thermostat. They are made very badly.  

I rebuild mine and  put in an ordinary thermostat.

Its a mechanic job, so it is may be best to change if you have not?

 

The other ting is may be result of a bad thermostat!?

[Alexandru]

 

She runs like a dream (as she's usually doing). I had a spare thermostat, installed it and it was ready to go. That ****** was stuck on closed. And no, no oil in the coolant and no coolant in the oil. The oil smells a bit of petrol, a bit too much for my nose, but I suppose that's due to the thermostat as well. I will service it next week, fresh oil and filters. Still not sure if I should replace the timing chain along with the water pump.

 

 

Yes, but a head gasket failure caused by overheating would mean a warped head and your red-ringed oilway will be the very first thing to fail in such a situation due to the large pressure differential between the oil and the coolant. Most wet liner head gasket failures occur this way, see any French engine for further proof, the fire rings will often fail as well subsequently.

Paradoxically the worst thing Alex could have done was to stop the engine when it overheated thereby shutting off coolant circulation, better to let it tick over with the fans running full blast until the temperature stabilised.

 

I haven't turned off the engine in the first place. That was my point as well, but, the fans were actually doing nothing since there was no coolant going through the radiator to cool the engine. Nope, this headgasket just doesn't want to die.

I really do wonder how the cooling circuit works. Why the interior fan was blowing cold air since the thermostat was on closed and coolant was boiling ? 

 

Later edit: after all these, I now find this connected somehow to the thermostat issue. Maybe it was somehow stuck for a long time (about 1500miles or so).

Edited 7 March, 2016 by Alexandru

[sepulchrave]

So all's well that ends well, I really thought you had replaced the thermostat already, it seems you were lazy and left it in the box!

[TMB]

I really do wonder how the cooling circuit works. Why the interior fan was blowing cold air since the thermostat was on closed and coolant was boiling ? 

 

 

 

The heater won't blow hot air if the thermostat is stuck shut even if the coolant is boiling because it's not circulating.

[Alexandru]

So all's well that ends well, I really thought you had replaced the thermostat already, it seems you were lazy and left it in the box!

 

I had no tools with me unfortunately. A few weeks ago I decided that I didn't really need them in the car, got them into a backpack and placed it somewhere in my house.