W202 C180 radiator blew apart

[wwatu]

Hi,

So my 94' C180, few days back, was city driving for a while, with pauses inbetween, everything really normal, then decided to go to drive-in, where just before paying, my radiator blew up, steam coming off and such, immideatly i shut down the engine. Now have some questions though.

I think the issue is with the fan clutch, though I'm not 100%, anyway ordered a second hand radiator and viscous clutch, got a sweet deal so, might see, maybe the clutch is better than mine.

Anyways, question being, I saw that the temp was in the same range as in the picture below, but in my opinion this shouldn't be enough to blow up the radiator and didn't get any warning lights either. Also, shouldn't there overflow valve if the pressure gets up to certain level? Just trying to figure out why the radiator blew up, so that it won't happen again when i install the new part. Could it possibly be due to a low level of coolant(no errors, tho i never really had in mind to check it since Im used to having an overflow tank, so it didn't come to mind) so the pressure was really big.

Also, the radiator cap was looking normal to me, anyways, here's a picture of my dirty blown up engine bay.

And also another question, when I refill the new radiator, I didn't saw no MIN-MAX marks on it, how would i even check if the tank is not transparent, so to which level I'd fill up the new one(warm or cold)


Thanks in advance!

 

[Stratman]

A blown head gasket could pressurise the cooling system. Do a compression test.

 

[Auto-mobile]

It's good that the radiator has lasted this long, it's a common (ish) fault I have seen several blow over the years, I'd imagine it's just the radiator that's given up, I'd repair it and monitor the temp while driving, anything up to 98c max is aceptable

 

[wwatu]

Alright, thanks for the anwsers, I think the seal between the upper tank and the radiator let up, since it's now leaking from there.

Also, compression tester unfortunately costs about 100€ and not that I know of someone has it. But it seems to be running normal and no oil/sludge in the cooling system.

And what about the new radiator coolant filling, at which level should I fill it since I didn't see any markings, I don't think It'd should be right to top.

 

[BlackC55]

It's a common issue. They crack and blow in spectacular fashion usually.

 

[Dec]

There is a top up marker about 1 ½ inches below the filler neck, you can’t see it through the coolant but you can feel it with your finger.
If you fill above this marker, the excess coolant will be expelled through the vent tube on to the ground as the coolant expands when it becomes hot.

Always check the coolant when it is cold, it should be approximately around that mark when cold. It might also be wise to replace the radiator filer cap with one of the correct rating

Dec

 

[wwatu]

Alright, up to that mark when engine's cold, but as the engine gets hotter shouldnt there be room for expansion? Since I dont have an expansion tank, that tube goes just to the ground.

 

[markjay]

It's a sealed system, the radiator cap has a pressure relief valve, when the pressure in the cooling system goes beyond a set value, the valve opens and the excess pressure is released (with some vapour or coolant).

The system is self regulating (unless the radiator cap is faulty). If you over-fill it, it will simply expel the excess coolant.

 

[Dec]

By way of further explanation, there is some air at the top of the radiator when it is cold, for example, when the radiator and cooling system are cold the contain about 95% coolant and 5% air, as the coolant heats up and expands, the increases in pressure inside the radiator causes the radiator cap to open which relieves the pressure by releases the 5% of air out through the tube at the radiator filler neck and so your radiator is now 100% coolant and no air.

When you park your car for the night, the coolant retracts as it cools down to cold, this creates a vacuum inside the radiator and a valve, in the middle of the radiator cap, opens and allows air to be sucked back into the radiator and you are now back to having 95% coolant and 5% air. In theory, you haven’t lost any coolant at all and you should only need to top up once a year, I had the same car/year that you have and I would need less than halve a cup of coolant per year.

What number/s are stamped on your radiator cap, you should see either 20 or 140 or both.

Dec

 

[wwatu]

On the radiator cap it's stamped 140.

So, I shouldn't just in case fill it to 100%, to count on valve opening, since the valve in my opinion should've opened before not to blow up the radiator, since I wouldn't want to blow it up again.

The radiator cap seems okay, spring moves nicely and the seal is ok.

Or maybe I should let the cooling system to warm up, to let the termostat be open, without having radiator cap on, having heater on max and then fill the system up to the mark.

 

[markjay]

The reason the cooling system is pressurised is to raise the boiling temperature of the coolant.

If you run the engine without the radiator cap in place, it will boil over pretty quick.

Fill it up with coolant up to the notch in the radiator neck, refit radiator cap, warm engine up properly with heater on, check under the car for any obvious leaks, then leave the engine to fully cool down. When stone cold, remove the readiator cap and refill with coolant to mark again, then refit the cap. That should do it.

 

[panason1c]

On the radiator cap it's stamped 140.

So, I shouldn't just in case fill it to 100%, to count on valve opening, since the valve in my opinion should've opened before not to blow up the radiator, since I wouldn't want to blow it up again.

The radiator cap seems okay, spring moves nicely and the seal is ok.

Or maybe I should let the cooling system to warm up, to let the termostat be open, without having radiator cap on, having heater on max and then fill the system up to the mark.

There is the possibility that a blown head gasket caused your rad to blow, therefore, after fitting the new rad and filling with coolant leave the cap off and run the engine until the stat opens (topping up as necessary as the air bleeds out) and if the hg is blown then it will be evident as the coolant will be expelled from the rad fairly rapidly and will be more evident as you rev the engine.

I knew someone who owned a shogun diesel and who's rad blew up (the seam down its side was completely blown open), he promptly went out and bought a new rad, fitted it, started the engine and withing a few minutes the new rad blew up exactly like the old one!..... a blown head gasket (between a cylinder and the water jacket) was directly pressurising the system!

 

[wwatu]

All right, I'll wait till I receive my parts, do some testing and come back with the results.

 

[wwatu]

So, back with the results.

Surprised and pleased of how easy job it was.

So, fitted the new rad, put in the coolant, let it idle, was topping up the coolant meanwhile it idled without the rad cap, it took only about 6L, while online it says it should 8.5L, but it couldn't take in no more, had heater on and on full blast also, also squeezed the hoses to let the air out.

So, without the rad cap on, I let it idle quite a while, 15min or more, couldn't get the temp up so after revving a while, I got it up to 80C max. The upper hose was quite hot, meanwhile the lower one cold, so this lets me believe that the thermostat may be broken and fully open all times, anyways no coolant expell when revving without rad cap, so I don't think that the head gasket is blown.

Shut down the engine, inspected the fan clutch, it kept spinning a while after shutting down the enigne, so im 100% sure that the clutch is bad, also cleaned it up before refitting radiator. Couldn't fit the new fan clutch tho, because didn't have the tools for that.

So, put on radiator cap and took it for a drive, couldn't get the temp up more than 80C, maybe just a 1mm max above 80C. Now engine is cooling, I'll check the level again tomorrow.

Also, question about the coolant level sensor, the one on the new rad, when I plug it in, brings up error in dash, no matter whether I clean it up with a towel or fill it in the coolant, still error.

When I unplug the connector, no error, also when I plug the old sensor, no error either, doesn't matter if clean or inside coolant.

So question being, how exactly do they work, are they both broken different way or what?

 

[Bellow]

When you park your car for the night, the coolant retracts as it cools down to cold, this creates a vacuum inside the radiator and a valve,

Yes.

in the middle of the radiator cap, opens and allows air to be sucked back into the radiator

No.

 

[Dec]

Yes.


No.

Could you elaborate on that?

Dec

 

[Dec]

So, back with the results.

Surprised and pleased of how easy job it was.

So, fitted the new rad, put in the coolant, let it idle, was topping up the coolant meanwhile it idled without the rad cap, it took only about 6L, while online it says it should 8.5L, but it couldn't take in no more, had heater on and on full blast also, also squeezed the hoses to let the air out.

So, without the rad cap on, I let it idle quite a while, 15min or more, couldn't get the temp up so after revving a while, I got it up to 80C max. The upper hose was quite hot, meanwhile the lower one cold, so this lets me believe that the thermostat may be broken and fully open all times, anyways no coolant expell when revving without rad cap, so I don't think that the head gasket is blown.

Shut down the engine, inspected the fan clutch, it kept spinning a while after shutting down the enigne, so im 100% sure that the clutch is bad, also cleaned it up before refitting radiator. Couldn't fit the new fan clutch tho, because didn't have the tools for that.

So, put on radiator cap and took it for a drive, couldn't get the temp up more than 80C, maybe just a 1mm max above 80C. Now engine is cooling, I'll check the level again tomorrow.

Also, question about the coolant level sensor, the one on the new rad, when I plug it in, brings up error in dash, no matter whether I clean it up with a towel or fill it in the coolant, still error.

When I unplug the connector, no error, also when I plug the old sensor, no error either, doesn't matter if clean or inside coolant.

So question being, how exactly do they work, are they both broken different way or what?

I don’t know exactly how the work but I believe the are connected in some way to the screen wash level sensor. Someone else may know more.

If you drive 3 miles at about 30 to 40mph, with a cold the engine to start with your temperature should reach just a shade over 80c

Dec

 

[Bellow]

Could you elaborate on that?

Nope. But I can apologise. Sorry, I clean forgot about the valve. When I think it through I realise that if the system were subjected to vacuum the hoses would collapse inwards - like my brain did!

 

[Dec]

Well you are sort of halve right, if that valve in the centre of the cap fails to open and let in air then the top hose will collapse, my old W202 top hose use to collapse sometimes so I presume its that valve that’s not opening, it probably happens quite often but you never usually notice it unless you open the bonnet after the engine has cooled down to cold.

Dec

 

[wwatu]

Searched around, and found that if the washer reservour sensor is faulty it'd show up that no coolant level also, so I might take that the new coolant level sensor is working properly and washer fluid sensor isn't since the old coolant level sensor didnt show up at all. Anyways, that part really doesn't matter.

So, tomorrow I'll check for if the upper hose is collapsed before I remove the cap, then remove cap, add coolant if necessary. Then start the car and go for a test drive immideatly, 5km for about 50km/h, maybe even do a video about it.

Few more questions tho, what should be the optimal temperature it reaches and holds, since I couldn't get over 80. The thermostat should open around 87C? Also, is my thermostat open/closed/partially opened/working, since my top hose was warm, when i revved it got hotter, while the lower hose was pretty much same cold always, shouldnt they be even? Also my radiator, from top right, it was hot, from top left really cold and anywhere between cold.

Also, online it says it fits about 8.5L, I fit in only about 6.