3CX overheat :(

[McSpud]

Hey folks,
I'm afraid I met some hardship with my '88 3cx over the weekend, it boiled over.
it blew its coolant/antifreeze out the pipe at the filler cap near the radiator. Of course, the wire to the temperature sender had fallen off and I got no warning... the alarm & light worked as soon as I'd stuck it back on

Anyway, I loosened the fanbelt, checked the pump, all seems ok, no leaks, play etc.
flushed out the radiator, no gunk came out.....Took out the block drain plug, flushed that out... no gunk there either.

Theres also no oil discoloration in the coolant, and no discolouration on the dipstick, so the head gasket should be ok.

I tried boiling the thermostat in a saucepan and it began opening at 82 degrees C, fully open at 92C.

I'm kinda stumped as to what the problem is. Anyway, I installed a new thermostat and fresh new coolant.

Do you think I've solved the problem, and also, how do I bleed the air from the coolant system? I was careful not to let any coolant escape from the cab radiator, so there shouldn't be any new air pockets introduced into that.
What do you think??
Cheers!

[essexpete]

I might be stating the obvious but is the external core/fins clean? I had trouble with an old 3C and it was only reall obvious when I removed the rad just how choked up it was.

[McSpud]

Yeah! thats the thing, it's like brand new! not as much as a fly stuck in it!
I can't understand what went wrong. I can only assume that the thermostat got stuck that one time.

I don't know how plausable my diagnosis is though....

[Jeremy Rowland]

This sounds to me like the head gasket has blown, all the right symptoms anyway. If you boiled the motor then there's also a fair chance that it may of suffered a partial heat seizure in which case the bore's and rings would be knackered.
Whilst I'm not too familiar with bleeding the cooling system on a JCB, the norm when I worked on the wagons was to let the temp built up till the stat opened, then top the system back up. Stubborn airlocks did require removal of hoses until coolant appeared but take care if you do that with a warm engine.
Once your sure that the system is fully bled then use the machine on max load and see if the motor boils again, if it does then I would put money on the head gasket being blown.#

Jeremy

[McSpud]

Gees Jeremy, my stomach is in a knot now!
But theres definitely no cross contamination of oil/water, Oil is still oil coloured, and when I drained the block, it was pure coolant came out, no funny colours or oily residues.

It's very very seldom it's worked at it's max capacity, so I'm wondering if there was an air pocket in it all along that went unnoticed until now....

I don't even want to think about the seizure stuff you mentioned... Still starts as easy as ever, barely one turn over and it starts, even when cold. I hope to god it's just an air pocket....

Cheers!
S

[Neversweat]

Not wanting to add to your woes but you don't always get oil in water / water in oil with a head gasket.If its blown from the cylinder into a water hole then normally it will just pressurise the cooling system.

Steve

[McSpud]

Gees, I was afraid that might be the case, although there's no bubbles coming up through the header tank, I suppose I'm trying to be optimistic about it, have any of you done head gaskets on these Perkins engines before? Is there anything I should be afraid of??

I'm not going to pull the head off it just yet, I'll wait & see does the coolant drop over a period before I decide what to do.

All things considered, rad was spotless when flushed, so was block, thermostat looked ok, behaved fairly normal in saucepan, no burst water pipes... I suppose I'm drawing the inevitable conclusion myself
is there any light in the tunnel lads??
S

[Neversweat]

Have you run it up again to operating tempature to see what - if anything - happens

Steve

[Jeremy Rowland]

Not wanting to add to your woes but you don't always get oil in water / water in oil with a head gasket.If its blown from the cylinder into a water hole then normally it will just pressurise the cooling system.

Steve

Seamus, I was about to point out to you what Steve has beaten me to say, furthermore I would suggest that you may not be able to see bubbles in the header tank if the head gasket had gone because sometimes the leak does not become apparent until the engine gets very hot.
I recall years ago when I worked the spanners I went out in an eight legger Sed Atki 400 with a Cummins NH250 engine and a driver to test a suspect head gasket failure. The best way? Easy we took her up a steep incline fully loaded, at first all appeared okay but as she worked the temperature started to climb, then there was a great whoosh as she emptied the entire contents of the cooling system out of the header tank behind the cab, believe me it was a sight too, yep she had blown a head gasket.
That was why I suggested that you test your machine under full load, its the best way to find out for sure without taking it to bits, if she does overheat then just shut her down and let it cool off before you put anymore coolant into the system.
As for a possible siezure I would say don't panic at this stage, if the motor had such a siezure then white to light coloured smoke from the exhaust would indicate this.

Jeremy

[McSpud]

Hey fellas,
you're a mine of information, I really appreciate it.

No, I haven't stressed it since I put the new stat & coolant into it, I just wanted to try educate myself a little first about any dangers likely to crop up if the worst is about to happen. At least this time the warning buzzer / alarm is working in the cab, so I'll get a sooner warning of over heat - not like last time.
I forgot to add, theres no white smoke either, just the normal type exhaust, manifold is dry also, just dry soot.
Hopefully, if it is the headgasket is gone, that thats the only damage.

The next question I have to face is, do I undertake this job myself, I would be handy enough at mechanical stuff like that, have torque wrench - will travel!!

I suppose it's not the end of the world, it's just unlucky

Thanks again lads,
S