Bursting pipes!

[Mikerb]

I recently rebuilt my JCB 3CX 1987, and it ran well for a few months, but then split a bottom hose and overheated. I replaced the hose but it was still overheating.

I checked the thermostat, which opened in hot water. Checked the water pump, which is in tact and doesn't spin on the shaft. blasted the radiator with water, which blew out some crap.

When I take the top water pipe off, not a lot of water comes out and there are bubbles coming out of the little hole (must be some sort of bypass hole as it has a little moving brass part in it) but not a lot of water. If I push the thermostat open with a screwdriver, water gushes out, so the water pump is working.

Are the bubbles from a blown head casket or from the water boiling in the bottom of the engine?

After washing the radiator out and running it hard, I opened the rad cap with a stick from a distance and it popped of about two foot in the air and made a gurgling sound, but no explosion of water. But I get the feeling the water isn't circulating properly. But don't know if the split hose cause the trouble or the trouble split the hose.

Any ideas what to do next? I'm not convinced the thermostat is working properly so will change that, possibly a new radiator and I suspect the head gasket needs doing again.

[agrimax]

Certainly replace the thermostat first and it might be worth changing the cap too. Don't know if the setup is the same as on my 82 white cab,but the pressure cap is on the expansion bottle and the main brass fill cap is above the thermostat housing. This brass cap must be sealed very tightly on mine,or the water will not circulate at all,and it boils.
Can you fill the system and remove the bottom hose of the rad handy and see if there is a good gush from it too.With the cap loosened to stop a vacuum. A good run of water should suggest the rad is clear. Any access to a coolant system pressure tester?
I would think the gasket is the problem though,(or a warped/cracked head--hopefully not!!) as the small bubbles would suggest such.

[Mrsmackpaul]

mate your head gasket is blown and compression is getting pushed into the cooling system or you have a cracked the head either way the head has to come off

Even it was the thermostat or the radiator cap it wouldnt build that much pressure and if you have already check the thermostat you know its ok very rarely does a radiator cap cause it to build pressure the cap would have to badly rusted so it couldnt move most times a motor will over heat from the radiator it is because it wont hold any pressure and the water just leaks out the overflow

just some thoughts

Paul

[essexpete]

If you think it is the head that is a problem it might save some future annoyance to get it pressure checked and also to make sure the gasket surface is true. I would also have the rad out and clean the external core very thoroughly and flush through. We had trouble with a head once and did not have it checked. Blew again when working hard. Had the rad out when changing the engine and the core was filthy with crud which could not be easily seen with oil cooler in front and big fan blades. I have a 20 yr old tractor that is relatively low houred and tends too get too worked hard. Done all the usual so I am going to change the rad as I figure it will be cheaper and less time consuming in the long run.

[Mikerb]

It's got a new cap, gasket and thermostat when I rebuilt the engine so pretty sure they're ok anyway, and I've washed the rad inside and out.

I'm also thinking along the lines of cracked head or then head gasket, which built up the pressure and blew the hose. Hoping it's just the gasket though but would be surprised if the new one has blown.

Looks like another strip down!!!

[Mrsmackpaul]

when the water leaked out is most likely when the head gasket blew I had a similar problem 12 months ago I pulled the head and the head gasket looked fine so then I crack tested the head as best I could and couldnt nothing it turned out the head was warped it was only 9thou out but enough to cause problems
Got the head decked and used heaps of copper spray on the head gasket and torqued it down a few times once it was running and warm never had any more trouble
mine the radiator had developed a small pin hole and once enough water leaked out it went real bad real quick didnt know any of this driving along until it was all to late

Paul

[Mikerb]

It's a good job that these engines aren't to hard to work on.

If the gasket was blown I assume it would be obvious with sooty or burnt marks on it?

Is it worth getting new head bolts while I'm at it? I used the old ones last time which I've heard is a bit of a no no!

There's an engineering company down the road, I'll get it top them if the gasket looks fine.

Will these problems ever end!!!!?

[Mrsmackpaul]

there are books that list the engines that need new head bolts each time the head is off I doubt you will but any good motor machining shop should be able to give the low down on the head bolts but never worry about changing them

I would get the head pressure tested while its off just to make sure and shouldnt cost much to do as has been mentioned above

One of the biggest reasons I find of clogged radiators in the core is it has been run with old radiator hoses that are perished and bits of rubber have gone thru and blocked

Paul

[Mikerb]

Got the head off today, and the head gasket has blown.





Looks like it's blown where there was a tiny splatter of weld from running welds down the liners to shrink them and get them out, I must have missed it and not cleaned it up!

At least it's not a cracked head.

[Mrsmackpaul]

cool bananas found the problem a quick clean up and she will be good to go

Paul