Strange overheat

Ok got a curly one, today was driving my 2.8 GU, traveled about 30 ks, and noticed the temp needle had shot to near high, so immediately pulled over, and found that water had been spewing out of the over flow bottle, and had sprayed all the way to the back wheel, no signs of cracked hoses or radiator, so I started her back up and filled with water into the radiator took near 2 litres, anyway I drove into the nearest town which was 2 ks away and parked it on the side of the road and left it there, as my wife had come to pick me up so I could continue to my destination. Anyway after getting back to my patrol she started with no problems,no missing no steam, so I continued to drive home, after a few hills and about 20 ks she overheated again, so pulled up and turned straight off, and from there we towed it home, my initial thoughts were cracked head or blown gasket, I removed the thermostat and that test fine, so put it back together and filled up with water again, and noticed very slight bubble now and then, and when I placed a few revs on it water was over flowing from the radiator, revs off and it stopped doing it, so I went for a 40+ K drive and not once did it overheat or blow coolant out, could I have a dodgy water pump? also when it was idling away it didnt seem like water was circulating to what I would expect it to be, or am I up for something more sinister? any advise greatly appreciated

Do you know what coolant ratio you are running? How long since the last coolant flush? How's the radiator condition? Just a few thoughts !!!

no idea on the coolant, only owned the bus for 2 weeks, radiator seems fine

Wash all the coolant down. Make sure you have a decent concentration. It will leave a residue where it leaks and evaporates. Keep an eye on it for the area it is leaking.

Might be worth doing a flush and fresh coolant...

Overflow from overflow bottle was the symptom of a head gasket blowing between the cylinders in our 4 cyl Nissan bus (no other symptoms). However before fearing the worst, try replacing the small hose between radiator & overflow pipe. If it has any air leak it can cause the same symptoms. Coolant gets hot, expands, but when it cools down does not get sucked back into radiator as it should.

sounds like a head/head gasket, get a tk test done to confirm

whats a tk test? will I need to remove the head for testing?

Hi mate,

Check the water pump and calorstat (it should open at 82 ° C, take the test in a pan of hot water), do you have the heater in the cabin, it is also possible that your malfunctioning radiator cap ...

Regards
petit caillou.

tk test detects exhaust in the cooling system, any mech will be able to do it or the kits are about $100 at repco

Quote:

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Originally Posted by Petit caillou

Hi mate,

Check the water pump and calorstat (it should open at 82 ° C, take the test in a pan of hot water), do you have the heater in the cabin, it is also possible that your malfunctioning radiator cap ...

Regards
petit caillou.

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I pulled the thermostat yesterday and that opened fine (could be faulty just because it opens doesnt make it right, it could be opening and closing eratically), it does have 100c stamped on it! I glowed it first thing this morning, and started perfectly no missing, no steam or water from exhaust,no water in the oil, no diesel in the radiator, runs sweet, it doesnt blow water out the radiator until it warms up and under revs, so tomorrow I will buy 2 new caps,thermostat and a water pump and go from there, i'm leaning away from the idea of cracked head because of no water in the oil or steaming and missing

Can you tell me how many kilometers you have on it and if the cylinder head gasket has been changed

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Originally Posted by Rickie3

i'm leaning away from the idea of cracked head because of no water in the oil or steaming and missing

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Like I said, no other symptoms on mine when the head gasket was blowing between cylinders . No oil in water or water in oil. No steaming & ran perfectly. Continuing to use the vehicle for 5000kms (we were on the NW coast of WA & tried to get to Darwin), just topping up the radiator when the overflow bottle filled, resulted in the top of the block being eroded between the cylinders. Block was irreparable & was cheaper to fit a replacement motor. Before buying a water pump try replacing the pipe as I suggested as well as the radiator cap. Minimal cost, easy to do, & it might fix the problem if you’re lucky.

Quote:

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Originally Posted by Petit caillou

Can you tell me how many kilometers you have on it and if the cylinder head gasket has been changed

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300000 k's cant tell ya if the gasket has been done, ive only owned it for 2 weeks and no history

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Originally Posted by Cuppa

Like I said, no other symptoms on mine when the head gasket was blowing between cylinders . No oil in water or water in oil. No steaming & ran perfectly. Continuing to use the vehicle for 5000kms (we were on the NW coast of WA & tried to get to Darwin), just topping up the radiator when the overflow bottle filled, resulted in the top of the block being eroded between the cylinders. Block was irreparable & was cheaper to fit a replacement motor. Before buying a water pump try replacing the pipe as I suggested as well as the radiator cap. Minimal cost, easy to do, & it might fix the problem if you’re lucky.

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Thanks cuppa I will try what you said

Well to put it politely, trying to remove a water pump from a GU is a prick!!! the fan was a doozy to unbolt, need pigmy fingers to try and get in there to undo them! after getting them out I thought yep quick and easy to remove pump "WRONG" have to remove top and bottom timing cover, to take the bottom cover off the harmonic balancer has to be removed also, so i'm stuck trying to remove the balancer, mind you the bolt came straight undone with no effort required, I flushed the radiator inside and out, the radiator on the outside fins was clogged with old dry mud, maybe this hasnt helped with cooling issues, the water pump has heaps of movement and sounds like a cement mixer, so as my first start to find the over heat spewing issue, ive bought new pump,thermostat and caps, if that fails to sort the issue, then its off with the head!

Yes, we would have told you if you asked...

And the timing belt could have been done at the same time by loosening the tensioner.

Quote:

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Originally Posted by Rickie3

Well to put it politely, trying to remove a water pump from a GU is a prick!!! the fan was a doozy to unbolt, need pigmy fingers to try and get in there to undo them! after getting them out I thought yep quick and easy to remove pump "WRONG" have to remove top and bottom timing cover, to take the bottom cover off the harmonic balancer has to be removed also, so i'm stuck trying to remove the balancer, mind you the bolt came straight undone with no effort required, I flushed the radiator inside and out, the radiator on the outside fins was clogged with old dry mud, maybe this hasnt helped with cooling issues, the water pump has heaps of movement and sounds like a cement mixer, so as my first start to find the over heat spewing issue, ive bought new pump,thermostat and caps, if that fails to sort the issue, then its off with the head!

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Agree with above ive just replaced my water pump you can remove it without taking the bottom section of cover off but need to be careful also take care undoing the pump bolts as one of mine was almost out and snapped off also check my post mud costs money as I ended up needing to take the bottom cover off to drill a snapped bolt out and you should see the pics of my harmonic balancer it gave no signs of being as bad as it was

Oh well got the job done, but she's still spewing water under revs and slight bubbles, so when I get time its head off, hope to christ it isnt cracked

If u have a crack between piston cylinder and water jacket u wont get water in ur oil sometimes. Just exhaust gasses out ur radiator. If ur car is getting hot as well as lifting the cap id say the cap probly works fine. Under revs it is not uncommon for water to be splashed out of ur radiator with the cap off as the water pump is spinning faster. My guess is maybe flush the cooling system from one end to the other to make sure there are no blockages. Secondly, that thermostat sounds a bit too high if it opens at 100c. Usually imports come withthermostats that high, not real flash for aussie conditions.
But I think shes been sold to you with a cracked or corroded head. Often exchange heads are cheaper than gettin urs rebuilt by some bloke. And then make sure u keep up that perfect ratio of coolant after. You never know what its eating out till its too late.

If you only have slight bubbles you might just have to bleed ur system better. To see if its your head and its lifting under higher temp warm her right up, stick a big piece of cardboard inbetween ur radiator n grill so itl get hotter quicker. If you start getting big exhaust gassy bubbles then your in for dramas

It turned out ok, my son now has the truck and hasnt had any issues, I put it down to a dodgy thermostat