Upper Radiator Hose Explodes While Driving, then code P0115

[brokenjago]

Hi,

I have a 1996 Toyota Camry, 4Cyl, 255,000 miles. (Although I believe the engine was replaced at 118,000.)

I was driving a friend and we were on surface streets (although we'd been driving on the freeway for about 20 minutes previous to this) when I hear a loud pop and huge amounts of thick opaque white smoke come from under the hood. Engine immediately dies. Middle of the road; pop the hood, see that the upper coolant hose has completely exploded at the point where it touches the metal going into the engine. Heat gauge is pegged, but sadly I don't know if that was due to the hose exploding or if it was at the top for a while.

Move the car to the side of the road; luckily there's enough hose left that I can remove the broken piece (which is about 1.5 inches/4cm long) and stretch it a little so I can reconnect and limp back home, which I wasn't too far from. So I re-connect the hose, fill it with a gallon of water, start the car with no trouble, idle and rev it for a bit while keeping a close eye on the heat gauge (which stays normal) and then drive back. Heat gauge stays at normal. No apparent difference in power, acceleration, idle, steering etc. I had just replaced the spark plugs one or two days before this happened.

Had the head gasket replaced a week or so ago, and that general area of the engine cleaned. Haven't checked my oil yet; I left it at home and haven't driven it since. I will be checking for milky residue in the morning. Since I've turned the car back on, I've had the Check Engine Light (CEL) on, returning one code: P0115 - Engine Coolant Temperature Circuit [Malfunction]. My fans work properly, turning on and blowing air into the radiator (presumably) whenever it's needed.

So I'm wondering why my coolant hose exploded, and what I can do to prevent this problem in the future + how to replace the sensor (or, more accurately, how to avoid replacing the sensor if it's in fact a different problem - blown fuse perhaps?)

Once before, briefly, the temp gauge started to creep up, but I accelerated mildly (to move to the side of the street) and it immediately went back to normal. I watched it for a few days after that but nothing unusual occurred so I let it go.

I'm going to go by my local parts shop and get a new radiator hose, and maybe a new ECT if it seems warranted. Also new coolant, obviously.

Any thoughts?

[hodgoes2001]

do your fans kick in as they should??

sounds like a new sensor and hose is needed...

all things considered though...

it could of been worse...

[brokenjago]

My fans work perfectly. I do want to be able to replace the hose and sensor and be on my way, but I really don't want something even worse to happen if I let my guard down and stop looking at the temp gauge.

[brokenjago]

Nothing guys? I took the car to Autozone; got a new hose, but haven't installed it, and new coolant which I haven't used yet. Light urban driving showed no problems, even with the AC on.

I took a look at the two sensors next to the upper hose at the engine and noticed that both have frayed, but not disconnected, wires. Could this be the problem? if so, should I get new wires or just splice some in there?

[oldfirebird]

I gotta assume it overheated causing the hose to burst (as opposed to the hose blowing up and the engine instantly overheating). There might have been air trapped in the coolant system after the head gasket job. Unless the hose was old, it shouldn't have exploded. The radiator cap should have let the pressure blow off. I'd replace the hose, cap and refill with coolant. Drive it around the block a few times with an eye on the gauge. Shut it down once it warms up, let it cool off and double check the coolant level in the radiator, not the overflow tank. I'd repair the wires you speak of for good measure. If the conductors aren't broken, re-insulate them at a minimum.

[brokenjago]

I took the radiator cap off to inspect it, and noticed an odd build up. It was sort of a soggy rubber material that easily came off. I cleaned it off and replaced it.

I've been running distilled water in there with the old hose for a few days to see if it would overheat again (since water has a much lower boiling point than coolant) but so far everything has been ok. I put electrical tape on the wires to the ECT sensor and after a day the check engine light went off on its own.

Looks like I'm just going to end up replacing the hose and filling it with coolant. I got undiluted since I don't like the idea of spending twice as much for adding water that costs me at most $1. Some places have said that a coolant/water ratio of up to 70(coolant)/30(water) is ok. Does it matter too much? I've also had a really hard time figuring out what the capacity of my radiator is. Quite irritating.

[JohnGD]

The engine blew a head gasket and a lot of that material ended up in the cooling system. But if the rad cap is working it should have release the pressure maybe the reservoir hose is all plugged up. How's the vacuum return valve on the rad cap? You may need to reverse flush the cooling system too.

Valvoline's Zerex Asian is only 50% premix, but it prices out nearly the same as Toyota Red, so that's what I would recommend - the red. Otherwise the Zerex G-05 is another alternative after a full distilled water flush.

[brokenjago]

If the engine blew a head gasket, which I'm not discounting, wouldn't there be something in the motor oil? Frequent checks have yielded nothing as far as something that shouldn't be in there being in there. The motor also runs just fine. What are other warning signs associated with a blown head gasket that I should watch for?

I didn't mean that there was sludge on my cap - there's not, and the fluid looks fine. There's a buildup of a compound that looks like it's got copper glitter in it, and it's very bright glitter at that. Very soft but not liquid, and easy to pull off.

I just had the head gasket replaced, as I mentioned above. it would suck a lot if I had to replace it again :/

So this morning I drained the radiator of the (mixture of mainly) water, flushed it with distilled, and installed the new upper hose and filled it with (roughly) 50/50 antifreeze/water. Drove it around, and wouldn't ya know, the overheating issues came back. I was... frustrated, to say the least. I didn't notice any problems until I drove up a fairly steep hill, and then the gauge kept going up and down and up and down. Idling made it worse, accelerating made it better... sometimes. Eventually I pulled over and topped off the radiator, which blew a trillion tons of steam (expectedly, obviously,) then parked it in a parking lot and let the fans run over the liquid without the engine running for a while.

Since then it's been fine. I noticed that this entire time the coolant reservoir remained at exactly the same level. That's weird, because I just bought a brand new one... could there be an issue there?

[oldfirebird]

Like I said in my last post, I bet there's air stuck in the cooling system. They can be a bear after they've been totally emptied. Warm it up, shut it off LET IT COOL DOWN, then top it off. Opening a hot radiator always ends badly. The copper filing you mention is stop-leak. Someone added it to avoid the head gasket job. That's only a band-aid solution however.