heh guys,
Driving home today I saw a cloud of coolant (smelled it around the same time) out of the rearview mirror. I was on the 520 floating bridge in Seattle with no place to pull over safely and by the time i got the truck to a safe place to stop, temps were already up around 230.

Rather than speculate on potential engine damage, I'm trying to figure out possible root causes. Hoses, Fan Clutch, Radiator and genuine 180 Thermostat were all done 4 months ago.

Underneath the hood, there was fluid everywhere, but I can't find a split or obvious point where a hose came loose. I did check the coolant level this morning before I left and everything looked good.

Any thoughts on what could cause that kind of a a failure ?

 

ok quick update. when i removed the expansion tank cap the change in pressure pushed more fluid out of the truck, making the point of failure pretty obvious. The lower hose to the Thermostat had blown off but had done so in a way that I couldn't see from above or below, until i started tugging on hoses in a now cooled engine.

Seems weird that the hose would come off now after 4 months of perfect operation. The silver jubilee clamp is still on the hose and there are no signs of stress on the hose.

 

further update. Refilled the cooling system as per the RAVE after reattaching the hose and clamp. There's now no visible leaks, but the truck continues to overheat.

I noticed that the cooling fan didn't come on at 208 as it should. I'll dig into that tomorrow and bleed the system again to make sure.

Anyone have any good ideas for what to look at next ?
Bad thermostat ?

 

No idea, get a pressure tester and find the Achilles heal.

230 is not so bad. Everything might be good once you find the leak.

 

It's hard to say what the exact problem could be but judging by the parts of the cooling system that you've already replaced recently I would guess that either your water pump is bad, the coolant cap, or the head gaskets.

How does your oil look? Any signs that water is mixing?

 

Oil looks good, I'll go grab a pressure tester tomorrow and see if i can find the source of the overheating. I forgot to mention that I already had replaced both the expansion tank and the cap in the last big service 4 months ago.

Any idea as to what would cause the lower radiator hose to completely blow off of the Thermostat like that ? Under what circumstances can the cooling system become overly pressurized to cause an event like that ?

A quick trawl through the LR forums does raise the spectre of the HG being a potential cause for the high pressure cooling system. I'll take a look at that tomorrow too.

 

I hate to even mention it, but here I go. My friend has an 03 that has a highly pressurized cooling system. We had to go through and replace all the hose spring clamps with screw down type because the hoses were popping off. His upper rad hose gets rock solid at operating temps.

Put an ultragauge on the car and it's running in the 220 range. I consulted a land rover tech I know who drives a D2 himself. He believes he has a crack in the block that is creating steam pressure.

Once you button it up, check the hoses for pressure.

 

Hmmm, still no conclusive smoking gun as to what caused the pressure build up. No exhaust gas in the coolant, no detectable coolant loss and the truck now idles where it was prior to the breakdown.
Hoses are back to being nice and soft, I'm at a bit of a loss. This weekend I'll pull the thermostat and check that it's opening properly.

 

if the lower hose blew off, i would guess a bad thermostat or a loose hose clamp. did you ever pressure test it after all the work you had done months ago?

 

Pressure test was good when the cooling system was rebuilt. A day after bleeding the system, temps are back to normal and there's no undue pressure build up in the hoses.

I'm going to order a new 180 degree thermostat anyway as it's a good thing to carry in the truck, along with a hose kit, coolant and extra clamps. I'll pull the existing thermostat at the weekend and check it as it's not inconceivable that it failed. The hose clamp on the lower hose was in good shape and I had to loosen it significantly to get the hose back on the thermostat.

So i'm back to square 1, no real understanding of why the hose blew off yet. In the meantime, i'm just using the truck for shorter errands. I'm getting close to making a decision on a new top hatted engine to replace the junk yard special in my truck right now. This may be the impetus to hurry up and decide whether i go that route or maybe fold and get an LR3 and build on that.