Strange overheating

Wondering if anyone can explain the circumstances that led to my disco overheating

drove 60ish miles to north wales no problem at all, stayed for a weekend and drove about alittle bit again no problems.

just before leaving to go back home checked all my fluids which I do regularly and noticed my expansion tank was low on coolant which it has never needed a top up, anyway started to drive home after topping up, done approx 58 miles just coming off the last junction near my house and noticed a lack of power, suddenly it was hard to stay above 60mph after previously travelling between 65-70 without a problem, then noticed the temp gauge starting to move up, then eased it to a steady 50mph and put all the fans on full blast, engine started to judder but then settled down again, strangely the hot air coming out of the vents suddenly went cold,the gauge was still sitting too high on the gauge but not in the red, drove it about half a mile off the motorway to my house, opened to bonnet to discover steam coming out of 1 of the heater matrix hoses.

put a new hose on filled the tank back up and took on a test drive, temp gauge rose far too fast and put fans on and they were blowing cold even when hot, then suddenly went hot and the temp gauge dropped to normal and has been ever since, only its now losing water and theres a haze of steam coming out the exhaust when idling so i suspect that last part of the motorway blew the headgasket :5bbanghead:

Sounds like it. Personally if I was driving a car that was running hot and the heater went cold I'd STOP! There and then, no question.

Don't know if you're aware that 300's need bleeding when re-filling the coolant system. A search on here will tell you how if you aren't.

LR's aren't renowned for the accuracy of the guages and temp wise should be treated as a guide to whats normal and what's not. Mine will boil the coolant well before the red but if it's running hotter than usual I know there's a problem.

Luckily HGF is not usually a big story with 300's, I'd bleed the system and limp to a garage for a sniff test. If there's exhaust gases in the coolant then it's head off, get it tested and if necessary machined then it's just a matter of one size thicker gasket, new bolts and away you go

+1 for beasty. 300's and failed head gaskets go hand in hand. whilst the head's off if it comes to it if they find cracking around the injector and glowplug ports. Follow the bleed instructions and becarefull of the top plastic bung if its not been replaced with a brass one already do it.

You are totally right I should of stopped straight away, however that brief moment when it started to judder once I eased it off and put the fans on it very slightly cooled down and felt normal, i suppose thats all it takes to blow the HG

have done a few HG in the past so as you say the 300tdi should be a doddle

bled it as best I could the first time and its continually lost water after even a shortish journey

Ill have another go of bleeding it properly tonight with the bungs taken off, luckily mine are already brass

thanks for your help anyway chaps

yep, went low, got air lock, overheated.

blue beasty said:

Sounds like it. Personally if I was driving a car that was running hot and the heater went cold I'd STOP! There and then, no question.

Don't know if you're aware that 300's need bleeding when re-filling the coolant system. A search on here will tell you how if you aren't.

LR's aren't renowned for the accuracy of the guages and temp wise should be treated as a guide to whats normal and what's not. Mine will boil the coolant well before the red but if it's running hotter than usual I know there's a problem.

Luckily HGF is not usually a big story with 300's, I'd bleed the system and limp to a garage for a sniff test. If there's exhaust gases in the coolant then it's head off, get it tested and if necessary machined then it's just a matter of one size thicker gasket, new bolts and away you go

Click to expand...

same size gasket, heads flat to start with.
gasket thickness is for piston protrusion.
thicker gasket may make it a bit smokier and alter the diesel rattle a bit, but will still run.
rest all good bb, just for info