Disco 1 Overheating Disco

hoopfish · Sep 27, 2015

So here we go.......
The Disco has been loosing coolant/water for the last couple of months,about a ltr a week. Can't find where it is going so have just ordered new top and bottom hoses, bleed plugs , bleed assembly pipe and thermostat. I replaced the water pump about a month ago.
For now i am using just water as a coolant,cant afford to constantly replace with coolant. It appears to have worked for a while but for the last week it has started overheating on short journeys. This morning i have drained the system, re filled, via bleed plugs etc. Took it for a short run and up the temp went. No heat from the heater, pipes all feel hot and under pressure. Released the cap slowly and water, as expected, started flowing out but the water was warm and not hot!. It sounded like someone was in side the rad with a hammer, which i'm guessing is the air being released?.
Am i missing something when filling up, over than the obvious of coolant, is this something more to do with the oil, which was changed end of last year?
Should i just scrap it and get a Nova?
Thanks in advance
Terry.

jamesmartin · Sep 27, 2015

using just water will rot the core plugs ,if you have no leak ie p gasket and rad gets hot all over top hose gets hot ,id look to fit a head gasket

hoopfish · Sep 27, 2015

Thanks again James. I know its an obvious question but need to insure I get the right gasket. Is this a 2 hole gasket,I ask because I don't know if it can move and cover one of the holes.

hoopfish · Sep 27, 2015

How easy is it to replace the core plugs whilst i am at it?

White_Disco · Sep 27, 2015

How old is the expansion tank cap? These need replaced occasionally, water lost as steam. Are you filling using the bung on top of the rad to get rid of the airlock ? Think there's a bung on thermostat housing too.

hoopfish · Sep 27, 2015

White_Disco said:
How old is the expansion tank cap? These need replaced occasionally, water lost as steam. Are you filling using the bung on top of the rad to get rid of the airlock ? Think there's a bung on thermostat housing too.

Good call because i did wonder about this. The only loss of fluid i can see is via the cap.Think i will order a new one and yes i do re fill via both bleed screws.

Gazbo · Sep 28, 2015

hoopfish said:
Good call because i did wonder about this.

I'd be 99% sure it is not the pressure cap, and as J.M. has said, you may need to be replacing the head gasket, the leaking gas of combustion is displacing the coolant in the engine cooling passages, the coolant has to be in contact with cooling passage surfaces to take heat out of the engine, the gas rises to the high points in the engine and prevents contact/cooling to the hottest bits, the head overheats in "micro boils", the banging and crackling you heard in the radiator would have been water flashing off as steam somewhere within the system.
Have you checked the thermostat out for correct operation?
You may not even see the boiling/overheating on the temperature gauge as it is monitored by an "immersion device" in the thermostat housing which does not pick up temps from steam/combustion gasses.

hoopfish · Sep 28, 2015

Gazbo said:
I'd be 99% sure it is not the pressure cap, and as J.M. has said, you may need to be replacing the head gasket, the leaking gas of combustion is displacing the coolant in the engine cooling passages, the coolant has to be in contact with cooling passage surfaces to take heat out of the engine, the gas rises to the high points in the engine and prevents contact/cooling to the hottest bits, the head overheats in "micro boils", the banging and crackling you heard in the radiator would have been water flashing off as steam somewhere within the system.
Have you checked the thermostat out for correct operation?
You may not even see the boiling/overheating on the temperature gauge as it is monitored by an "immersion device" in the thermostat housing which does not pick up temps from steam/combustion gasses.

Good answer, so for someone as dumb as me!. The fix is what?

markSX · Sep 28, 2015

hoopfish said:
Good answer, so for someone as dumb as me!. The fix is what?

Pull the head off, check the head for cracks, if no cracks put the head back on with new gasket.

Gazbo · Sep 29, 2015

hoopfish said:
so for someone as dumb as me!. The fix is what?

Sorry mate, was not trying to make out you were stupid, but it's just that I've seen a lot of clutching at straws with overheating/coolant loss issues with Disco Tdi's, and you might as well "cut to the chase", that being, although it is reasonable practice in most cases and maybe on other vehicles to chase through on all possible causes that may be contributing to your problem, history on the Disco Tdi dictates that one overheating/coolant loss event will in 99% of cases would most certainly lead to a head gasket failure if not a stuffed head, if not immediately most certainly soon after.
The solution to your problem is remove the head, have it checked out for flatness, warpage and for water jacket cracks/leakage i.e. a good pressure testing, have any remedial work done or buy a replacement new or S/H.
Replace the head on the engine with a new head gasket, (I use the Victor Rienze MLMS gaskets, because I have found they give better long term results), but others will probably like the original type composite gaskets, in which case either will be ok. I also replace all the head bolts, about $100 per set here, but worth it for peace of mind of not having one snap after you have done all the good work (Note, all these ways of doing things are the way I operate, not everyone will agree and may recommend a different way to go about it.)
There are some great instructional videos on Youtube on Tdi HG replacement, done by some clever guys from over your way, have a look at some of those for a good guide, also there is lot's of info/help available through here.
Good luck with it all.

hoopfish · Sep 29, 2015

Gazbo said:
Sorry mate, was not trying to make out you were stupid, but it's just that I've seen a lot of clutching at straws with overheating/coolant loss issues with Disco Tdi's, and you might as well "cut to the chase", that being, although it is reasonable practice in most cases and maybe on other vehicles to chase through on all possible causes that may be contributing to your problem, history on the Disco Tdi dictates that one overheating/coolant loss event will in 99% of cases would most certainly lead to a head gasket failure if not a stuffed head, if not immediately most certainly soon after.
The solution to your problem is remove the head, have it checked out for flatness, warpage and for water jacket cracks/leakage i.e. a good pressure testing, have any remedial work done or buy a replacement new or S/H.
Replace the head on the engine with a new head gasket, (I use the Victor Rienze MLMS gaskets, because I have found they give better long term results), but others will probably like the original type composite gaskets, in which case either will be ok. I also replace all the head bolts, about $100 per set here, but worth it for peace of mind of not having one snap after you have done all the good work (Note, all these ways of doing things are the way I operate, not everyone will agree and may recommend a different way to go about it.)
There are some great instructional videos on Youtube on Tdi HG replacement, done by some clever guys from over your way, have a look at some of those for a good guide, also there is lot's of info/help available through here.
Good luck with it all.

Thanks for the help Gazbo, you are right on the point about clutching at straws. I was about to order all new hoses, thermostat etc etc.
I have now ordered an OEM gasket and a new torque wrench. Looks like my weekend is sorted!

hoopfish · Sep 29, 2015

One more question!!!!
Do we use an angle gauge or tipex?

Dippypud · Sep 29, 2015

We are talking 300TDi ?
I used the flats and is easier and accurate...
My tip is to have a fat elastic band to hand to hold the two back bolts together when lifting the head off and re-fitting ...
Pick a corner of the hex bolt head, mark it with a pen/scriber/Tippex, what have you and a corresponding mark on the head .
Turn the bolt until the next corner lines up with the spot on the head....and you have just tightened 60° .
Simple, each flat of the bolt head making 60° of the 360° rotation.
For the 20° turn you mark a third of the width of the flat and tighten to the spot on the head...

Dippypud · Sep 29, 2015

Have you checked the heater hoses across the back of the head, if you have a pin hole leak it'll flow down and evaporate before you've spotted it ...
Chuck some talc around and see if it washes off in strange places ... oo errr missus ...

hoopfish · Sep 29, 2015

Cheers Dippypud, i have checked all hoses as best as i can, i will try the talc trick though.
I will go with the flat method for tightening and i will also get me a big elastic band.
Any tips for getting the rocker cover off and back on, valve clearance etc?

Dippypud · Sep 29, 2015

Not really, a straight forward thing ... soak the exhaust studs/nuts in GT85 or whatever for a couple of days before you try and undo them, they may not snap then, (if you can have access to some spares, just in case) ...
New rocker seal, new manifold gaskets, new leak-off pipes, check glow plugs for operation ...
Have patience with the injectors, they can be tight ...

hoopfish · Sep 29, 2015

OK so spoke to my local lr dealer who has told me that putting a 3 hole gasket in place of a 2 hole gasket will be fine?

Is this right ?

hoopfish · Sep 29, 2015

ok, so taking the head off tomorrow and sending it to be hot pressure tested and faced, £100.
Oil change, filter change, leak back pipes, p gasket, manifold gasket, head gasket, head bolts, new feeler gauges, coolant and thermostat.
Anything i have missed?

markSX · Sep 29, 2015

Don't forget a first aid kit for the skinned knuckles.

Also a small set of steps, caravan steps are a good height, makes reaching things much easier.

Gazbo · Sep 30, 2015

hoopfish said:
Do we use an angle gauge or tipex?

Your choice, I use a rotation angle gauge because Land Rovers are not the only vehicles I play with, some of those others use odd angles for tensioning. If you are dealing with moves of 90 degrees then the pencil mark/scribed line method is pretty well spot on.
Not sure if anyone has mentioned this, but, while the head is off check out the condition/integrity of the threads in the top of the head which secure rocker shaft.assembly, one head all nicely fitted and tensioned up on that new head gasket, fitting the rocker shaft............bingo, one or more of those threads strip out as you are fitting the rockers back on, access to the back one is a real pain for heli-coiling once the head is fitted and you wont want lots of thread shavings through your engine, so my advice, test all the threads to the specified torque by tightening the bolts/studs down on to a spacer, whilst the head is off, if they fail (strip out), have all the threads Heli-Coiled, (M8) problem goes away and stays away.
Valve clearances all, .2mm (.008", in the old money)
Also there is not a need to remove the exhaust manifold/turbo from the down pipe if you don't want to, just undo the manifold nuts that hold it to the head and pull the assembly aside, not too far as that puts too much strain on the turbo oil drain and the exhaust engine pipe flexible, tie it back with a bit of wire.
An inverted milk crate is perfect height to work off and get over the front for the average height spanner handler.

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