Dead head, help me understnad why

[Doug G.]

I lost my first head when a hose split and dumped the contents, all sorted new hoses and new head. Since then I have had three strange over heating incidents, last one fatal (another head).

My local LR man seem the business but can not find the cause of my three incidents. It has been back to him a few times, had it a week once but nothing showed up and he drove it every day.

He has flushed the cooling system several times and put some stuff in to clean the system out, again several times. He put on a new thermostat and re checked every hose for leeks, none.

There seems to be talk of some type type of air lock causing the problem. I did get a gurgling noise at the drivers foot well which I now guess is air gurgling around. On two ocasions the engine ran a very long time, once to wales and once to the lake district with not heat issue showing. Next morning after checking water level the engine overheated withing minutes of starting. Strange also that headting did not work just prior to the overheating.

After each incident I let the engine cool down, took off the expansion tank cap (was under preasure) and filled with water. After that the engine ran fine again, back from wales and lake district.

Last incident same thing, all the way to wales fine and next day over heated first thing in the morning except this time total death and time for a new head.

So, what is going on? As stated my LR guy is very good with 30 years of pure LR experiance and he has ripped the carp out of the thing and says can find not one thing wrong.

I need some fresh ideas because I can not afford to keep being recovered from all over the UK and heads are very expensive every 6mo.

[JohnL]

My guess would be head gasket or improperly torqued head.

I had a catastrophic coolant leak which necessitated a head replacement and initially all was fine but within a few months it started overheating and losing coolant. I had a pressure test done which found nothing and a CO2 sniff also reported no combustion gasses in the coolant. I showed it to three garages (one a LR specialist) who were as stumped as I was. I was in denial about the head gasket but In desperation I ripped the head off and found a small area where the gasket had failed. Whether it was a duff gasket (patten but from an engine specialist) or me not torquing the head down correctly I'll never know but a new (OE) gasket cured it.

Re torquing the head: your man may have 30 years LR experience but a Discovery head is quite flimsy compared to a Series one and MUST be torqued as per the manual.

The refill also needs care to avoid air-locks.

Good luck,

John

[Les Henson]

I fill the cooling system on some engines with it ticking over. You never normally get an air lock by doing this. You should get no noises at all from the cooling system if everything is ok. Don't rely on temperature guages etc - hot air won't make them work, so you could have a problem and your guage won't tell you. If I had this kind of problem with an engine, I would totally dismantle it down to the last nut and bolt.

Les.

[Andy]

have you used new headbolts with the replacement heads? i had a car that used to eat headgaskets till i replaced the bolts, it would appear after too many uses they streach & dont apply full clamping force.

i do similar to Les. i fill the system, start the car with the cap off & keep topping it up as the level drops. i only ever fill the expansion tank, i dont bother with the cap in the top of the thermostat housing.

only other thing i can think of is check the threads where the headbolts enter the block, could be a damaged thread preventing the bolts clamping correctly.

[Doug G.]

Not sure about first head and bolts but he did say put new bolts on this time because felt the old ones had streached.

[Ivan]

My 2p worth. when you checked the coolant level after the long trip did it need filling ? Also during your 2 long trips did you have the heater on ? Could be a leaking heater matrix which will only show up when the heater is turned on. I had a similar gurgling noise when the heater matrix on my discovery went. just drove everywhere wuith the heater off until I could get it replaced.

If this sounds like a load of rubbish please accept my apologies

Ivan

[Doug G.]

After long trip did not need coolant, checked next morning. Also, did run the heater and have noticed a gugling sound.

I pointed this out to the local LR guy but he says heating system is fine.

[Andy]

disco heater matrixes are full flow 100% of the time anyway. turning the heater to cold only changes the way the air flows, it doesnt stop coolant flowing through the heater.

[waveydave]

Doug what engine are we talking about here?

200tdi/300tdi/2.0mpi/td5 or v8 ?

Differnt engines have differnt problems.

[Doug G.]

It has a 300tdi engine.

before and after most trips I check the water level, never seems to be low. Can it be low but still indicate normal in the expansion tank?

Also, how do you know if there is air in the system? I was getting the guggles in the heater which I now know was air. Is there an easy way to bleed air?

Each time it has overheated it has been sudden. I have had the gurgles for a long time but never userstood what that was, could there have been a long term air lock that was causing the head to go or was it the head causing the air in the system?

Got it back the weekend and the mechanic swear he has gone through the entire system and notihing. Gave it another flush to ensure rad and system clear, water is looking nice and clean now so no carp floating through.

Still puzzeled, since the first over heating I check fluid level almost every trip and have never seen it low thats why I dont understand. Next to last time I checked the fluid before I started and it was perfect, pulled out and drove 5 min then it overheated and Mildly miffed all the fluid out the expansion cap.

[BogMonster]

My Discovery 4.0 gurgles through the heater after startup in the morning almost every time, always has done for the last 4 years so I don't think its necessarily something to be terribly worried about.