Help before i torch this car.

[hangover]

For the last few months on and off i have been having cooling issues with my TDI disco, this culminated in me doing the head gasket 3 weeks ago.

2 yo head checked and passed , elring composite gasket and new bolt set. Ran well with the occasional temp rise just after slowing down from 80/100 kph, replaced viscous fan clutch as it hadnt been replaced in my near 10 year ownership, ran cooler on the highway at 100kph but still the occasional temp rise.

Radiator removed and cleaned/rodded (professionally) but bloody thing is still overheating which it was doing before the gasket change, expansion cap replaced and waterpump is 3yo and all hoses 2yo.

When the temp goes up it mostly comes back down quickly and sometimes loses some coolant, can also hear gurgling thru the heater core but there are no leaks and aircon drains are clear.

[ejparrott]

200 or 300?

[stephencdavies]

Possibly an air lock in the top hose. i'd run without the thermostat in until the issue has been sorted

[hangover]

300TDI, sorry i thought i had it in my signature which has disappeared. It all points to an airlock but for the life of me i cant purge the air out no matter what i try, my next step is to check the thermostat which is only a few weeks old and genuine LR and then check the waterpump again and possibly swap it for a spare pump.

I also thought about bypassing the heater just to see if i can purge it easier and confirm that it is the issue.

[simonr]

I had repeated similar overheating issues with my Tdi and did most of the things you have. Several people suggested a mysterious 'Air lock' - but I couldn't see why it would have one now, but not before. I have a feeling that 'Air Lock' is code for 'Sorry mate, I haven't a clue!'

What it turned out to be was the Radiator. Although it looked fine from the outside and had been thoroughly flushed / cleaned, most of the fins inbetween the front & back faces (which looked fine) had corroded and were not providing any significant cooling.

First off, I replaced it with a cheap radiator bought at Newbury which fixed most of the problems, except when towing (up Birdlip Hill notably). At the very least it showed where the problem was (and I sold it on at the next Newbury) Then I replaced this with an AliSport radiator - and the problems all vanished! I could tow 3.5 Ton up Birdlip hill without the needle moving!

Si

[hangover]

I had repeated similar overheating issues with my Tdi and did most of the things you have. Several people suggested a mysterious 'Air lock' - but I couldn't see why it would have one now, but not before. I have a feeling that 'Air Lock' is code for 'Sorry mate, I haven't a clue!'

What it turned out to be was the Radiator. Although it looked fine from the outside and had been thoroughly flushed / cleaned, most of the fins inbetween the front & back faces (which looked fine) had corroded and were not providing any significant cooling.

First off, I replaced it with a cheap radiator bought at Newbury which fixed most of the problems, except when towing (up Birdlip Hill notably). At the very least it showed where the problem was (and I sold it on at the next Newbury) Then I replaced this with an AliSport radiator - and the problems all vanished! I could tow 3.5 Ton up Birdlip hill without the needle moving!

Si

Yeah i thought having the rad reco'd would solve my issues but it hasnt so far.

[steve b]

Did you get the head pressure tested when it was off ?

Your symptom's could suggest a crack to the water jacket , a chemical sniff test in the header tank may show it too

cheers

Steveb

[bushwhacker]

This may sound silly but I had similar problems with "air locks" with my 300 Disco.

Someone suggested filling the water system with the expansion tank held up as high as possible (at least higher than the thermo bleed nut) and bleed it also with the tank raised as high as possible.

I was at a loss as to the problem and done the above it worked for me. Land Rovers "boy o boy"

[steve b]

When you say all hoses new , did you replace the small bore bleed - off hoses from 'stat housing to the rad/header tank ? these can get blocked over several years , check the bleed pipe stub on 'stat housing is clear too

cheers

Steveb

[hangover]

When you say all hoses new , did you replace the small bore bleed - off hoses from 'stat housing to the rad/header tank ? these can get blocked over several years , check the bleed pipe stub on 'stat housing is clear too

cheers

Steveb

I replaced the plastic ejector with a brass Y fitting a few months before doing the HG, but i did check all the fittings for blockages.

[Boydie]

This overheating and air locking seems to be a common problem with the 300Tdi engine, try this.

Make up a fitting to screw into the thermostat bleed plug, mine is a PVC nipple that goes from the NPT thread to 1/2" PVC pipe, a short length of pipe(1" long) to connect this nipple to a PVC reducer from 1/2" to 2" then a length of 2" PVC pipe about 2' long (500mm) --- this is all glued together with PVC pipe glue, -- screw this assembly into the thermostat housing.

This is your coolant filler for this operation.

Okay, with the car on LEVEL ground fill the system remove the header tank cap and the plug from the top of the radiator.

Fill the system until water/coolant flows out of the radiator plug. Replace the plug and fit the header tank cap. ---- you will have noticed that on level ground the mid point on the filler tank is equal to the height of the top of the radiator ! ---

Next fill the tube with coolant until it is 3/4 full, RUN the engine until the thermostat is fully open, the coolant level in the tube will drop as any remaining air is discharged from the system.

Remove the filler tube, replace the thermostat plug. You should have removed all the air locks and air from the coolant system.

[honitonhobbit]

I would also point out that you cannot trust any 'new' parts.

A friend who owns a garage reckons that most of their work comes from fixing faulty parts fitted by other garages/enthusiasts

Check the rad - as Simon says the fins are essential, then the fan/viscous coupling, then the water pump ( I replace water pumps as a service item - every three years). Get a pressure test done... All the usual checks

You can move the header tank up wards to improve bleeding. Also fit a heating radiator valve in both the thermostat housing and the radiator. These have a bleed screw built in

[BogMonster]

I have never had a problem with 300Tdis bleeding. Fill through expansion tank with the radiator bung out, then put the bung in when it overflows and fill the tank a bit more, start and idle it, revving occasionally until it is circulating in the expansion tank, running for 5-10 min till the heater air is at least slightly warm, then go for a gentle run (<40mph) until the engine is at normal temp. Check and top up level as needed, job done.

In one of my old 90s I had an issue with slight overheating which as stated was due to all the fins rotting out, new rad sorted the problem. Mine came from Bearmach at a very reasonable price. I wouldn't bother trying to recore or otherwise resuscitate an old radiator.

[hangover]

I made up an extension from a brass fitting, some rubber hose and fitted a funnel on top similar to what Boydie described. Filled untill the expansion tank was half full then placed cap on, continued filling untill rad was full.

Then filled from funnel untill funnel was holding coolant, started and ran engine til warm and squeezed all the hoses to push out any trapped air.

Been driving the last few days 56Klms round trip to work and although not overheating or losing coolant i'm still getting that gurgling ( more like swooshing ) under the dash.

Never had this much trouble bleeding it before, only part i havent replaced is the waterpump which i did notice had a little sideways shaft movement but not leaking.

I was told the rad was about 20% blocked when i had it cleaned.

[honitonhobbit]

Heater matrix is in the dash - did you run up the heater on max for about ten minutes?

[hangover]

Heater matrix is in the dash - did you run up the heater on max for about ten minutes?

Yes not that it makes much difference without a tap in the system, more to check when it starts to blow warm/hot air to tell when its got flow.

I spoke too soon and overheated on the way to work , gaskets are cheap but if the heads gone its more $$ and labour to replace - again.

[sierrafery]

Unfortunately that gurgling sound you mentioned in the first post looks very like combustion gas leak into the cooling system, which can be HG or crack in the head...i've seen this few times on various diesel engines (Td5, 300Tdi, Td4) .that's why you can't bleed it cos gasses keep coming

[hangover]

Unfortunately that gurgling sound you mentioned in the first post looks very like combustion gas leak into the cooling system, which can be HG or crack in the head...i've seen this few times on various diesel engines (Td5, 300Tdi, Td4) .that's why you can't bleed it cos gasses keep coming

Yes i believe it is the gasket most likely from a warped head (my fault as i probably didnt check it properly), engine runs at normal temp until trapped air prevents flow, spare head is being skimmed and will be fitted on the weekend.

Oh well, as they say **** happens .

[honitonhobbit]

My local engine specialists have a liquid that they can fill the cracks with (in some cases) prior to skimming. It works very well

[hangover]

Pulled head this morning and confirmed gasket blown between 2 and 3 as per normal, also found welch plug on rear of head was leaking.

Replacement head on and torqued down just need to adjust tappets and fill with coolant.

[hangover]

Thought i should provide an update, had my spare head hardness tested then skimmed then fitted a new elring composite gasket and new head bolts.

Combined with the new viscous fan clutch and reco'd radiator its running very cool and as smooth as ever (for a tdi ), should be good for another 360K klms.

[bushwhacker]

Happy motoring.

[hangover]

Happy motoring.

Indeed, went away for the weekend towing my camper trailer thru long hills and didnt miss a beat , plus 6 hours of medium to hard 4wding and the fuel economy has increased a bit.

[steve b]

A few pic's Mr Hangover if possible ? Always good to see a pic or two

A good outcome then , will you get the old head tested to see where the failure(s) are ?

cheers

Steveb

[hangover]

A few pic's Mr Hangover if possible ? Always good to see a pic or two

A good outcome then , will you get the old head tested to see where the failure(s) are ?

cheers

Steveb

I already knew where it failed, core plug at rear of head was leaking although it was a combination of the head, viscous on its way out and partially blocked radiator so the core plug was just the last piece of the puzzle.

The removed head is only 2yo so will get it checked and skimmed and sit it on the a shelf in the shed until i can find a cheap short motor to rebuild.