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colin tandy

bleeding cooling system 300 tdi discovery

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hi all can anyone please tell me the best way to bleed the cooling system on a 300 tdi discovery...seem to have a air lock somewhere cant get warm air through the vents.. ive just replaced head gasket put it all back together with new thermosat ect..struggling with this

cheers

colin

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Should the same as a Defender I think - take the cap off the radiator, fill through the header tank until coolant comes out the top of the rad, put the bung back in and continue filling then run at idle until it is up to temperature.

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Top up via the thermostat housing plug first, then top up the rad, then the expansion bottle. Run engine till the thermostat opens,stop and let engine go cold and check levels again.

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Both slightly wrong...

From RAVE (Steps 1 to 3 are draining):

Refit

CAUTION: In order to expel ALL air from

the cooling system, follow the procedures

carefully.

NOTE: Refill procedure is slow but can be

accelerated by squeezing hoses to assist

removal of air from the system.

4. Add correct mix of coolant into expansion tank

until radiator is full (as seen through plug hole on

top of radiator). See LUBRICANTS, FLUIDS

AND CAPACITIES, Information, Anti-Freeze

CAUTION: Take care to avoid excess

coolant spillage from radiator.

5. Fit radiator plug.

6. Continue adding coolant into expansion tank

until coolant appears in thermostat housing.

CAUTION: Take care to avoid excess

coolant spillage from thermostat housing.

7. Fit thermostat housing plug.

8. Check coolant in expansion tank is level with

indicator post. Add more coolant if necessary.

9. Start engine and run for 5 minutes.

10. Allow engine to cool, check coolant level in

expansion tank; top up to level indicator post if

necessary.

11. Fit expansion tank filler cap.

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You did replace the thermostat the correct way round, i.e with the tiny hole in the flange up, didn't you?

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There is a slight problem with the Disco as opposed to the Defender. The header tank is lower in relation to the engine on a Disco. So you may find that if you follow exactly the procedure above that eventually there is almost no air space in the header tank. So then, while leaving the thermostat plug in, siphon a little coolant out of the header tank.

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I had some trouble bleeding the system on my Discovery after a head gasket change, I used the Rave method but I couldn't get the cabin heater to work i.e there was an airlock somewhere.

I traced the air lock to the pipe that runs along the inlet manifold, to get rid of it I raised the expansion tank as high as the hoses would allow and ran the engine till it was warm (without the expansion tank cap) and hey presto, hot air from the heater!

Basically just agreeing with what Jim has already said about the expansion tank being slightly lower.

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when re-filling after a head gasket change I filled up to the required level in the header tank and replaced the cap, then opened up the thermstat housing plug and fillied with about antoher 1 - 1.5 litres.

This seemed to work fine right up to the point the power steering pump fell off and the engine overheated a bit as there was no drive to the water pump

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when re-filling after a head gasket change I filled up to the required level in the header tank and replaced the cap, then opened up the thermstat housing plug and fillied with about antoher 1 - 1.5 litres.

This seemed to work fine right up to the point the power steering pump fell off and the engine overheated a bit as there was no drive to the water pump

The best way I 've found if the heater air locks after filling is through the heater flow connection.

This is the pipe that rises off the head at the rear, not the metal pipe that runs along the head.

Undo the hose from the connection on the top of the head and lift it vertically in the air. Place a thumb, someone elses, over the head connection and fill the hose with a coolant mix. Quickly refit the hose whilst coolant is pouring out. Usually works first time.

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Hi, 300 tdi disco

I have tried all methods of bleeding the system ,

heater hose at back of the block,

connecting the heater hoses together to avoid poss matrix prob then bleeding,

running the car for long period with cap off ,

squeezing hoses,

bleed valve at rad and thermo,

all as suggested in this topic,

Still as i type the car is outside ticking over now for about 2 hrs and a constant strem of bubbles are coming up thru the exp tank,

Heater is cold, no moisture at exhaust, no evidence of water in oil, and the water pump is in good cond, thermostat removed!,

any ideas

Wade

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If you rev the engine for a couple of seconds and the let it of, with the expansion cap of , does the water level rise ?

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If you rev the engine for a couple of seconds and the let it of, with the expansion cap of , does the water level rise ?

Just tried it and no it doesnt

Its been ticking over for about 2 hrs now and the engine temp is still below half,

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Just tried it and no it doesnt

Its been ticking over for about 2 hrs now and the engine temp is still below half,

correct that, it comes up abit but has i release the throttle but seems to be more air than water then returns to a steady flow of air

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Check fluid level is about half way to 3/4 up the expansion tank, put cap on, turn heater to full demist hot, take a container with coolant with you,take for a short drive, round sharp corners up and down hill if possible, keeping an eye on the temp gauge, if it does the same as mine did, you will hear a gurgling/knocking noise from in the heater area , the temp gauge will suddenly rise and then fall,you will feel hot air blast from the heater, stop the car, carefully take of expansion cap and top up with coolant mix , replace cap , start up and all should be hunky dorey!

Worked for mine worth a go?!

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Check fluid level is about half way to 3/4 up the expansion tank, put cap on, turn heater to full demist hot, take a container with coolant with you,take for a short drive, round sharp corners up and down hill if possible, keeping an eye on the temp gauge, if it does the same as mine did, you will hear a gurgling/knocking noise from in the heater area , the temp gauge will suddenly rise and then fall,you will feel hot air blast from the heater, stop the car, carefully take of expansion cap and top up with coolant mix , replace cap , start up and all should be hunky dorey!

Worked for mine worth a go?!

right gonna nip out and try that now!!

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right gonna nip out and try that now!!

wen out bumpy mountain track as said , just got hot after a bit and stayed there no hot air ,didnt want to cook it!!

worth a try tho thx

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wen out bumpy mountain track as said , just got hot after a bit and stayed there no hot air ,didnt want to cook it!!

worth a try tho thx

OK back to basics.... what work have you done to the engine to necessitate bleeding?

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Tesco had some cheap funnels a little while ago which fitted perfectly into the expansion tank, allowing you to fill the system up with water above the level of the top of the engine. The header tank is actually below the top of the engine, which is the main reason why you can't bleed them easily. I opened the plastic bung on the thermostat housing a little and filled it up with the funnel attachment until the water came out of the thermostat housing while the engine was running. I also opened the bung on the rad and with revving and squeezing the pipework seemed to get the air out pretty easily.

In your situation however, eventually all the air should be pushed out anyway so if you are just getting loads of air out then perhaps there is another issue? With the engine running and getting hot, is there any hot air coming out of the blowers?

You didn't fit an MLS gasket did you? There is a love/hate thread on here about these gaskets. If not, did you fit a good quality gasket? Also, did you get your head checked? 300Tdi heads are well known for cracking, 200Tdi's are not quite as bad but still prone.

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Tesco had some cheap funnels a little while ago which fitted perfectly into the expansion tank, allowing you to fill the system up with water above the level of the top of the engine. The header tank is actually below the top of the engine, which is the main reason why you can't bleed them easily. I opened the plastic bung on the thermostat housing a little and filled it up with the funnel attachment until the water came out of the thermostat housing while the engine was running. I also opened the bung on the rad and with revving and squeezing the pipework seemed to get the air out pretty easily.

In your situation however, eventually all the air should be pushed out anyway so if you are just getting loads of air out then perhaps there is another issue? With the engine running and getting hot, is there any hot air coming out of the blowers?

You didn't fit an MLS gasket did you? There is a love/hate thread on here about these gaskets. If not, did you fit a good quality gasket? Also, did you get your head checked? 300Tdi heads are well known for cracking, 200Tdi's are not quite as bad but still prone.

Appreciate all help , i have spent 3 days under the bonnet now (Ithink I need my head checking!!!!!), tried allsorts of methods , finally gave up and got it transported to a bunch of landrover lads down near Gibraltar, who incidentally are very helpful and know their stuff and are members of

Gib4x4

http://www.club4x4gib.com/home

check out the site even if for a bit of support,they organize offroad trips in southern spain, portugal and north africa, they also have access to parts ,mechanical help , and tons of experience,

thanks for all your help, Wade

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If you've got it sorted now then no need ot put this, however, an alternative I have used at work is to park uphill at an angle so the header tank is the highest point and fill with the engine running

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hi i have had problems with mine and change the head and head gasket then the waterpump was leaking so changed that turnout out it was the rad was leaking i suggest you bypass it and block the little over flow pipe and and try warm it up, thats what i did with mine and it works the heating great meaning i needed a new rad :(

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Right then! first news from the Mechanic , is the head gasket , but on further investigation I got the good news that the head has gone, WOOHOO!!!

So now looking for a replacement head , saw on Paddocks site prices from 225 Quid to 310 quid, couldnt see what the difference was anyone got a clue or some advice!!

cheers Wade.

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