water pump/head gasket

[mobyone]

hello all,

i got the 300 tdi engine swap from my old disco1 into another disco1 done, and now i am not sure about if the engine is running right.

so, firstly it drives, and changes gear fine. it is just i feel it is getting really hot on the thermostat housing but never the rad top hose. and i have i believe, no airlocks and the thermostat opens fine.

so my question is, with the little rubber hose from thermo housing to expansion tank off at thermo housing, should water pump out freely at idle, as mine does not. and i took off the water pump to check it had vanes still, which it does.

also, if the plastic threaded plug on the housing is off with engine running, again should water pump out freely as mine does not.

it is a pain in the arse, as the engine worked fine in my last disco, and now i get white smoke/steam out of the exhaust after about 10 mins ish of it just idling which suggest to me the head gasket, but the water is not being pushed out of the expansion tank.

now i have never really dealt with cooling probs on these, but i find it odd that the water does not pump out of the thermo housing when running.

as allways, thanks in advance(les,k88mud and cipx2 as i rekon you guys will be first to reply) and indeed everyone else who does reply.

richard

[Les Henson]

If you remove the plasic plug from the top of the thermostat housing, then water should come out if the engine is running, but not if it's switched off (it's the highest point of the cooling system). Same with the bypass hose. The thermostat doesn't completely shut off flow anyway - it bleeds even when cold. Normally you could remove the thermostat and see if the circulation is normal (it'll take ages for the engine to warm up though). Water into the engine doesn't always cause pressure in the cooling system - it depends where the leak is.

Les.

[mobyone]

i thought that it should, will it come out like it is being pumped, or will it just bubble out without much gusto?

i just find it really strange.

what is the correct way to fill up with coolant from rad bottom hose off, engine drained.

i reconnected all hoses, opened thermo top plastic plug opened expansion tank and then filled it that way, is this correct.

if not, can you tell me proper procedure?

regards

richard

[Les Henson]

I just start the engine and then slowly fill from the header tank with the plug on the radiator removed. Once the radiator is full, I replace the plug and top up the header tank to the correct level. There will be a very small amount of air in the top of the thermostat housing - under the plug, but this doesn't usually cause any problems and gets pushed out by the flow anyway. The plasic plug has a bad habit of breaking anyway, so people either fit a metal one, or just leave it alone.

Les.

[cipx2]

There should be some coolant flowing out the bypass hose at the thermostat housing if you remove it while the engine is running faster than idle, is cold and the cooling circuit is bled properly. Same with thermostat housing plug (engine cold or warm).

But removing these bits isn't my idea of checking the cooling system. Once the bits removed, the system will draw air, very soon air will reach the pump, will stop running properly and you'd have to bleed the system again.

First thing is to make sure:

- the thermostat is working as it should (which it seems you did, but I would just fit a new genuine/oem one, don't buy aftermarket!) and it's fitted the correct way round, with the tiny hole up.

- bleed the system properly

- start the engine keeping an eye on the temp gauge and checking if the cabin heater warms up, then if the top radiator hose warms up and then the bottom one.

Presuming the coolant temp gauge works as it should, don't let the engine run if the needle goes past the horizontal even with as much as a needle width. If you wait until approaching the red zone, the engine will be already toast.

This is how I fill and bleed the coolant system on my 300tdi:

1. Remove all caps (radiator, exp tank and thermostat)

2. Pour coolant in the exp tank until the radiator is full

3. Fit the radiator cap

4. Continue to add coolant to the exp tank until it is at the correct level in the tank (maybe 3-4 mm more)

5. Fit the exp tank cap

6. Add coolant through the thermostat housing hole until it fills up

7. Fit the thermostat housing plug

8. Start the engine looking for the usual, rev it after it heats up a bit (30-40C), maybe take it for a spin after I check for leaks etc (it will heat up faster and I can keep the revs up without disturbing the neighborhood)

9. After reaching operating temp I stop the engine, carefully undo the thermostat plug couple of turns, air will start hissing out, when coolant start coming out I tight back the plug. The coolant system will be under pressure when the engine is warm (actually I make use of it) so watch out!

10. Next morning I check the coolant level and add coolant if necessary

11. I repeat step 9 after a journey (10-15 mile at least), there will still be some air in

12. Repeat step 10 the morning after and set the level spot on (to use it for future reference)

From now on, if nothing wrong with the engine, repeating step 11 will show no air coming out.

Actually, I cheat from step 8 and I blow in the exp tank to make some pressure, repeat one more time, check level the next day and then I let the coolant level switch to tell me if something's wrong . After 2-3 days I do step 9 after a fairly long drive.

If you really want to see if the coolant comes out that bypass hose, you'll have to remove the hose from the other end, plug the hole from where you removed the hose and extend the hose with another piece into the exp tank (remove the exp tank cap). I think there's no need to lift the tank further up. Start the engine and see what it comes out the extended hose. All these with the engine cold. Once warmed up, the thermostat will start opening and the flow through this hose will be significantly reduced.