Head Gasket or am i missing something?

[fozsug]

Right chaps. My 96 300tdi, 87.000 miles, has developed a running hot problem. Driving round town and normal driving, temp gauge stays in the middle. On the motorway temp gauge stays in the middle until i hit a long hill, then it rises up to the top of the white, if i back off the power it drops down, once up the hill it drops down to normal.

It has:-

New water pump (genuine)

New P gasket

Alisports Radiator

Alisports full width intercooler

New genuine thermostat

New hoses

Turbo boost 1.0 bar

Injection Pump NOT tweeked , new reconditioned

New genuine lift pump

Flushed the cooling system, new antifreeze

Heater works fine

No air bubbles in expansion tank

Water level doesnt rise when reved and then let go

No loss of coolant

Sniff test fine

No water in the oil

Pulls like a train

No white smoke

No black smoke

No grey smoke

New temperature sender

Compressions good on all cylinders

This problem has just come on and i have not changed or done any work prior to the fault coming on.

I dont want to take the head off unnecesarily, so any other ideas would be very gratefully recieved.

If the concessous is Head Gasket, what type... MLS or Composite?

Thanks in advance

Tony

[zim]

What fan setup ?

[fozsug]

What fan setup ?

16 inch pacet with X eng switch, never came on till this started to happen, and doesnt seem to cool it down any quicker. If i put the internal heater on to full blast seems to help bring the temp down a bit quicker .

[disco_al]

Injection Pump NOT tweeked , new reconditioned

that could be part of the problem. in the instructions that came with mine, it said that you have to turn the pump diaphragm all the way up to compensate for the extra air being drawn in from the i/c.

if it runs too lean then you will get higher combustion temperatures, which could lead to melted pistons.....

[fozsug]

that could be part of the problem. in the instructions that came with mine, it said that you have to turn the pump diaphragm all the way up to compensate for the extra air being drawn in from the i/c.

if it runs too lean then you will get higher combustion temperatures, which could lead to melted pistons.....

I didn't fit the intercooler it was fitted when i bought it. I replaced the injection pump as the old one seized up. Didnt realise that NOT tweaking the pump could cause higher combustion temperatures. Strange that it has only just started to happen when the pump was fitted about a year ago now. Dont suppose you have the "tweaking" instructions so i can try and see if it makes any difference?

Don't think the pistons have melted yet as compresssions are good and it runs too well

Thanks

Tony

[DrRob]

You could try bunging the standard viscous cooling fan on and disable the pacets and see if that helps.

As always, only do one tweak at a time to eliminate...

[fozsug]

You could try bunging the standard viscous cooling fan on and disable the pacets and see if that helps.

As always, only do one tweak at a time to eliminate...

Great minds think alike..... tried that at lunch time....made no difference.

I was under the impression that the 'ram' effect of air at high speed ie on the motorway was more effective than a fan, fans only come in to play in stationary traffic or high load off road or towing....but maybee ive got that wrong.... wouldnt be the first time!

Thanks for the idea though

Tony

[disco_al]

i'll have a look to see if i've still got them somewhere, if not drop allipsort an email, i'm sure they will send you the instructions.

[fozsug]

Tweaked the pump yesterday.....and it made it worse, got hot even on a slight hill ... so put it back to original setting.

So my gut feeling says it must be head gasket?!

Any other ideas before i strip it down?

And lastly Composite or Multi layer steel head gasket?

Thanks in advance

Tony

[moose]

So my gut feeling says it must be head gasket?!

And lastly Composite or Multi layer steel head gasket?

I did the head on my 300 a few months back and fitted MLS gasket, always used the composite before.

I think the main thing is that there is no give with the steel gasket so the mating surfaces have to be perfectly flat... make sure the head is skimmed and i gave the block face a good clean up with a scotch pad.

I am happy with the MLS gasket as my 300 disco gets flogged mercilessly towing the other truck around so will prob be using MLS gaskets from now on. They should be better as made from metal so are let likely to blow apart.

paul

[fozsug]

I did the head on my 300 a few months back and fitted MLS gasket, always used the composite before.

I think the main thing is that there is no give with the steel gasket so the mating surfaces have to be perfectly flat... make sure the head is skimmed and i gave the block face a good clean up with a scotch pad.

I am happy with the MLS gasket as my 300 disco gets flogged mercilessly towing the other truck around so will prob be using MLS gaskets from now on. They should be better as made from metal so are let likely to blow apart.

paul

Thanks for that. Any sign of oil leak from gasket? as that seems to be the commom complaint of the MLS.

Thanks

Tony

[moose]

Thanks for that. Any sign of oil leak from gasket? as that seems to be the commom complaint of the MLS.

don't think so..... I try not to open the bonnet if i can get way on that truck

[fozsug]

don't think so..... I try not to open the bonnet if i can get way on that truck

Don't blame you..... every time i open my bonnet....my bank balance decreases dramatically

Thanks

Tony

[TheRecklessEngineer]

if it runs too lean then you will get higher combustion temperatures, which could lead to melted pistons.....

Errrmmm.....diesels always run lean. Even at full load there's still about 30% excess air.

If you've got an overheating problem you don't want to be adding more fuel.

[Thys]

Good evening Fozug,

Here are more things to check in your Disco:

1. Does the water level stay constant, or for that matter, is there loss of coolant?

2. With all the work on the radiator and the inter cooler; is the fan shroud re-fitted correctly and docked properly?

3. Were all the rubbers on the sides and front of the radiator frame put back, and if, with the replacement units installed, are they sealing properly to prevent hot air being sucked back to the front of the radiator?

4. Is the bottom front of the radiator frame against the back of the front bumper assembly? A gap will cause air to by-pass the radiator (this was my Disco's root cause for the hight running temperature).

5. Last one: Check the rotational direction of the electric fans in front of the radiator. A change in the wiring polarity can cause them to turn in the wrong direction, thus pulling hot air back, or stalling the air flow in ideal conditions. All radiator/condensor cooling fans must suck air from the front and blow it over the radiator/condensor towards the engine.

I hope one of these will help you.

[fozsug]

Good evening Fozug,

Here are more things to check in your Disco:

1. Does the water level stay constant yes, or for that matter, is there loss of coolant No?

2. With all the work on the radiator and the inter cooler; is the fan shroud re-fitted correctly and docked properly Yes?

3. Were all the rubbers on the sides and front of the radiator frame put back, and if, with the replacement units installed, are they sealing properly to prevent hot air being sucked back to the front of the radiator Yes?

4. Is the bottom front of the radiator frame against the back of the front bumper assembly? A gap will cause air to by-pass the radiator Yes(this was my Disco's root cause for the hight running temperature).

5. Last one: Check the rotational direction of the electric fans in front of the radiator. A change in the wiring polarity can cause them to turn in the wrong direction, thus pulling hot air back, or stalling the air flow in ideal conditions. All radiator/condensor cooling fans must suck air from the front and blow it over the radiator/condensor towards the engine Yes.

I hope one of these will help you.

Hi

Thanks foe the reply....Yes to all of the above.

I have noticed that if i put the heater blower fan on to full blow hot, this bring the temperature down, so i am still erring towards head gasket

Tony

[TheRecklessEngineer]

I'm leaning away from the head gasket. If it is gone to the point that your engine is overheating, then you will see other signs too - like coolant loss/bubbles in coolant and a stink of exhaust in the expansion tank.

I would check your thermostat again. Just because it's new doesn't mean it's good. Pull it out and refit housing. See if you can make it overheat - if everything else is fine, you won't make the temperature gauge move from cold. If something else is the issue then it will behave as normal.

[fozsug]

I'm leaning away from the head gasket. If it is gone to the point that your engine is overheating, then you will see other signs too - like coolant loss/bubbles in coolant and a stink of exhaust in the expansion tank.

I would check your thermostat again. Just because it's new doesn't mean it's good. Pull it out and refit housing. See if you can make it overheat - if everything else is fine, you won't make the temperature gauge move from cold. If something else is the issue then it will behave as normal.

Took thermostat out and took for a drive.... took longer to get hot but still got hot under load up hill on motorway.

Put new genuine thermostat in..... still the same.

So bit the bullet and replaced the head gasket and head, there was no sign of head gasket gone on old one, cylinders looked fine, no signs of cracks, pistons fine, not even much carbon build up.

Run up after new gasket and head fitted ,still no bubbles in expansion tank, sniff test fine, no leaks, no crankcase pressure. Took for drive and still the same, sitting at 60/65 up a hill gets to the top off the white, back off and starts to drop, town driving no problems.

I am at a loss what to try next. I suppose i need to perhaps try a different radiator, even though the Alisports one is not even 6 months old?

Any suggestion would be greatly appreciated as i am completely stumped by this?!!!

Thanks in advance

Tony

[mayur]

You should still have you viscos fan that helps abit and as you go up the hill does the heating go hot or cold ?? Of cold air bubble

[fozsug]

Have had electric fans on for over a year with no vicous fan, was fine all summer even when towing a fully laden plant trailer

Heating gets hotter the hotter the engine is.

There are no air bubbles, no air lock in heater, no water loss.

Water level remains constant.

Pulling my hair out now as need to get sorted as got alot of work to do with it.

Any other suggestions greatfully recieved!!!!!

Thanks

Tony

[disco_al]

as i have only quickly glanced through this again just now, have you changed the temp sender? and are you sure the water pump is ok? even though it still turns, it may not be pumping enough coolant.

i would edge on the side of caution and get some cooling system flush in it, back flush the heater matrix and rad and then refill with a good 50/50 mix of coolant.

[fozsug]

as i have only quickly glanced through this again just now, have you changed the temp sender? and are you sure the water pump is ok? even though it still turns, it may not be pumping enough coolant.

i would edge on the side of caution and get some cooling system flush in it, back flush the heater matrix and rad and then refill with a good 50/50 mix of coolant.

Thanks for the reply Al.

When i did the head gasket yesterday, i stuck a hose on the heater matrix for about half an hour, at it seemed to flow through fine, tried to do the same with the rad but its difficult to see if flow is good.

It is a brand new genuine water pump.

Its on its third genuine temp sender!

When i have pulled over when its got hot, the expansion tank and all the hoses are very hot, saying to me that water flow is ok.

Any ideas how to check the flow through the radiator?

Thanks

Tony

[TheRecklessEngineer]

I have to say I am slightly suspicious of the alisport radiator. Why was is changed? What was wrong with the original? The TDi radiator is well overspec'd for the engine - I've driven round in a 300 Disco with no fan at all in 48 degree ambient heat and been fine. Back flush and check all fins on both sides.

Have you definately got the thermostat in the right way up? The jiggle pin must be at the top. Check the old thermostat by chucking it in a pan of water and boiling.

At this stage I'd be checking the water pump again too - pop it off and check that all is ok. While off, backflush the block too.

There must be something fairly serious to overheat a TDi. The heater matrix alone will cool one with these ambient temperatures.

[fozsug]

I have to say I am slightly suspicious of the alisport radiator. Why was is changed? What was wrong with the original? The TDi radiator is well overspec'd for the engine - I've driven round in a 300 Disco with no fan at all in 48 degree ambient heat and been fine. Back flush and check all fins on both sides.

Have you definately got the thermostat in the right way up? The jiggle pin must be at the top. Check the old thermostat by chucking it in a pan of water and boiling.

At this stage I'd be checking the water pump again too - pop it off and check that all is ok. While off, backflush the block too.

There must be something fairly serious to overheat a TDi. The heater matrix alone will cool one with these ambient temperatures.

Thanks for the reply

The original radiator all fins had gone and sprang a leak

The fins are fine both sides

Put the Ali sports one in as i do alot of towing

By "back flush" do you mean. I have put a hose pipe in the bottom and waited for water to come out the top.

Thermostat definately in the right way up with pin at top, tested in boiling water before i fitted new genuine one so i know is ok.

The water pump was only fitted Two weeks ago as the old one bearing started to go and it started to leak. Again genuine part fitted.

How do you Backflush the block?

Any other sugestions or do i go for Radiator and heater matrix. Everything else is new!!

Thanks

Tony

[TheRecklessEngineer]

Again, I'd still pop it off and check it. If you replaced it only two weeks ago then it should come apart fine.

Yes - stick a hosepipe in the bottom and wait for water to come out the top.

I can't remember how the 300 TDi cooling circuit works off the top of my head, but I do remember that the outlet from the jackets is at the back before going to the heater matrix. Stuff a hosepipe on there with the water pump off and check water pours out the front.

Have you checked for an air lock in the thermostat housing?