300tdi head gasket failure? Huge coolant loss

I replaced the head gasket about six weeks ago. It started perfectly and ran well.

I've towed my trailer with it a couple of times with no issues.

Today I went to the sawmill and towed home a load which was probably 2.5 tonnes. About a mile from home which is on top of a hill, I noticed the temperature gauge was in the red, and that the heater was blowing cold air, I made it home just as the oil pressure warning light came on.

The expansion tank was under pressure and coolant was splashed inside the engine bay, possibly by the fan. I couldnt see an obvious leak or disconnected hose. The engine struggled to turn when hot, but would happily restart when cold. I checked the radiator, it took about a litre of water to refil it, and I checked the thermostat housing, and it was empty, about a litre filled that too.

When I restarted it there was no pressure in the expansion tank. There are no signs of oil in the water or water in the oil.

So what is going on?

Can you suggest a check list to find the source of the problem.

rad hot all over when engine up to temp ,top hose hot ,heads if been hot enough first time round can move again when upto temp

That sounds a a bit gobildygook.

mcmoonter said:

That sounds a a bit gobildygook.

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check the radiator all over its surface area to find out if theres any cooler spots. this indicates bad water passage and little cooling effect. possibly silted and bunged up, or circulation issue.
check top hose to find out if its hot. cool hose idicates circulation issue, pump or stat or blockage.
if heads already been boiled and expanded, could alter expansion rates on subsequent overheating. never experienced this one.
un gobbledegooked.

edit
how many miles since last change, and what type of head gasket did you use.
did you fit it or did a garage do it?
did you follow the head bolt tightening sequence?
have you tweaked the pump?
have you checked the timing?
did you refill the coolant properly?

as above,,, how olds your thermostat....

Thanks for that. I replaced the thermostat and the temperature sender unit when I replaced the 'head. I will run it up to temperature tomorrow and check the radiator.

Worst case scenario? Would just the head be toast or would the bottom end be toast too?

Where is the cheapest place to source a new head?

EDIT

I changed the oil last week.
Probably less than 250 miles since the head gasket change.
Multi layered metal gasket - manufacturer? - I'd need to check, suspect Britpart.
Diligently followed torque sequence.
I turned the knurled wheel under the diaphram a full turn.
I've not touched the timing.
I thought I had refilled the coolant properly. There were no issues till today.

usually bottom end ok, but as your pressure light came on then i'd be concerned.
how long was it on for?

nrgserv said:

check the radiator all over its surface area to find out if theres any cooler spots. this indicates bad water passage and little cooling effect. possibly silted and bunged up, or circulation issue.
check top hose to find out if its hot. cool hose idicates circulation issue, pump or stat or blockage.
if heads already been boiled and expanded, could alter expansion rates on subsequent overheating. never experienced this one.
un gobbledegooked.

edit
how many miles since last change, and what type of head gasket did you use.
did you fit it or did a garage do it?
did you follow the head bolt tightening sequence?
have you tweaked the pump?
have you checked the timing?
did you refill the coolant properly?

Click to expand...

its not uncommon with ali heads ,once its been hot enough ,valve seats can drop out ,but usually head moves again ,

jamesmartin said:

its not uncommon with ali heads ,once its been hot enough ,valve seats can drop out ,but usually head moves again ,

Click to expand...

cheers jim, will bear this one in mind

The oil light came on for perhaps a minute. When I restarted it the light stayed off. I will run it up to temp tomorrow and check both the cooling and the oil pressure.

There were no unusual noises from the engine.

mcmoonter said:

Thanks for that. I replaced the thermostat and the temperature sender unit when I replaced the 'head. I will run it up to temperature tomorrow and check the radiator.

Worst case scenario? Would just the head be toast or would the bottom end be toast too?

Where is the cheapest place to source a new head?

EDIT

I changed the oil last week.
Probably less than 250 miles since the head gasket change.
Multi layered metal gasket - manufacturer? - I'd need to check, suspect Britpart. hmmmm.....
Diligently followed torque sequence.
I turned the knurled wheel under the diaphram a full turn.
I've not touched the timing.
I thought I had refilled the coolant properly. There were no issues till today.

Click to expand...

mcmoonter said:

The oil light came on for perhaps a minute. When I restarted it the light stayed off. I will run it up to temp tomorrow and check both the cooling and the oil pressure.

There were no unusual noises from the engine.

Click to expand...

never used a britpart hg, heard too many horror stories.
all pump tweaks ive read, are a quarter turn. never done one myself.
a minutes a long time with low oil pressure. might be lucky!
were you still under load without oil pressure?

were you still under load without oil pressure?

Click to expand...

I just reversed into the yard, so little more than idle.

Multi layered metal gasket - manufacturer? - I'd need to check, suspect Britpart. hmmmm.....

Click to expand...

never used a britpart hg, heard too many horror stories.

Click to expand...

I'd heard that metal laminate gaskets were the way to go. Who else other than Britpart make these gaskets?
Are the fibre gaskets better?

mcmoonter said:

I just reversed into the yard, so little more than idle.





I'd heard that metal laminate gaskets were the way to go. Who else other than Britpart make these gaskets?
Are the fibre gaskets better?

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always gone on recomendation of elring or payen head gasket.
not had a problem so far. bought thru a local engine remanufacturer.
(where i also get pressure tests and skims from)

Update - I refilled the cooling system and restarted the engine. The low oil pressure warning light went out immediatly with no knocks or rattles.
I struggled to bleed air from the heater matrix, and ended up jacking the front up to expel the air. The car idled for twenty minutes or so with no appreciable increase in water temperture. No warm air at the heater and no real increase in temperature at the radiator hoses. There was no pressure at the header tank or the thermostat housing plug.

When I rebuilt it I fitted a new thermostat. I wonder if it could have failed after the overheating in the open position. The fan is keeping the radiator permanently cool. The dash temp gauge sits at the 9 0'clock normal position.

I'm going to get a new thermostat and more antifreeze again tomorrow.

I'm thinking there may have been a minor airlock before the overheating. Though the heater did work.

300's will rarely get warm on tickover. i usually wedge the accelerator at 2000rpm ish and leave it for 10 - 15 mins.
to bleed, remove header tank cap, rad bung and stat bung.
fill thru header till water flows from rad bung hole.
replace header tank cap and rad bung and fill thru stat housing.
(i use a funnel wedged into stat housing and fill it half full, squeeze top hose till bubbles stop coming up thru funnel)
replace stat bung and run fast idle with heaters set to hot and blowing.
takes about a roll up and tackle clear up's worth of time to blow warm.

does your viscous fan work correctly and is the rad full of mud from playing in puddles?

edit
worth checking the 3 way connector between stat housing, rad and header tank for blockages too.

Thanks for that. The rad is clean externally, I will give it a flush through and check the three way hose too.

I went for a spin uphill after it had been idling up to temp. It made no difference, all the hoses and rad were cool which makes me suspect the 'stat is open.

The viscous fan seems to be working, certainly it turns when cool.

Give it an oil change while you are at it , use a high detergent oil . If in any doubt its worth fitting a simple oil pressure gauge with a T piece at the sensor to keep the stock one . This gives a much better indication of oil probs before they happen unlike the stock light that tells you after the problem . The oil pump arrangrment on the 300 is less than ideal bring buried as it is so if in any doubt the above stuff has got to be worth it . I have killed more 300 emgines by by overheats than any other fashion . And I have killed a few , something I am NOT proud of .

Update update.

I checked the thermostat and it was fine. I filled the heater matrix by disconnecting the feed hose from the rear of the head. I couldnt get access to the jubilee clip that held the bottom radiator hose on because of the fan shroud. I've ordered a viscous fan spanner to get it out of the way. I may try and borrow one tomorrow to speed things up.

Operating temperatures were still low. Barely heating the radiator and heater hoses. I took it for a drive up some hills, I briefly had heat through the heater vents. Driving back up hill to home, the gauge went up to the red. But the coolant in the expansion tank although under pressure was only tepid. Water flowed out though not under explosive pressure like a head gasket failure. The radiator was nearly empty. No steam through the exhaust, no knocks or bangs. Oil pressure light remained out. Still no oil in the water or water in the oil.

Anything I've missed?

The poor circulation and inability to expel the air from the coolant has led me to suspect the water pump. I have heard tales of the impeller parting from the spindle. Once removed it seemed ok. It has a metal impeller. The bearing feels sound.

While looking on ebay I noticed pumps being sold with a 'P' gasket. A metal gasket which sitsbetween the pump housing and the cylinder block.

Would the failure of this gasket have any bearing on my problems?

mcmoonter said:

The poor circulation and inability to expel the air from the coolant has led me to suspect the water pump. I have heard tales of the impeller parting from the spindle. Once removed it seemed ok. It has a metal impeller. The bearing feels sound.

While looking on ebay I noticed pumps being sold with a 'P' gasket. A metal gasket which sitsbetween the pump housing and the cylinder block.

Would the failure of this gasket have any bearing on my problems?

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it would only cause coolant loss ,evident with staining down front of block where housing joins it