P38 DSE Overheating (yet another)

sorting either a new head or a head rebuild. is there a specific cause to this cracking in the head, or is it just a casting fault? would be nice to avoid it happening again!!!!

lil4399 said:

sorting either a new head or a head rebuild. is there a specific cause to this cracking in the head, or is it just a casting fault? would be nice to avoid it happening again!!!!

Click to expand...

There can be many reasons why a head cracks. Bad stress relief in manufacture can be one. But usually with a vehicle it is down to engine overheating. An airlock can cause localised extreme stress allowing one area to heat and expand more than another. Water pump failure is know on these engines. If the overheat is not spotted straight away that can cause a crack. There are not many that crack and cause overheating spontaniously, more often than not the engine has been subjected to overheating sometime previously, which creates the conditions for later failure. Same thing with the V8.

The plot continues to thicken ......
Took the RR to my mechanic and he is not sure its a cracked head, he can't beleive the engines runs perfect without overheating until I run it for a long run up big hills. He thinks its a rad problem - he thinks cooling is marginal under normal conditions (even in this heatwave) and then can't cope under heavy load. Obviously a new rad is cheaper than a new head, anyone had any similar experience?
I will get to the bottom of this eventually!!!

I'm sorry to say that these symptoms are just like the ones I had. I didn't want to believe it was the head for the same reason as you have given so I spent a small fortune on other cheaper possiblities that just didn't work.
I see your posts and can't see anything further than your problem being a cracked head but I wish you well if you choose to eliminate all possibilities first.
Good Luck

M51 engines are not renowned for over-heating, even with plastic impellored water-pumps. All your symptoms point at a cracked head so do a sniffer test, that will give the truth.Even with an enlarged oil cooler I have never encountered cooling problems on the way through the Sahara so its not design faults, removing the air-con condenser will help but thats not solving the problem.Binning the viscous fan and fitting two electric ones is really only needed if you want to save 5% fuel or tow in low ratio for a distance, look for something interrupting coolant flow, collapsing pipes,scaled radiator,air locks etc, as somebody pointed out, if the baby pipe from rad to tank is not totally clear you will never be able to bleed the system.

I had exactly the same problem onmy beloved P38 97', i changed all the usual bits water pump, thermostat, rad, rad cap etc.. and even fitted twim elec kenlow fans £300 !! after doing all the sniff tests it still didn't show that the head was cracked even though hair line it didnt show up until it was under serious strain i.e. pulling my snail.. finally after all was done i gave up removed the head and had it dye tested and surprise surprise the head had a hair line fracture..Replacement head /gaskets later and all was well.. just wish i'd gone with the head initally, would have worked out a lot cheaper.. GOOD LUCK

Anyone know of Bridge Cylinder Heads in Hyde? they have the best price so far (just under £500 + vat)
I would prefer a recommendation before I buy if possible!

About bleeding air locks, this aplies to DSE's?
How do you do it?
And the sniff test, how can i do it?

I have just done a trip about 750miles (average speed 65miles/h) and i suspect the car is overpressuring (temp gauge at midle, everything looks fine), at the end of the trip when i removed the cap from expansion tank the water looks like is boiling (engine running)...
(the engine had a major repair about 2months ago)....
Any clues?

Many thanks
Joao

I've been following this thread over the last few weeks.
I bought a 98 Range Rover dse. After a few days I started having all the problems mentioned here. Luckily the garage I bought it from is standing over it.
So far the radnhas been checked, water pump replaced, new thermostat and switch(needed replacing)
he was advised to check o rings despite there not being any warning signs such as the usual wet passenger floor, and guess what they are leaking, not a massive amount but he's hoping that these were the culprits.
Dash is out now and hopefully will get to test it on the motorway to see if that was the problem. If not he's gonna do the head for me.
I have to say I'm getting incredible service from this guy, and all for nothing!! Could be the best car I've ever bought yet.

Thought this might be of help to others. Any thoughts on whether this could be causing the problem?

jonasserra said:

About bleeding air locks, this aplies to DSE's?
How do you do it?
And the sniff test, how can i do it?

I have just done a trip about 750miles (average speed 65miles/h) and i suspect the car is overpressuring (temp gauge at midle, everything looks fine), at the end of the trip when i removed the cap from expansion tank the water looks like is boiling (engine running)...
(the engine had a major repair about 2months ago)....
Any clues?

Many thanks
Joao

Click to expand...

There is nothing wrong. The system is supposed to pressurise to raise boiling point of coolant. DO NOT remove cap with engine hot, ONLY when engine is cool. Removing cap with engine running and whilst it is hot will always expel water from system.

Update
Sick and tired of having an overheating problem.
Towed the boat back from a fishing trip and plastic top of radiator cracked once again. Limped home, 10 litres of water every 20kms.

So, I bit the bullet, thought this is my last spend.
(British parts - not britpart).
Ordered:-
1. Genuine Radiator
2. Genuine expansion tank
3. Genuine viscous fan
4. Genuine radiator cowling
5. Copy, condensor.

Put it all together and no more overheating!!!!
Work that out?

Remember, I had changed everything, the only difference this time is original equipment.

I am a happy fella now.
No overheating.

kzrocky said:

Update
Sick and tired of having an overheating problem.
Towed the boat back from a fishing trip and plastic top of radiator cracked once again. Limped home, 10 litres of water every 20kms.

So, I bit the bullet, thought this is my last spend.
(British parts - not britpart).
Ordered:-
1. Genuine Radiator
2. Genuine expansion tank
3. Genuine viscous fan
4. Genuine radiator cowling
5. Copy, condensor.

Put it all together and no more overheating!!!!
Work that out?

Remember, I had changed everything, the only difference this time is original equipment.

I am a happy fella now.
No overheating.

Click to expand...

For extra security, add a thermostat to bring on the aircon condensor fans when the car is working hard.

Datatek said:

For extra security, add a thermostat to bring on the aircon condensor fans when the car is working hard.

Click to expand...

Tried that already, bridged the relay. Made no difference.
Now, cause I changed the Fan, Radiator, Tank all for genuine, something in that equation made a difference. Im suspecting the non-genuine radiator as the culprit.

Im a little concerned reading the above as i have ordered a radiator from island 4x4 to replace a 10 year old genuine radiator. Im now wondering if i should have bought a genuine one?

There has been a few other threads on this in the past where it's been found that recon radiators don't have the baffle in the top. Without this, the coolant will go straight through the top of the radiator and out again. With the baffle there, it's forced down and through the radiator and hence cooled more.

Hello,

When i swaped my old engine for a bmw 525tds, the mechanic made some holes in the thermostat....
Noticed then that engine temp barely goes above the blue zone..
I wonder if this is a reliable solution....
(owner manual states that normal engine temp neddle at the gauge stays at midle)

jonasserra said:

Hello,

When i swaped my old engine for a bmw 525tds, the mechanic made some holes in the thermostat....
Noticed then that engine temp barely goes above the blue zone..
I wonder if this is a reliable solution....
(owner manual states that normal engine temp neddle at the gauge stays at midle)

Click to expand...

Engine is not running hot enough then. It will be very inefficient. Fit a proper stat. One without mechanic created holes in it.