B

Bertie Wooster

Member
I've just had the head gasket changed on my Discovery 2, TD5. The head was repaired - welded where there was corrosion, skimmed and pressure tested. But I'm not sure my problems are cured.

1) When started from cold, with no pressure in the cooling system, the top hose starts to pressurise in 30 seconds. Within one minute the sides can't be squashed together.
2) The cooling system remains pressurised after driving, even when stone cold, after leaving the car for 24hrs, pressure is released when the header tank cap is removed.
3) With the header tank raised and the top hose bleed screw removed coolant flows from the bleed hole without bubbles. If the engine is started, at tick over bubbles froth from the bleed scres like a shaken beer can. These stop immediately the entgine is stopped.

These don't sound right to me. Is this normal or do you think the head going to have to come off again?

Many thanks.
 
You could try replacing the header tank cap, as they have been known to go, but it may not be that and i am sure others will be along soon.
Did it do that before you had the head work done, or is this completely new behaviour? Does it overheat? Did you change the stat recently?
Hmm!!
 
That doesn't sound good for a head gasket replacement, it sounds like a good reason to change the head gasket.
Who did the work?
Are all the dowels in place?

I assume Stanleysteamer is pointing toward the expansion tank cap because you are saying it's pressurising and only releasing when the cap is released.
Good idea to check that first then.
 
Bantam1 said:
That doesn't sound good for a head gasket replacement, it sounds like a good reason to change the head gasket.
Who did the work?
Are all the dowels in place?

I assume Stanleysteamer is pointing toward the expansion tank cap because you are saying it's pressurising and only releasing when the cap is released.
Good idea to check that first then.
Click to expand...
I'm saying this for 2 reasons, One is because I have come across others on this forum saying they sometimes give up the ghost but secondarily, although this may be old skool nowadays, once upon a time rad caps used to haver a spring in them to keep the cap closed but then also had a valve in them so that once the engine cooled the system opened to atmosphere to allow air back into the system. I don't think the expansion cap is like that but I expect there must be the equivalent somewhere on the system.
But then again, I could be wrong, I often am.;)
 
I was wondering if he had the tools to do a compression test and a leakdown test, and he could also test the coolant for presence of other stuff if, again, he has the kit with the liquid in it that changes colour.
Recently on another part of the forum there was a guy who thought he might have put his head gasket on wrong, upside down or summat. Don't know if tyhat is possible in this case.
Or could he have accidentally got the wrong gasket? Again, unlikely I'd a thought.
 
Hi All, many thanks for your suggestions and ideas. I drove it about 10 miles since the head was done and it lost around a pint of water (I wondered if this could be a released air lock). I haven't found a leak - but if there is one it can't be too bad because the system remains pressurised overnight.
Gasket was changed by a neighbour and friend who runs a small workshop part time. I would normally have helped but am shielding so that wasn't possible. I'm not sure if a compression and leakdown test is possible, but can certainly buy a kit for testing for combustion gasses. I wonder how sensitive they are? Could gasses in the water which remained in the system from before the head gasket change give a positive?
I've replaced the thermostat just in case that was a problem, and can certainly try a new header tank cap. Easier and cheaper than taking the head of again!!
Thanks again for your ideas.
 
Bertie Wooster said:
I've just had the head gasket changed on my Discovery 2, TD5. The head was repaired - welded where there was corrosion, skimmed and pressure tested. But I'm not sure my problems are cured.

1) When started from cold, with no pressure in the cooling system, the top hose starts to pressurise in 30 seconds. Within one minute the sides can't be squashed together.
2) The cooling system remains pressurised after driving, even when stone cold, after leaving the car for 24hrs, pressure is released when the header tank cap is removed.
3) With the header tank raised and the top hose bleed screw removed coolant flows from the bleed hole without bubbles. If the engine is started, at tick over bubbles froth from the bleed scres like a shaken beer can. These stop immediately the entgine is stopped.

These don't sound right to me. Is this normal or do you think the head going to have to come off again?

Many thanks.
Click to expand...
A pressurised cooling system after 24 hours when stone cold is a pretty good indicator of a head gasket failure or cracked head. Exactly the symptom I had on a car with a failed gasket.

One check you can do is to fill the header tank up to the level of the cap, just below the overflow pipe, with the engine stone cold. Start the engine and look for a continuous stream of bubbles in the tank (with the cap off of course:rolleyes:). Continuous bubbles can only be coming from a gasket etc leak. Your "bleed screw" check really is the same thing too. It does sound like quite a large leak, much more severe than the one I had.

Good luck!

PP.
 
PopPops said:
A pressurised cooling system after 24 hours when stone cold is a pretty good indicator of a head gasket failure or cracked head. Exactly the symptom I had on a car with a failed gasket.

One check you can do is to fill the header tank up to the level of the cap, just below the overflow pipe, with the engine stone cold. Start the engine and look for a continuous stream of bubbles in the tank (with the cap off of course:rolleyes:). Continuous bubbles can only be coming from a gasket etc leak. Your "bleed screw" check really is the same thing too. It does sound like quite a large leak, much more severe than the one I had.

Good luck!

PP.
Click to expand...
I've done that but you have to pinch off the circulation pipe otherwise it is difficult to see the bubbles.
As for the gases check, I've only ever done the test once but I doubt you'd have any "left over" gases in the coolant if you changed it at the time of the head work.
 
Stanleysteamer said:
I've done that but you have to pinch off the circulation pipe otherwise it is difficult to see the bubbles.
As for the gases check, I've only ever done the test once but I doubt you'd have any "left over" gases in the coolant if you changed it at the time of the head work.
Click to expand...
Yes, I feel that this leak is large enough to see in all that turbulence!
 
Hi All,
It's been a while - I'm still self-isolating which makes most things very slow. However, I thought I'd report progress. The head has been off, the gasket was leaking, a possible corrosion problem was welded, head skimmed, tested and replaced. No better!
Head came of again and was replaced with genuine Land Rover gasket and head bolts, again no better!
I didn't have the head tested again because of the time and expense. If it failed then a new head would be needed and it was quicker and easier just to replace it and test it on the car.
So, the problem could be a head or the block, whichever I think it's time for a replacement engine.
Thanks for all your earlier suggestions.
 
Bertie Wooster said:
Hi All,
It's been a while - I'm still self-isolating which makes most things very slow. However, I thought I'd report progress. The head has been off, the gasket was leaking, a possible corrosion problem was welded, head skimmed, tested and replaced. No better!
Head came of again and was replaced with genuine Land Rover gasket and head bolts, again no better!
I didn't have the head tested again because of the time and expense. If it failed then a new head would be needed and it was quicker and easier just to replace it and test it on the car.
So, the problem could be a head or the block, whichever I think it's time for a replacement engine.
Thanks for all your earlier suggestions.
Click to expand...
Before going for a replacement engine and all that entails, can I strongly suggest you have a compression and a leakdown test done. That may well point you in the direction of a diagnosis. If the compression is not coming from a cylinder head leak then I am at a loss to say where else it could be coming from as compression only takes place in the cylinder. Although there is generally a much lower bit of compression in the sump and lower part of the engine, hence the engine breather, but I cannot think of a connection between that and your problem and I doubt it would be stong enough to do what is happening.
 
Hi Stanleysteamer,
Many thanks for that suggestion, and certainly I could do that test. My thoughts were that that if there was a head problem then a new (to me) head would possibly be around £500, this would then have to be tested, injectors swapped and new gasket and bolts bought. Cost would be approaching £1000. If the block was at fault (warped or cracked) then it's time for a new engine. If I could fine a spares or repair Disco with a rusted chassis and good engine then this might be a better route. But I'm open to all suggestions.

Thanks again. :)
 
Give Heathy (Paul) a call at Discovery2parts, based in Essex, but ships everywhere. He'll no doubt be able to provide a good used head or engine. He's a really good guy.
Paul on
01206 211623 - office
07828 278465
07760 955966
07840 428888
 
Hello, many thanks for those ideas. I have tested for combustion gasses, and the coolant is contaminated with them. So there's a leak somewhere. A spot of corrosion was found on the head and this was welded to repair it. After a skim and pressure test it was replaced but there was no improvement so I'm wondering if there is a crack in the block, or perhaps a warped block, and I'm reluctant to spend more time and money chasing the problem. A replacement engine may be cheaper and easier ...... so, thanks for the contact details for Discpvery2parts. I tried ringing today but no answer, I'll try again tomorrow. Cheers.
 
Bertie Wooster said:
Hello, many thanks for those ideas. I have tested for combustion gasses, and the coolant is contaminated with them. So there's a leak somewhere. A spot of corrosion was found on the head and this was welded to repair it. After a skim and pressure test it was replaced but there was no improvement so I'm wondering if there is a crack in the block, or perhaps a warped block, and I'm reluctant to spend more time and money chasing the problem. A replacement engine may be cheaper and easier ...... so, thanks for the contact details for Discpvery2parts. I tried ringing today but no answer, I'll try again tomorrow. Cheers.
Click to expand...
If the head was pressure tested, surely at the same time they put a straight edge across the head to see if it is warped? I have had that done and it literally took seconds.
Getting a head off is not that difficult although it is a heavy lump, then you could take it for skimming yourself and the only expense would be the actual skim and a new gasket set.
Don't know how often blocks warp and need decking and don't even know if decking is possible with a diesel of this kind, but in my experience block warping is much less common.
I do realise that if you have never done this and/or are a bit cagey about doing it, it might put you off. But if you are considering an engine change, who is going to do the labout on that?
Trouble is we all have different experience and therefore confidence. Will he want the old engine back as an exchange? If not once you've got it changed you could play with the old one just to see what it is like and enjoy yourself under less pressure.
 
VERY unlikely the block is warped, heads do get warped and need skimming, although LR say this is forbidden, as the surface of the head, although aluminum has been "hardened" somehow. Rather than skimmed, I suggest it should be "resurfaced" to remove any twist, but ONLY if it is warped. If not warped don't touch it other than clean it. I am about to do exactly this.
 
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