• 4 April 2016 at 16:34 #51850

    After many faultless miles I suffered a sudden increase in water temperature which suggested a head gasket or worse. After cooling and refilling large bubbles were finding there way to the top of the radiator, in burps so to speak rather than continuous flow. I now have the head off and a nice little gap blown in the copper gasket between 3 & 4, effectively straddling the water channel. There is no immediate sign of cracking although this is a very preliminary diagnosis ( there was no water loss either other than in steam and expansion). Is it a possibility that the blow between the cylinders could locally super heat the water to create the bubbles? I might have driven no more than 20 miles with the damage. Regrettably this occurred on a test drive prior to a December wedding function which I carried out as the temperatures were cool and the bride needy! Other than at the initial failure, water temperature did not exceed 80 degs. Any advice most welcome before I fit a new gasket etc. and find the water issue still with me.

    4 April 2016 at 18:06 #51852

    The most likely scenario is that the gasket failure has resulted in compression pressure leaking through to the water jacket. That would certainly result in the bubbles you see.
    That said, clean everything up and check for cracks; let’s hope it’s simply the gasket.

    5 April 2016 at 12:43 #51853

    Also check that there is no water in the oil – so maybe change the oil to be on the safe side ?

    Julian Messent
    5 April 2016 at 16:50 #51854

    Hi Bob,

    On the 4.5 litre engine the head / block face is “Dry” this means that there are no waterways within the head sealing faces, water only passes to the head via the aluminium transfer poorts on the exhaust side so bubbling must have been caused by something else.

    Simply clean up, check the deck and head are flat, and if so, fit a new gasket and test.
    Probably all you need.
    Do an oil change at the same time though as you will probably get some crap into the oiul return holes so always best to be safe.


    David Bracey
    10 April 2016 at 02:53 #51858


    Could you post a photo of your damaged gasket?

    Have you discovered the cause of the air/gases getting into your water? I’ve just developed similar problems. Yet to start stripping down and doing a compression test although no power loss.


    14 April 2016 at 09:17 #51861

    I have the head off now and there is a good piece of gasket missing between 3 and 4. No apparent cracks anywhere so hopefully that is it! The fact that it straddles the waterway may mean localized heating hence the strange bubble format. One of the head studs is also very close to the break and could add extra heating perhaps. a I will certainly change the oil etc, as I would anyway.
    I refitted an annealed gasket with “well seal” last time, which has obviously not lasted forever. I guess firstly the annealing process is pretty hit and miss and the well seal means a lot of scraping now. Do you fit the gasket dry, oiled or what?
    I have a couple of photos but cannot upload them as the file size is too large. I can send them by email if that helps, or advice on how to load them hear would be helpful.
    Sorry for the delay in replying, I wonder if we have a “notify me by email” of any replies, in the forum?

    14 April 2016 at 10:04 #51862

    I think I am feeling pleased with myself for resizing a couple of photos, to upload. Hope they work!

    Attached files

    Richard Branch
    14 April 2016 at 20:31 #51863

    I don’t have an answer to your question however to post pictures (on most forums I use) I prefer to host the image somewhere like Photobucket or Flickr and them simply post the link (url) from the hosting site into my post on the forum. Much easier and it means you don’t have to resize etc. People reading the thread can enlarge the image properly to see the detail if necessary.

    15 April 2016 at 10:10 #51864

    There are on-line image resizers. A Google search will find plenty. Never tried one but I guess they do the job.

    David Bracey
    18 April 2016 at 07:57 #51866

    davidbracey wrote: Adam,

    Could you post a photo of your damaged gasket?

    Have you discovered the cause of the air/gases getting into your water? I’ve just developed similar problems. Yet to start stripping down and doing a compression test although no power loss.


    An update on my own situation.

    Fortunately I don’t have any significant problem but it’s worth sharing. The only problem I appear to have had has been that the radiator cap wasn’t effecting a seal. What I experienced was frothing water/anti-freeze splurting out of the cap and being thrown onto my windscreen. I was concerned about what was causing it to froth up and suspected water pump cavitation caused by a restriction on the suction line from the radiator or air being sucked in somewhere. No such problem could be found. Several experiments mixing up anti-freeze and water in buckets with a food blender showed that they will froth up through normal mixing. Sorting out the radiator cap alone appears to have solved this problem. I did 150 miles at about 60-65mph on Saturday and neither the car or I suffered any ill-effects.

    18 April 2016 at 08:31 #51867

    Yes David, this is a similar problem I had a year or 2 ago. I think there may be a slight “design fault” with the LG45 cap and you need to be absolutely certain that it goes down flat onto the neck – with a decent cork or similar seal. I solved my problem by paying particular attention to the cap and also to the seal. Also, as you probably know, only fill up the header tank inside to a level which is equivalent to the top edge of the badge (fixed outside).

    18 April 2016 at 08:34 #51868

    Sounds like the moral of the story is, that the 4.5 is a pretty robust engine and we are overly sensitive to the simple things! Glad that all is well. It is worth ensuring that the spring seated overflow valve is clear and don’t overfill the header tank. If the water is expanding and cannot get out, the radiator cap is not man enough to contain it. Hence wet windscreen.

    David Bracey
    18 April 2016 at 12:23 #51870

    I’ve come to accept that these Lagonda’s are like petulant children. When thing’s aren’t going exactly as they want they protest in the strongest terms. Not always proportional to the problem!

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