I seem to recall my head bolts being a 5/8ths socket

That looks about right, 5/8ths of an inch is 15.875mm which would explain why a 16mm plug socket fits nigh on perfectly.

Thanks guys - I'd have replied last night, but my ipad couldn't open the site for some reason.

Today, I have bought a 16mm single hex impact socket. That should see me right. The gun has some serious grunt if needed. I've actually also ordered a 5/8 socket too, because..... well, just because!

On the mudguard question. I can feel that there's some sort of metal strengthener inside the rubber. Because I haven't got one off yet, I can't tell if it's fully enclosed, or if a new one could be 'slotted in' to the plastic sleeve?? If it's mild steel, in a place like that. it's always going to rust and disappear quickly.

Would it be acceptable to just cut a P38 mudguard shaped piece out of a larger one where there's no metal stiffener - like a lorry mudguard - and then screw that in place; or does that belong to the Order of Much Naffness?

They have mild steel inside them which seems to have come from Toyota, as they are very prone to rust. I removed mine and haven’t reinstalled any. New ones are available but cost more than you would expect for what they are. If you cut some rubber to fit, let us know how it turned out.

As mine is ex-police, it still has the huge Spraystopper mudguards on it which are just cut from a sheet of this https://www.truckware.co.uk/acatalog/Anti-Spray_Mudflaps_-_Manufactured_by_Clearpass.html. There would be nothing to stop you cutting them more to the size of the original ones and using the original mounting points (if they are still there that is)

Right. Bggr and F*ck. Thanks for the replies on the mudguards, Gents, but that question's somewhat on the back burner now.

I think I'm facing a serious 'reappraisal' moment.

Armed with my 16mm impact socket, and my impact gun, I went back out to the garage. According to the data sheet (I've just checked) the gun will deliver 610Nm of torque. It is making no headway at all with these bolts.

So I tried the manual approach. On #2 bolt (the one tucked into the recess, with the head covered in nice, slippy old engine oil) a 600mm 1/2 breaker bar with a tube on the end, giving a 4.5ft lever, and my 16mm single hex plug socket. The socket snapped.

I hate giving up on things like this, so I "could" get a 3/4 drive, 5/8 impact socket (if such a thing exists - doesn't seem so on the basis of a quick google) and drag my 3/4" breaker bar out of the back of the drawer and try this with a 6ft scaffolding pole, but short of that, I think I've thrown everything I have at this. 16mm doesn't seem like too good a fit, I have to say. I now also realise that the 5/8 one on the way to me will probably be too 'fat' to get onto some of these bolts. Before taking any final decisions I'll probably get a deep 5/8 impact socket sent up (non for sale locally) and try that. But that would really be me having shot my bolt - pun absolutely not intended - I'd have nothing else to go to short of the grinder.

"Rather annoyed" locking up the garage. Calmed down a little now, but it's still a watershed moment I feel.

I guess I could just 'weigh it in' - not really keen on that, because I don't like giving up on things, but common sense has to come into it somewhere.

I could maybe take a grinder to the head, butcher it and get a reconditioned one, but if I can't get the bolts to shift with heads on them, I can't see that it's going to be any easier as a bare stud.

Buy another one, and strip this for parts?

So I'm looking for thoughts and other suggestions please?

A recon engine (quick look) is the best part of £5,000 and that doesn't seem sensible; spend a few £100 and inherit someone else's problems? that doesn't seem too sensible either. Graduate from planning to only remove the heads, to lifting the engine out and take it to a local machine shop...? I'd have to invest in an engine crane and other bits and pieces.

Don't really know. Not a happy bunny I'm afraid. I think it's compounded by the fact that I've run into this brick wall on the very first head bolt.....

This all happened about an hour or so ago, so still quite fresh. I suspect if I sleep on this, weighing it in might emerge as the more sensible approach, cutting my losses.

If I was to put the wheels back on and get it trailered to a garage, do they have any magic tricks they could use to get round a problem like this?

Like I often say, any suggestions gratefully appreciated, but particularly tonight!

That may be why only one head was off before? I've never had a problem getting them out but it has involved a serious amount of grunt and a big long bar. Maybe my plug socket is a better quality one that yours? They do tend to go with a hell of a crack though. I use the plug socket with a 2" extension so the handle clears the head casting and my big bar. The short extension means there's less chance of it twisting sideways. 3/4" drive, 6 point impact socket should shift it.

Of course your other option is that as the head gaskets aren't blown and you are only replacing them as a preventative measure, just leave them......

Maybe some good quality freezer spray will sufficiently"crack" the rust on the headbolt.............just a guess

Or see how many of them will move with brute force and use some cobalt drills to drill the head off those that won't shift?

Heat the bolt ? Could be corrosion ? 610nm should be ample to shift bolts ----- you were doing anti clockwise ? Loss of patients/ temper can effect logical reasoning ---- give up have a cuppa and relax tackle fresh another day 🤗

Thanks Richard, yeah - just leaving them be and fixing the coolant leak is definitely an option. I thougt I'd included that in my little rant, but I must have edited it out without realising.

Because of the big oily stains on the front of the heads, I do wonder if perhaps there might be some leak there, but as far as I'm aware there are no mechanical signs of it. Runs fine as far as I can tell, no unusual smoke, pulls well, and I think the only coolant it's using is the stuff that's leaking. If I do this, I'll clean that gunk off and then keep an eye on it. At least this way I could take any further decisions a step removed from a 'moment of crisis'.

This would dent my confidence in the car a little though - a low mileage engine is one thing. A low mileage engine with issues you couldn't fix would be another.

Ho hum.

A lot more reading on stuck cylinder head bolts suggests stuff like heating, or even cutting the heads off the bolts with a dremel. That might work on the outer ones - not a hope on the ones inside. I did search for a 3/4 drive 5/8 socket, but I don't think such a thing exists. The search was defaulting to 1-5/8 sockets...

I've also been researching the ebay price of breaker engines.... maybe for future reference. They're not unreasonable, but it would surely be a bit of a lottery.

Sorry guys - hadn't seen the other replies coming in.

Totally agree - walk away and calm down is a good idea. And yes, I was using the gun anti-clockwise 😎! Haven't tried freezer spray, but there could be a first time.

Further question though, on the point about removing some, and drilling out the remainder - presumably by removing the bolts 'randomly' it's more likely the head would warp and need attention (though they are obviously stone cold.)

I used a 3’ bar (piece of pipe around my breaker bar). I understand why people spend the money on ARP studs. It’s probably my stubbornness but if it was me I would persist in removing the head.

Leave heads alone your water leakage WILL BE RAD ----- I kept finding small puddles under vogue it was rad & fan blowing it around ----- soooi bet your rad let go --- the tubes in rad are billux ----- got bigger tubes in a Morris minor rad 🙄

I'm also stubborn, and I've bought ARP studs... sitting on the shelf.

And I'm near 100% sure the water is from the valley gasket, not the head or the radiator - which looks to be in pretty good condition. I was able to trace pink coolant deposits from the bellhousing, up to the starter, and to the back of the valley gasket. In fact I was just about able to see the actual coolant leaking down at one point. There's a pic above (not brilliant) which shows more dried, pink coolant deposits.

But I still don't 'have to' remove the heads. They were just on the basis of 'seeing as I'm going to be in there, and a slight chance that one of them has a weeping gasket, so it's now a case of stubborn vs sensible...

it could be lock tighted in so you will need heat for that , try the other bolts just to see if they move , also try a good smack with a heavy hammer on the head of the bolt , try forwards and reverse with the rattle gun if its possible put some heat on it around the block area even a heat gun might do it just take longer.

Don't try heat as the alloy will expand more than the steel and make it tighter. A good smack may help though. See how many you can crack undone, just an 1/8th of a turn will be enough that the head won't be distorted, and if you need to drill the heads off the remaining stuck ones. When I took my engine out, 3 of the flex plate bolts came out but the fourth refused to budge until I'd rounded it off. I started off with a 2mm drill down the centre of it for the depth of the head, then went up a bit at a time until I reached 8mm and the head just fell off. Cobalt drills, cutting fluid and patience. With a head bolt it won't matter if you aren't completely central as the holes in the heads are bigger than the bolt diameter.

the heat is to loosen the lock tight .thats if its been used (they use heat on outboard motors all the time )it will not do any damage ,your only warming it up not cooking it.

Thanks again guys,
I went round the tool shops here this morning. No sign of a deep 16mm 1/2 drive socket (far less a 5/8)- but someone did wonder if the bolts might be loctited in..
I went to the local Precision machine shop and spoke to a guy there. He suggested a 3/4 drive, 5/8 impact socket. That is a strange beast in the UK. He also suggested (as above) a good solid whack on the head of the bolts with a brass drift - said it could be surprisingly effective.
Came back to work, and have now ordered a 3/4 drive, 5/8 deep socket from the States.. and a set of heavy brass drifts. I have also got a set of cobalt bits (the machine shop guy grimaced when I mentioned that - pretty crude from their perspective I suppose) but one way or another, these heads are coming off.....
While I'm waiting for these new things to arrive, I'll have a go at getting the RHS mudguard, wing liner and manifold off. Perhaps the bolts on the RHS head will be easier, and give me a wee confidence boost.

Only just seen the head bolt saga, I had similar once, use a halfords 10 mm plug socket ( 16mm ) and a breaker bar, I use a 3/4 bar as no flex, not had one I can’t get undone yet, if slightly rounded I use a grip tight socket ( Chicago brand)