Plucking up the courage... Head gasket and cambelt

2.5 N/A head gasket replacement - Land Rover Technical Archive - LR4x4 - The Land Rover Forum is pretty useful. Hotspots seems to be easy to ..ahem.. spot. But roll pins, not heard of those.

The roll pins hold the hotspots in place. There is a little groove in the head and hotspot for them. You just line them up and gently tap into place. One per hotspot. I then filed the ends of them smooth with a stone so that they do not protrude, otherwise they will damage the gasket.

If the hotspots fall out of the head, check carefully for cracks in the head.

So, this is what the head looked like. Note the crack from hot point to valve (I think inlet) and severe pitting of the head over that cylinder. Could this have caused rough running? The overheating itself could be due to a failed thermostat. The head gasket itself was metal and seemed to be in tact.

Yes it would cause rough running. Sadly the head is toast. When this happened to me, I bought a new head of ebay which turned out to be warped!

What might have caused it? I'd like to put that right before plonking on a replacement head. It was running like a sack of spanners before it overheated.

I had a slightly warped head on mine, bent push rods, cracked pistons and it was mainly due to timing belt snap and over heating, I would get your blocked checked also before you put a new head on it.

2ndyouth said:

So, this is what the head looked like. Note the crack from hot point to valve (I think inlet) and severe pitting of the head over that cylinder. Could this have caused rough running? The overheating itself could be due to a failed thermostat. The head gasket itself was metal and seemed to be in tact.

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pitting is a sign of water entering cylinder, and so would cause coolant loss and later over heating

RodneyA said:

I had a slightly warped head on mine, bent push rods, cracked pistons and it was mainly due to timing belt snap and over heating, I would get your blocked checked also before you put a new head on it.

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id check injectors with cracked pistons

Any DIY way to check them? Engine rebuild has skinned me so far

My comment was intended as a warning rather than a suggestion.

Is there any wisdom available on the codes for the cylinder heads? A couple of places I've called are offering different codes and I'd like to know that what I'm buying will fit.

Give Turner Engineering a call and they will point you in the right direction regarding parts, I recently done a full rebuild and sourced nearly all parts from them, fantastic service and very knowledgable.

They're just 14 miles up the road from me. I'll give them a call in the morning although the website said that an exchange head with the usual bits & bobs installed (which is very convenient) is £395 + VAT!

Really like to know what destroyed mine in the first place though.

They'll be able to tell you that easy, this is all new to me also after finding out my engine is damaged, not sure how mine happened also

Are you rebuilding it yourself or having it done?

I was toying with buying another 12j from eBay but you just don't know what you're buying and I've never pulled an engine and refitted before. Also, without a garage, I'm weather dependent and the fettling has to fit around an unfriendly work pattern.

Not sure the whole thing is worth the money of getting it done professionally. That's the penalty for not viewing before you bid.

Spoke with Turners. Very pleasant and knowledgeable but only had new heads available which make it very pricey. Found a Cornish company that will give me a reconditioned one for a £300 saving.

Should be with me Monday next week.

Nice, what's the condition of your bores and pistons?

My new pistons arrived from Turners today



My block has been rebored and cleaned, on the top anyway lol.

presumably bored to the actual piston size minus 2 thou for honing to finished size?

As far as I can tell there's no damage. There's a bit of blackening which shouldn't really be a surprise. No perceptible damage to the bores than can be seen or felt with the fingers although you can feel a ridge running around the top of the bore at the point where the piston reaches. There is no sideways movement of the pistons in the bores. Not very scientific but, short of taking the block out and sending it away, there's not much I can say. Once I get a known good head back on I could do a compression test.

What other indications might I look for?