EBay Head - opinions on some pitting
Discussion
Always nice to clean up your eBay bargain and find something unexpected.
I'm no engine expert, and this is my first foray into headgaskets changes. The plan was to pop a new and lower mileage head with hotter cams in to save me the task of swapping cams about, but I gave found some marks the plastic scraper won't touch. You can see them on the right of the picture, just outside the fire ring. There are a few others, but these are the ones I can feel with my finger
All opinions welcome.
I'm no engine expert, and this is my first foray into headgaskets changes. The plan was to pop a new and lower mileage head with hotter cams in to save me the task of swapping cams about, but I gave found some marks the plastic scraper won't touch. You can see them on the right of the picture, just outside the fire ring. There are a few others, but these are the ones I can feel with my finger
All opinions welcome.
Edited by Smitters on Monday 25th February 12:56
Head doesn't look in brilliant condition to me.
The marks look enough to weaken the gasket seal, plus look at the condition of the valve areas. Main 1 shown, looks very oily and potentially not well sealed valves. Look at the cylinder above and valves again look poorly seated, plus colour of valve indicates a blown gasket/coolant issue, plus lots of oil too.
Always difficult to judge via picture, but I wouldn't be in any rush to fit that as it is.
The marks look enough to weaken the gasket seal, plus look at the condition of the valve areas. Main 1 shown, looks very oily and potentially not well sealed valves. Look at the cylinder above and valves again look poorly seated, plus colour of valve indicates a blown gasket/coolant issue, plus lots of oil too.
Always difficult to judge via picture, but I wouldn't be in any rush to fit that as it is.
227bhp said:
Looks like a porous casting
No it doesn't. It's outside of the fire ring and not really consequential. A new gasket would seal on that ok. However I'd go over the head with 80 grit wrapped round a block of wood and lubricated with paraffin or diesel and then finish with 120 grit.Mignon said:
227bhp said:
Looks like a porous casting
No it doesn't. It's outside of the fire ring and not really consequential. A new gasket would seal on that ok. However I'd go over the head with 80 grit wrapped round a block of wood and lubricated with paraffin or diesel and then finish with 120 grit.these are classical casting porosity indents in Rover K heads. The double line also shows it had a new head gaset before.
The K is very sensitive towards these as the classical head gasket only sells across a narrow seal line.
the newer N-series designs have a few mm wide flat sealing rings.
You can do either/or:
-peen the fire ring area with a ball tipped tool and skim the head afterwards. DVS aka Dave Andrews is the man how did and/or published this first.
-fit a MLS with a shim to seal against pores
-fit a SAIC N-series gasket with wide firerings and not worry about it.
Best: peen, skim and add N-series head gasket
The K is very sensitive towards these as the classical head gasket only sells across a narrow seal line.
the newer N-series designs have a few mm wide flat sealing rings.
You can do either/or:
-peen the fire ring area with a ball tipped tool and skim the head afterwards. DVS aka Dave Andrews is the man how did and/or published this first.
-fit a MLS with a shim to seal against pores
-fit a SAIC N-series gasket with wide firerings and not worry about it.
Best: peen, skim and add N-series head gasket
227bhp said:
Vas ist das?
Maybe https://www.eliseparts.com/products/show/29/1246/p...Looks as if some people have put a lot of work into tackling problems like this.
When Land Rover was owned by Ford they introduced a MLS head gasket and a shim. It was called the head saver shim. It is a 0.3mm coated stainless steel shim that sits between head gasket and the cylinder head. Its task is to specifically cover porosity in the sealing area.
It won‘t prevent indentation of the head by the head gasket if the aluminium anneals and turns soft from overheating. It is too thin.
The newer N-series gaskets have a very different fire ring design. They moved from a steel wire surrounded by a thin aluminium foil to a few mm wide and flat sealing area. This reduced the pressure on the aluminium making it more tolerant to the cylinder head turning soft and it covers pores better. The severity of the pore issue is nice to see in the OP.
The heads are made from a heat treated hardend alloy called LM25. It turns soft again if it is heated beyond 130°C. At 130°C it takes thousands of hours, at 150C, hundreds of hours, at 180C minutes.
It won‘t prevent indentation of the head by the head gasket if the aluminium anneals and turns soft from overheating. It is too thin.
The newer N-series gaskets have a very different fire ring design. They moved from a steel wire surrounded by a thin aluminium foil to a few mm wide and flat sealing area. This reduced the pressure on the aluminium making it more tolerant to the cylinder head turning soft and it covers pores better. The severity of the pore issue is nice to see in the OP.
The heads are made from a heat treated hardend alloy called LM25. It turns soft again if it is heated beyond 130°C. At 130°C it takes thousands of hours, at 150C, hundreds of hours, at 180C minutes.
In contrast to what eliseparts say, the shim does not prevent indentation into the head shall it turn soft. I know it as it happened to me. It is only 0.3mm thick and bends once the head surface give way and deforms. The main purpose of the shim in the MLS kit is to seal imperfection such as pores.
This head has pores, but has not turned soft. -> it is a good one. :-)
If they anneal and turn soft, the head gasket's fire ring indents a about 0.5-1mm wide and 0.1mm and deeper groove in the head with a round profile just like the head gasket's fire ring. It looks like someone dogged a trench around the chamber.
Here is a picture of a severe example. It commonly starts at the hotter exhaust side of the head.
There are thicker shims made from stainless or copper. Once you reach 1 mm or more thickness, this will prevent indentation.
These thicker shims can be used to "rescue" damaged, but valuable heads by skimmed them by the thickness of the shim and reworking of the edges.
Examples are big valved and heavily ported heads or rare motorsport Rover K MS or MS2 heads.
This head has pores, but has not turned soft. -> it is a good one. :-)
If they anneal and turn soft, the head gasket's fire ring indents a about 0.5-1mm wide and 0.1mm and deeper groove in the head with a round profile just like the head gasket's fire ring. It looks like someone dogged a trench around the chamber.
Here is a picture of a severe example. It commonly starts at the hotter exhaust side of the head.
There are thicker shims made from stainless or copper. Once you reach 1 mm or more thickness, this will prevent indentation.
These thicker shims can be used to "rescue" damaged, but valuable heads by skimmed them by the thickness of the shim and reworking of the edges.
Examples are big valved and heavily ported heads or rare motorsport Rover K MS or MS2 heads.
Edited by Ive on Tuesday 26th February 08:33
I think the mls gasket would be the way to go, once the head has been determined to be ok.
It looks like it has had a severe leak, possible head gasket failure before. It needs to be checked for squareness, and ideally pressure checking too. Valves look like they need grinding in too.
Just putting that on with any gasket is likely to be a waste of time and money. That head is not in a good state overall, not just that pitting, which by itself could allow premature failure.
It looks like it has had a severe leak, possible head gasket failure before. It needs to be checked for squareness, and ideally pressure checking too. Valves look like they need grinding in too.
Just putting that on with any gasket is likely to be a waste of time and money. That head is not in a good state overall, not just that pitting, which by itself could allow premature failure.
In my experience (of over 900 K series heads), I would hardness test it (it looks as if it isnt indented, but worth doing), less than 95 brinell on the exhaust side of the head and its scrap. I would then peen down the fire ring area (my Wiki on seloc.org will show how its done), then skim to clean. That should make it bomb proof.
The MLS gasket has proven less reliable with breaches across the fire ring when liner heights are not perfect. I use the payen BW750 elastomer gsket in conjunction with a peen/skim, if the liners are little low then you can thin down the compression bars at either end of the gasket by a few thou and this should help mitigate against the possibility of a fire ring breach.
Sometimes the damage outside the fire ring is the result of the percussive affects of local boiling of the coolant exacerbated by electrolytic action.
Dave
The MLS gasket has proven less reliable with breaches across the fire ring when liner heights are not perfect. I use the payen BW750 elastomer gsket in conjunction with a peen/skim, if the liners are little low then you can thin down the compression bars at either end of the gasket by a few thou and this should help mitigate against the possibility of a fire ring breach.
Sometimes the damage outside the fire ring is the result of the percussive affects of local boiling of the coolant exacerbated by electrolytic action.
Dave
Edited by DVandrews on Tuesday 26th February 17:36
Edited by DVandrews on Tuesday 26th February 17:37
227bhp said:
How has it got like that then do you think? It isn't corrosion or from anything combustion related, just looks like bad casting to me.
It's just a bit of corrosion from where the gasket was leaking into a waterway. There are no fire ring indentations. It's a solid casting. Just needs a light skim. Nothing I haven't seen a hundred times in the past. I've resurfaced worse than that by hand with wet & dry paper wrapped round a wooden block.Thank you everyone for the opinions and advice.
Dave - thanks for the pointer to SELOC. I've checked the liners and they're a bit variable, though all above the deck, so I'm using the 750. I'll dig out the details on shaving the elastomer - I've read it and bookmarked it, somewhere!
This is going onto a really low budget car, so I'll take on what I can myself to improve the situation and go from there.
Dave - thanks for the pointer to SELOC. I've checked the liners and they're a bit variable, though all above the deck, so I'm using the 750. I'll dig out the details on shaving the elastomer - I've read it and bookmarked it, somewhere!
This is going onto a really low budget car, so I'll take on what I can myself to improve the situation and go from there.
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