cylinder head corrosion - can it be fixed properly?

[Randell]

as a followup to the fairly tragic end of this thread: http://www.bimmer.info/forum/showthread.php?t=22262

the head has just come off, there is corrosion around cylinder 6 which has caused hydrolock. there seems to be no other damage (phew). must have been the starter motor making that dreadful noise

not sure what caused this, the head gasket was done 80000km ago so it must have been between then and now, maybe an poor HG job.. being run on green coolant by the PO probably didn't help either

the head has been sent to a shop to get pressure tested and get a quote on skimming and welding, but that sounds like a recipe for future problems.. my mechanic insists that this is a solid solution because they have 'new methods' for welding heads.. JBweld ? :D

am i better off sourcing a good second hand head? i won't get the quote for a couple of days, i'm assuming it won't be cheap.. what's the cost generally for a head repair of this nature?

the news was better than i was expecting but it's still gonna run out of my budget and i don't get paid for another 15 days... ahhh, i feel like a smoker going through withdrawals!

[genphreak]

They can weld the surface of alloy heads fine, but a lot of cracks are too hard to fix without risk of a split at a later date. I'd insist on seeing it when it comes back from the machine shop. It's good news the block is ok, but how can they be sure? What broke when it made that horrible noise??? Cylinder 6 is the one that goes wrong- as the rear one is the hardest to get to when the engine is in the car. If the headjob was not done well last time this could might be a where problems occur if there was any foreign material in the gasket. The gasket should be carefuly inspected on removal, and the (renewed) surfaces, when brought back together, should be perfect to the touch and eye.

Check the parts listing on the valvegear section in www.realoem.com (http://www.realoem.com) so you can go over the head and make sure it is all there and the right way round (are they good w BMW heads?) particularly the little bolts at the rear are installed the right way round and with the right o-ring. These are damn near impossible to check once the engine is in. Important are the coolant orifices so the coolant can circulate into the head okay- with bad coolant and problems these tend to block with scale and oxidised iron from the block. If your shop or mechanic isn't very familiar with M30s you should do all this unless they are really methodical people and highly competent that will check the right book on all the little things and check their suppliers work over well; a lot of mechanics expect the head to come back ready to go on and will only notice something that leaks or is missing, not a nut screwed in incorrectly... or an oilsprayer bar installed around the wrong way. The big problem in Aus (you may know), apart from saying after the fact that 'it's not my fault but theirs', is that any of us used to working on local cars have trouble changing our approach, the BMW way is very specific and can seem silly and weird to people that do not 'know better', if u comprenendt vhat vee mean, ya?

Also, make sure the mechanic is guaranteeing their work so you don't have to npay if it needs to be done again. Best thing is to be paying a fixed fee (from someone who knows how to compelte this exact job of course)...

[Paul in NZ]

my take Randell is this....How do youknow that a second hand head is any better?When you say corrosion what do you mean?

[rob101]

I am thinking perhaps a build up of scale,
because SOMEBODY didn't change his coolant often enough
I read into this one day after reading all the blue coolant arguments, basically when the coolant goes too acidic you get scale and too basic you get corrosion (could be the other way around). they are not the same thing.
but if you have too much scale it clogs the coolant passages in the head.

[genphreak]

I am thinking perhaps a build up of scale,
because SOMEBODY didn't change his coolant often enough
I read into this one day after reading all the blue coolant arguments, basically when the coolant goes too acidic you get scale and too basic you get corrosion (could be the other way around). they are not the same thing.
but if you have too much scale it clogs the coolant passages in the head.Yep, and on M30 that means Cylinder 6 first once you check it out; the rear passages around 6 are always the first to clog up- the lack of cooling there causing a hotspot that can make life very hard for the gasket... I think that's hit it on the head Rob- yet another L6 awfully polluted by the wrong coolant.

[rob101]

Yep, and on M30 that means Cylinder 6 first once you check it out; the rear passages around 6 are always the first to clog up- the lack of cooling there causing a hotspot that can make life very hard for the gasket... I think that's hit it on the head Rob- yet another L6 awfully polluted by the wrong coolant.
well, i wouldn't say the wrong coolant, you can use decent green coolant (castrol) IF YOU CHANGE IT EVERY YEAR. blue just has more "residual alkalinity" so it will last longer before going acidic. all coolants unfortunately go acidic after a while its just a matter of how quickly.
that was what my research led me to believe.

[genphreak]

well, i wouldn't say the wrong coolant, you can use decent green coolant (castrol) IF YOU CHANGE IT EVERY YEAR. blue just has more "residual alkalinity" so it will last longer before going acidic. all coolants unfortunately go acidic after a while its just a matter of how quickly.
that was what my research led me to believe.Yes perhaps, but with the stories we see all the time, it is not worth being 99.9999% right is it?

I reckon one should only use the factory stuff, period: I learned this (again) another way just recently; I bought some red Nulon stuff in a my gf's mum's Toyota Camry, the books all said ok, but Toyota said only add this Part# (can of red concentrate) we sell. I wish I did, cos I later found the fill procedure pretty much makes a proper flush with premix damned hard.

So there we go. Next year its going to get the right Toyota stuff and that's that. I'm not ever messing with different coolants again!

[joshua43214]

Jaguar had a terrible problem with the heads pitting on the inline 6 engines. They issued a service bulitin telling you to pull the head and use JB Weld to fill the pits. I have done this on serveral cars and had good results. You just can't fill any pits that are on the sealing portion of the head gasket.

If they can weld it and stand behind the work, I see no reason not to let them do it. Did they offer any suggestions as to the cause of the sound? or are they just saying that they have to fix this before they can go any farther? If they have the head off, they can check for a bent rod by comparing piston hights to each other.

[Jon K]

Seriously - with the availability of M30 heads, I would honestly buy a used one, have it checked for cracks, make sure it's straight, mayeb swap your valves and train swapped over and going that route. Welding the aluminum head is fine if you have a surface crack x-rayed and proven to not be that bad, but trying to repair corrosion with a weld - sounds like a lot of mystery work to me.

How does an aluminum head corrode by the way?!


Btw - hopefully the snap noise you heard wasn't teeth stripping off of the starter and or flywheel.

[rob101]

Yes perhaps, but with the stories we see all the time, it is not worth being 99.9999% right is it?

I reckon one should only use the factory stuff, period: I learned this (again) another way just recently; I bought some red Nulon stuff in a my gf's mum's Toyota Camry, the books all said ok, but Toyota said only add this Part# (can of red concentrate) we sell. I wish I did, cos I later found the fill procedure pretty much makes a proper flush with premix damned hard.

So there we go. Next year its going to get the right Toyota stuff and that's that. I'm not ever messing with different coolants again!
yeah the red stuff you have to be careful
some of that has organic additives and some is just your normal green coolant with red dye in it.
anyhow i was surprised to find that the premix castrol stuff has a BMW UK approval
explain that one!
and as i said before its not corrosion its scale!

[Randell]

just got a call from the mechanic.. 80000km ago the head gasket was done, i knew that, what i didn't know is the head was also repaired using such quality methods as..... JBWeld. :(

i know the mechanic that did it, he's a cowboy and you can tell as soon as you see him. the woman owner at the time patched it up and sold the car - typical. Then i buy the car seeing a 'head overhaul' on the service history and think i'm getting a solid one! hah! although i have to say, for a JBWeld fix to last 80kkm is a testament to the product

anyway, it needs EIGHT welds. that sounds like a hell of a lot to me, but my mechanic works on a lot of M30s and he assures me it will be solid afterwards. he insisted that the bottom end is solid and it looks fine and shouldn't be a problem.. I've known this guy for a fair while, he worked on my dad's merc for years and he's a good guy, so i trust his judjement

I asked about sourcing a second hand head that hasn't been damaged, but he said firstly it's quite difficult to find one, secondly it's expensive ($900AU) and thirdly you can't be sure that's it's gonna be any good

soo.. i'm gonna go ahead with this welding.. all up with new hoses and all labour it will tip $2000, which is bad but not too bad.. i can manage that.. i'm gonna go have a look at it all when the head comes back before it goes back together

then i will have to seriously consider selling it.. i won't get bad karma cause i fixed it all properly! i had JUSt got over the fear of the car breaking, it was solid for a long time.. but now i can just see a new golf gti parked in my driveway.. but .. but ...no! I LOVE THIS CAR ... somebody help me, i need counselling! :D

[genphreak]

Seriously - with the availability of M30 heads, I would honestly buy a used one, have it checked for cracks, make sure it's straight, mayeb swap your valves and train swapped over and going that route. Welding the aluminum head is fine if you have a surface crack x-rayed and proven to not be that bad, but trying to repair corrosion with a weld - sounds like a lot of mystery work to me. How does an aluminum head corrode by the way?! In Perth, WA M30s are far rarer, and breakers charge wayyy over the odds throughout Australia, so Perth would be the worst in that way. Buying another car and parting it is the cheapest way if one can manage the effort. There are good M30 e32s and e34s on eBay.com.au for as little as $4000.

Pitting happens when coolant boils under the gasket after the seal has broken. It is the same process as geothermal erosion in rock; the contiuous heating/cooling expanison and contraction keeps eating away at the materials. However here cylinder pressure and perhaps also combustion by products combine and make for an acidic cocktail, held in and working away on the aluminium (and the steel of the block- beware) until you crack it open and see the mess created.

Randall, may I also suggest;
Be extra careful inspecting the coolant passages in the block and head back there on 6- they must be nice and clear.
Make sure the cooling system is well flushed, block and radiator seperately, and replace only with BMW cool blue coolant of course...
Be sure to change the O2 sensor as well, With your problem (let alone a poor fix prior) I can gurantee you it will be toast, and will also be a lot to do with poor idle prior to the hydrolock. :)Thing is... what caused the horrible noise??? Euwww.

[genphreak]

yeah the red stuff you have to be careful
some of that has organic additives and some is just your normal green coolant with red dye in it.
anyhow i was surprised to find that the premix castrol stuff has a BMW UK approval
explain that one!
and as i said before its not corrosion its scale!Yea I saw that post Rob, thing is I don't trust british automtive engineers. I had a Land Rover once. A lot of it is plain comon sense, and a lot else was just plain dumb. They've been in the business for too long for any excuse for that car, and the list of engeineering disasters is endless with other Brit mobiles. The problem is cultural they can't get over themselves and collaborate with foreigners properly. I know, I was once English :)

With my Bimmer, I stick wit da Deutsche dokumentation!

[rob101]

when coolant boils under the gasket after the seal has broken. It is the same process as geothermal erosion in rock; the contiuous heating/cooling expanison and contraction keeps eating away at the materials. However here cylinder pressure and perhaps also combustion by products combine and make for an acidic cocktail, held in and working away on the aluminium (and the steel of the block- beware) until you crack it open and see the mess created.

don't forget galavanic corrosion between the grey iron in the block and the aluminium in the head.

[rob101]

Yea I saw that post Rob, thing is I don't trust british automtive engineers. I had a Land Rover once. A lot of it is plain comon sense, and a lot else was just plain dumb. They've been in the business for too long for any excuse for that car, and the list of engeineering disasters is endless with other Brit mobiles. The problem is cultural they can't get over themselves and collaborate with foreigners properly. I know, I was once English :)

With my Bimmer, I stick wit da Deutsche dokumentation!
well, i didn't only make my mind up because of the approval. i did some research and head scratching of my own. and since BMW isn't the first company to make grey iron blocks with aluminium heads i wonder wtf? do i need some uber insane coolant for. answer: its long life BUT you can get the same effect from changing your coolant often.
PS i had my coolant changed by one of the local specialist BMW workshops here and ALL they do is BMW's nothing else (they stressed that when i first talked to them) and guess what they put green in there too. so i am not saying you're wrong but i am convinced that you can use good quality green coolant and not destroy your engine's coolant passages if you change it once a year rather than once every 2 years.

[genphreak]

I am sure you are not wrong about it. I must say I'd far rather have a 2 year window all the same- the oem coolant isn't that expensive even from the dealer.

On a side note; I wonder what happens to those bimmers when their owners sell them or they stop getting serviced by that indy mechanic... it seems to me that people will leave the green coolant in there and then the car is toast within say what 12-36 months? It seems a bad thing to do to me. At least one can feel silly for getting problems later on when you (earlier) changed the coolant for something that was not only unreccommended, but a different colour & brand.

I can see why BMW, Volvo and Saab differentiate, as people would rightly be annoyed if the dealers were installing green coolant and problems as bad as this arose all over the place when people stopped returning their cars to them as religiously as they should to fit in with the service routines. The cars would start getting reputations for blown head gaskets... (which perhaps they already do) (cries). They simply cannot risk that.

[genphreak]

don't forget galavanic corrosion between the grey iron in the block and the aluminium in the head.That's the word for it. It's the reason only the head cops the loss, but the block can too... I have seen that happen once. That's why I thought the combustion by-products could be a problem

[Jon K]

I still think the noise might have been some flywheel teeth or start teeth shearing

[Randell]

I still think the noise might have been some flywheel teeth or start teeth shearing

yeah i forgot about that noise! i just called my mechanic, he said it was caused by the starter motor pinion (?) snapping back when it was hydrolocked. i'm not sure what this means. he said it's a scary sound, but once he cleared the cylinder he started the engine and it was fine, no odd noises or anything. i'll take his word for it

genphreak, i will definitely have the cooling system flushed, and i'll see about a new o2 sensor, my fuel consumption has been ridiculous recently (17L/100km). it used to be 14.5, and i'm less of a lead foot now than i used to be!

thanks for the advice guys

[Jon K]

yeah i forgot about that noise! i just called my mechanic, he said it was caused by the starter motor pinion (?) snapping back when it was hydrolocked. i'm not sure what this means. he said it's a scary sound, but once he cleared the cylinder he started the engine and it was fine, no odd noises or anything. i'll take his word for it

genphreak, i will definitely have the cooling system flushed, and i'll see about a new o2 sensor, my fuel consumption has been ridiculous recently (17L/100km). it used to be 14.5, and i'm less of a lead foot now than i used to be!

thanks for the advice guys


:) thought so - they aren't usually "broken" but they can strip teeth.

[genphreak]

yeah i forgot about that noise! i just called my mechanic, he said it was caused by the starter motor pinion (?) snapping back when it was hydrolocked. i'm not sure what this means. he said it's a scary sound, but once he cleared the cylinder he started the engine and it was fine, no odd noises or anything. i'll take his word for it genphreak, i will definitely have the cooling system flushed, and i'll see about a new o2 sensor, my fuel consumption has been ridiculous recently (17L/100km). it used to be 14.5, and i'm less of a lead foot now than i used to be! thanks for the advice guys Yes, 14 is what you can get- but the o2 has to be good, its a replacement item anyway. Bugger to change, its easiest to have it done on a lift in a shop so one can get to it, or else you generally have to jack the car up AND drop the exhaust :p

I have a spare here which is good but used, also have many other head parts and so on if you need things, but it sounds like you are getting it all sorted just fine. New Bosch O2s with the right connecteor are just over $100US from bmaparts and u can generally find universal 3 wire types for $50US. :) Nick

[rob101]

An interesting fact i'd previously heard that BMW is low phosphate, now i found a reason that they specify that.


Hard water that contains high amounts of calcium and magnesium can react with phosphates in the additive package to form sediment and scale. That's why European vehicle manufacturers use antifreezes that contain no phosphates (hard water is common in Europe). European antifreeze may be dyed blue, yellow (Mercedes) or pink (VW and Audi).

Tap water in North America also contains calcium, but isn't as hard as European tap water so phosphates are considered okay to use here.
http://www.babcox.com/editorial/tr/tr110046.htm
if anyone is interested... very good link:D
specs for BMW coolant mainly for myself ;)
GLYSANTIN ***174; G 48

Reserve alkalinity of 10 ml
Method: ASTM D 1121
Value: 13 - 15
Unit: ml HCl 0,1 mol/l

Density, 20 ***176;C
Method: DIN 51 757 procedure 4
Value: 1,121 - 1,123
Unit: g/cm***179;

Water content
Method: DIN 51 777 part 1
Value: max. 3,5
Unit: %

pH-value
Method: ASTM D 1287
Value: 7,1 - 7,3

[genphreak]

Cool link Rob, also pertinent to us;

The higher the percentage of dissolved minerals and salts in the coolant, the better it conducts electricity and the faster the aluminum is eaten away. As long as the corrosion inhibitors are working, the process is held in check. But once they're used up, corrosion starts to eat away. The most vulnerable components are usually the thinnest, which include the radiator and heater core.

We get a heck of a lot of heater cores dying out in our cars... Nick

[rob101]

Cool link Rob, also pertinent to us;

The higher the percentage of dissolved minerals and salts in the coolant, the better it conducts electricity and the faster the aluminum is eaten away. As long as the corrosion inhibitors are working, the process is held in check. But once they're used up, corrosion starts to eat away. The most vulnerable components are usually the thinnest, which include the radiator and heater core.

We get a heck of a lot of heater cores dying out in our cars... Nick
deminerialised water for the win ;)

[genphreak]

deminerialised water for the win ;)...dows?

Ummm, not sure what u mean..

Lucky here tho, Sydney has soft water... I think its unique City in Oz; in that respect.

[rob101]

...dows?

Ummm, not sure what u mean..

Lucky here tho, Sydney has soft water... I think its unique City in Oz; in that respect.
lol sorry
I thought everyone used Demineralised/distilled/denatured water to mix in with their coolant
meaning hard or soft tap water is irrelevant.
sorry to have caused confusion

[genphreak]

lol sorry I thought everyone used Demineralised/distilled/denatured water to mix in with their coolant meaning hard or soft tap water is irrelevant. sorry to have caused confusionI think most back yarders don't... I doubt a lot of shops manage it either, especally in Sydney anyway mate.

[rob101]

http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/a/AntiFreezeNF_B1843_05.pdf
green/blue colour
"typical" reserve alkalinity and pH seem strangely in between the bmw specifications.......
low phosphate as well.
very interesting!

[535ise]

Just thought i'd post this picture up to show a bad M30 water way so people know what to look out for, you can see where the metal has eroded and is right by the compression/cylinder ring on the H/G, i guess the next stage is the cylinder ring rots away and/or more metal goes from the water way until the gasket isn't compressed properly at that spot and starts to leak ?

http://img105.imageshack.us/img105/9195/head7nr.jpg

[632 Regal]

that is definetly caused by antifreeze gone bad. Get another head and pop it on.