chris_bramley Posted September 2, 2005 Share Posted September 2, 2005 Which sucks. Can anyone point me to the best replacement (steel) head gasket, how much it is and where to get from? i could also use a water pump and a new cam belt while I'm at it. I'm looking on the bright side - the garage next door gave me Kudos for doing the Heater Matrix myself and said if I can do that with little instructions and no manual, not being a mechanic, then I should have half the problem doing the head gasket! lol Any instructions for doing this would be appreciated So, since losing boost, I've had this chain: - boost loss fixed by replacing all turbo pipes with new - rad blows due to combination of resotred pressure and radweld (put there to fix faulty heater matrix I think) - rad replaced, heater matrix replaced, new rad pipes at firewall installed, put back together - I find that the overheat also killed the head gasket! I believe the term is argh. Still, since doing all this I have gone from knowing little to being fairly proficient with cars Link to comment Share on other sites More sharing options...
paul mac Posted September 2, 2005 Share Posted September 2, 2005 the best head gasket is stock toyota unless you specificly want to lower the compresion with one of those thicker jobbys, after changing the head gasket while doing the valve stem seals i would say the most usefull thing i had was a manual for the engine (available ont ebay) and when you get the head skimmed take it to a shop that no what there doing with regards to the RA (smoothness) of the finish, this caused me some grief when i took it to the local machine shop i think the most modern head they'de skimmed was a mark 2 escort and RA meant "rough arse", also take the opportunity to do the valve stem seals aswell, i think the head gasket set from toyo cost about £170 but included valve stem seals, inlet and exhaust gaskets plus cam shaft seals Link to comment Share on other sites More sharing options...
TLicense Posted September 2, 2005 Share Posted September 2, 2005 Shit mate, been through the wars a bit haven't you. The items you listed, I personally, would get them all from Toyota. (There's a few people on here that could get you discounts if need be) As far a manual on how to replace the head, there's a repair manual on mkiv.com that explains step by step. Oh whilst I remember, you may also want to ask whoever you get your parts from for the rest of the gaskets you'll need (turbo, inlet manifold, exhaust manifold etc. etc - They're all listed in the manual on mkiv.com) Best of luck! Link to comment Share on other sites More sharing options...
TLicense Posted September 2, 2005 Share Posted September 2, 2005 the best head gasket is stock toyota unless you specificly want to lower the compresion with one of those thicker jobbys, after changing the head gasket while doing the valve stem seals i would say the most usefull thing i had was a manual for the engine (available ont ebay) and when you get the head skimmed take it to a shop that no what there doing with regards to the RA (smoothness) of the finish, this caused me some grief when i took it to the local machine shop i think the most modern head they'de skimmed was a mark 2 escort and RA meant "rough arse", also take the opportunity to do the valve stem seals aswell, i think the head gasket set from toyo cost about £170 but included valve stem seals, inlet and exhaust gaskets plus cam shaft seals By RA, I take it you mean surface finish quality. A standard finish should give you a 0.8ra which should be fine. That's the equivalent to a standard quality mill, which is what you would want to use to skim a head at the very least anyway. I'm not sure how you would skim a head and get a worse finish than that anyway. Maybe by hand? Link to comment Share on other sites More sharing options...
paul mac Posted September 2, 2005 Share Posted September 2, 2005 By RA, I take it you mean surface finish quality. A standard finish should give you a 0.8ra which should be fine. That's the equivalent to a standard quality mill, which is what you would want to use to skim a head at the very least anyway. I'm not sure how you would skim a head and get a worse finish than that anyway. Maybe by hand? RA (roughness average) multi layer laminated steel head gaskets (supra) need to have a surface finish at least to 20 RA most backstreet machine shops will aim at between 50 to a 100 RA (if they even know what RA is, mine did'nt) if you are getting a head skimmed tell the machine shop you require a finish down to 20 RA if they look at you with a blank expression walk away until you find one that knows what your talking about Link to comment Share on other sites More sharing options...
TLicense Posted September 2, 2005 Share Posted September 2, 2005 All the metalwork I've ever issued has had a maximum ra of 0.8. If it's going to be polished then you could go much tighter, but I don't think you would need it. I've no idea what you would use to get anything above 0.8 as some of the mills I've seen used to make some of the parts I've had hace been practically pre-historic! Link to comment Share on other sites More sharing options...
Nic Posted September 2, 2005 Share Posted September 2, 2005 Chris I know someone in UK who may have a brand new OEM Toyota head gasket for sale, I'll get them to contact you. Or alternatively I could get you a new HKS one if you need. Link to comment Share on other sites More sharing options...
paul mac Posted September 2, 2005 Share Posted September 2, 2005 All the metalwork I've ever issued has had a maximum ra of 0.8. If it's going to be polished then you could go much tighter, but I don't think you would need it. I've no idea what you would use to get anything above 0.8 as some of the mills I've seen used to make some of the parts I've had hace been practically pre-historic! sorry if your a machinist fella, but the guys i took mine too i asked for a smoother finish than normal, when i went to pick the head up i asked the guy what RA the finish was he looked at me like i was speakin chinese and said "dunno whatevre the miller will do", when i got the head checked by peeps who knew what i was after they measured the finish at between 70-80 RA which is way to rough for a MLS type gasket, i'me just trying to make sure Chris does'nt make the same mistakes as i did, read this Chris and all will become apparent http://www.aa1car.com/library/2003/eb30320.htm Link to comment Share on other sites More sharing options...
TLicense Posted September 2, 2005 Share Posted September 2, 2005 For sure mate Link to comment Share on other sites More sharing options...
chris_bramley Posted September 3, 2005 Author Share Posted September 3, 2005 Chris I know someone in UK who may have a brand new OEM Toyota head gasket for sale, I'll get them to contact you. Or alternatively I could get you a new HKS one if you need. Thanks! Is there any point in lowering the compression? I thought the supra needed a low compression anyway cos it's turbo'd... depends how muh they are i guess. so I have to do ALL the gaskets for everything? £170!! for a gasket!! lol horrific, toyota RAPE us all Link to comment Share on other sites More sharing options...
chris_bramley Posted September 3, 2005 Author Share Posted September 3, 2005 sorry if your a machinist fella, but the guys i took mine too i asked for a smoother finish than normal, when i went to pick the head up i asked the guy what RA the finish was he looked at me like i was speakin chinese and said "dunno whatevre the miller will do", when i got the head checked by peeps who knew what i was after they measured the finish at between 70-80 RA which is way to rough for a MLS type gasket, i'me just trying to make sure Chris does'nt make the same mistakes as i did, read this Chris and all will become apparent http://www.aa1car.com/library/2003/eb30320.htm Thanks for the thought - luckily I'm next to a garage which can get my head skimmed, pressure checked and laser checked for £75 they get it done for audi's mercs and beamers all the time so chances are ra won't leave a blank expression! Link to comment Share on other sites More sharing options...
JohnA Posted September 3, 2005 Share Posted September 3, 2005 ...Is there any point in lowering the compression? I thought the supra needed a low compression anyway cos it's turbo'd..... long story this, but if you intend to run a LOT of boost and reach the point where you have to lower the compression ratio, you are *much* better advised to lower it properly, by fitting lower-compression pistons that keep the shape of the combustion chamber the way Toyota intended it to be. Thicker head gaskets create a Frankestein shape, with the squish band becoming part of the combustion chamber. The optimal ignition curves will be all different, don't do this without a standalone like AEM. On the gasket subject, I have got a supraTT set from ebay, don't laugh, it's got all of these gaskets plus stem seals and what have you, £80-90 it was. The HG looks like the original too, with that sticky surface. An experienced member from here had a close look at it and felt it was like the OEM part, FWIW... Link to comment Share on other sites More sharing options...
JohnK Posted September 3, 2005 Share Posted September 3, 2005 Ra is just one way to measure surface finish, there are several different scales that can be used, Ra is the most common here in the UK. 3.2 Ra is a general machining tolerance which most things are machined within. 0.8 Ra is about the best you will get on a mill anything lower and your talking grinding, lapping or polishing. 70 to 80 ra would be like a very corse thread! I think they must be using one of the other scales. Link to comment Share on other sites More sharing options...
Nic Posted September 3, 2005 Share Posted September 3, 2005 Exciting photo of a 2mm HKS head gasket attached that I've just collected for a member today. Link to comment Share on other sites More sharing options...
bromy Posted September 3, 2005 Share Posted September 3, 2005 Ra is just one way to measure surface finish, there are several different scales that can be used, Ra is the most common here in the UK. 3.2 Ra is a general machining tolerance which most things are machined within. 0.8 Ra is about the best you will get on a mill anything lower and your talking grinding, lapping or polishing. 70 to 80 ra would be like a very corse thread! I think they must be using one of the other scales. Another scale also used is microinch (um), we use it for valve work for the petrochemical industry mostly in the us, we can mill to .4 Ra surface finish using ceramic inserts with a wiper also in the milling head, but as john says for a normal machine shop anything better than .8 Ra then your into grinding territory. Link to comment Share on other sites More sharing options...
chris_bramley Posted September 4, 2005 Author Share Posted September 4, 2005 Exciting photo of a 2mm HKS head gasket attached that I've just collected for a member today. And how much are these? and are they better than the stock? Link to comment Share on other sites More sharing options...
Nic Posted September 4, 2005 Share Posted September 4, 2005 And how much are these? and are they better than the stock? Link to comment Share on other sites More sharing options...
JohnA Posted September 5, 2005 Share Posted September 5, 2005 I would be happy if someone could define to me what constitutes a 'better' head gasket. One that does or doesn't distort the shape of the chamber? One that does or doesn't give way under extreme pressures protecting the pistons? One that is reusable, cheaper, easier to align and torque, what? Link to comment Share on other sites More sharing options...
paul mac Posted September 5, 2005 Share Posted September 5, 2005 I would be happy if someone could define to me what constitutes a 'better' head gasket. One that does or doesn't distort the shape of the chamber? One that does or doesn't give way under extreme pressures protecting the pistons? One that is reusable, cheaper, easier to align and torque, what? IMHO you cant get better than Mr Toyotas original Link to comment Share on other sites More sharing options...
JohnA Posted September 5, 2005 Share Posted September 5, 2005 There are loads of carparts sold as 'uprated' and when someone seriously compares them to the (new) stock items they really are of inferior quality, compromising the original design (creating problems that can be fixed with yet more 'uprated' crap) and overpriced. Not everything in the aftermarket is garbage, but it seems to me that misrepresentation is the norm. Add some internet/magazine hype and hey presto...a star is born! But let's stick to the subject: what is an 'uprated' or 'performance' headgasket? The equivalent of a titanium plate welded between cyl head and block? That sure won't blow even under severe detonation, lol. Is *that* what people are after? Having to junk the engine because they try to avoid blowing a gasket? What next? soldering all the fuses at home, to avoid paying for new ones? EDIT: here is a relevant example from the US forum. The rate (and kind) of failures of aftermarket parts indicates the difference in build quality and R&D compared to OEM parts. Buyer beware. Link to comment Share on other sites More sharing options...
chris_bramley Posted September 5, 2005 Author Share Posted September 5, 2005 I want something that will stand up well to up to 1.4 bar on twin hybrids, and then later a big single. Far as I am told oem will be fine as long as I'm sensible... Link to comment Share on other sites More sharing options...
JohnA Posted September 5, 2005 Share Posted September 5, 2005 Stock gaskets are very good, as long as you avoid detonation. If you detonate severely, no gasket will survive. The point is that you want the HG to be the weakest link deliberately, or else you're looking at melted pistons within a fraction of a second... See it as a fuse. Link to comment Share on other sites More sharing options...
chris_bramley Posted September 5, 2005 Author Share Posted September 5, 2005 If you detonate severely, no gasket will survive. I fully intend not to detonate! So not a problem for now. I'll look at it more when I upgrade the systems again. Link to comment Share on other sites More sharing options...
chris_bramley Posted September 7, 2005 Author Share Posted September 7, 2005 Right, I've decided on OEM - anyone got a good price for it? OR - does anyone have a price and detailed list for the whole engine gasket set I've heard about? I understand it has head, rocker, central, manifold, valve stem seals, the lot, and someone mentioned not much more than £200 - anyone got any info? Link to comment Share on other sites More sharing options...
paul mac Posted September 7, 2005 Share Posted September 7, 2005 Right, I've decided on OEM - anyone got a good price for it? OR - does anyone have a price and detailed list for the whole engine gasket set I've heard about? I understand it has head, rocker, central, manifold, valve stem seals, the lot, and someone mentioned not much more than £200 - anyone got any info? the kit you want is the de-coke head gasket kit, part number for a j-spec (non vvti) 4112-46055, it has all the bits you mention plus camshaft oil seals and various other bits and bobs that i cant remember, price £171.64 including vat Link to comment Share on other sites More sharing options...
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