bigbloodyturbo Posted July 14, 2011 Share Posted July 14, 2011 Need a bit of advise from someone. I blew my HG last year, it started missing occasionally when still in vacuum but ran fine when on boost. Took it easy but noticed it was using coolant, problem got worse untill it really spat the dummy out one day and i had a sniff test done on the coolant, it showed hydrocarbons in the coolant. I've stripped the engine and now have a bare cylinder head on my bench. I cannot see where the gasket teared but it was starting to delaminate when i took the head off. The engine never overheated and the temp gauge never moved. I checked the head with a straight edge and toyota quote 0.1mm allowance, i could not fit a 0.1mm feeler in anywhere on the head. There was a place where i could fit a 0.05 in but toyota says this is allowable. I'm about to take it to the head shop to have it checked for hardness and was going to get it skimmed whether it needed it or not. Has anyone got any advise on this? should i get it skimmed either way as i've went to all the trouble of stripping it. Are the figures in the toyota workshop manual good? Or should i just buy another head from Mr.T and be done with it? Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted July 14, 2011 Share Posted July 14, 2011 Personally, if the Toyota manual says .1mm then thats what Id go with. You maybe could call your local dealer and see if the limits have changed? Chris Wilson will be the man with the know how Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 14, 2011 Share Posted July 14, 2011 (edited) I'd personally run a dti or verdict clock all over the head face when its sat on a milling machine, that will give you a much more accurate check than a straight edge and feeler gauges, the head company should do that before they skim it. If its within the tolerance listed then it wont do any harm to have it skimmed and wont need much taken off. If it needs more than the tolerance then the heads pretty much scrap as the cam journals will be out of line by the same amount the head face is. Edited July 14, 2011 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted July 14, 2011 Author Share Posted July 14, 2011 Thanks for the reponses, i'm going to run it over to the Aberdeen headshop today, spoke to the guy yesterday and he said he can do a check for the hardness and skim it aswell as re-seat the valves. I'm assuming that if reconditioning heads is their bread and butter then they should be able to tell me if the head is warped and if so by how much before they machine it. I dont believe the engine has ever been stripped in its life so i believe it has never been skimmed before. I'll see what they say. Do you think i should have it faced off even if they say its in tolerance? Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 14, 2011 Share Posted July 14, 2011 I've skimmed plenty of cylinder heads and never once done this without checking it before i started, infact you should run a clock over it to make sure its sat on the machine correctly. If its in tolerance for what it costs i'd skim it but only the minimal amount off required to get a full clean up. Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted July 14, 2011 Author Share Posted July 14, 2011 I've skimmed plenty of cylinder heads and never once done this without checking it before i started, infact you should run a clock over it to make sure its sat on the machine correctly. If its in tolerance for what it costs i'd skim it but only the minimal amount off required to get a full clean up. Ok, that's what i'll do then, just want to have some info for the guy when i'm talking to him. He'll do all the necessary measuring i'm sure, would like to be confident that everything is done and ok before i put it back on as the gasket set was bloody expensive. Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted July 14, 2011 Author Share Posted July 14, 2011 Just had a call from the guy working on the head. He says he's tested the hardness and its fine, he's pressure tested it and its passed and he checked the valves and they are all ok. It had a slight warp in it of 5 thou but he said that its almost negligable and doesn't carry through to the topside. Looks like its ok thank god. Quote Link to comment Share on other sites More sharing options...
Dnk Posted August 18, 2011 Share Posted August 18, 2011 Sorry i missed your reply, 0.005" thou is over Toyotas limit and in engineering circles quite a lot. I hope the cam journals are okay, every head i've checked when they've had a full length warp the cam journals were out of line by pretty much the same as the head face which isn't good at all Quote Link to comment Share on other sites More sharing options...
Hellstrom Posted August 18, 2011 Share Posted August 18, 2011 are you using a steel headgasket by anychance? make sure that the block is straight and dont have any pits in it as this will make the steel gasket leak. also before doing anything to the head i would pressure test it to make sure its not leaking due to a crack or somthing. Quote Link to comment Share on other sites More sharing options...
Dnk Posted August 18, 2011 Share Posted August 18, 2011 are you using a steel headgasket by anychance? make sure that the block is straight and dont have any pits in it as this will make the steel gasket leak. also before doing anything to the head i would pressure test it to make sure its not leaking due to a crack or somthing. The op says its been pressure tested in post number 7 ! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 18, 2011 Share Posted August 18, 2011 If it's 5 thou out I would get it lightly machined, just take the minimum off to clean the sealing face. If there are witness marks away from the sealing arae don't worry, it shows the absolute minimum has been removed. As dnk says, 5 thou is quite a lot. Now it's off and all that.... Quote Link to comment Share on other sites More sharing options...
Guest BradMD Posted August 18, 2011 Share Posted August 18, 2011 Hi, i might need my head to be skimmed too as the head gasket has blown, question is do you have to change the stretched head bolts when you take out the head? I've found some but they're quite expensive and would prefere if i didn't have to get them. Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted August 18, 2011 Share Posted August 18, 2011 you will deffo need new bolts , puting the old streachd bolts back in would be crazyness. i want to know if any measures should be taken in terms of replacement gasket thickness to keep the comp ratio in check Quote Link to comment Share on other sites More sharing options...
Guest BradMD Posted August 18, 2011 Share Posted August 18, 2011 Well its only a minuscule amount being shaved off, so it would slightly increase the power output of the engine right? does anything else need to be adjusted tho when skimming the head? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 18, 2011 Share Posted August 18, 2011 It theoretically will aid off boost performance, but you almost certainly won't notice any change. It will also theoretically limit how much boost you can run without hitting det. It will also put the stock cam timing marks out, but unless you machine a 1/16 inch or more off the head it won't be significant. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 18, 2011 Share Posted August 18, 2011 The stock head bolts are not torque to yield so, on a tight budget, they can be reused if undamaged. Be SURE the female splines in the heads are PERFECT. DO NOT reuse bolts that are less than so or they may well strip the splines and will need drilling out. Where will the swarf go....? Quote Link to comment Share on other sites More sharing options...
Rich8v Posted August 19, 2011 Share Posted August 19, 2011 The stock head bolts are not torque to yield so, on a tight budget, they can be reused if undamaged. Be SURE the female splines in the heads are PERFECT. DO NOT reuse bolts that are less than so or they may well strip the splines and will need drilling out. Where will the swarf go....? Just to add to that the manual says, Using a venier caliper, measure the thread outside diameter of the bolt Standard outside diameter: 10.8 - 11.0mm (0.425 - 0.433 in.) Minimum outside diameter: 10.7mm (0.421 in.) If diameter is less than minimum, replace the bolt. Quote Link to comment Share on other sites More sharing options...
Guest BradMD Posted August 19, 2011 Share Posted August 19, 2011 It theoretically will aid off boost performance, but you almost certainly won't notice any change. It will also theoretically limit how much boost you can run without hitting det. 1/16 inch or more off the head it won't be significant. Do you mean cam timing marks will be fine, as well as everything else, once you DON'T skim more then 1/16 of an inch? Quote Link to comment Share on other sites More sharing options...
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