cute wee gem Posted March 27, 2009 Share Posted March 27, 2009 So yeah my head bolts have been used like 5 times. block and head skimmed. blows head gaskets after 5mins (been through 4) So I got a genuine Isuzu gasket and some new head bolts. I assume they're TTY? alan head things anyway. Should I re-torque using these or not? Link to comment Share on other sites More sharing options...
fuel Posted March 27, 2009 Share Posted March 27, 2009 find out if they are TTY and if so what exact torque and angle settings they need, chances are being an older engine it's pre-TTY and they could do with a re-torque. Most head gasket suppliers these days supply mono torque head gaskets anyway which don't require re-torquing. Do you know where the gasket blows each time? Link to comment Share on other sites More sharing options...
cute wee gem Posted March 27, 2009 Author Share Posted March 27, 2009 Between 1&2 and 3&4 so basically looses shit loads of compression and makes fuck all power, the only 2 places it blows. Doesn't have the "angle" style torque settings, I've tried searching but can't find if they're TTY or not? Had 2 monotorques and they both fucked out. Genuine Isuzu one isn't monotorque. Link to comment Share on other sites More sharing options...
fuel Posted March 27, 2009 Share Posted March 27, 2009 if Isuzu gasket isn't monotorque, and given the age of the motor I doubt it has TTY head-bolts. TTY head-bolts typically have torque settings like 20Nm, slacken off, 45Nm, slacken off, 55Nm + 90deg etc but not all do. If it's just your normal 55ft.lbs or thereabouts headbolts then I don't think they will be TTY. Mitsubishi 4G63 headbolts sure aren't TTY right up until the first of the Evos. Link to comment Share on other sites More sharing options...
cute wee gem Posted March 27, 2009 Author Share Posted March 27, 2009 65nm, 85nm, 100nm is the procedure from ACL. Isuzu book says 85, 98nm. I didn't think they were TTY but keep hearing different opinions and I can't see why it keeps blowing. Do normal head bolts fail after a few uses? I've personally used them 3 times plus the original owner of the coupe has probably used them twice as it had a new gasket when I got it. So they could have been used 6-7 times for all I know. Got new ones anyway so will try tonight with new gasket and see what happens. Link to comment Share on other sites More sharing options...
isnowi Posted March 27, 2009 Share Posted March 27, 2009 65nm, 85nm, 100nm is the procedure from ACL. Isuzu book says 85, 98nm.I didn't think they were TTY but keep hearing different opinions and I can't see why it keeps blowing. Do normal head bolts fail after a few uses? I've personally used them 3 times plus the original owner of the coupe has probably used them twice as it had a new gasket when I got it. So they could have been used 6-7 times for all I know. Got new ones anyway so will try tonight with new gasket and see what happens. All bolts will stretch to a degree, could be that yours have done just that and are working there way loose ever so slightly. Is your head still flat? Link to comment Share on other sites More sharing options...
forced Posted March 27, 2009 Share Posted March 27, 2009 The problem is probably your head that's toast. Best fix would be to look for another one. Cutting them too much weakens them, Some types of head are weak to start with. To be totally realistic the Isuzu Piazza was a lemon from the day it left the factory. Lots of them ended up at the wreakers cos the dizzy crapped out with no spares available. Steve Link to comment Share on other sites More sharing options...
cute wee gem Posted March 27, 2009 Author Share Posted March 27, 2009 Head's fine, it's had quite a few hours porting and o/s valves etc put in, why would I do that to a dud head? Funny you say they're lemons, I'm almost on the verge of buying another Piazza. Half the problem with "no spares" is because Holden only seem to deal with Aus and never look into Japan for parts. This is only taken from the dealership nearest me so maybe others are different, I don't know. Link to comment Share on other sites More sharing options...
cute wee gem Posted March 27, 2009 Author Share Posted March 27, 2009 65nm, 85nm, 100nm is the procedure from ACL. Isuzu book says 85, 98nm.I didn't think they were TTY but keep hearing different opinions and I can't see why it keeps blowing. Do normal head bolts fail after a few uses? I've personally used them 3 times plus the original owner of the coupe has probably used them twice as it had a new gasket when I got it. So they could have been used 6-7 times for all I know. Got new ones anyway so will try tonight with new gasket and see what happens. All bolts will stretch to a degree, could be that yours have done just that and are working there way loose ever so slightly. Is your head still flat? I put a s/edge on it before and I was having trouble getting the .057mm under it (where the gaskets blow) the reccomended warp is no more than 0.20 so that looks pretty good to me Just letting it cool down now and will re-torque it. Link to comment Share on other sites More sharing options...
forced Posted March 27, 2009 Share Posted March 27, 2009 Head's fine, it's had quite a few hours porting and o/s valves etc put in, why would I do that to a dud head? . You should think of a head as like a giant block of rubber with big holes in it. When there's pressure in the combustion chamber, it lifts slightly,depending on how strong it is , or isn't, unsealing itsself, then seals again. Measure it all you like, it will always be flat. The thinner the face,the bigger the holes, the more it lifts. Just like a Hillman Hunter alloy head. Steve Link to comment Share on other sites More sharing options...
RUNAMUCK Posted March 27, 2009 Share Posted March 27, 2009 Is the head made of alluminium? (dunno fuck all about your brand) When you get a head hot, aluminium can lose it's hardness. Doesn't have to be cracked, or warped. The washers of the head bolts will pull down into the aluinium, and you lose all your clamping force. Also the fire ring of the head gasket can pull into the head a tiny bit, and again cause it to blow. If you've had it skimmed and it keeeps popping, thats the likely cause IMO. Link to comment Share on other sites More sharing options...
mikuni Posted March 27, 2009 Share Posted March 27, 2009 ^ yes, it is alloy. And like many early alloy heads they can get porous over time and cause these sorts of issues. To be totally realistic the Isuzu Piazza was a lemon from the day it left the factory. Lots of them ended up at the wreakers cos the dizzy crapped out with no spares available.Steve So of course, this means that your head is toast Tom. Isuzu G series engines are renown for being "bullet proof". I agree with your first comment though, when a head has been played with so much it can potentially cause issues but the above comment is just rubbish. Link to comment Share on other sites More sharing options...
Testament Posted March 29, 2009 Share Posted March 29, 2009 TTY bolts will very often have a "waisted" smaller diameter section, thats how they control the yield point. if the bolts a just straight up from the thread to the head I would be 99% sure they are just regular bolts. Still I would be suspect after using them 3-4 times, as they do get stretched after a few uses. Every time you you re-use any headbolts you should inspect them all carefully for damaged threads, corrosion etc. Link to comment Share on other sites More sharing options...
CaMpylobacter Posted March 29, 2009 Share Posted March 29, 2009 retorque fo' sho if not TTY/if they don't have an angular torque. surely it can't hurt i had monotorque stz on the criz but i retorqued anyway. glad i did too coz half of the middle ones were loose as fuck after only 15min of running in the shed. have done about 6000-8000k on it and no probs with gasket Link to comment Share on other sites More sharing options...
mixmasterlex Posted March 29, 2009 Share Posted March 29, 2009 thread steal... Its a good idea to re-tourqe after a few thousand kms of running a rebuilt motor yah? Link to comment Share on other sites More sharing options...
Unclejake Posted March 29, 2009 Share Posted March 29, 2009 I CBF reading the entire thread but something ain't right and it won't be the bolts (unless they are too long). Assuming you are 100% happy with the head then check the block for warpage (it does happen) and also lay the gasket on the head and look at where the fire ring is on each chamber. If the chambers have been worked and a fire ring is hanging into the chamber she's a gonna blow bro. Peace Link to comment Share on other sites More sharing options...
RUNAMUCK Posted March 30, 2009 Share Posted March 30, 2009 UJ does have a good point there. I used to work with a muppet who's race car kept on blowing headgaskets. The heads had been skimmed shitloads, and the bolts were too long. The threads were bottoming out and preventing a sufficent amount of clamping force being acheived. Link to comment Share on other sites More sharing options...
cute wee gem Posted March 30, 2009 Author Share Posted March 30, 2009 I CBF reading the entire thread but something ain't right and it won't be the bolts (unless they are too long).Assuming you are 100% happy with the head then check the block for warpage (it does happen) and also lay the gasket on the head and look at where the fire ring is on each chamber. If the chambers have been worked and a fire ring is hanging into the chamber she's a gonna blow bro. Peace Block has been skimmed also. It has been bored .5mm but the gasket has no overhang. All seems to be sweet so far after 3 days driving, so hopefully it doesn't blow over time. I fail at engines. Link to comment Share on other sites More sharing options...
KKtrips Posted March 30, 2009 Share Posted March 30, 2009 CBF reading whole thread but an important tip is to make sure retorque is done when engine is stone cold.. KTHXBAI Link to comment Share on other sites More sharing options...
phatt20 Posted February 16, 2010 Share Posted February 16, 2010 its not detonating is it? doesnt take much of that to pop a headgasket Link to comment Share on other sites More sharing options...
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