7M-GE head torque

zer_gravity · 01-03-2007, 06:19 PM

hello! first post here, hoping i can get some info from some of the gear heads here

in case you're wondering my name was supposed to be zero_gravity. damn typos!

so i'm going to be a bit of a jerk and deviate from the norm here - i don't own a supra. i've got a '90 7M-GE Cressida. so as i understand it essentially a non turbo mk III supra with a different body.

so here's where i am sitting right now. about 99% sure that i've got BHG or at least the early signs. getting some nice thick white exaust on startup that clears once the engine reaches operating temperature. it does not overheat. i've noticed more recently that after running the reservoir will nearly fill. i don't yet have a lot of oil contamination - nothing on the dipstick but after about 500-700kms some dark brown muddy contamination starts to build up on the oil cap. its not yet that milky consistancy. ive also heard some gurgling from behind the dash, but thats not a common occurance. and the final nail in the coffin - got a compression test. front cylinder is about 180psi. as you go back to #6 it drops down to about 140psi.

i've ordered a head gasket set from toyota and i've got a great mechanic to get the job done. i'd do it myself but i don't have the time and this guy will do it for about $375 (not including parts). so as far as i understand, the stock 58 ft-lbs is too loose which is what is thought to cause BHG's. so what torque should i look at if i'm not doing any mods to the engine at this time? i've read that 70 ft-lbs should do it. any comments?

also, getting some 'might as well while its apart' maintence done. here's my list so far, please feel free to critique it and add.

1. flush radiator

2. check/replace timing belt

3. clean any carburization from cylinder heads/walls using a wire brush - thanks to the online MK3 TSRM.

worthwhile to check vlavle lash and clean valves? anything else i forgot? thanks for any help!

IHateHacks · 01-03-2007, 10:02 PM

A wire brush is not the tool to use on cylinder walls, the cylinder head sealing surfaces or the block sealing surface. I used a whiz wheel, which is an air tool much like a die grinder except its angled and the wheel is made of 3M Scotch material which is made for aluminum. A wire wheel would take off too much metal and a wire brush will just ruin the sealing surface.

You're not sending the head out to have it tested for cracks or warpage?

zer_gravity · 01-03-2007, 11:49 PM

actually the mechanic i am taking my car to will be sending the head out for machining. if there is any cracks, i'm sure he'll let me know lol. as for warpage, the shop can take care of that easily.

i know that cracks are possible, but i'm kind of doubting it here. its very very unlikely that the car has ever overheated and as i mentioned before my problems are very very minor. this is just getting it done before it gets bad and while i have some money.

also, would the mechanic not have found indication of cracks when he looked it over and did the compression test?

01-03-2007, 06:19 PM	#1
zer_gravity Stock Join Date: Jan 2007 Location: Canada Posts: 5	7M-GE head torque hello! first post here, hoping i can get some info from some of the gear heads here in case you're wondering my name was supposed to be zero_gravity. damn typos! so i'm going to be a bit of a jerk and deviate from the norm here - i don't own a supra. i've got a '90 7M-GE Cressida. so as i understand it essentially a non turbo mk III supra with a different body. so here's where i am sitting right now. about 99% sure that i've got BHG or at least the early signs. getting some nice thick white exaust on startup that clears once the engine reaches operating temperature. it does not overheat. i've noticed more recently that after running the reservoir will nearly fill. i don't yet have a lot of oil contamination - nothing on the dipstick but after about 500-700kms some dark brown muddy contamination starts to build up on the oil cap. its not yet that milky consistancy. ive also heard some gurgling from behind the dash, but thats not a common occurance. and the final nail in the coffin - got a compression test. front cylinder is about 180psi. as you go back to #6 it drops down to about 140psi. i've ordered a head gasket set from toyota and i've got a great mechanic to get the job done. i'd do it myself but i don't have the time and this guy will do it for about $375 (not including parts). so as far as i understand, the stock 58 ft-lbs is too loose which is what is thought to cause BHG's. so what torque should i look at if i'm not doing any mods to the engine at this time? i've read that 70 ft-lbs should do it. any comments? also, getting some 'might as well while its apart' maintence done. here's my list so far, please feel free to critique it and add. 1. flush radiator 2. check/replace timing belt 3. clean any carburization from cylinder heads/walls using a wire brush - thanks to the online MK3 TSRM. worthwhile to check vlavle lash and clean valves? anything else i forgot? thanks for any help!

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01-03-2007, 10:02 PM	#2
IHateHacks 20psi boost Join Date: May 2006 Location: New Haven/Hamden Posts: 793	A wire brush is not the tool to use on cylinder walls, the cylinder head sealing surfaces or the block sealing surface. I used a whiz wheel, which is an air tool much like a die grinder except its angled and the wheel is made of 3M Scotch material which is made for aluminum. A wire wheel would take off too much metal and a wire brush will just ruin the sealing surface. You're not sending the head out to have it tested for cracks or warpage?

01-03-2007, 11:49 PM	#3
zer_gravity Stock Join Date: Jan 2007 Location: Canada Posts: 5	actually the mechanic i am taking my car to will be sending the head out for machining. if there is any cracks, i'm sure he'll let me know lol. as for warpage, the shop can take care of that easily. i know that cracks are possible, but i'm kind of doubting it here. its very very unlikely that the car has ever overheated and as i mentioned before my problems are very very minor. this is just getting it done before it gets bad and while i have some money. also, would the mechanic not have found indication of cracks when he looked it over and did the compression test?