Bhg

cvbikeguy · 04-16-2010, 05:02 PM

so it finally happened. after trial and error countless times i believe my head gasket finally blew. as some of you may now i did a rebuild of my 7mge. now at 270 miles i was on the freeway and smoke was dumping out of the car. engine and interior was fludded with smoke. 30 seconds after it stopped. i was pretty much home so i drove it the rest of the way. parked it and double checked my temp and pressure. both were fine.

after a couple hours watching tv and debating i realized that my oil pressure was inconsistent in the past couple days. i go back out there and turn on the car and the "birdcage" signal pops up. yea and of course it all clicks. i look in my radiator and see poop in there. BHG

so now im just trying to figure out what to do and what caused this. i have arp bolts in and never pushed the engine too much. so do i rebuild it again and start from scratch? or do i sell and move on. it doesnt help that i dont have anyone in the area to help with the build. any advice is welcome.

thanks

cre · 04-16-2010, 07:58 PM

sorry to gear that man...but 300 miles is Way too soon for youto have not done something significantly wrong..... only three possibilities come to mind: improper torque,cracked head or block; or the lower timing belt cover was not cut with the block.

kamikazemkiii · 04-16-2010, 08:10 PM

Sorry to hear that man, ive got a new headgasket if you need it

cre · 04-16-2010, 08:29 PM

did you chase the head bolt threads with a tap? torque in multiple passes and in the right order me?

as long as the head and block aren't warped I'd redo the HG.

cvbikeguy · 04-16-2010, 08:38 PM

even though i followed the tsrm i just wonder if i just f'ed something up of whatever. also i didnt get the new head machined but i did buy a rebuilt one on ebnay for $400 and it says it was already shaved and ready to be slapped on. you think i might have messed up on the head bolts?

cvbikeguy · 04-16-2010, 08:59 PM

Quote:

Originally Posted by kamikazemkiii

Sorry to hear that man, ive got a new headgasket if you need it

how much? thanks

Quote:

Originally Posted by cre

did you chase the head bolt threads with a tap? torque in multiple passes and in the right order me?

as long as the head and block aren't warped I'd redo the HG.

whats chase and tap? couldnt find it in the tsrm

suprabahamut · 04-16-2010, 09:04 PM

Did a shop rebuild the engine for you? I know a person who got there motor rebuilt, and the shop torqued the head bolts at the wrong torque, because it was listed wrong in the manual. He even told them to change the torque because it is a problem, but I guess they did not believe him. In the end the tech had to rebuild the motor at no charge, but they bought a replacement instead I guess cheaper. It took some time to get it back, but if some one did this to you, you can get it at least get it fixed at little to no charge.

cvbikeguy · 04-16-2010, 09:11 PM

Quote:

Originally Posted by suprabahamut

Did a shop rebuild the engine for you? I know a person who got there motor rebuilt, and the shop torqued the head bolts at the wrong torque, because it was listed wrong in the manual. He even told them to change the torque because it is a problem, but I guess they did not believe him. In the end the tech had to rebuild the motor at no charge, but they bought a replacement instead I guess cheaper. It took some time to get it back, but if some one did this to you, you can get it at least get it fixed at little to no charge.

no i actually did it myself and torqued them down to 80lbs. but i think cre might be right about the chase and tap. too bad i dont know what the hell it is.

hey cre would i still be able to use my arp bolts?

cre · 04-17-2010, 02:20 AM

Chasing threads is a pretty standard practice. You get a tap (thing used to thread holes for bolts) of the same size and pitch of our headbolts and you thread it into the holes (and keep adding oil to lubricate and clear out debris). As you thread it in AND as you thread it out it cuts the metal of the threads back to the right shape and size for the bolts/studs. Not doing this may cause the bolt to reach a given torque level but not provide the actual axial clamping force you want (ie: the shit don't turn so easy so you think it's done too soon).

I really wish they made hollow studs for our cars.... that's the only way to get really close to a given clamping force. Hollow's are great.

Yes, the headbolts are reusable.

80lbs is high... don't go over manufacturer specs just becaust you think it'll be better... you'll break something.

Also, rebuilt of not, you don't know what shape the head was in... could have warped from inappropriate storage. Measure it with a machinist's straight edge (not just a metal ruler!

).

cvbikeguy · 04-17-2010, 04:13 PM

Quote:

Originally Posted by cre

Chasing threads is a pretty standard practice. You get a tap (thing used to thread holes for bolts) of the same size and pitch of our headbolts and you thread it into the holes (and keep adding oil to lubricate and clear out debris). As you thread it in AND as you thread it out it cuts the metal of the threads back to the right shape and size for the bolts/studs. Not doing this may cause the bolt to reach a given torque level but not provide the actual axial clamping force you want (ie: the shit don't turn so easy so you think it's done too soon).

I really wish they made hollow studs for our cars.... that's the only way to get really close to a given clamping force. Hollow's are great.

Yes, the headbolts are reusable.

80lbs is high... don't go over manufacturer specs just becaust you think it'll be better... you'll break something.

Also, rebuilt of not, you don't know what shape the head was in... could have warped from inappropriate storage. Measure it with a machinist's straight edge (not just a metal ruler!

).

dang. how hard is it to chase threads yourself? and i want to make sure im doing this correctly. also i know the tsrm says 56lb for torque on the head and everyone says its too low. ive seen some do 70lb and then some do 90lb for arp. what do you recommend.

also i think im going to pull the engine out and put it on a stand. so i have a couple questions. how hard is it to drop in a fully assembled engine? would the wire harness be a problem. also i heard that cork oil pan gaskets are no good. whats the best way to seal this? im also going to be double checking all my seals and i think that my rear main seal might be leaking but should be fine.

im hoping that if all goes well i can swap out the tranny during this process.

thanks again guys, let me know if there is anything i should check that could be damaged from the engine.

04-16-2010, 05:02 PM	#1
cvbikeguy 3" Exhaust Join Date: Nov 2009 Location: Castro Valley, CA Posts: 248	Bhg so it finally happened. after trial and error countless times i believe my head gasket finally blew. as some of you may now i did a rebuild of my 7mge. now at 270 miles i was on the freeway and smoke was dumping out of the car. engine and interior was fludded with smoke. 30 seconds after it stopped. i was pretty much home so i drove it the rest of the way. parked it and double checked my temp and pressure. both were fine. after a couple hours watching tv and debating i realized that my oil pressure was inconsistent in the past couple days. i go back out there and turn on the car and the "birdcage" signal pops up. yea and of course it all clicks. i look in my radiator and see poop in there. BHG so now im just trying to figure out what to do and what caused this. i have arp bolts in and never pushed the engine too much. so do i rebuild it again and start from scratch? or do i sell and move on. it doesnt help that i dont have anyone in the area to help with the build. any advice is welcome. thanks __________________ 86 MKIII Supra East Bay, CA 7mge rebuild. http://www.toyota-supra.info/forums/...-tomorrow.html MKIII commercial http://www.youtube.com/watch?v=HY9W3...om=PL&index=27 lightening build http://www.toyota-supra.info/forums/...ing-build.html

04-16-2010, 07:58 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	sorry to gear that man...but 300 miles is Way too soon for youto have not done something significantly wrong..... only three possibilities come to mind: improper torque,cracked head or block; or the lower timing belt cover was not cut with the block. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

04-16-2010, 08:29 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	did you chase the head bolt threads with a tap? torque in multiple passes and in the right order me? as long as the head and block aren't warped I'd redo the HG. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

04-16-2010, 08:38 PM	#5
cvbikeguy 3" Exhaust Join Date: Nov 2009 Location: Castro Valley, CA Posts: 248	even though i followed the tsrm i just wonder if i just f'ed something up of whatever. also i didnt get the new head machined but i did buy a rebuilt one on ebnay for $400 and it says it was already shaved and ready to be slapped on. you think i might have messed up on the head bolts? __________________ 86 MKIII Supra East Bay, CA 7mge rebuild. http://www.toyota-supra.info/forums/...-tomorrow.html MKIII commercial http://www.youtube.com/watch?v=HY9W3...om=PL&index=27 lightening build http://www.toyota-supra.info/forums/...ing-build.html

04-17-2010, 02:20 AM	#9
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Chasing threads is a pretty standard practice. You get a tap (thing used to thread holes for bolts) of the same size and pitch of our headbolts and you thread it into the holes (and keep adding oil to lubricate and clear out debris). As you thread it in AND as you thread it out it cuts the metal of the threads back to the right shape and size for the bolts/studs. Not doing this may cause the bolt to reach a given torque level but not provide the actual axial clamping force you want (ie: the shit don't turn so easy so you think it's done too soon). I really wish they made hollow studs for our cars.... that's the only way to get really close to a given clamping force. Hollow's are great. Yes, the headbolts are reusable. 80lbs is high... don't go over manufacturer specs just becaust you think it'll be better... you'll break something. Also, rebuilt of not, you don't know what shape the head was in... could have warped from inappropriate storage. Measure it with a machinist's straight edge (not just a metal ruler! ). __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

04-16-2010, 08:10 PM	#3
kamikazemkiii 3" Exhaust Join Date: Mar 2009 Location: raleigh Posts: 138	Sorry to hear that man, ive got a new headgasket if you need it

04-16-2010, 09:04 PM	#7
suprabahamut 3" Exhaust Join Date: May 2007 Location: greensboro Posts: 242	Did a shop rebuild the engine for you? I know a person who got there motor rebuilt, and the shop torqued the head bolts at the wrong torque, because it was listed wrong in the manual. He even told them to change the torque because it is a problem, but I guess they did not believe him. In the end the tech had to rebuild the motor at no charge, but they bought a replacement instead I guess cheaper. It took some time to get it back, but if some one did this to you, you can get it at least get it fixed at little to no charge.