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

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.

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

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.

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?

how much? thanks

whats chase and tap? couldnt find it in the tsrm

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?

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.

Pulling the engine on these cars is fairly straightforward. You can leave it almost fully assembled if you pull the wiring harness with the engine. All you have to do is remove your glovebox, unplug the harness from the ECU, and push the wires and the grommet out through the firewall into the engine bay. Then just find the couple of connectors that go to body electronics, and you're good to go.

IMO, it's easiest to pull the transmission with the engine. Helps maintain the proper angle when removing it from the car, and then you don't have to deal with the PITA bolts at the top of the bellhousing.

And one last thing, remove your hood! First time I didn't think it through and halfway through the process I had to stop to get that thing out of the way

Chasing the threads is easy. Just do it when you've got some energy and patience left. ;) What you want is an "Intermediate" or "taper" type. I'll dig up the size when I have a moment. The only real trick is keeping the tap VERY well lubed and cleaning out the hole frequently (especially important with a block that hasn't had the threads chased in a long time). So, you take head off and clean out the bolt hole thoroughly, lube the tap with some lightweight motor oil, start threading the tap in (getting it started is the tricky part, DO NOT LET IT MISTHREAD!!!!!!!!!!!), then slowly and steadily thread the tap in half way or so. Now remove and clean the tap and finish threading it into the bolt hole. Remove the tap, clean it and the hole out thoroughly and thread the tap back into the hole and chase it the whole way to be sure everything is smooth. Remove the tap, clean out the hole and tap again and move on to the next.

When I say the manufacturer's specs I meant the manufacturer of the fastener... not the car. ARP specifies 75ft lbs for 7M head bolts and 90ft lbs for 7M head studs.

By the way, there is actually a difference between a "chase" and a "tap". A chase is generally a little undersized and doesn't cut the block material as much. These are intended to correct misshapen threads. Taps are intended for cutting new threads into a material. The difference with a cast iron block isn't a critical one, although I think with an aluminum block a tap in place of a chase would be a big no-no.

ok so maybe that will be a better option than getting it down to the block and then removing it. either way i will be taking the tranny out at the same time then swapping in the r154. and yea i cant imagine pulling the engine with the good still on.

lol oh man. ive used a tap and dye before is this somewhat the same? and once i tap the holes i wont need bigger size bolts? and how much resistance should i be feeling when i do this? wow so many questions. where can i buy this and how long does it need to be? and should i apply rtv to my bolts when i install them? thanks for all the info. my patience has greatly improved from this car. im actually excited to hack at this more with the tranny coming in. i also want to upgrade the suspension like we talked about earlier with bushings, shocks and springs. ill also be prepping the interior.im working locally so transportation isnt a must anymore.

thanks again

man i love reading all your threads thanks for the knowledge!!!

No, you'll use the stock size bolts. You're not tapping the holes any larger, you're tapping at their current size to just clear out material which has swelled and to reshape them so that the bolts can go in without any resistance which would skew the torque readings.

Make sure to THOROUGHLY lubricate the bolt threads with a good moly based lube. If you used moly lube prior (you should have, if you didn't there's major mistake #2) you can soften it up by massaging a little oil into it, but I'dd add some fresh grease too.

tighten in the correct order in multiple passes. I generally torque in 15 to 20 ft lb increments. First pass @ 30, second @ 45, third @ 60, fourth at 75. If I'm using studs I'll do it that way up to 90 (did last night in fact).

The tap length doesn't matter, but they're fairly standard. You want one the same size and pitch of the stock head bolts. A bottoming tap is even better but they're a lot more expensive. Unlike a taper they'll cut evenly all the way to the bottom, but it isn't critical here.

Buy or borrow or rent a machinist's straight edge and check the block and head for warpage as shown in the TSRM. Make sure the lower rear timing plate's deck does NOT sit any higher than the block's deck!!!! If it does it will keep the head from coming down all the way and evenly.

Absolutely not!

Wikipedia has some good info on the different types and how they work.

http://en.wikipedia.org/wiki/Taps_and_dies

lol its nice to know my pain and struggles can be of service to someone else :p.

id rather post all my problems to help others that are going through the same thing. once i start hacking away ill post up picks. ill also do that for when the interior comes out (i think im just walking into trouble) hope

moly and grease on the threads?

wow im sorry to say that i failed to check that. wiki is my middle name

thanks cre. who knows possibly in a couple months i can actually get this running

http://store.driftmotion.com/static/i-tap12x125.php

As for the moly thing... torque values vary depending on the type of lubricant used. Where a fastener may only require 90ft lbs with a good moly used to luge the threads it may require as much as 130ft lbs if only lubed with 30 weight oil.

Damn sorry to hear this man, I'd just cry. (I'm pissed off enough just having an oil leak from the turbo after reassembly!!!) think it's pretty much been covered here in that the threads need to be as clean as the rest of the job really if it's gonna hold. I cleaned mine with a combo of 2 stroke oil & an old bolt with slots cut up the length of the thread in the same fashion as a bottoming tap but obviously with the small advantage of only removing crap not fresh iron) & after that blasted them out thoroughly with brake cleaner until a rag on a screwdriver came out of each hole clean. Also I took a clean bolt & made sure it went in by hand with the same force, right to the bottom of each hole with no sticky bits. Then plugged the holes with blue roll until I was ready to throw the head on. In short the holes need to be good for eating your dinner off & then some.
Also if you're reusing bolts after any time or a HG blow make sure (ideally with a die nut) that the threads on those are perfect too. As cre mentioned you wouldn't believe how little crap or even just a different lube can affect torque readings opposed to clamping force...

Oh one more thing I didn't notice mentioned was the dowels front and back, their holes also need to be clean & the surface of the dowel perfect or the head could potentially stick on those. Front one on my motor had to be swapped as it had been mauled & burred by the gorilla that did the last rebuild so professionally :umno:. 90ft/lb by the way is what my stock bolts are at right now, if you have ARP 100ft/lb would be my choice for peace of mind (and obviously a retorque after 150/200miles max.).

Best of luck for take two, for once I'm gonna hope it's NOT 3rd time lucky!!!

EDIT-: Oh cre, on the subject of hollow studs surely one could have ARP's or even stock bolts drilled part way up to create the same effect (I'm thinking simply as a place for any remaining shit to go, instead of it hydraulicking up under the base of the stud/bolt hence making it feel tighter than it is) provided it was done accurately & not on a hand drill & vice of course!

A blind 20% bump in pressure is way too big to go and just recommend to everyone. The reason for the jump from 58 to 75 is that 58 is a commonly used torque value for cast iron heads. 75 is used in most things aluminum (your wheels, for example). People far more educated on matter than you and I came up with these values, their warranties are based on these values (yes, they will be able to tell). The head isn't as beefy as people like to think and the bolts and studs aren't immortal. Any, I'll reiterate that the value also depends on the lubricant used... if you're using 30 weight oil, your about right on... moly... well, whoops.

You can't really drill fasteners without compromising their elasticity. There's no way you're going to keep them cool enough for starters. And it has nothing to do with creating a vent, it's for measuring stretch and calculating the real clamping force. :bigthumb:

The dowels are not considered reusable actually... no reason they shouldn't be except that they're tapped into the block and getting them back out requires either pounding then in the rest of the way so they fall into the coolant passages or mauling the living hell out of them to pull them out the top. This came from a Toyota tech, there's nothing in the TSRM on the matter as they don't expect you to remove them at all.

Good point well made & no I wasn't really considering the use of moly lubes (which I now note you recommended earlier) as I'm a cheapskate (read blind-skint!) and my 90 on stock bolts was achieved using 2t oil IIRC. I wasn't really recommending anyone else go for 100 on ARP bolts mind, just observing that if I had fitted them I would have probably gone that far (but then I guess if I could afford ARP bolts I could afford decent assembly lube also so maybe not...) :dunno:

Again good point on drilling of fasteners, looks like someone's not really got their brain in gear yet today... Think a beer or three might get me cogs turning again... (Am I gonna end up famous for saying "it seemed a good idea at the time" some day?)

Anyway I got the hint that the dowels aren't really intended to be removed by the way said lump was mauled at the front of my motor, I'm still cursing the now defunct total-engine ltd! but it's still gotta be worth remembering that the holes in the head have to be clean too & checking the same bodgery hasn't happened as mine resulting in a burr that the head could sit on, and the 150/200mi retorque is essential IMO no matter what anyone says it's a hassle but what price being sure it's not settled?

wow so im pretty sure my mistake wasnt the threads but the moly lube. i used it the first time i re assembled the head but on the second and third and fourth and.....

so by the time i had the finished product i used 30 weight at 85 lb of torque.

when i was torquing the bolts they went in smooth with no slipping but should i still tap them? i know for sure im going to check my head for warpage and have it cleaned. bet its all nasty. should i do anything to the block?


thanks for this valuable info. i would of had no idea and probably would have repeated the process. kinda funny that i have had this supra for quite some time but have barely driven it but still manage to continue projects while starting new ones.....

im hopeless.