Reman 7MGTE w/3000 miles, STOCK Toyota head bolt torque - Should I retorque to 72? - Toyota Nation Forum : Toyota Car and Truck Forums

ToyFan420 · 08-06-2007, 06:47 PM

The subject says it all, and I hate to start another thread on this topic, but I couldn't seem to find a case quite like mine. The engine was purchased from JER, and they told me that they use stock Toyota specs for head bolt torque (55 - 61ish?), with stock type bolts, I'd imagine. There are a few thousand miles on the clock since the engine was installed, and I am going to ask that infamous question: should I retorque to 72?

The stock gasket lasted to about 150k on stock boost, and after warping the head, a reman was installed. My Dad just shipped me the car recently. I plan on running about 16 lbs of boost with a 60-1 trim CT26 (eventually). I probably wouldn't worry about anything if I was planning on leaving things stock, but the fact that the head gasket WILL blow (much sooner than any modern design should) just pisses me off.

***bgrieger*** · 08-06-2007, 10:54 PM

no. If you want to upgrade the turbo and run that much boost, you will want to replace it with a metal gasket with all the appropriate machine shop work required to correctly install it.

If you plan to remain stock, you can retorque, and you might be fine. Many retorque and find the gasket fails shortly after due to shifting of the seal while torquing the bolts down.

Jeeves · 08-07-2007, 04:18 PM

+1. Don't retorque stock bolts, they stretch and will be worse over all. Pull it apart, machine down the head and block, and install a mhg with ARP studs and get it done the right way.

ToyFan420 · 08-08-2007, 06:25 AM

The shop that was working on the car pulled the head twice, and replaced the head gasket twice. They NEVER checked runout on the head or block. Dummies. So the third time around, my Dad opted for the rebuilt. It is frustrating to know that the job could have been done right the first time, machined, with HKS gasket and ARP's. Thanks all for the input! Looks like I'll be running stock boost for a while, as my car projects are piling up...

shaeff · 08-08-2007, 04:14 PM

i read a tech article written by (reg reimer?) some time ago- and the stock bolts have identical tensile strength as the mkiv's head bolts, which are torqued to 70+ ft lbs. i'm on the re-torque bandwagon. i did it to numerous supras and never had a problem (and one of them had a modified JDM motor with 40k on it- and it never failed or showed signs of failure)

this is, of course, a do it at your own risk type deal.

but 52ft lbs makes me nervous as all hell (and that's what gives the 7M a bad name!)

-shaeff

CRE · 08-09-2007, 02:10 AM

If the bolts are the original head bolts I wouldn't personally retorque them as high as 70lbs. If they used new Toyota head bolts I'm with Shaeff, retorque them to 70lbs. There is always the potential for trouble, but when alot of people retorque after 500 - 1000 I don't think you're in any more jeopardy than they. At the moment I can only remember reading a post by 1 person who had a retorque fail and he was still on the original HG and well past 100K.

ToyFan420 · 08-09-2007, 05:38 PM

Quote:

Originally Posted by CRE

At the moment I can only remember reading a post by 1 person who had a retorque fail and he was still on the original HG and well past 100K.

This brings up an excellent point. Has anyone on this board had first hand experience with a failed retorque? What is the weak point? Bolts, gasket, or both? I'm sure that this issue has already been beaten to death, but I'm having a hard time understanding what the actual implications of a retorque are. If the tensile strength of an OEM type bolt allows that amount of torque to be applied, are we worrying about only the pressure exerted on the head gasket? I've reused metal exhaust type gaskets, and just torqued them a "bit" past specs. I know that there is a huge difference between that and a head gasket in a forced induction application, but what really happens after a retorque fails?

shaeff · 08-09-2007, 08:34 PM

^ if anything, the gasket would be the weak point. (the theory is that you're pinching it, and actually making it lose it's seal)

-shaeff

CRE · 08-09-2007, 11:28 PM

Yeah, I should add that the post I read was by someone running the stock composite head gasket. Composite gaskets are far more prone to damage than metal.

Jeeves · 08-10-2007, 12:59 PM

The problem with a blown HG/retorque is once you retorque and it fails, how do you isolate what part failed? Measure bolts? Measure the head/block? If the HG sees detonation it'll distort either way... so, it's tough to just simply say when the HG itself fails..

CRE · 08-11-2007, 12:12 AM

No one said "sure it's safe and nothing bad can happen". YES, there is the possibility that the HG will fail. If the bolts are new and they were put on with the stock torque stretching had better not be a problem... if it is, they got the bolts at Home Depot.

Regardless of whether a bolt fails or the HG fails, at the point that you've got oil in your coolant, coolant in your oil or you're pumping exhaust gas into either you're going to be pulling the head.

I do agree that at that amount of boost he should run a MHG for piece of mind though. I missed that when I replied earlier.

ToyFan420 · 08-13-2007, 08:54 AM

Quote:

Originally Posted by CRE

I do agree that at that amount of boost he should run a MHG for piece of mind though. I missed that when I replied earlier.

Yes, it seems like a moot point. From what I understand, I would not feel comfortable running that kind of boost with a stock composite gasket and stock bolts anyways. Oh well, I'll just add it to the list...

shaeff · 08-14-2007, 09:19 PM

i'll state this again and again- the stock bolts are not to blame. it's the low torque spec.

i would have no problems running stock bolts on a MHG at 72ft lbs. it's not like they're weak, they're just not reusable...

-shaeff

CRE · 08-14-2007, 10:17 PM

Actually, the stock bolts are more than beefy enough to stand up to a couple reinstallations. Age is the reason I recommend people replace them with new ones. I prefer having additional insurance as well, as such i do run ARPs, but I really wouldn't have any problem with using new OEM bolts or even reinstalling them a second time if I had to pull the head.

1988Supradreams · 08-25-2007, 01:00 PM

100FT LBS on my OEM Toyota HG, and no problems whatsoever. And I beat the snot out of it before it got RODKNOCK haw haw haw. But then again I'm running ARP studs. Stock bolts might do okay with a slight retorque, just don't get too gung-ho with them. Like previously mentioned, they DO stretch, but not so much that a retorque would make it worse... +1 for retorque to 80 ft/lb.