silvercobra

Hello,

I blew a head gasket...again...on my 95 Toyota 4Runner. The first time my dad fixed it over the course of a Summer, but this time I took it to a mechanic. He was supposed to call me when he got the head off so I could bring him the new head bolts I bought but he did not and just re-used them. I know you are not supposed to re-use TTY bolts because of the stretching, so my question is: Since I already have bought new head bolts would it be smart to go back in and replace them? It was a while back when my dad did the first repair so I don't remember how deep in the actual bolts are, is it worth the effort to put the new ones in or pay someone to?

camo31_10.50

yes....i'd make the mechanic do it...and make him do it for free..any fricken mechanic should know not to reuse them....hell even i know that and i'm only 19!!!

OutlawMike

Damn,

That is a crappy mechanic. My condolences on this one, I feel for you.

There is a particular sequence that the FSM says to torque the head bolts, a pattern if you will. As I recall (off the top of my head) you initially torque them in the pattern to a low torque setting, just to seat them. Then you rotate them, in the pattern, 90 degrees. Then you rotate them again, in the pattern, 90 degrees.

If you were going to swap them, you really need to remove all of the head bolts, and then follow the torque procedure. I would not torque the head down without removing the inake manifold, as it does apply force to the head at the gasket interface. So, you have to remove the plenum and then the fuel rails, and then the intake manifold. Then remove the valve covers, and then take out all of the head bolts. I think that the FSM says to remove the cams to get at the head bolts, but as I recall I could get in there without removing the cams.

Then, there is the question of the head gasket. Do you re-use the one that is in there, or do you put new ones in? My gut says new head gasket, but maybe there are others on here who have another opinion. If you do a new head gasket, you have to pull the exhaust and the timing belt to lift the heads up. Essentially you are doing the whole job over again.

I am a Mechanical Design Engineer by trade and have run across the use of TTY bolts in my job. They really should not ever, ever, ever by re-used, they are one time use only. After installation they are permanently elongated and necked down, by design intent. When you re-use them you most likely will not get the intended, uniform clamp force on the head to the block.

I personallly believe a fair number of the second and third blown headgaskets are due to re-use of the head bolts on the 3VZE. That, and the crazy exhaust routing that overheats the #6 cylinder.

Or, you could let it ride and hope you get lucky.

Good luck.

Mike

RMA

what engine ?

the 22re head bolts are not TTY .. per FSM no need to replace them

the 3.0 head bolts are .. should be replaced

but for $40 might as well change them .

pruney81

If he already buttoned it back up and torqued them down properly I wouldn't worry about it. I certainly wouldn't ask him to tear into the thing again for free as the 3VZE is a bitch to work on. It's not a small job to take the heads off. That said, I would be a little upset if you told him to wait for you to bring him the new head bolts and he didn't listen, so just call him and let him know that you aren't happy and if the head gaskets fail prematurely take it back to him and use the head bolt issue as leverage for him to repair it again the "right" way. I'm sure people will scoff at this but I have a buddy who has worked at a Toyota dealership for years as a mechanic and he told me they always re-use the head bolts when doing the head gaskets on the 3VZE.

OutlawMike

Hence why they blow the second and third time. Even the dealerships get this one wrong. TTY bolts should never be re-used. They are a great way to ensure an even, uniform clamp load in an assembly, but by their nature, they are one time use only. Once you take the bolt past the elastic limit and permanently elongate the bolt, it will not apply the same clamp load for the same factory torque procedure. Depending on where each individual bolt started out on the stress strain curve, you may push the bolt over the top of the curve and receive significantly less clamp load for further rotation of the bolt, it will just continue to elongate.

Oh, and I really wonder if they charge them for new bolts at the dealership, but do not put them in. Sneaky they are....

TOYOTA 1

x2...

meswoleshane

I agree with this.

Brhesson

my brother and I are repairing the head gasket on a 93 4runner --3vze-- v6 4wd that I picked up for $1200. My dad had an 84 truck that I grew up loving as well. To the point, yes the head bolts are made to deform at torque requirements my OEM. Reusing them is about as useful as grabbing some spare bolts at the hardware store and throwing Everything back together. You might as well put liquid nail in lue of a head gasket. It's just dumb.

I'm considering an old man emu suspension kit (2" lift). I am wondering if I should use the ball joint spacers or new torque bar for the front.

I'm also intending on new headers to avoid the stock 6th cylinder exhaust issues. Has anyone any advice about NWOR or Doug Thorley headers? Should I do a 1" bodylift to avoid alot of fabrication to get the headers in, etc? I've searched the forums but since we have the same vehicle I was hoping we could talk.

Thanks

mastacox

It's pretty common for DIY'ers to re-use the head bolts, and it isn't really that big of a deal. If they all torqued back down, you're probably fine. If your gasket goes again, it probably won't be because of the head bolts.

That being said, I would have the mechanic refund you the cost of a new set of head bolts, ~$70. And see if he's willing to give some sort of warrantee in writing.

mt_goat

I wouldn't worry about it now, the biggest danger of re-using them is they might break as you torque it down. If none broke, and it is not leaking, all is probably good.

OutlawMike

I completely disagree, from experience designing TTY bolts into mechanical assemblies. If the bolt breaks or not is not the indicator for proper clamp load from a TTY bolt. The bolt is designed with a thin section in it so that when it is torque it permanently elongates in that thin area. This is the area above the threads, which is smaller than the minor diameter of the threads. The bolt stretches and necks down in that area.

For the alloy they are made from there is a relatively flat portion (compared to the initial part of the curve, link below) of the stress strain curve where the bolt will maintain about the same clamp load on the head for any given amount of further rotation. If you get every bolt in the head into that flat portion of the curve, you get uniform and repeatable clamp load for every bolt, regardless of thread clearances, lubrication, surface finish, etc, etc.

That is the great thing about them, rather than shooting for a set torque on a wrench, which yields widely varying clamp loads due to friction, you get the bolt into the flat part of the curve and you then have even clamp load. You can use less bolts in the assembly and give more room for other design features (intake ports, exhaust ports, valves, coolant passageways, etc.)

The problem when you reuse them is that the bolt has been permanently elongated and necked down. The next time you use the bolt you are pushing it further along the flat part of the curve and towards the backside of the curve. When you reach that area of the curve, the more you turn the bolt, the LESS clamp load it puts on the head, it just stretches out and necks down further. Bam, blown headgasket.

On a 22RE, different story, those bolts are not TTY. On the 3VZE, they are and need to be replaced every time.

The link below is an good explanation of TTY bolts and why they are used:

http://www.acl.co.nz/Tech/Torque%20T...0Headbolts.pdf

mastacox

Disagree all you want, but the fact is people re use TTY bolts all the time with relatively good results. The 3VZ has notorious head gasket issues because it's difficult to seal materials with different coefficients of thermal expansion together, not due to reusing TTY head bolts.

OutlawMike

I got a chuckle out of the liquid nails for a head gasket. If they have a high temp version, that might work...or not.

I will PM you.

Mike

Teuf

I reused mine (22re), out of not knowing i should have replaced them, and from what i see i do not need to, well dayyang......

mt_goat

Yes, if I was doing a head gasket on a 3.0 I'd use new bolts but if someone else did it for me and they didn't, I wouldn't worry about it now unless of coarse it was leaking. I'll just add to this what EB had to say on the subject and leave it at that. I quote EB:

mt_goat

That is a good link, I edited my statement to clarify what I meant Mike. Thanks

OutlawMike

Na, your fine with the 22RE, they are "normal" head bolts. They are torqued into the elastic range, not the plastic range of the bolt material. So, no worries, you can re-use those just fine.

OutlawMike

I have that link bookmarked, I reference it so much in regards to the TTY bolts. Even some of my fellow ME's at work need a refresher course on the concept from time to time.

Another place they use them in the 3VZE are the main bearing bolts in the bottom end, and I bet not many people replace those either. But, that is and iron-iron assembly, not aluminum-iron. The differential expansion rate of the aluminum versus the cast iron makes things even worse.

IngSoc

Hahahah sorry that one got to me... Reminds me of night at the roxbury

, " See even your brother isnt convinced... Thats cuss he actually uses his brain." I dont know one way or the other in truth but if the bolts are bought, he told him to replace them, well sounds like he didnt do the job right and its the mechanics damn fault for not following the instructions of the factory and most importantly the costumer. If it were my job I would HAVE to go back and redo it.... With that said I sure as hell wouldnt make that mistake twice. Only problim is pissing off your mechanic is like pissing off you doctor or waitress.


P.S. in no way was I tring to be insulting... just that little bit crossed my mind when I red that tid bit.

BTW