can head bolts be reused?

[whitebroncoii87]

hi, can they be put back as is? or must i get a new set? or maybe put white plumbing tape around the threads so I can reuse old bolts? thank you!

 

[Mac]

What engine and year? Newer engines are torque to yield and are one time only.
Dave

 

[straycat]

Some of my friends usually replace the head bolts since they do get stretched out from the torque of being tightened down. The last rebuild I did was on my Sammy and I replaced the head gaskets and the head bolts just to make sure. Some people tell me they have used the old ones and had issues and some others have used the old ones and never had any problems. 50/50 chance. I would just use new ones to tell you the truth.

 

[adsm08]

2.9 head bolts are not reusable. The only 2.9 I have ever seen blow a head gasket rather than crack the head itself was one that had the bolts reused.

 

[RonD]

No, you should never reuse head bolts, even old style "regular" head bolts, lol.

Head bolts need to hold quite a bit of pressure as cylinders fire, above 1,500psi.
But the real issue is the repeated heating up and cooling down over the years of use, the bolts stretch.
Metal gets fatigued with the daily expansion and contraction.
And any one old enough will remember a "regular" head bolt just failing, no overheating, although that could cause it as well, one head bolt would just break one day, usually during warmup.

The newer TTY(torque to yield) bolts handle this expansion and contraction much better, and were needed for aluminum heads in any case, but are better even with cast heads.
The TTY bolts are stretched, on purpose, when tightened to specs, when removed they do not return to normal length, so at this point they have less stretching ability.

Can you reuse heads bolts?
yes, if they are not broken, lol.

Should you reuse head bolts?
Never, not even the old "regular" head bolts, and especially not the newer TTY head bolts.

What are the chances of an old head bolt failing?
Doesn't matter, heck a new head bolt could fail, but here's the thing................
You will spend 8-14 hours replacing head gaskets, and at a minimum $150, probably more.
Is saving $40(or less) for a new set of head bolts worth it?
Your money, your time, your choice.

 

[Mark_88]

Well, on a 4 cylinder it may be a bit different than others...so probably excludes anything in a Bronco II...never seen a 4 banger in a bronco that wasn't boosted...

Anyway...I had my 2.3 Ranger for 14 years and reused head bolts all the time...however, I would periodically swap in newer or cleaner bolts so that I always had the clean ones...and I swapped heads at least three times in that 14 years...mostly due to cracking heads and not snapped bolts.

The last set of bolts came from a 87 Mustang with only 100,000 km on the clock...

However, having stated my personal experience and preferences...there is wisdom behind using new bolts that my desire to reuse things didn't allow...so it the engine is going to be there for a long time...or you want it to be...don't skimp on things as critical as head bolts...skimp on things like underwear for those wonderful "HOLY $HIPS" moments...

 

[whitebroncoii87]

what if the bolts look good and not deformed? anyone used white plumbing tape around the threads?

 

[Mark_88]

The plumbing tape is a thread sealer that works great on joints that may leak...but not so great on automotive applications. My Dad used to use it on fuel and brake lines and I did the same for many years...until my carb got plugged up with it...but that was my fault for putting it too close to the end and not covering it properly...

In an engine at temp I'd say it would probably melt and gum things up if anything. The head bolts are not usually sealing anything so no real reason to stop them from leaking...the bottom threads go into the block and the top is usually recessed into the head...unless it runs through a cooling duct...and I do recall reading of some engines that have that...Chevy comes to mind...but I can't remember exactly...

 

[Kayakcrazy]

No engine builders I know reuse head bolts. They arent that much , buy new ones

 

[AllanD]

the head bolts of the 2.3 at least to the end of 1987 are not TTY and are thus reuseable.
I believe the 3.0 are also reuseable.

the 2.8, 2,9 and 4.0 have ALWAYS been TTY bolts and those must ALWAYS be replaced
as for putting anything on the threads? long standing doctrine is clean fresh engine oil ONLY.

Teflon tape would reduce the rotational torque considerably and thus make it far too easy to over-torque the bolts.

AD

 

[adsm08]

what if the bolts look good and not deformed?

The bolts are deformed. You will not be able to see it with the naked eye. If you have new bolts and old bolts next to each other and a micrometer you may be able to find the deformation, but it's not so much about a change in shape as it is a loss of elasticity.

Like Ron said, your time, your money, your choice. For the guy who is picky enough to pull an engine apart and replace the lifters just because they are a bit noisy you sure are picking an odd place to try really hard to justify cutting a corner. Especially in light of your little freak out over finding coolant in a few cylinders after you popped the heads off.

 

[AndyB.]

Head bolts for 2.8: D1FZ-6345-A. Not a torque to yield fastener.

Head bolts for a 2.9 or 4.0: E6TZ-6065-A. These are torque to yield fasteners.

 

[whitebroncoii87]

Ha, i guess this is a new concept for me that some bolts cannot be reused even when they look perfectly fine that made me grapple with it a little bit when I first heard it.. If they screw back in good and tightened to the right torque, have they not done their job already? I guess in microscopic ways you can say they may or may not have.. I have no idea.. I tend to want to hope engines are not perfectionist like that, but maybe they are. I did go get a box of new head bolts today though, but turned out there were only 8 in the box so I ended up putting 8 new ones and 8 old ones back. I did mix them between the two banks though. Ha, we'll see what happens..

Hey can I squeeze in a question here? which piston pairs reach tdc together, is it 1 & 5, 4 & 3, 2 & 6? I already put my heads back so can't see the pistons in action. Thank you, you've been really helpful!

 

[AndyB.]

How did you tighten the head bolts? Following the bolt sequence, first round is 22 ft-lbs, second round is 51-55 ft-lbs, third round is turn 90 degrees.

 

[RonD]

No head bolts should be reused, old style or new(TTY), if you want to remove your head(s) multiple times then use studs instead of bolts, studs are a totally different fastener type and can be reused, but even they have their limits.

As for the old bolts it's an opinion based on seeing more than a few broken bolts, and breaking 1 or 2 on reassembly myself.

Plain and simple it is a gamble, you are betting your time and money(for gaskets) against making $40(what you saved on head bolts)
To me that is just a bad bet

Look at the firing order to see piston pairs.
divide the order in half and put one below the other, i.e.:
2.9l 1-4-2-5-3-6

1-4-2
5-3-6

So 1-5, 4-3, and 2-6 are matched pairs

4 cylinder, 1-3-4-2
1-3
4-2

So 1-4 and 3-2 are matched pairs