Good idea to retorque head bolts after a gasket change or not?


#1

I am about to dig into an engine for a head gasket change and will have the head inspected by a shop before re-assembly.

I have seen references to people suggesting that head bolts be retorqued after a time. Some suggest driving the engine about 500-1000 miles before checking the spec once again. Others suggest putting the head on and just letting it sit for between 1 and 3 days and then retorque without putting the engine in operation. I guess the gasket will crush or creep during this time, relaxing the torque on the bolts. This would be the easier method for myself as I could leave the valve cover loose for this time and then put it on correctly after the second check.

Others suggest doing nothing. Just torque to spec and drive.

Anyone have an idea here on what is the best way to go? This is a 1994 Geo Metro with the 1.0L 3 cylinder engine by the way.


#2

I am also using an OEM head gasket and aftermarket re-useable (non TTY) head bolts on this job.


#3

The head bolts weren’t re-torqued at the factory when the engine was built, so why should you re-torque them?

I just install the head bolts, torque them to spec, button the engine up and drive.

Tester


#4

No need to retorque after assembly. After all, Geo didn’t request customers to return their vehicles for head bolt service after the first 1000 miles when the car was new.


#5

To each their own but I always torque them twice before buttoning up an engine. The second torquing is usually done after the engine has been sitting all day or overnight. That allows time for the head gaskets to relax a bit and which in turn can cause some looseness of the head bolts.

After 1000 miles and if possible, my preference is to go back and recheck them.


#6

@cwatkin

I’m with @asemaster and @tester on this one

If the manufacturer didn’t require retorquing, I wouldn’t do it. You’re just making more work for yourself

I’ve worked on countless engines where no retorquing was required. And I didn’t retorque. And there were no ill effects


#7

Where I worked many many years ago, we used to re-torque. I am not sure if those cars called for it or no, but I also remember that I felt it was not necessary as every time, there were right where they should had been and my wrench would just click.


#8

Years ago the old composite head gaskets had a requirement to retorque the head gaskets after a certain length of time. Read the installation instructions. If no mention is made to retorque then you are good to go. When I attended diesel mechanics class in the early 70’s…we always retorqued all cylinder heads after the engines were rebuilt. The engines were run for 2 hours then allowed to cool down before being retorqued to specs.


#9

Some points to be made.
How many of those head gasket complaints on this forum of seepage, weepage, or in some cases just flat giving up (no overheating involved) are due to the lack of a retorque?
How many motorists or mechanics assume that “it’s just one of them things”; all rhetorically asked.

What’s the most common complaint on this board? Subaru head gaskets.
At one time Subaru said retorque and there were no issues.
Subaru said retorques are no longer necessary.
Subaru head gaskets started seeping.
Subaru issued a service bulletin which stated head bolts were to he retorqued in the event of seepage.
It would seem to me that it’s better to err on the side of caution.

Just some food for thought anyway.

What cwatkin could do is replace the gasket, allow it to sit overnight, etc, and then recheck those head bolts to see if things have relaxed a little after sitting for a bit.


#10

@ok4450

I tend to disagree, if the engine in question uses mls head gaskets or tty bolts

Those bolts are generally not to be reused . . . and if you loosen them, for the purpose of retorquing, you ARE reusing them

And I’m 99% certain the same thing goes for mls gaskets

There may be some exceptions, but I’d like somebody to post some kind of factory documents stating that it’s okay and/or required to retorque a mls gasket or reuse tty bolts

That said, I have a strong hunch that @cwatkin is not using a mls gasket on that metro motor


#11

@ok4450

That is why I’ve never recommended anybody purchase Subaru vehicles

If you have to go back and re-torque the head bolts after installing the heads and gaskets, there’s a major flaw in the engine design.

I know of no other vehicle manufacturer that requires re-torquing of the head bolts once they’re torqued to spec.

Tester


#12

To me, the question is were the OEM bolts tty? The OP is using aftermarket non tty headbolts but if the factory headbolts were tty, I see a big issue here. If you are using an OEM gasket, you need to use the OEM type bolts and follow the procedures or else you will be redoing this job soon.


#13

The head bolts I ordered are NOT TTY and are intended to be re-used if the head ever has to come off. No, the manual doesn’t state to re-torque the bolts. I have an FSM for my year car.

I think I will simply let the engine sit overnight or so with the valve cover loose and check the torque the next day. I wasn’t planning to loosen the bolts. I was just going to re-check the spec in the pattern specified in the manual so I would only be turning bolts if the gasket had relaxed some.

There is a forum dedicated to these little cars and I see people doing it both ways. Neither group ever seems to have any issues with leaks or other problems so I don’t think either way is a bad idea.

I agree that driving 1000 mile and doing this makes more work. Just leaving the valve cover loose and removing it to re-torque the next day is easy. I see nothing wrong with doing this.


#14

It’s not right or wrong to go back and re-check the torque. It’s just not required.

Once the torque has been set on the fasteners, they’re in a static state of torque. That means the fasteners can’t get any looser or any tighter.

But if you want to go to bed with that warm/fuzzy feeling that the head bolts were re-torqued, by all means, re-torque the head bolts.

Tester


#15

Double-checking the torque after it sits for a few days seems a good compromise. I can’t see how that would cause any harm, and it might well do some good. Make sure you follow the recommended tightening order of course.


#16

I see that you ordered non tty bolts. The question is, were the factory bolts tty?


#17

I can see it now.

Customer comes in and asks, “Are the new head gaskets installed?”

And I say, “Yes.”

Customer asks, “Can I take the vehicle?”

And I say, “No”.

Customer asks, “Why not?”

I tell the customer that, “I have to let the head bolts rest for a few hours/days so I can re-check the head bolt torque”.

I would become the laughing stock of the auto repair business in my area!

Tester


#18

If I had a Subaru I had changed head-gaskets on, I would drive it and drain the oil at the next oil change interval and then remove the valve covers and re-torque the heads. I probably wouldn’t do that on anything else but an air cooled VW or Porsche.
After all, the way Subaru did it failed.


#19

My point is this and it’s not necessarily true of the old iron engines with cast iron blocks and heads. I’m referring to iron blocks with aluminum heads or all aluminum engines.

When someone registers on this forum and poses a question about why the head gasket has let go on their car or why it’s weeping coolant or anti-freeze can any of you state without any caveats whatsoever that the problem was NOT caused by loosening of the head bolts; either from the factory or after a HG job was done?

I might add that Subarus is not the only one. At one time Nissan recommended a head bolt check on their pickups. Nissan decided this was a colossal waste of time and money so they discontinued that procedure.
What happened shortly afterwards? The head gaskets started weeping (or puking in some cases) engine oil from an overhead cam oil pressure feed port.
Odds are retightening the bolts would have stopped the problem but the policy was to replace the head gasket, torque the head bolts, and then recheck them in a 1000 miles.
I never saw anyone laughing at Nissan Motor Company over that recommendation.

I might ask this. How many of you know with 100% certainty that the head bolts on any head gasket job you did remained tight and there was never a problem with the head gasket for the remaining life of the vehicle?

Take a 1000 identical cars, replace the HGs, and do NOT recheck the head bolts. If 5 or 10 of that number turn out to be a problem for failure to do so that strikes me as a preventable problem.

As I said, I just brought this up as food for thought.


#20

Scenario . . .

Nissan comes into the shop with a seeping/leaking head gasket

Shop prepares estimate for retorquing the head bolts. And the shop tells the customer in writing there is no guarantee this will actually work. Customers signs this understanding, and agrees to the repair

Shop retorques the head bolts . . . who cares if they were loose or not, that’s not the point here . . . and replaces the valve cover gasket

Shop cleans off all residue and corrects all fluid levels

Shop leaves car idling for a few hours. No signs of seepage/leakage seen

Customer is told to pay bill and pick up car

Customer picks up car

Customer returns in 1 month, with murder in his eyes. Head gasket is once again leaking.

Customer either doesn’t care that they signed the understanding, that the retorquing might not fix the problem

Or customer denies signing this understanding

When presented with his signature, he claims it’s a forgery

The only thing going through customer’s mind is “I paid money, and they didn’t fix the problem.”

Imagine what’s going to happen when the shop tells the customer that they’ll have to replace the headgasket, for a large sum of money

When the shop tells the customer “Sir, we retorqued the head bolts, thinking it would fix the leak. It didn’t work, now we have to replace the headgasket, in order to fix the leak” . . . the customer’s response will be “You told me it’s going to cost x amount of dollars to fix the problem. Your fix didn’t work, and now you’re telling me it’s going to cost a lot more, to fix the problem. What kind of shop are you?! You guys obviously don’t know what you’re doing”

Rest assured, whether the customer goes for the headgasket or not, he will not be a repeat customer. And he’s going to badmouth the shop to his neighbors, friends, relatives, churchgoers, etc.Odds are retightening the bolts would have stopped the problem

Do the job the right way, the first time . . .