4.7 Head Torque Steps

Piv · Oct 16, 2019

New to the forum and couldn't seem to locate any info on head torque steps.

I am getting ready to replace the heads, timing chains, etc on my son-in-law's 2001 4.7 Grand Cherokee Jeep that we think has a blown head gasket.

The manual I have says the steps to torque the heads are:
Step 1: Tighten bolts 1-10 to 15 ft. lbs.
Step 2: Tighten bolts 1-10 to 35 ft lbs, tighten bolts 11-14 to 18 ft lbs
Step 3: Tighten bolts 1-10 to 90 degrees, Tighten bolts 11-14 to 19 ft lbs.

Does this look right? The reason I ask is that I saw a video where the heads were torqued to 90 degrees twice (total of 180 degrees) on a 2002 Grand Cherokee 4.7 Jeep. I've never used the angle torque method before but it looks pretty straight forward. I plan to use a angle gauge for this.

Just want to be sure I have the steps right and only torque to 90 degrees one time. Thanks for any clarification on this.

Piv · Oct 18, 2019

After doing some more searching I did find a post on this issue. Seems that the torque steps and values have been a previous topic.

I plan to just stick with the torque steps/values as indicated in the shop manual and consider it done....unless anyone has experienced an issue and would suggest doing it differently.

Thanks
Piv

99wjtx · Oct 18, 2019

The service manual procedure is the "right" way to do it but that's predicated on using high quality, properly calibrated tools and new OE bolts into exceptionally clean (better yet new) block bolt holes with a properly trained and experienced skill set.

In a DIY scenario under less than ideal conditions, you may find that you have inadequately or inconsistently torqued down the heads which may require a re-work of one sort or another.

I speak from experience and so in practical terms I'm not a fan of torque plus angle.

Piv · Oct 20, 2019

Thanks for the thoughts and comments. I've never used the torque plus angle so not real sure about it - just received a torque angle gauge in the mail. I guess that I just wouldn't know what the final torque value would be and was curious to see if there was a better way. Planning to run a tap down the head bolt holes, good blow with air and lightly oil to get them as clean/true as possible.

Once I go through the service manual steps, I may check it out to see if I can determine what the final torque value is.

FanTech · Oct 21, 2019

The overall intent is not too get them to a certain torque value. It's to get them to a clamp load. Torque and clamp load are very inconsistent, especially at high loads. The initial torque takes up the slack and then the following angle change gives you a known bolt stretch. It's my understanding that the bolts will NOT yield. (So don't confuse this with torque-to-yield.
There is no need to re-tap the holes, clean junk out of them.

99wjtx · Oct 21, 2019

That's right. The factory service manual says that while the procedure is torque plus angle, the bolts are not a torque to yield design. I guess I missed that when I did a rebuild. I bought new head bolts and maybe that wasn't really necessary.

FanTech · Oct 21, 2019

99wjtx said:
That's right. The factory service manual says that while the procedure is torque plus angle, the bolts are not a torque to yield design. I guess I missed that when I did a rebuild. I bought new head bolts and maybe that wasn't really necessary.

It's not, as long as they haven't yielded but that can be hard to tell. The thread diameter will get smaller as the bolt necks down. Considering the importance of the bolts though, it definitely doesn't hurt to get new ones.

Piv · Oct 22, 2019

Definitely good to know. Now that you all have confirmed the shop manual steps and shared some insights, I'm feeling a lot better about the whole thing....
Thanks for taking the time to get me going in the right direction.

Think I am going with new head bolts. I'm going to do the tear-down next weekend.

4.7 Head Torque Steps

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