Intake manifold bolt snapped inside the block!

[Meat coyote racing]

I've had a weird idle / driveability issues recently and was trying to track down the issue. During my search, I narrowed it down to a vacuum leak. Upon further investigation I found a bolt in my intake manifold that was loose. I tried to tighten it and it would just spin. Removed the intake manifold to find this!!!!!

Luckily, I got it out. What's concerning is I think there is a thread problem (in the block) because this is the second time its happened. I have an incredible torque wrench and know it wasn't over tightened. I'm wondering if there is a machine shop that might be able to check the threads out to see if there are any issues. Advice and ridicule welcome lol.

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[ugstang17]

Obtain a bottom tap and clean the threads out with it. A bottom tap is flat on the end and the cut leads go all the way to the tip. Less chance of it cocking and taking too much material off the existing threads AND it will clean the threads to the bottom of hte blind hole. A starter tap would not be advisable to use. Prior to obtain some canned air to blow out the blind hole. When cleaning the threads make sure you use tap oil. KROIL will be a fine option. Worse comes to worse if there is not enough thread to hold, you can likely helicoil it. Looks like there is more than enough material around the hole to do that and it would be a legit fix. The latter may be done by a machine shop expert if you have not done one yourself.

Also obtain a higher rated bolt. See if ARP has a suitable replacement. Verify the torque spec Ford says to use. Intake bolts are not that high of a torque spec. Seems to my recollection 20-30 ftlb comes to mind when we pulled my head unit and intake on my FI setup a few months back to inspect for concerns that tuner had. The stock plastic intake may not be torqued as heavy though.

Take your time. Don't get in a hurry. Clean and clean and clean again after complete. Do not use an air compressor as it can blow chips everywhere. Canned air will suffice and you can control it better.

 

[Meat coyote racing]

Obtain a bottom tap and clean the threads out with it. A bottom tap is flat on the end and the cut leads go all the way to the tip. Less chance of it cocking and taking too much material off the existing threads AND it will clean the threads to the bottom of hte blind hole. A starter tap would not be advisable to use. Prior to obtain some canned air to blow out the blind hole. When cleaning the threads make sure you use tap oil. KROIL will be a fine option. Worse comes to worse if there is not enough thread to hold, you can likely helicoil it. Looks like there is more than enough material around the hole to do that and it would be a legit fix. The latter may be done by a machine shop expert if you have not done one yourself.

Also obtain a higher rated bolt. See if ARP has a suitable replacement. Verify the torque spec Ford says to use. Intake bolts are not that high of a torque spec. Seems to my recollection 20-30 ftlb comes to mind when we pulled my head unit and intake on my FI setup a few months back to inspect for concerns that tuner had. The stock plastic intake may not be torqued as heavy though.

Take your time. Don't get in a hurry. Clean and clean and clean again after complete. Do not use an air compressor as it can blow chips everywhere. Canned air will suffice and you can control it better.

Thanks for the detailed response. I am going to get my hands on a bottom tap. Does the bottom tap only have to be inserted and screwed down one time to get a thorough clean? I assume the use would probably be dictated until its clean, correct?

I am definitely going to take my time and clean. I noticed that tiny specs of dust/ a grain of sand fell into the intake port and is resting on a few of the valves (probably 3 out of 8 ports). I am very OCD and it freaked me out; there are probably only 3 or 4 tiny specs in each of the observed ports. I ordered tiny shop vac attachments to get the dust/ grains of sand out. I will use a q-tip to clean hard to reach sports on the top of the outside of the block.

I have an old intake manifold I can pull a replacement bolt out of. As much as I am reluctant to admit, it was probably user error rather than the fault of my torque wrench.

Thanks for the tip on the canned air. I will definitely pick some up before I start. This was a horrifying experience I don't plan on ever having to go through again.

- Zack

 

[ugstang17]

A tap will only have to make one pass to remove any imperfections in a threaded hole. Allow it to start itself, Do not force it. Do not continue to turn it when it hits bottom. Any chips it makes when making the pass will be captured in the flutes on the tap. The tap fluid/oil not helps lubricate but also helps trap the chips in the flutes though a few will remain and need to be blown out with canned air. Place a rag over the hole as well when blowing out the ships to avoid blowing them everywhere and WHERE SAFETY GLASSES so you don't rick getting anything in your eye when blowing the hole out. Remember you are cutting threads but in this case only removing imperfections if there are any.

 

[ugstang17]

Two last things...not used to giving tap use instructions.

After making a revolution in several shorter turns, reverse direction for 1/8th to 1/4 turn. This breaks up the chip keeping the fines smaller, collecting them in the flutes (the grooves cut down the length of the tap) and jeeps the cutting threads clean.

Last - use a proper tap handle. DO NOT ATTEMPT TO USE A CRESCENT WRENCH. While skilled machinest workers with years of experience may do this as a last resort even they have messed up the tapping process doing this as it causes side load and once a tap has started its thread its going to finish that way. The result is a thread that has threads that are angled and/or 'wollered out' with respect to the starter hole and not parallel with the hole. Bolts will not seat squarely when this occurs. It's easy enough to do with a tap handle. Using the wrong tool will only increase the risk of this.

 

[ugstang17]

The torque spec is 15ftlb 89 lb-in for the stock intake btw or more precisely 177inch/lb. After which you TTY the bolt an additional 45 degrees.

Here is the manual reference - http://iihs.net/fsm/?d=829&f=Intake Manifold.pdf&p=5

Correction here. The spec above is for

 

[sigintel]

The torque spec is 15ftlb for the stock intake btw or more precisely 177inch/lb if you have a torque wrench that sensitive. Most standard torque wrenches start at 15-20 ft/pound. Good ones like a Snap On may have a wider more accurate range.

NOOOOOOOO!!! LOL...

5th gen Mustang S197 w Coyote gen1:
89inlb+45deg.

6th gen Mustang S550 w Coyote gen2 Engines:
OEM Coyote 5.0 V8 intake manifold bolts are M6 1.0 pitch grade 10.9 torque 100inlb + 30 deg.

S550 2.3ecoboost are M8 177inlb !
Do not use 2.3ecoboost M8 bolt torques on the smaller 5.0 Coyote M6 bolts or they will snap like in these pics above.

https://latemodel.cachefly.net/downloads/instructions/FordInstShtM-6007-A50NA.pdf
https://lmr.com/products/mustang-50-coyote-motor-torque-specs

 

[ugstang17]

NOOOOOOOO!!! LOL...

From the Ford Factory manuals:
OEM Coyote 5.0 V8 intake manifold bolts are M6 1.0 pitch grade 10.9 torque 100inlb + 30 deg.

The 2.3ecoboost are M8 177inlb !

Do not use 2.3ecoboost M8 bolt torques on the smaller 5.0 Coyote M6 bolts or they will snap like in these pics above.

https://latemodel.cachefly.net/downloads/instructions/FordInstShtM-6007-A50NA.pdf
https://lmr.com/products/mustang-50-coyote-motor-torque-specs

I think I figured out my error since I do not have access to any ecoboost manuals. The Roush SC head unit uses M8 bolts to mate up to the intercooler intake. I had at about the time I posted that, pulled the head unit to inspect for oil build up in the head unit and intercooler due to some light throttle tip in issues I was experiencing. You are correct. I had a brain fart. Good catch. I have corrected the post you question.

 

[decableguy2000]

I would use a thread chaser before a tap to clean the threads up. Taps are for cutting threads and you my remove to much material. If it has happened more than once, I'd opt for a helicoil or a time sert.

 

[DivineStrike]

Ugh... so I learned the hard way to realize where I get my tq specs from. Didn’t want my hand tighten to be too tight so I untorqued them and tightened one to what I thought was the proper tq spec. Nope turns out that was for the 4cyl Who’s Messing with a 4cyl’s intake manifold anyhow? Lol anyhow sheared the bolt right off.

Anyone know how to replace the retained bolts on the manifold or what to replace them with?

 

[WildHorse]

Anyone know how to replace the retained bolts on the manifold or what to replace them with?

https://www.mustang6g.com/forums/threads/help-broken-intake-manifold-bolt-removal.157263/

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