I am new to this forum when it comes to posting however I've used this for help on all the fixes i've done before, so if I posted to the wrong part of the forum apologies now.

About a week ago I dug into my 2001 360 to replace the plenum gasket. Didn't have the money to get the Hughes plate, but got all new gaskets, shorter bolts, and even decided to do a few other things when I was in there. After replacing the gasket and hand tightening the bolts on the plate, I started to torque them down following the manual starting with 48 in/lb. After snapping two of those bolts I decided I should look for help. I'm I over torquing? How long should the bolts be? I bought bolts that were about a 1/4 in shorter than stock ones, and got grade 5. In the end of things I should have gotten the hughes kit, but it's a little late for that now. Very frustrated. Any comments help!

Thank you!

 

Well that's the correct torque for the first step..... and it broke??? That seems REALLY odd. Did they thread in nice? Correct threads??? If they are snapping off at 48in/lbs, wonder if you just got some bad bolts?

 

could you have had oil in the bolt holes and hydrolocked the bolts? I've never done this so I don't know how they feel when it happens......or if those are even closed end holes they bolt into

 

Make sure you're talking inch/pounds not foot/pounds on your torque wrench.

Just sayin'...

 

Ill try to blow out the hole with an air compressor and then maybe add some lubricant to thread better. It threaded all the way down by hand and then I tried to tighten it. I do know that I am using a ft pound torque wrench so I'm set at 4 ft pounds for the first step. I guess I'll try to get it out with an easy out and then try again.

 

Yes I'm set at 4 ft pounds on my wrench

 

Might want to check to ensure that the bolts are not bottoming out in the holes. When I did my plenum gasket, I ran a thread tap through each hole to ensure the threads in the intake manifold plenum plate holes were clean and free of burrs. Also, be sure to start each bolt by hand to ensure you aren't cross-threading the bolt and causing it to bind.

Also, most budget torque wrenches aren't very accurate at the extreme low or high ends. I did use a good quality inch-pound torque wrench and loctite on the bolt threads for good measure. Might want to consider borrowing an inch-pound torque wrench from a good mechanic friend.

 

Good point on the torque wrench. I have access to a snap on wrench and i'll do it with that. The bolts that I bought may have still bottomed out in the hole and snapped off because of it. I'll have to try and get it out tomorrow. Thanks for the help.

 

If you can, also run a thread tap through each bolt hole to ensure the threads are clean. Measure the depth of each bolt hole by using a stiff wire and measure it against the plenum bolts you are using to see if the bolts are too long or not.

 

Got everything back together. Now I am idlig at around 1500 rpm. I'm sure I accidentally snapped one of those little plastic vacuum hoses and will look into that tomorrow. However my alternator also stopped putting out power. I don't know why this is. It worked fine before the fix and I made sure all connections were made. Any suggestions?