-- Message Boards -- 1968 California Special Limited Edition Ford Mustang GT/CS
D I S C U S S I O N . F O R U M
1968 GT/CS & HCS
2007+ GT/CS
1966-1967 HCS


Old 09/24/2009, 11:17 AM   #1

Joined: Jul 05
Posts: 53

Intake manifold bolts keep coming loose


I have an Edelbrock Performer 289 manifold on my '68 GT/CS 289 engine with the original cast iron cylinder heads. I'm using ARP stainless steel bolts to attach the manifold to the heads. I've used the directions provided with the manifold to torque the bolts in the correct order and with the correct torque. But, they keep coming loose after a while.

Are there supposed to be lockwashers under the bolt heads? (There are just flat washers there now that came with the ARP bolt set). If so, what kind of lockwasher?

Or, should I use something like blue (removable) Loctite on the bolts?

Thanks in advance,

Harry Z.

Harry Zisko
\'68 GT/CS
harryz is offline   Reply With Quote
Old 09/24/2009, 11:54 AM   #2
My Car Details
franklinair's Avatar

Location: Franklin, NC
Joined: Mar 07
Posts: 4,380

My Garage
It is not uncommon to have to re-torque the manifold bolts after initial installation. How long has the manifold been installed (time and/or miles)?
You can also use the blue Loctite- it certainly won't harm anything.

franklinair is offline   Reply With Quote
Old 09/24/2009, 12:22 PM   #3

Joined: Jul 05
Posts: 53

Intake manifold bolts keep coming loose

Aloha Neil,

The bolts have been re-torqued a few times... they just seem to come loose on a regular basis.

It's not my torque wrench, either. I'd been having problems with intake manifold leaks and had replaced the gaskets a few times with no relief. Finally took it to a professional mechanic. He was able to get it installed so it wasn't leaking, but the bolts did loosen. And I don't drive the car that much....

Mahalo for your feedback,

Harry Z.

Harry Zisko
\'68 GT/CS
harryz is offline   Reply With Quote
Old 09/24/2009, 12:42 PM   #4
My Car Details
tomcwarren's Avatar

Location: Phoenix, AZ (Ahwatukee)
Joined: Apr 08
Posts: 126

See if there's anything in this thread that helps, Harry.

You might also try calling Edelbrock's tech line - I'm sure they've dealt with this problem before, and/or can recommend bolt type/length/torque/loctite-or-not, etc. Very sharp guys when I had to call about my Performer RPM.

tomcwarren is offline   Reply With Quote
Old 09/24/2009, 01:26 PM   #5

Joined: Jul 05
Posts: 53

Aloha Tom,

Mahalo for your suggestions. I had put off calling Edelbrock's support line as the last time I called I literally had to wait 45 minutes to talk with someone. Today, I only had to wait about 5 minutes.

The advice I got was to put a little bit of silicone seal (RTV) on the threads at the end of the bolts. This is apparently what the guys at Edelbrock's testing facility do.

What was kind of interesting is that he remarked that small block Chevy's have this problem with manifold bolts coming loose all the time. Maybe that's why I did not find much info on this problem in any Ford forum. :-)

Again, mahalo for your suggestion.

Harry Z.

Harry Zisko
\'68 GT/CS
harryz is offline   Reply With Quote
Old 09/24/2009, 04:30 PM   #6
Mosesatm's Avatar

Location: Spokane, Washington
Joined: Jan 05
Posts: 8,148

Harry, how far do the bolts stick up above the manifold when the threads first catch?

Your bolts may be too short and you don't have enough thread to hold them in place.
Mosesatm is offline   Reply With Quote
Old 09/24/2009, 04:33 PM   #7
robert campbell
My Car Details

Location: Bremerton Washington
Joined: Apr 07
Posts: 4,171

My Garage
Some questions:
What gasket are you using?
Are you using the cork valley seals?
Did you “chase” (clean) the holes in the head that the bolts go into?
Do you torque the bolts in three 30 percent increments?
Do your bolts have an expanded washer surface where they contact the manifold?

I would say that your intake bolts are not loosening up. Physically backing out. The relationship between the squeeze you had changes as the intake settles into the gasket. The cork gasket on the valley can exacerbate this. I use a thick bead of RTV on the valley vice the cork. You should use a couple of long headless studs or saw the head of a bolt off to ensure you lower the manifold perfectly onto the beads of RTV on the valley. Then pull them out and use your bolts. The RTV puts no pressure on the ends of the intake as you torque it down.

Your bolts should screw in and out easily with no wrench until they contact the manifold. Ensure that they do not bottom out or encounter any “gauling” to a depth far lower than they would be in the torqued position with the manifold on.

I use motor oil to ensure the bolts thread in and out easily. I would not use silcone seal on the threads at all. Now you must have a flat washer or a bolt with a built in washer to contact the intake. I will even put a spot of oil or grease on both sides of the washer to ensure in does not gaul against the intake as you torque the manifold. The idea is even equal pressure on each bolt with no gualing of any kind as it squeezes the gasket in the proper torque order. Do not use a lock washer as it digs in.

I would suspect that you should check the torque two or three times after you drive it a bit. After a few heat up and cool down cycles, in should settle in and not seem loose and need re-torqueing all the time. A check from time to time is always wise with an aluminum intake. They are prone to expanding and contracting at different rates than cast iron pieces. This can cause them to change the squeeze on the intake gasket.

robert campbell is offline   Reply With Quote
Old 09/24/2009, 04:59 PM   #8
My Car Details
CougarCJ's Avatar
Spaceman Spiff

Location: Beautiful Willamette Valley
Joined: Jul 06
Posts: 1,982

My Garage
Thumbs up

Excellent reply Rob!

I would even go a step further to prove that the bolts are or aren't loosening. I would put a mark on them, a drop of dye or paint. On the edge of the bolt, washer, and intake.

Scott Behncke
1968 GT/CS 302-4V Honors flysis incone beezis onchest nobis inob keesis
West Coast Classic Cougar A good source for Mustang mechanical parts too.
CougarCJ is offline   Reply With Quote
Old 09/24/2009, 06:41 PM   #9
Ruppstang's Avatar

Location: Weeping Water, NE.
Joined: May 09
Posts: 2,749

My Garage
On the exhaust manifold I have had trouble keeping them tight too. The down side to using ss bolts. I ended replacing mine with the correct ramp lock bolts mainly because it is a MCA concours car. You might try tab locks on the ss bolts. Marty
It must have been too late when I posted that. I was thinking exhaust manifold. Never mind. Rob's ideas were good I would try that. Marty

Last edited by Ruppstang; 09/25/2009 at 05:39 AM..
Ruppstang is offline   Reply With Quote
Old 09/24/2009, 07:37 PM   #10
My Car Details
66hcs-conv's Avatar
66 HCS-conv, Columbine blue & 2001 Cobra conv

Location: Loveland, Colorado
Joined: Apr 07
Posts: 321

My Garage

Just a thought here, but is it possible the bolts are stretching? I've heard of that happening with head bolts, but probably not on an intake.

OK, never mind!

66hcs-conv is offline   Reply With Quote
Old 09/24/2009, 08:07 PM   #11
rvrtrash's Avatar
So many cars, so little time!

Location: Post Falls, Id.
Joined: Apr 03
Posts: 3,526

My Garage
Harry, long time, no see buddy! Welcome back!


The wannabe formerly known as an owner.
rvrtrash is offline   Reply With Quote
Old 09/27/2009, 11:50 PM   #12

Joined: Jul 05
Posts: 53

Aloha everyone,

Mahalo for all the advice, it is greatly appreciated.

I am using FelPro gaskets as specified by Edelbrock. Bolts are stainless steel so I highly doubt they are stretching with only 20 ft-lbs. of torque on them. Torque on bolts applied in two steps (10 ft-lbs, then 20 ft-lbs) using the sequence prescribed by Edelbrock. After going through the torque sequence at the 20 ft-lb level, I go back through again and again until the torque wrench just "clicks" with no further turning of the bolts. Repeat after a few hot/cold cycles. Bolts still get loose after a while. @#@$$#%#@$%$$%

One other thing... I cannot use a bead of silicon seal at the front / rear of the block. Have to use the cork gaskets otherwise the manifold sits too low on the heads and the bolt holes do not line up. I discussed this with the Edelbrock support tech guy, and he believes that when the manifold was milled (to match the heads which had been milled) the machinist took too much material off the manifold. I have suspected this for a while (due to incessant leaks no matter what I do). I have no idea if this somehow contributes to the bolt loosening problem, but maybe it does.

I had purchased a new manifold about a year ago cuz I thought this one was perhaps cracked. Did not use it when it turned out not to be cracked. So, now I'm going to locate a competant machinist to mill the new manifold and find out what he needs to know to mill the new manifold correctly (i.e. do I need to pull the heads for him to inspect / measure?).

But this will have to wait a few weeks so I can take care of family stuff. I'll update when I (finally) get to fixing this.

P.S. to Steve: Aloha to you, too! Been a while since we've talked... got layed off in February and haven't found anything yet. Going to start my own computer services business (a la "Geek Squad") and be my own boss.

Again, mahalo nui loa (thank you very much) for all the advice.

Harry Z.

Harry Zisko
\'68 GT/CS
harryz is offline   Reply With Quote
Reply Forums > GT/CS and HCS Forums > GT/CS and HCS Discussions

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Intake Manifold Color? 68Fan GT/CS and HCS Discussions 6 05/20/2006 12:07 PM
Intake Manifolds for 428 CJs PB GT/CS GT/CS and HCS Discussions 10 03/31/2006 07:12 PM
Cobra Hi-Rise intake manifold charles GT/CS and HCS Discussions 0 11/21/2004 11:05 AM
4V Intake manifold differences 302cid CalPaul GT/CS and HCS Discussions 3 10/07/2004 12:50 PM
exhaust manifold bolts Talan423 GT/CS and HCS Discussions 3 05/13/2004 03:24 PM

All times are GMT -7. The time now is 06:19 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.

This site created, owned and maintained by Jon Hanna - Copyright © 1996-2011
All rights reserved. is not affiliated with Ford Motor Company

ShowCase vBulletin Plugins by Drive Thru Online, Inc.