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Old 09/24/2009, 11:17 AM   #1
harryz
 

Joined: Jul 05
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Intake manifold bolts keep coming loose

Aloha,

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
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Old 09/24/2009, 11:54 AM   #2
franklinair
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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.

Neil
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Old 09/24/2009, 12:22 PM   #3
harryz
 

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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.

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Old 09/24/2009, 12:42 PM   #4
tomcwarren
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See if there's anything in this thread that helps, Harry.

http://www.1969stang.com/mustang/for...ead.php?t=5836

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.

Tom
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Old 09/24/2009, 01:26 PM   #5
harryz
 

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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.

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Old 09/24/2009, 04:30 PM   #6
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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.
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Old 09/24/2009, 04:33 PM   #7
robert campbell
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Harry,
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.

Rob
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Old 09/24/2009, 04:59 PM   #8
CougarCJ
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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.
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Old 09/24/2009, 06:41 PM   #9
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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..
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Old 09/24/2009, 07:37 PM   #10
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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!

Dave
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Old 09/24/2009, 08:07 PM   #11
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Harry, long time, no see buddy! Welcome back!

Steve

The wannabe formerly known as an owner.
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Old 09/27/2009, 11:50 PM   #12
harryz
 

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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.

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\'68 GT/CS
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