Lock for exhaust manifold bolts

[emerystora]

A lot of you that have had problems with blown or leaking exhaust
manifold gaskets might find that you no longer have the little locks
that GM originally put on your engine manifold. This is part number
399423. It is a small metal plate that goes under the two outside
bolts on each end of the manifold (there is not one for the center
bolt). After the bolts are torqued there are small tabs that are
bent against the flat of the bolt head and it keeps the bolts from
loosening when the manifold expands and shrinks when getting hot and
cold.

I would suggest that you torque the bolts to specs, drive about 500
miles and then retorque them and then set the locking tabs. I
suspect this will cure a lot of leakage problems for many of you.

The original part number is still good and any GMC/Olds/Caddy/Chev GM
dealer can order them for you if they don't have them in stock. My
local Olds dealer got them in two days for me from the Denver parts
warehouse with no shipping charge.

You will need four of that part number.

Emery Stora
77 Kingsley
Santa Fe, NM

 

[richard waters]

> A lot of you that have had problems with blown or leaking exhaust
> manifold gaskets might find that you no longer have the little locks
> that GM originally put on your engine manifold. This is part number
> 399423. It is a small metal plate that goes under the two outside
> bolts on each end of the manifold (there is not one for the center
> bolt). After the bolts are torqued there are small tabs that are
> bent against the flat of the bolt head and it keeps the bolts from
> loosening when the manifold expands and shrinks when getting hot and
> cold.

Emery,
I called a few Olds dealers today and none had stock on the 399423. They
said they could be ordered but that it would take a few days. I'm
planning on reassembling my manifolds tomorrow because I want to drive
the GMC in the annual "Woodward Dream Cruise." Any reason why I can't
use lock washers? Or I wonder if I can install the locks at a later
date? Or maybe I'll wait until the next time I redo the manifold
gaskets. Cinnabar just used some thick flat washers when they did the
job last year and that worked for a while.

One thing I am sure of if I don't use some sort of locking device I'll be
checking the torque on the bolts on a frequent basis. I think that was
my undoing. I never checked the torque in 10,000 miles. The fel-pro
1439 gaskets that Cinnabar installed didn't fail. The bolts just
loosened up.
Richard

 

[richard waters]

> > Any reason why I can't
> > use lock washers? Or I wonder if I can install the locks at a later
> > date? Or maybe I'll wait until the next time I redo the manifold
> > gaskets. Cinnabar just used some thick flat washers when they did the
> > job last year and that worked for a while.
>
> Richard
>
> difference or not but I am running no gaskets. Called my local GMC
> dealer----no luck. Called Cinnabar and have the locks headed my way.
> >From where I sit I dont think lock washers work. I have taken to many
> off that no longer have much spring to them. I will admit that these
> were on race cars but I dont think things are much different on our ladies.
> Thats what I am trying to do.
>
> Arch
>

I wonder why Cinnabar doesn't use locks in their own shop. I just did my manifold
gaskets the other day and I tried to find locks at local Olds dealers and no
dice. It was going to take 2-3 days to get them in. I didn't want to wait that
long. It didn't even occur to me that Cinnabar would have them even thought they
don't use them. I could have had them the next day had I called Cinnabar.

Now I think I have a leak near one of my mufflers. The mufflers are fairly new.
The manifolds sound nice and quiet now. I only have 30 miles on the new gaskets.
I plan on driving 250 miles this weekend. Hopefully they will continue to be
quiet.
Richard