GMCforum: GMCnet » recommended 455 valve cover gasket

Home » Public Forums » GMCnet » recommended 455 valve cover gasket (and process)

Show: Today's Messages :: Polls :: Message Navigator

Thu, 08 March 2018 14:40

lqqkatjon

Messages: 2324
Registered: October 2010
Location: St. Cloud, MN

Karma: 5

Senior Member

did some quick searching and did not find what I was looking for, sorry if this is a repeat.

Have some spring work, that is going to include replacing the exhaust manifolds with headers, and it will be getting a new exhaust system. I am also going to replace my oil dipstick tube, and relocate the tranny dipstick to the front hatch.

While I am at it, I am going to replace my valve cover gaskets, since I believe they are leaking slightly. So I ask What is the recommended method, and/or gasket/sealant combination to use for the 455.

Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/

Report message to a moderator

Thu, 08 March 2018 20:46

Carl S.

Messages: 4186
Registered: January 2009
Location: Tucson, AZ.

Karma: 13

Senior Member

Jon,

You'll want to use a rubber valve cover gasket. There is a 'steel core' rubber gasket on Ebay that looks interesting.

You don't really need any sealant. If you DO use RTV, it will make them REALLY hard to remove at a later date

Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member

Report message to a moderator

Thu, 08 March 2018 21:50

Dennis S

Messages: 3046
Registered: November 2005

Karma: 2

Senior Member

Jon
Like Carl I used a rubber valve cover gasket (FPP-1658, but may no longer be available) I just used a little oil on each side.
I also used valve cover force spreaders, but you may need to use slightly longer bolts. And if you use a spreader on the bolt under the AC bracket you may need to grind the bracket for clearance.

Example
https://www.walmart.com/ip/VALVE-COVER-SPREADER-BARS-4-BLACK-FINISHED/973893302?wmlspartner=wlpa&selectedSellerId=837&adid=2222222222814419537 3&wl0=&wl1=g&wl2=m&wl3=253427111225&wl4=pla-418851192878&wl5=9013542&wl6=&wl7=&wl8=&wl9=pla&wl10=112343835 &wl11=online&wl12=973893302&wl13=&veh=sem

And - the valve covers are often bent from over- tightening, so flatten them before re-installing.

Dennis

lqqkatjon wrote on Thu, 08 March 2018 14:40

did some quick searching and did not find what I was looking for, sorry if this is a repeat.

Have some spring work, that is going to include replacing the exhaust manifolds with headers, and it will be getting a new exhaust system. I am also going to replace my oil dipstick tube, and relocate the tranny dipstick to the front hatch.

While I am at it, I am going to replace my valve cover gaskets, since I believe they are leaking slightly. So I ask What is the recommended method, and/or gasket/sealant combination to use for the 455.

Dennis S
73 Painted Desert 230
Memphis TN Metro

Report message to a moderator

Fri, 09 March 2018 01:07

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

Mahle (Victor Reinze) VS38305-TC

Currently on closeout at Rock Auto for $3.61

Rubberized Cork with steel stiffener.

The package says it fits both 403 and 455.

I just put a set on a 403. I lightly siliconed the valve cover side and used the bolts to line it up. Turned it over and let it sit on a flat surface overnight to cure. (with the bolts still inserted to maintain alignment.)

Do not apply and sealer on the engine side when installed. That makes them easily removable and reusable in the future.

Use of the bolt spreaders is optional. Also available from Rock Auto under "tools". I did not use them but they are a great idea.

I ought to order an other set as a spare.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

Report message to a moderator

Sat, 10 March 2018 08:59

rgogan

Messages: 82
Registered: February 2004
Location: Milwaukee, WI

Karma: 0

Member

My GMC Motorhome shop manual recommends RTV only without a gasket citing superior results and stating the factory stopped using the gasket for the valve cover even though it is pictured in the manual. This is what I always used. I had a rebuilt engine put in 30,000 mi ago and now the valve cover on the driver's side is leaking. Will let you know if the rebuilder used a gasket or straight RTV when I take it apart.

Report message to a moderator

Sat, 10 March 2018 10:43

Bullitthead

Messages: 1411
Registered: November 2013

Karma: 5

Senior Member

I've used same method as Ken since RTV came on the market, except I don't wait overnight. About 15 to 30 minutes will skin it and pin it to the cover, unless it is a SBPITA cover that has to be finagled into place against gravity for long enough to get cramps in your hand. Definitely let it cure as long as possible in that case. Almost always seal the gasket to the removable part/cover,unless it has a groove in its' design. Also notice that some gaskets have small metal spacers embedded in them which will be disastrous if they get into the engine oil intake. Some of them will fit through the screen! If you have to scrape the old cooked gaskets off, pack the whole internal area with clean rags before you pull the first piece off. Use a reduced vacuum to carefully remove the wayward scraps from the rags before you pull them out. You might want to count them before and after Razz

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.

Report message to a moderator

Sat, 10 March 2018 11:44

Chris Tyler

Messages: 458
Registered: September 2013
Location: Odessa FL

Karma: 7

Senior Member

What I have done for years is use a cheap cork gasket sprayed with 2 coats silver spray paint. This seals it and prvents it fronm absorbing oil.
Then glue it in plce with 3 m weatherstrip adhesive to the vlve cover and a coat of anti seize on the head side.
Never had one fail or leak yet, even when frequently removed to set the valves.

76 Glenbrook

Report message to a moderator

Re: [GMCnet] recommended 455 valve cover gasket [message #329884 is a reply to message #329881]

Sat, 10 March 2018 13:07

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

The usual problem is that the hold down fasteners have been over tightened
at some point. Cork gaskets eventually will deteriorate over time, and
crack and leak. Then along comes someone with a socket and tightens them
some more. Remove the valve covers and scrape and clean every last little
bit of old gasket and cement from both surfaces. Sunday morning, going to
church, clean. Then using a very solid backup piece, straighten out all the
puckers created from the overtightening. Use a straight edge along the
sealing lip to check your work. Once that surface is straight, then use
your gasket of choice. Cork, composite, steel sandwich with silicone
ribbons, (my favorite) or silicone sealant, (my least favorite). Used in
the correct manner, all will work, IF THE COVERS ARE STRAIGHT.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Mar 10, 2018 10:12 AM, "Chris Tyler" wrote:

> What I have done for years is use a cheap cork gasket sprayed with 2 coats
> silver spray paint. This seals it and prvents it fronm absorbing oil.
> Then glue it in plce with 3 m weatherstrip adhesive to the vlve cover and
> a coat of anti seize on the head side.
> Never had one fail or leak yet, even when frequently removed to set the
> valves.
> --
> 76 Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Report message to a moderator

Sat, 10 March 2018 19:21

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

The 403 that I am working on was seeping oil at both the front and rear of the covers. When I removed the valve covers I found that straight silicone was used with no gasket. The silicone was coming loose on the ends causing the leaks. So the Mahle - Victor Reize gaskets is what I used.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

Report message to a moderator

Previous Topic:	Type II (75,76) HVAC changes.
Next Topic:	Any GMC from Florida going to Tucson

Goto Forum:

-=] Back to Top [=-

Current Time: Sat Jun 29 04:03:01 CDT 2024

Total time taken to generate the page: 0.04852 seconds