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1959 Cadillac Valve Cover Gaskets

Started by gkhashem, October 13, 2020, 09:15:41 AM

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gkhashem

I changed mine about 6 years ago when I go the car and they did not appear to leak again until recently.

When I got the car they had been leaking, so now I did not warp the covers as far as I can see. I torqued them per specs.

I used Fel-pro gaskets before, cork ones. But the leak seems to be towards the rear of each cover (firewall side) ever so slightly. The car has been about 4500 miles in that time but why are they leaking again.

So any suggestions on a better gasket.
1959 Oldsmobile 98 Holiday Sports Sedan
1960 Cadillac Coupe Deville (CLC Sr #72)
1964 Oldsmobile 98 Town Sedan (OCA 1st)
1970 GMC C1500
1977 Oldsmobile 98 Regency Coupe
1978 Cadillac Coupe Deville (CLC Sr Crown #959)*
1992 Oldsmobile 98 (OCA 1st)
1996 Oldsmobile 98
*CLC Past President's Preservation

Past Cadillacs
1959 Coupe Deville
1966 Coupe Deville (Sr #861)*
1991 Eldorado Biarritz (Sr #838)

Big Fins

The real problem is lack of a better fastener position. The stamping of the covers is too thin to hold up. The heating and cooling process warps them ever so slightly so that the raised edge on the head that meets the cover doesn't meet after a while. That little piece of metal that is under the fastener does almost no good at all to distribute the torque of the fastener itself.

The best thing that you can do once you verify the covers are straight is to apply a bead of gasket maker to the heads' raised edge, let it cure for a few minutes and then replace the cover.
Current:
1976 Eldorado Convertible in Crystal Blue FireMist with white interior and top. (Misty Blue)
1969 Fleetwood Brougham in Chalice Gold FireMist with matching interior and top. (The Old Man) SOLD!

Past and much missed:
1977 Brougham de Elegance
1976 Eldorado Convertible
1972 Fleetwood Brougham
1971 Sedan de Ville
1970 de Ville Convertible
1969 Sedan de Ville
1959 Sedan deVille

Cadman-iac

Good morning George,
  Not knowing how many miles are on your engine,  I would think it possible that the drain back passages may be restricted by sludge buildup, causing the oil to pool in the covers,  and seeping out from the heating and cooling cycles and the expansion and contraction of the parts.
When you replaced the gaskets last time,  did you inspect the drainage passages for possible problems?
The other possible cause would be a warped cover. But those are the only things that I can think of.

HTH,
Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

gkhashem

The car now has 45,050 miles and had 39,932 when bought.

I guess I should check the drain passages , the leaks are at the rear of the covers. I do not think the covers are warped.
1959 Oldsmobile 98 Holiday Sports Sedan
1960 Cadillac Coupe Deville (CLC Sr #72)
1964 Oldsmobile 98 Town Sedan (OCA 1st)
1970 GMC C1500
1977 Oldsmobile 98 Regency Coupe
1978 Cadillac Coupe Deville (CLC Sr Crown #959)*
1992 Oldsmobile 98 (OCA 1st)
1996 Oldsmobile 98
*CLC Past President's Preservation

Past Cadillacs
1959 Coupe Deville
1966 Coupe Deville (Sr #861)*
1991 Eldorado Biarritz (Sr #838)

Eric DeVirgilis CLC# 8621

Ah another victim of the famous too-thin-gasket syndrome. Mikey C had devised a solution but I don't recall what it is now... ???
A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

Cadman-iac

  The last time I had a leakage problem,  I just quit putting oil in it, and strangely enough,  it soon stopped leaking,...... and running. I'm thinking that wasn't the correct course of action.

Sorry,  just trying to inject a little humor into an otherwise lousy year. Please pardon my sense of humor.

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

gkhashem

Quote from: Eric DeVirgilis CLC# 8621 on October 13, 2020, 03:06:14 PM
Ah another victim of the famous too-thin-gasket syndrome. Mikey C had devised a solution but I don't recall what it is now... ???

Find out if you can.
1959 Oldsmobile 98 Holiday Sports Sedan
1960 Cadillac Coupe Deville (CLC Sr #72)
1964 Oldsmobile 98 Town Sedan (OCA 1st)
1970 GMC C1500
1977 Oldsmobile 98 Regency Coupe
1978 Cadillac Coupe Deville (CLC Sr Crown #959)*
1992 Oldsmobile 98 (OCA 1st)
1996 Oldsmobile 98
*CLC Past President's Preservation

Past Cadillacs
1959 Coupe Deville
1966 Coupe Deville (Sr #861)*
1991 Eldorado Biarritz (Sr #838)

savemy67

Hello George,

Nothing lasts forever.

Most automotive seals and gaskets need to be changed at some point in time.  This is a function of time, mileage, environmental conditions etc.  I would argue that six years and 4500 is pretty good for a few dollars worth of cork gaskets.

In the case of gaskets that are sandwiched between two reasonably flat iron surfaces that are bolted together with several tens of foot pounds of torque, longevity is enhanced.  In the case of valve cover gaskets, not so much.

I have seen aftermarket valve cover retainers that spread the load across a few inches of the valve cover flange.  Think of a small inverted leaf spring.  Leaking gaskets at the rear of the head - where gravity exerts its inexorable pull due to the angle of the engine - should be expected, unless you "maintain" the assembly.

I am sure you change the oil and filter, why not consider a similar process when it comes to a flimsy cork gasket, and a thin steel stamping bolted to a cast iron cylinder head with four small screws torqued to a few inch-pounds?

There are several fixes (found on this forum) to prevent leaking valve covers, but none of them is truly permanent.  Its the nature of the beast.

Richard, please keep up the humor.

Respectfully submitted,

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Daddio

George, When you have the valve covers off, check their trimmed edge and compare it to the gasket thickness. These edges may be 'bottoming out' on the head, not allowing the gasket to compress and seal.
I went to a gasket vendor at a local auto flea market (remember those??) and found a thicker set of cork gaskets.
Or, you could use 2 thin gaskets per head, longer bolts may be needed.
Mike

1956 Thunderbird
SOLD - 1959 Eldorado Biarritz

walt chomosh #23510

George,
  Been there and done that!....then I discovered Permatex's "the right stuff". It cost more then the other gasket cements but can be stored in your refrigerator for years. (available at mostly all parts stores) Trust me, it works.....problem solved...walt...tulsa,ok

gkhashem

Great suggestions so far.

I have been looking at the various gaskets and have noticed as best as I can that they do vary in thickness.

Any suggestions on the thickest gasket available out there?
1959 Oldsmobile 98 Holiday Sports Sedan
1960 Cadillac Coupe Deville (CLC Sr #72)
1964 Oldsmobile 98 Town Sedan (OCA 1st)
1970 GMC C1500
1977 Oldsmobile 98 Regency Coupe
1978 Cadillac Coupe Deville (CLC Sr Crown #959)*
1992 Oldsmobile 98 (OCA 1st)
1996 Oldsmobile 98
*CLC Past President's Preservation

Past Cadillacs
1959 Coupe Deville
1966 Coupe Deville (Sr #861)*
1991 Eldorado Biarritz (Sr #838)

marty55cdv

   Obviously not original,  but I put these on my 60 with good results, https://www.summitracing.com/parts/trd-4993?rrec=true
Marty Smith
  CLC #22760
41 60 Special http://bit.ly/1Wm0GvT
55 CDV http://bit.ly/1G933IY
56 Fleetwood
1958 Extended Deck http://bit.ly/1NPYhGC
1959 Fleetwood  http://bit.ly/1OFsrOE
1960 Series 62 Coupe
1960 Sedan DeVille  4 window Flattop
63 Fleetwood http://bit.ly/1iSz17J
1964 Eldorado http://bit.ly/1Wm17GA  (Living in California now)
1988 EBC http://bit.ly/1iSACKz

Cadman-iac

Hi George,

  As an additional tip to what Mike said,  test fit the cover on the head and see if that lip on the cover goes over the edge of the head as it should,  or if it's resting on top of the head. It may require a mirror in order to check the rear edges,  but that may reveal a problem.
  The other suggestion about the load spreaders,  or clips, or whatever they are called, does help. A small block Chevy valve cover is practically identical in design as the 390 Cadillac, and I have used those for the same problem with good results.
They are about 4" long with a hump, or bump, on each end that applies pressure outboard of the bolt to even out the pressure on the cover,  as much as it's possible that is.
Hope this is helpful and you solve your problem easily.

Rick

  Christopher,  thanks!
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"