The sience of gaskets

[John Vardanian]

I find gaskets supplied by the various parts dealers to be substandard in fit (not to mention unnecessarily expensive), so I always cut my own. It is timeconsuming, but it is the only way to get a perfect fit.

There are gasket papers of varying thickness on the market. Does anyone know how the thickness of a gasket is arrived? In other words, how does the manufacturer determine what thickness to use in each applications?

john

[Rudy van Daalen Wetters]

John,

Interesting point about gaskets. I like to make my own as well. Some aftermarket ones are paper thin and I would be hesitant to use them. I have seen new oil pan gaskets just slide apart on Jaguars. They seem to be made up of layers of thin paper. I think that depending on the application may be a big factor on relative thickness. I believe that some early cars like Bugattis did not use gaskets because the machining tolerances were so exact that they did not need any, which I find amazing. I need to pull the lower pan on my GTE and was wondering if anyone makes gaskets for this or do I make my own?

Rudy s/n 4001

[John Vardanian]

Rudy,

Most parts suppliers, like T. Rutlands or GT Car Parts carry the oil pan gasket. I didn't have much luke with the fit of the one I got, so now I always cut my own; however, it is a time consuming proposition.

If you haven't removed the oil pan for awhile, you'll be surprised to find the amount of sludge sediment.

john

[Rudy van Daalen Wetters]

John,

Thanks for the information regarding the gasket for the oil pan. I am anxious to get that pan off and see what is lurking inside. Also curious to see the oil pickup screen. All good for preventive maintenance.

Regards,

Rudy s/n 4001

[fest]

I recently had to make a Gasket from scratch
to replace the one on the Vacuum Pump Cover
which was not included in the Gasket Set I got
(nor was listed in the Parts Manual)

Naturally, I had to pull apart the Vacuum Pump-
I could not just put it back on
without a peek inside, now could I?
in the process, the original Gasket was destroyed
so I was pretty much comitted at that point

I measured the thickness of the old Gasket
(1.5mm maybe? I forget)
and then turned to one of my favorite resources:
http://www.mcmaster.com
(have not scored a Hard Copy Catalogue BTW)

I selected 'Premium Compressed Aramid/Buna-N' Gasket Material
in this case 1/64" x 6" x 6" P/N 9470K25 @ $1.53 ea
as that was pretty close to the original thickness
(actually slightly thicker, but that is OK because of compression)

this material was described as follows:
'resists most acids and alkalis, water, steam,
oil, and detergents...-40 to 400 Deg F...1000 psi'
BINGO!...sounds like it will do nicely

available in many various thickness / size sheets up to 1/8" x 30 x 60

Note: I would be hesitant to use this material
in direct contact with Gasoline, as this is not mentioned in specs

many other choices of Materials / sizes are available-
I chose this material beacuse it met the criteria
including 1/64" thickness (which is somewhat uncommon)

only concern with material
was that it was labeled as being hazardous when cut-
I did, however, emerge unscathed
Gasket came out great, I might add

[tyang]

Another handy item to have for gasket making is a leather punch. With homemade gaskets, or trimming holes of ready made gaskets, a leather punch allows you to make pretty accurate holes. Never assume the gasket kit gaskets actually fit. The holes are usually slightly off, so check them for fit, and trim accordingly.

Tom

[John Vardanian]

Gasket thickness is very important for certain places like the valve covers, only because of the two little bolts that fasten the distributor drive base to the valve cover. If the gasket wasn't the right thickness the holes would not match and the bolts would not mount. But if it weren't for these two bolts would it matter what thickness gasket one should use? I don't know. This is why I started this post.

Since we are on the subject of gaskets, what type or brand of RTV is prefered? I like using the bright orange only because I can see the little stray bits and pieces during cleanup.

I put the question of RTV's to a friend who's been racing and maintaining his 250 TR for decades. He said he only smeared ordinary grease on both faces of the gasket and torqued the valve covers down to spec. I followed his advice... boy what a mess after only a short drive.

I suppose when the cars were new the aluminum surfaces were perfect, but years of impatient "mechanics" ruined the surfaces to the point where some kind of filler must be used along with the paper gaskets.

john

[fest]

as I mentioned, I measured the thickness of the old gasket
and went from there
this seems to be the best way to proceed
(provided one can salvage a good enough scrap to measure!)
if that fails, the 'clay' method can be employed
i.e. apply small bit of Modeling Clay to surface
press Mating Parts into place
remove Parts
Carefully cut Clay
and measure thickness

as for 'Goop': I had asked about 'Red Paste' and Hylomar
and got some pretty good answers from you all
(see earlier thread)

I have been using Permatex 'Ultra Copper'
for applications that call for RTV
and Permatex Hylomar for general Gasket Dressing
(this on the advice of Ian, who contends it 'sticks like shit on a blanket'

[Chris Coios]

A number of people have suggested "GORE-TEX" gasket tape, which is described on the packaging as "expanded PTFE sealant tape". This is supposed to be great stuff, high tech, flexible in application. Good for cam covers, sumps, etc., where linear gaskets apply. Reportedly, it goes around corners, adheres well, but you have to punch/trim the holes for studs, (necessary for any gasket you would make). Never tried it, but it is highly recommended by those who have.

Chris

[John Vardanian]

Thanks, Chris. I suppose this Gortex material comes in different thicknesses and can be ordered through a competent parts supplier.

john