Raw water pump gasket sealant?
Roger Mexico
with an Oberdorfer unit (sorry, don't have the part number handy) about
a year ago. At the time I purchased a spare impeller kit, and the guy
at the store removed the pump cover to ensure I got the right kit. I
asked him about sealant on the paper cover gasket (it came dry from the
manufacturer) and he said that nothing was needed, and the stuff would
just work its way into the pump and damage the impeller.
Anyway about a month ago I noticed telltale green on the pump, and when
I removed the cover I found the gasket had totally disintegrated. I
don't know if the water leaks were a result of the gasket failure, or
the gasket failed because water was leaking past it. I suspect the
latter, and failure resulted from reusing the original gasket when we
removed the cover in the store.
All of which leads to a few questions:
Was the leak likely due to the reuse of the gasket, perhaps improperly
tightened?
Would it help to use some sort of gasket compound on the new paper gasket?
I see some references to using RTC Blue sealant as a replacement for
paper gaskets, others say avoid it, any comments?
Any other sage advice on keeping fluids where they belong?
Thank y'all kindly for your input.
--
Roger Mexico roger_...@nospm.hotmail.com (remove nospm.)
jps
news:zuA%9.23614$2y.11...@twister.austin.rr.com...
...snip...
> Would it help to use some sort of gasket compound on the new paper gasket?
>
> I see some references to using RTC Blue sealant as a replacement for
> paper gaskets, others say avoid it, any comments?
>
> Any other sage advice on keeping fluids where they belong?
>
> Thank y'all kindly for your input.
>
> --
> Roger Mexico roger_...@nospm.hotmail.com (remove nospm.)
I had a similar experience with an old Sherwood raw water pump last year.
Paper gasket, mating surfaces not in the best shape. Advise was to use
motor oil on the gasket. It dripped but not enough to make me crazy.
Two days ago I decided it was the next thing on my list and cracked the pump
open to see what I could spy. Like yours, my paper gasket had deteriorated
pretty well and there was some superficial deterioration of the pump cover
where it mates with the pump body. Got my wet sandpaper out and set at the
galley table and removed a few thousanths off the interior surface of the
cover. Cleaned up very well.
I inspected the impeller (in very good condition) and reassembled. Instead
of coating the paper gasket with oil, I grabbed a rubber glove and used a
finger to lightly coat the paper gasket with some high temp silicone (it's
what I had on board) on both sides. I reassembled the pump and tightened to
cover screws gently. Once the silicone had a chance to set up I tightened
the cover screws a little more. Although I haven't tested it yet (the new
paint on the bracket needs to dry) I'm pretty certain that baby's going to
hold its water.
I'm not certain I'd go gooping up the works trying to "form" a gasket with
silicone but the idea of coating the paper to account for surface
imperfections seems to make pretty good sense. Downside: It could be a
bitch of job to get that cover off the next time I need to service the pump.
jps
jps
news:zuA%9.23614$2y.11...@twister.austin.rr.com...
...snip...
> Would it help to use some sort of gasket compound on the new paper gasket?
>
> I see some references to using RTC Blue sealant as a replacement for
> paper gaskets, others say avoid it, any comments?
>
> Any other sage advice on keeping fluids where they belong?
>
> Thank y'all kindly for your input.
>
> --
> Roger Mexico roger_...@nospm.hotmail.com (remove nospm.)
I had a similar experience with an old Sherwood raw water pump last year.
K. Smith
The issue with the sealant isn't so much it'll goop the works up
but it might make the cover sit a few thou higher on the case & it's
the clearance between the impeller & the cover plate that sets the
sealing on both sides of the impeller.
The paper gaskets are really thin for that reason & if you use
silicon you're probably better off not to include the gasket at all.
Once your silicone has cured with the screws not tightened as
described, if you now try to pull it down hard it'll crack the
silicone anyway & if you don't pull the plate up close you'll have
too much impeller side clearance.
K
jps
news:3E3FA76D...@tpg.com.au...
...snip
> The issue with the sealant isn't so much it'll goop the works up
> but it might make the cover sit a few thou higher on the case & it's
> the clearance between the impeller & the cover plate that sets the
> sealing on both sides of the impeller.
>
> The paper gaskets are really thin for that reason & if you use
> silicon you're probably better off not to include the gasket at all.
>
> Once your silicone has cured with the screws not tightened as
> described, if you now try to pull it down hard it'll crack the
> silicone anyway & if you don't pull the plate up close you'll have
> too much impeller side clearance.
>
> K
If someone uses what would be considered a "normal" amount of silicone to
form a gasket and just tightened it down, much of the silicone would end up
inside the pump body.
Nearly every silicone "gasket" type product advises light pressue until
cured (24 hours) and then tighten. Why would they do this if this if the
product would "crack?" That doesn't seem consistent with the nature of
silicone.
Since I basically got the paper "wet" I don't expect the paper's width was
doubled. There was still solid contact between the impeller and the pump
cover.
Thanks for your thoughts.
jps
Roger Mexico
temp sealant as a wetting agent won't hurt. The dry paper gasket is
perhaps 10 mils thick (that's about the limit of resolution of my el
cheapo micrometer, namely 1/128") so I think I'll try trimming it
outside one of the screw holes so I can check the clearance with a
feeler gauge before and after using the silicone. If I learn anything
I'll post a followup for the record.
Thanks to all for the help.
Gene Kearns wrote:
> Improper torquing of mating surfaces will cause fretting corrosion. I
> suspect that is why you paper gasket "went away". I have used grease
> and silicone to "wet" the gasket as you describe, with excellent
> results.
>
> While it is technically correct to "create" the gasket with silicone
> at minimum torque and then apply correct torque after the silicone has
> set, this is not the intent here.
>
> "Wetting" the gasket should leave a film of only a couple of thousands
> thick. This is a little extra insurance and may allow the gasket to
> be re-used in a pinch.
Calif Bill
The gaskets that always shifted and leaked oil.
Bill
"Karl Denninger" <ka...@FS.Denninger.Net> wrote in message
news:b1pkhu$j8p$0...@pita.alt.net...
>
> In article <v3uun53...@corp.supernews.com>, jps <tr...@thedump.com>
wrote:
>
> Coat one side with oil, put the RTV on the other. Wait until it tacks up,
> then assemble. It will come apart easily and is also reusable.
>
> I've got two raw-water pump pipe gaskets that I made out of the stuff, and
> they are completely water-tight. The paper gaskets always leaked a bit;
the
> mating surfaces are nowhere near perfect any more.
>
> --
> --
> Karl Denninger (ka...@denninger.net) Internet Consultant & Kids Rights
Activist
> http://www.denninger.net Cost-effective Consulting
> http://childrens-justice.org Working for family and children's rights
> http://diversunion.org Improving relationships between Divers and Shops
jps
I just confirmed the "wet" test worked. Reassembled the bits and pieces
today and fired up the engine. Lots of water passing and no drip.
jps
"Roger Mexico" <roger_...@nospm.hotmail.com> wrote in message
news:4EU%9.2076$%U2.1...@twister.austin.rr.com...
Des
> I'll post a followup for the record.
So here's the belated results:
I first tested sealing the gasket with a spare Sherwood pump. I
rubbed a very thin layer of engine oil on the bronze mating surfaces
to prevent the RTV Blue sealant from sticking, then rubbed a thin
layer of the sealant on the paper gasket, just enough to wet the
paper, but not enough to have any visible buildup on it. Assembled
the pump, hand tightened (sorry no torque reading but just until I
felt a bit of resistance from the gasket) let the sealant set up, then
pulled the cover back off. The gasket came away smoothly, behaving
more like a rubber than a paper gasket. There was a very thin ring of
sealant (say about 20 mil thick) that had squeezed into the pump
chamber. It didn't interfere with the impeller and even if chunks
broke off I think they're small enough to just head out the raw water
discharge.
Anyway, on to the Oberdorfer pump. Checked the cover clearance using
feeler gauges. With the dry gasket, about 8 mil. Used the same
procedure with the sealant as above. With the sealant, the clearance
was about 10 mil. Let the sealant set up, have now run the engine a
few hours and no signs of leaks. So I'm calling this a fix. But if
the problem resurfaces, I'll let y'all know.
Cheers, and thanks again.