Waterpump opinion survey

Traditional V8 front mount water pump.

Gasket, RTV, or both?

GO!

both

Both

Gasket with weatherstrip adhesive to hold in place while assembling.

I usually coat the gasket in a very light skim of RTV on both sides.  Shouldn't be needed for sealing, but it keeps the gasket in place during install.  

My choice is high tack gasket sealant just to keep gaskets in place. Make sure to tighten properly.

Skim coat of rtv on each side of the gasket. Mostly just too hold the gasket in place during assembly.

Another vote for both.  I spent a lot of last summer on cooling system issues on the 351C in my 1969 Cougar.  I used Permatex Indian Head shellac and was impressed.  Tacky and created a good seal.  Messy as all get out however (none got on my hootus).

And sealer on the threads if they go into a water jacket.  

In reply to Kramer :

oooh, good addendum. What sealer on bolts into water jackets?

A light coat of RTV on the bolts should work.  Realistically though, I've never sealed the water pump and timing cover bolts that go into water jackets on the Jeep and I've never had one leak a single drop once it was properly tightened.  

For me it depends on the gasket material.  But nearly always RTV.  Some of the printed/impregnated gaskets don't need it, but any paper or cork will need RTV.

Gasket and some of this on both sides.

In reply to Toyman01 :

I take a similar approach, but use this instead:

In reply to jstand :

That is also good stuff. I've used them both.

Be sure the surfaces are really clean before you do anything.   Any little pieces of old gasket or sealer are leak paths.

I have seen more gasket failures from leaving out that part of the job than any other reason other than forgetting to install the gasket and/or sealer in the first place.

RTV is good gasket maker, but not so good at gasket sealing.  The hi-tack and Indian Head are good at sealing (as is Permatex No. 1 and No. 2), but not good at gasket making.  

RTV isn't a good thread sealer.  Use the brown stuff. 

ultraclyde said:

In reply to Kramer :

oooh, good addendum. What sealer on bolts into water jackets?

I use PST (aka "pipe dope") on any bolt (head or water pump) that goes into a water jacket. 

Did this the year before on my Firebird, did Permatex water pump gasket maker on the bolts that went into the water jacket and then only used some grease on both sides of the gasket to help hold it in place and seal.  Followed instructions on the gasket maker on cure time before torquing to spec and then let it cure for 24 hours before adding back coolant and bleeding the system.  No leaks and have been good since.

Just fair warning... The Indian Head and Permatex aviation 3H is psychotically hard to remove.  Future water pump changes will be a royal pain.  They cure like toffee.  I used some Indian Head on a Pontiac water pump once and I had to pry so hard that I broke the cast timing cover getting it off.

Black RTV will seal perfectly well enough and comes off with a razor blade or a wire wheel easily.  You actually don't need the black, you could do blue, but black is a little more universal.  Good for water and oil.

When I put RTV on a gasket, I put it on very sparingly.  Your hands will get messy, but put a little on both sides and rub it like you're cleaning your glasses.  Smear it around thin.  When you install it, little or no RTV should squeeze out.  You should be able to see the gasket through the RTV.  It should be thin enough that its translucent.

Another option is a spray gasket sealer.  It's not quite as good as RTV, but it comes off with solvent.

This is the good stuff for spray.

This is the good stuff for RTV.

If the surfaces are smooth and flat it shouldn't need anything on the gasket, but whatever you put on there, like Curtis said, should be very thin so you don't have a bunch of squeeze out. You don't want RTV boogers floating around the system possibly clogging radiator tubes or one of the smaller coolant holes in the head gasket. 

I've kinda been turned onto the wonders of permatex #2, just don't get any on your clothes, it does not wash out. 

snailmont5oh said:

ultraclyde said:

In reply to Kramer :

oooh, good addendum. What sealer on bolts into water jackets?

I use PST (aka "pipe dope") on any bolt (head or water pump) that goes into a water jacket. 

I second that.  Doesn't have to be anything special.  I got some ARP teflon thread sealant once and I'm convinced its exactly the same as teflon paste you buy at Lowes.

The last water pump I did was on an '04 Mitsu Lancer - 2.0 iron block, and all I used was the supplied paper gasket and nothing else.  I made sure the surface on the block was clean and torqued the bolts down to spec.  No leaks.   As someone else stated it's imperative to start with a clean/flat mating surface.  

Whatever sealant you put on, it's gotta be a THIN layer.

Curtis said:

snailmont5oh said:

ultraclyde said:

In reply to Kramer :

oooh, good addendum. What sealer on bolts into water jackets?

I use PST (aka "pipe dope") on any bolt (head or water pump) that goes into a water jacket. 

I second that.  Doesn't have to be anything special.  I got some ARP teflon thread sealant once and I'm convinced its exactly the same as teflon paste you buy at Lowes.

Use PST on air fittings, too.  Any pipe threads for that matter.  Seals much better than Teflon tape.  Which is crap.

In reply to Curtis :

When using RTV, have you ever tried to use a very small bead?  So that you don't have to smear it with your fingers?  I got one of those tube applicators (kind of a trigger set up), and then cut a very mall diagonal across the tip so that's about 1mm bead.

A buddy of mine showed me that, where you also finger tight the system and then tighten it up fully after about 10 min.  Works great.