Cooling system repair/replacement

[RiggerRob]

So I decided to go ahead and preemptively replace the radiator, thermostat, and water pump on my '84 4WD. I don't know the history on any of these components so I just figured it would be best to replace them all instead of trying to troubleshoot one item at a time, since I noticed that the car tends to run towards the hot side on long distance summer runs (i.e. to Nashville from my home in Asheville, NC). I got a double row radiator and a failsafe type thermostat and a new (not remanned) water pump.

My questions about this are:

- When replacing the gaskets on the water pump and thermostat ,do I still need to use Permatex or some other 'gasket maker' on the new parts? It seems like every replacement water pump I've seen has this stuff squeezing out the sides of it - is this because it's necessary or because people are just too lazy to install the gaskets properly?

- After flushing the system, is it okay to use the same coolant that I drained out or is it better to use all new coolant?

Thanks in advance!

[Highlander]

HI Rob, I use High Tack on paper gaskets, not gasket eliminator or silicone, way neater overall, but definitely use some sort of sealant on the gaskets- its worth not having to go back in later. When you pull the water pump, look out for weeping from behind the suction housing (the water pump attaches to it, it's between the water pump and the block). There's an o-ring behind it that tends to weep and leak coolant down the front of the engine-one of those 'mystery leaks' that occurs.
Do you know for sure how old the coolant is? If not, I'd not reuse it, however you don't have the winter temps that I do, so freezing is less of a concern.
In my Austin-Healeys I run just a wee bit of anti-freeze to act as a rust inhibitor, and drain it over the winter. reason being that coolant/anti-freeze doesn't conduct heat as well as water does. The Austins really enjoy running at 190*F when its 90+ outside.
-- Sorry off topic, you might consider running just enough anti-freeze/anti-boil in your coolant to keep the rust down- Just a thought-but DON"T forget to make it good for your winter temps before long!

[Petros]

You should replace your coolant about every two years, three max. Flush the system when you replace it to clean out deposits. You should also replace your radiator cap, they can wear out or go bad. So the thermostat, rad cap and coolant should be replaced about every 2 to 3 years and you will never have any cooling system problems.

Use ONLY filtered or distilled water in the mix, other water leaves deposits that will ruin the new radiator. I have found the new water pumps last about 100k miles, no need to replace that any sooner. Rebuilt water pumps are junk, not worth any savings at all, new ones are only about $35, why mess with a cheap rebuilt one.

The gasket dressing make it MUCH easier to clean off the gasket next time you have remove the part. I actually use anti-seize on the t-stat housing that way I can reuse the gasket (if it is not damaged it can be reused), I have also used it on the water pump gasket. It makes it just fall off without any scraping next time you replace the water pump.

Important! Put high tack gasket sealant on the edge of the thermostat to keep it in place while you install the housing (it wants to fall out of position and you can not tell until you blow all of that new antifreeze out all over the ground).

Save that old radiator, unless you know it is leaky, it will make a good spare. flush it out and put some wd40 or similar in it to keep it from corroding while in storage.