I had to replace the thermostat on my 95 nissan pickup. now the water temp is too high and i can hear it bubbling in the resevoir tank when i shut it down after a few miles of warming it up.. The heater is also cold until the guage reads extreme. the wiggler valve is in the same spot as i removed it, which is about the 1 o' clock postion. did i do something wrong?

The thermostat regulates engine temperature. Without it, there's no temp regulation, so of course the temp is going up and down. It's time to check coolant level, the radiator for plugged tubing, the water pump for proper operation. Those are the things you should have done way before removing the thermostat. That was a really bad decision.

Try changing radiator cap if there is no water in the oil it is not a head gasket could be system just needs a flush. It could also be the water pump is not pumping well try the cap first.

sounds like thermostat is starting to stick close replace thermostat

It certainly can cause the condition, but so can TONS of other items: coolant level, bubbles in the coolant (air bleeds), reaiator restrictions.

You could test the thermostat, pull it and put into measured temprature water and observe it as you raise the temprature...

is your water pump circulating the water nissans used to have a problem with impellers on pump
leave rad cap off and run enginge should see water circulating when stat opens

Sounds like there may be water or condensation entering your distributor cap. Cheap fix and might be obvious if you inspect its inside.. look for corrosion or moisture.

When the car is completely cool,check the electric fan(s) for smooth rotation.

Clean/check/change the thermo sensor,contact and wire.

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Excavate air pocket in coolant system / check for head gasket leak

This test will kill two birds with one stone.

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MAKE SURE THE COOLANT SYSTEM and ENGINE IS COLD!

RAN THIS TEST IN A WELL VENTILATED AREA ONLY!

You will spill some coolant during this air pocket purge test.......BE KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!

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Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .

Top of the coolant reserve tank

Let it ran for 10-15 minutes.

Monitor for air pockets escaping from coolant reserve tank.

Small amount of bubbles is OK at 1-5 minute mark

After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.

If you do not see any in rush of bubbles then your thermostat may be partially stuck or rusted badly inside the thermostat hosing.

Give the thermostat host few gentle taps.

If you see larger bubbles surfacing after 15 minutes then should do a hydrocarbon (HC) dye test to test for potential head gasket leak.

Let engine cold down and top off coolant reserve tank.

Start monitor for coolant lost

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A coolant flush is require every 2 years or 24,000 miles.

I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.

Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.

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It may need the radiator boiled out at a shop.

you could have an air lock in the system. Run with rad cap off and cycle the thermostat, adding coolant as required. Or a possible heater core.

I had the same problem with my 95 Pickup when I got it a couple of years ago -- replaced water pump, thermostat, flushed radiator, etc. I finally noticed that the area where the radiator cap seats in the top tank (which is plastic) had a couple of gouges, which was keeping the cap from sealing properly. I cleaned it up as best I could, then bonded a large washer (used a grinder to get the exact size) into the neck for the radiator cap to seat on. Haven't had a problem since.