beach50

The heater on my Maxima (1995 SE with climate control…approximately 225,000 miles) barely gives off any heat. I tried running it with the front end elevated hoping the problem was air in the heater hose or heater core. I’m now guessing the problem is thermostat or a clogged heater core. [I’ve noticed in some other similar forum posts regarding heater problems that the culprit was the thermostat despite that the engine temperature seemed to go up to where it normally was on the dashboard thermometer.]

I thought I’d first try to change the thermostat. I’m not much of a backyard mechanic but noticed that the Service Manual differs from the Haynes Repair Manual.

The Service Manual simply states:

1. Drain coolant from drain plugs on both sides of cylinder block and radiator.
2 Remove lower radiator hose.
3. Remove water inlet and thermostat assembly.
DO NOT DISASSEMBLE WATER INLET AND THERMOSTAT. REPLACE THEM AS A UNIT, IF NECCESARY.
4. Install thermostat and giggle valve facing upward.
*After installation, run engine for a few minutes, and check for leaks.
*Be careful not to spill coolant over engine compartment. Use a rag to absorb.

The Haynes Repair Manual states in addition to remove the drivebelts and idler pulley bracket, scrape off the old gasket, clean with lacquer thinner and apply bead or TRV sealant to cover.

QUESTIONS:
1) I would rather not touch the drivebelts and idler pulley bracket…..a mechanic recently replaced the belts and adjusted the idler pulley bracket. Do I have to remove the drivebelts and idler pulley bracket to replace the thermostat?

2) The drain plugs on the cylinder block have never been opened before and I’d rather not touch them now…..do I have to? Would just removing the drain plug from the radiator suffice for replacing the thermostat? (I do see that it would be easy for coolant to spill down the water inlet/thermostat assembly and spill onto the alternator)

3) Any guess on whether the gasket will come off easily? If the new water inlet/thermostat assembly comes with a gasket, then I don’t need to apply bead or TRV sealant right?

Thanks in advance for any replies or suggestions. It looks like I can get the water inlet/thermostat assembly on ebay.

The Wizard

iTrader: (43)

When in doubt, follow the FSM

1) No
2) No, just open the drain on the radiator and let it drain.
3) Really easy. No RTV needed. Thermostat has its own unique metal like crush gasket (sold separately).

Buy OEM only on this, and the OEM crush gasket. It's actually a reasonably price part at about $35 from the dealer. Gasket is just a few bucks more.

edwardh1

I bought an aftermarket thermostat for an Isuzu once, it did not have the factory hole with giggle valve. it had no hole which might mess up warmup.
I drilled a 1/8 inch or smaller hole in the thermostat plate but had no jiggle valve (what does that do, keep the hole clean?)

M in KC

Follow the Wizards advice.