[CodyVella]

Hey guys,

So last night we replaced the Rad, water pump, timing belt and thermostat on my '02 Xterra SE/SC. We filled the new rad up with about 8L of coolant and ran the truck to try and bleed the system. Now, we didn't think to open the bleed bolt on the intake because apparently we lack common sense. However, we did the same service on my old R50 Pathfinder (VG33E) and just ran the truck with the rad cap off to bleed the system. On the R50 once the thermostat opened it started to burp all the air out the rad cap, and we filled as needed. Not so with my Xterra apparently. There was never any burping of air out the rad cap. In fact, after almost 20 minutes at idle, and a few laps around the block (maybe 5km of driving) the new thermostat never opened, the lower rad hose remained stone cold. The temp gauge never went above half, but still. Over 20 minutes of idle plus some driving, we figured the thermostat should open, no?

We tried the same thing again with the bleed valve open, however it still yielded no results. I'm more confused though about the thermostat not opening, and the truck not overheating.

Any ideas? Is there a different way to bleed the system?

 

[hellrazor762]

Did you have the heat on while trying to burp the system?

 

[CodyVella]

Tried it with the heat on and the heat off.

Today someone suggested to me that the VG engine may circulate coolant in reverse. As in the coolant that has been cooled by the rad enters the engine through the lower rad hose, and the hot coolant enters the rad through the upper rad hose. therefore in theory the lower rad hose shouldn't be hot. Does this makes sense?

I drove it 85km without shutting it down and it never overheated (including a few stops of 5 minutes or so where it idled). So the thermostat has to be opening, otherwise it would have overheated right?

 

[RacerXXL]

The air bleed screw is simple just open the air bleed and add coolant at the filler neck until coolant comes out at the air bleed with a cold engine.

From the FSM

—REFILLING ENGINE COOLANT—

1. Install reservoir tank, radiator drain plug, and cylinder block drain plugs.

2. Fill radiator slowly with coolant until coolant spills from the air relief plug, then install air relief plug.

3. Fill radiator and reservoir tank to specified level. Pour coolant through coolant filler neck slowly to allow air is system to escape.

4. Warm up engine to normal operating temperature without
radiator cap installed.

5. Run engine at 3,000 rpm for 10 seconds and return to idle speed.

Repeat two or three times.

Watch coolant temperature gauge so as not to overheat the engine.
6. Stop engine and cool it down.

Cool down using a fan to reduce the time.

If necessary, refill radiator up to filler neck with coolant

7. Refill reservoir tank to Max line with coolant.

8. Repeat step 5 through step 7 two or more times with radiator cap installed until coolant level no longer drops.

9. Check cooling system for leaks with engine running.

10. Warm up engine, and check for sound of coolant flow while
running engine from idle up to 3,000 rpm with heater temperature
control set at several positions between COOL and HOT.

Sound may be noticeable at heater water cock.

11. If sound is heard, bleed air from cooling system by repeating
steps 5 through 7 until coolant level no longer drops.

Clean excess coolant from engine.