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Replacing thermostat

Tiny
MARKIEJI
  • MEMBER
  • 1998 HONDA PASSPORT
Six cylinder four wheel drive automatic 222,229 miles.

I need to replace the thermostat. Where can I find an exploded view of the intake manifold plenum, coolant tubes and thermostat? I need to see what I need to remove to get to the thermostat and it is buried under a lot of stuff. I looked at Haynes repair manual, but what they show cannot be right for my model. I have a V6-3.2L engine (RLV type). These cars are essentially Isuzu's with Honda logos as you know.
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Tuesday, September 22nd, 2009 AT 4:17 PM

10 Replies

Tiny
MATHIASO
  • MECHANIC
  • 1,209 POSTS
Removal and Installation of thermostat:

Disconnect the negative battery cable.
Drain engine coolant from the radiator and engine.
Disconnect radiator hose from the inlet pipe.
Remove the thermostat housing, then remove the thermostat (2),


https://www.2carpros.com/forum/automotive_pictures/46384_thermosta_1.jpg



To install:

Install the thermostat into the outlet pipe (4) making sure that the air hole is in the up position.
Install thermostat housing and tighten the bolts to 18 ft. lbs. (25 Nm).
Attach the radiator hose to the inlet pipe.
Refill the engine with the proper type and amount of coolant.
Connect the negative battery cable.
Start engine and check for coolant leakage.

This may help, if not let me know.
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Tuesday, September 22nd, 2009 AT 5:54 PM
Tiny
MARKIEJI
  • MEMBER
  • 3 POSTS
This is very helpful, thank you. But, my immediate concern and question is the process of actually getting to the thermostat housing. It is under a lot of other things that I need to remove. I was hoping for an exploded view of the things I need to remove to actually get to the thermostat housing. I was told that I had to remove the intake manifold plenum. how do I do that?

Here is a picture of what I am dealing with. The thermostat housing is buried under a lot of stuff.

An exploded view like the one you provided for the thermostat housing is what I am hoping for. Thank you.


https://www.2carpros.com/forum/automotive_pictures/412531_400s_1.jpg

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+12
Tuesday, September 22nd, 2009 AT 7:14 PM
Tiny
MATHIASO
  • MECHANIC
  • 1,209 POSTS
Can you see the big hose from the air filter from the picture you sent me?
It is attached with clamp on throttle body.
Above the belt there is a hose from the radiator upper part (radiator upper hose) drain radiator before removing it.
The inlet under the big hose from the air filter have bolt, attached to the engine block.
Remove the bolt and the thermostat is right there.

Let me know.
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+6
Wednesday, September 23rd, 2009 AT 2:35 AM
Tiny
MGANDERS
  • MEMBER
  • 4 POSTS
I have the same problem. It appears to get to the thermostat you have to remove the intake manifold. I tried doing it without removing the intake manifold but was unable to get to the back bolts. The wiring harness is blocking access from the front, and the manifold blocks access from the top. Anybody have any idea for the 1998-2002 Honda Passport thermostat?
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Friday, October 2nd, 2009 AT 8:35 PM
Tiny
MGANDERS
  • MEMBER
  • 4 POSTS
So turns out you do have to remove the intake manifold. Crazy! What a horrible design. I found a number of sites that confirm this is the case. Here is one:
https://www.2carpros.com/topics/cooling-system/thermostat

This site has some great FAQs about the Passport (Rodeo).
http://www.isuzufaq.com/

They have a section in there that explains how to remove the intake manifold. Does not sound too bad but what a pain just for a thermostat!

I am starting to think it is not worth my while and am tempted to see how much a Honda shop would charge. I am guessing in the hundreds, but maybe worth not spending two days working on the thing.

Good luck. I will let you know what I do.
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Friday, October 2nd, 2009 AT 9:09 PM
Tiny
MGANDERS
  • MEMBER
  • 4 POSTS
By the way. If you do decide to do this I was told to use an OEM thermostat, and to absolutely make sure to replace the intake manifold gasket.
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Friday, October 2nd, 2009 AT 9:17 PM
Tiny
MATHIASO
  • MECHANIC
  • 1,209 POSTS


https://www.2carpros.com/forum/automotive_pictures/46384_new_1.jpg



you need extension to get in there underneath to get the bolts before getting the thermostat out.
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Friday, October 2nd, 2009 AT 9:18 PM
Tiny
MGANDERS
  • MEMBER
  • 4 POSTS
That is exactly what I hoped as well. But to no avail unfortunately. Even with my 12mm swivel ball socket I could not get to the back bolts. There is just not enough room. I gave up when I realized that even if I did manage to get the bolts loose that getting it out and back in with the new thermostat would be an even bigger feat. But maybe I am missing something.
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Friday, October 2nd, 2009 AT 9:44 PM
Tiny
MARKIEJI
  • MEMBER
  • 3 POSTS
The quote I got from the dealer was $260.00 to replace the thermostat. My local repair guy (whom I like) quoted $290.00! So, that tells you it is a job to replace them.

Mathiaso -- I did remove the hoses and connections you show in the photo. But the actual thermostat housing is not revealed. It is much deeper under the intake manifold. So I guess the question now is, what is the procedure for removing the intake manifold?

Mganders -- thank you for the leads to additional information.
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Saturday, October 3rd, 2009 AT 1:09 PM
Tiny
MATHIASO
  • MECHANIC
  • 1,209 POSTS
Remove or disconnect the following:

this is going to be a long shot.

Negative battery cable .

Engine cover.

Air cleaner assembly .

Accelerator cable cruise control cable.

Brake booster vacuum line.

Manifold Absolute Pressure (MAP) sensor
connector Idle Air Control (IAC) valve connector.

Throttle Position (TP) sensor connector .

Canister purge solenoid connector Electronic .

Vacuum Sensing Valve (EVSV) connector and vacuum line Exhaust Gas Re-circulation (EGR) valve .

Positive Crankcase Ventilation (PCV) valve and hose .

Pressure regulator vacuum line Ventilation hose Throttle body Fuel lines Fuel injector connectors .

Intake manifold ( finally).


https://www.2carpros.com/forum/automotive_pictures/46384_intake_1.jpg



hope this help you.
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Saturday, October 3rd, 2009 AT 6:46 PM

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