Passport Overheating after long idle

[clemnj]

I have a 1995 1/2 Honda Passport which recently began overheating after idleing for a prolonged period. The engine will warm up as usual and stay at a constant temperature for 10-15 minutes while idleing, at which point the temperature begins to rise. If the engine is idled up around 1500 rpm, the temperature goes down to normal. I've tightened the drivebelt for the waterpump, but that's all so far. Any thoughts?

[amigo-2k]

old, bad radiator.

bad thermostat.

[Ramblin Fever]

Probably in need of a whole cooling system tune-up. I wouldn't keep driving it until you're able to solve it, these are all aluminum engines.

Let us know what you find.

[clemnj]

not thermostat or radiator cap

[Canucklehead]

Originally Posted by clemnj

not thermostat or radiator cap

Bad fan clutch perhaps.

[amigo-2k]

whats the history the the radiator? is it original?

[clemnj]

radiator was replaced about 5 years ago, and the coolant looks clean. There doesnt seem to be any coolant exchange between the radiator and the resevoir bottle, however. Should there be?

Also, water pump was replaced within the last three years with timing belt change.

[Ramblin Fever]

Do you do any driving down muddy, tall-grass, or farm/ranch roads; if so, give your radiator a good washing with a garden hose, but don't bend the fins.

Yes, I believe there should be some fluid exchanging back & forth between reserve tank & radiator.

[trooperbc]

[quote=clemnj]radiator ....There doesnt seem to be any coolant exchange between the radiator and the resevoir bottle, however. Should there be?
...quote]

not thermostat or radiator cap

when i connect the two, i wonder...

did you use an oem dealer radiator cap and a themostat from isuzu?
both of these are known to be problems if not using the stuff from the dealer.

the way the coolant reservoir works is that it gets overflow from the radiator as it heats up, and as it cools down vacuum pulls in coolant from the reservoir if the radiator needs it. if the radiator cap isn't working correctly it can hinder this function. also, if the radiator cap isn't the correct range (even if stant says it is) then it could be releasing pressure sooner than it should.

if either or both of these is non-dealer, i'd change them. i'm betting on the radiator cap, from here.

//bc

[Ramblin Fever]

I was thinking about this, I agree with Trooperbc, if there's no exchange between the two, it's got to be a bad radiator cap.

One thing I've learned about Isuzu's, ALWAYS use OEM replacements!

[clemnj]

The K.I.S.S. Method prevails again!

Boosted the coolant level in the radiator directly, instead of through the resevoir bottle. The coolant level in the bottle has always been full, and the radiator level always appeared full, but the engine was always warm when I checked it. Wen I checked it cold, it looked a little low, so I added a little water and now its not overheating.

"Keep it simple stupid"

[Ramblin Fever]

DEFINITELY replace your radiator cap then, because it's not doing it's job - it should be sucking coolant back in after engine cools off.

[trooperbc]

Originally Posted by clemnj

The K.I.S.S. Method prevails again!..."Keep it simple stupid"

absolutely, and in this case you have defined the problem as the radiator cap. good

//bc

P>S>if you don't take care of it, it's more than just adding coolant to the radiator and that solves the problem. if the cap is not holding pressure when it should and releasing when it should you are risking overpressurizing the system and a weak link (hose, radiator tube, whatever) will show up.

btw, what did you install for the thermostat and for the radiator cap?

[clemnj]

The thermostat and Cap are aftermarket, from Autozone.

It all seems to be working correctly now, fluid is exchanging between the radiator and resevoir bottle.

[trooperbc]

Originally Posted by clemnj

The thermostat and Cap are aftermarket, from Autozone.

It all seems to be working correctly now, fluid is exchanging between the radiator and resevoir bottle.

that's good. now you have time to get the dealer isuzu parts. one painless way is through stcharles isuzu in missouri who gives discount, free shipping, no minimum, no tax, and good expertize from Merlin, ask for him
just call (although waiting on hold can be a bit of a pain)

http://isuzu.stcharlesauto.com/Department-Parts.aspx

good luck

//bc