overheat - sort of

the engine temp on my 93 rodeo 3.2L will go from normal range to just under the red marks, stay there maybe 20-30 seconds, and drop back to normal range. I assumed it was the thermostat and replaced it. no change. It's not loosing coolant. when it goes hot it will not blow hot air through the cabin heating system. Any suggestions?

Have you done a radiator flush recently?

Do you have the original radiator? If so, it's probably in need of replacement due to internal corrosion.

You May Have Air In The System

It's a replacement radiator, though not new. It appeared clean and in good shape. No corrosion or gunk in the bottom.

How do you de-air a coolant system?

DO THIS WHEN ENGIN IS COOL
remove the upper hose from the pipes at the rear of the engine on the pass side remove radiator cap pour in coolant /water as needed untill it starts to pour out of the hose and pipe reinstall hose to pipe top off radiator start it up let it reach operating temp be sure radiator gets hot add coolant if needed should be good to go after that

Did you recently replace the rad?

How old is your water pump?

the proper way to de-air your coolant system is to crank the engine ( COLD ) and remove the radiator cap . the top radiator hoes just needs a little squezing. you want to see bubbles most people call it burping.but just to be safe have you checked all of your wires make sure their all good HOW long has this been going on

+1 for air pocket in the cooling system. Seen it many times.

sorry but your wrong on this one rizay it may work on an old 350 or some of the 4 cyl engines
doing what you are describing will not rid this system completly of air I am an isuzu tech and an confident in my description of getting the air out

Well now you all got me confused, I've always aired it out as Rizay has described and have never had an issue. Did it this way on both Rodeo's without a problem.

may work but try the way i described its much less time consuming and all air will be gone no margin for error
why take a chance of overheating your vehicle and possibly cracking a head

Hey, 2eyefish, is headgasket cracking common on these 3.2L's, specifically the 94-97yrs??

DO THIS WHEN ENGIN IS COOL
remove the upper hose from the pipes at the rear of the engine on the pass side...
are these the heater hoses?

thanks
//bc

It Is Not Common To Have Any Head Gasket Problems On These More Of A Head Problem When They Overheat

Yes Troop Heater Hoses

ok, what's not being said, exactly, the reason this works is because this hose at that point is the highest point of the coolant system. right? so the air is going to go up to that point. right?

anyway, i too have success filling, running with the heater on high and so forth. i can see why the hose method would be quicker, but i'm always reluctant to screw around with an old hose that is sealing ok now, but what might get 'disturbed' if twisted and pulled.

i like that kind of tip, though


//bc

I wonder if the old way has always worked for me because I allow it to run for quite some time with the heater on high, radiator cap off.

The top hose in the back isn't too bad to get to, but if you had to replace them, they are a PAIN.

I...The top hose in the back isn't too bad to get to, but if you had to replace them, they are a PAIN.

exactly.

i findly found where the ocassional whiff of coolant was coming from --one of the heater hoses at the firewall end.

i'm starting to do research now on how to access that thing --it not only is right up against the engine but in a little built-in recess in the firewall, imposssible to access without removing something or maybe the jack-up-the-transmission-trick that i think i saw as a jlemond tip to access the coolant temp sensor on the cooland crossover manifold back there. ahhh, fun, that.

//bc

It's easy with the manifold off, but then you're looking at a gasket set.

It's easy with the manifold off, but then you're looking at a gasket set.

yes, but getting to that point isn't so easy. :grinyes:
plus, i've got a bunch of other stuff to do with the brakes and wheel studs and bearing repack and. . .

plus . . . my intake manifold gaskets are original and fine and i don't want to tempt fate, either. . . (shhh-h-h-h-h-h)

I hear all of that. I had some whistling after doing all of the work under the intake awhile back. Very distinct sound.

I did the heater hose at firewall method, and it appears to have fixed the issue.

Thanks