'96 3.2L V-6 Rodeo - Overheating Fixed!!!

Being a Ford guy, I have much experience working on my cars and trucks, but I haven't had much experience working on a GM/Isuzu vehicle before. I'm kind of a stubborn SOB though, so I thought I could quickly diagnose my daughter's overheating problem on her '96 Rodeo. I saw many posts on this site regarding overheating problems with the 3.2L engine. Mostly when idling in traffic like we have here in Atlanta. I tried the old standard methods of replacing the t'stat and doing the rad flush, to no avail. I did however, notice several posts by someone saying to replace the entire radiator and it kept coming to mind as something I'd do as a last resort.

Well folks, let me tell you that I tried that last resort last night and it was the correct answer. After replacing the water pump (which was due anyway at 103K), the thermal fan clutch, and the t'stat, I did the radiator replacement.

Using my OBDII scantool and a laptop, I monitored the actual coolant temp while idling, driving under normal conditions, and under high performance conditions with the following results. I saw a 60 degree peak-peak temperature difference between the stock radiator and the new one. The wild temperature fluctations that everyone describes here were minimized, and the "heat soak" issue described on the site is much less of an impact. As an example, running without the t'stat installed, I see an average peak temp of about 159 degress, vs. 220 with the old radiator. When I put the termostat back in, I expect an average peak of somewhere around 190-195 degrees which is optimum.

So, the moral of this story is; if you start to have overheating issues and your thermostat works properly, check your fan clutch using the method described elsewhere on the site and check the water pump for leaks. If everything looks normal, the radiator is the most likely culprit. Believe me, you don't want to pay for a new water pump installation without trying the radiator first.

I'll be happy to answer any questions.

UPDATE:

After reinstalling the 175 degree T'stat the engine peak temps ranged between 180 and 189 degress depending on the operating situation. That beats the heck out of the high 2 teens to 220's before. Ambient local weather was in the 70's at the time the tests were run. Checked "heat soak" temps afterwards and coolant temp climbed to 193 before it began to roll back into the 180's.

I would have to say these temps should reflect a properly operating cooling system since all the components were replaced and the system was totally purged and refilled with new coolant.

Hopefully this info will come in handy to someone at some point.

UB10

I'm going to post a link to your post!

-RYan

I got a 1995 and mines overheatin im goin to try the t stat,where the hell is the damn thing

UB10 - Good onya mate! It's always great when someone posts details about their solution to a problem.

mwm - diagram from http://www.myisuzuparts.com/ thermostat is item #1

http://i190.photobucket.com/albums/z200/boritz_bucket/ThermostatSmall.jpg

Very important to make sure to ONLY use an OEM Isuzu thermostat; using anything other then this, the engine will not remain cool enough.

It's actually in a very accessible spot and easy to replace. Don't forget the gasket.

It's actually in a very accessible spot and easy to replace. Don't forget the gasket.


yes it is unlike the one on my Saturn which is at the bottom of the block so you lose all liquid when you change it. :shakehead

It's actually in a very accessible spot and easy to replace. Don't forget the gasket.
Lucky you. On 2nd gens its under the intake pleneum :screwy:. The plenum has to come off to replace the t'stat. :banghead:

I got a 1995 and mines overheatin im goin to try the t stat,where the hell is the damn thing

Mines fixed, drove 1100km on the weekend without a problem Now if i can only get my drivers side windsheild wiper to start wipping again, damn linkage im assuming

Well...Unfortunately i'm also in need of taking on this task...already got the T-stat/gasket done....still over heating....guys at the shop said "water pump"...and i can't afford the $400+ ($300 in labor)they want...is this a rather simple/regular task replacement? or am i looking at an ass buster? lol...i've worked on my Camaro,Celica and Taurus in the past....but this would be the 1st on my truck,and i def need it resolved asap :runaround:
...or sadly it becomes a trade in :frown:.
thnx for any help,
have a great weekend,
JimC

The water pump is under the timing cover and driven by the timing belt. It is recommended both be done at the same time. Then you should change the tensioner and idler pulley, too. It took me the better part of a day to do it all, but I saved some labor costs and know it was done right. I did it all with only the Haynes manual and it was the second timing belt and water pump I've ever done.