My '86 Trooper with the 2.3 liter has been running hot. I have also noticed that there is a coolant smell when I turn on the heater. When the heater goes on, it cools the engine off and puts it back to (guage- reading) normal. It seems that it runs especially hotter when pushing around 3000+ rpms while on the highway. The odd thing is that it doesn't appear to be losing much coolant at all... maybe just enough to get that smell....
Any insights or suggestions appreciated

When you turn on the heater, the heater core essentially becomes an add-on radiator.

It sounds as though you have two separate problems. First, it sounds like your radiator is plugged, at least partially. Second, the smell when you turn on the heater is most likely a pin-hole in the heater core.

I would attack the radiator problem first. I personally would put in a new radiator if the old one is bad. The cost of a new radiator is trivial (<$150) compared with the cost of repairing the damage if you overheat the engine (>$500). Given the time of year, you can probably defer the heater core for a while if cash flow is a problem. Sooner or later you are going to have to replace the heater core, also.

I had a similar problem on my 91 Trooper with 2.8L V6. This happened in the Seattle area in the Nov. Dec. time frame. The heater core was leaking into the cabin. This gives out the unmistakeable sickly sweet smell of antifreeze, fogs up the windows, makes everything you touch sticky, AND causes the engine to overheat. Since the amount of fluid on the floorboards was not near the amount of what the coolant system can hold, the overheating can be attributed to system pressure.

Without the proper pressure within the system, the steam will vent out of the radiator cap (which happened on two occassions), and the overflow line, and this is what depleted the system of most all the coolant. I'm so impressed however, with the incredible little GM 60 degree V6. It now has 200K miles on it and is still running strong even after experiencing this little ordeal.

I called the only remaining Isuzu dealer in the area, and found that the heater cores for the 91' and older Troopers come as a complete unit with the box, fan, etc. and sell for over $400. That's more than I paid for my entire vehicle. So, I called the guy that I bought the engine from for my sons 87' Trooper. He had 4 Troopers in the back of his house, sold me a core that he removed and tested, for $45. This was a good deal to me.

He no longer has any heater cores, but you can contact Covey's Auto Parts in Marysville Washington (they have a ton of old troopers in their yard). The number is (360) 653-1006. They remove the parts themselves and they do ship as well.

Good luck and happy troopin'

Bryce Canyon <img src="/forums/images/graemlins/patriot.gif" alt="" />

I've been looking at heater cores myself lately...

Wondering if anyone has sucessfully transplanted one of the cheaper cores from a completely different vehicle?

Anyone know of a site that has dimensions of various cores ?

advanceautoparts.com has new ones for $87 and free shipping. Or you can buy a used one for $20-50