Here is how to replace the heater hose fittings on GM’s 3800 series v6 engine. On this engine, they run between the engine block and belt tensioner. I’m not exactly sure what the logic behind that was, but it does help cool the tensioner down even though it isn’t necessary. I’m replacing the ones on a 1999 Buick, but this engine was used in multiple cars and minivans from 1995-2007. The replacement process will remain mostly the same for each one.
The fittings that came from the factory were plastic and turn brittle eventually – I used an upgraded part made from cast aluminum for only $4 more than the OEM replacement.
In order to remove the two heater hose fittings, the alternator and belt tensioner both have to be removed. The alternator removal is the same as on the Chevy Venture I wrote about a while back, but I’ll show how much easier it is to replace in the Buick only because there’s more room to work.
I’ll backtrack a bit from where the last picture was taken and show the bolts that hold the alternator on:
That’s all you have to do to change the alternator.
Once all the bolts are removed, pull the belt tensioner out. The heater hose fittings are just friction fit but will probably break off when you pull. Once the tensioner is removed, pry any remaining plastic parts out of it and out of the engine block. Lubricate the o-rings on the new heater hose fittings with oil and press them in. Press the tensioner back into place on the side of the engine and reinstall the bolts.
This part was too messy for me to take pictures of, but here are pictures of the new fittings in place:
Put the bolts back into the tensioner and reinstall the alternator + serpentine belt.
While the engine is off, I poured water down the side and everywhere else I saw dye to wash it off. That way any new leaks will be apparent.
Replace the coolant overflow and the bar that runs over it, then fill the radiator with coolant and purge any air from the system (tip – there’s a bleeder valve on top of the thermostat).
That should just about do it. This is a pretty easy job that requires minimal tools, and I have even done it on similar cars in a parking lot without much trouble.