Alternator and Thermostat Replacement (How-to)

[marinegrunt]

I replaced the thermostat in our Envoy last night so thought I'd post a how-to. I tried searching and couldn't find one. If one already exists let me know and I'll take this one down. I've had to the t-stat a few times and found it much easier to remove the alternator first. If you don't remove it the job will probably take you longer than if you had. Once the alternator is out you have all kinds of room. Although you don't have to, one thing I normally do when working under the hood is to lift the hood up even higher by using a ratchet strap hooked to the luggage rack. It gives you so much more head room and you don't have to worry about the hood prop rod being in the way. It only takes a minute. Just be sure to use a rag or something on the front of the hood to keep the hook from making contact with the paint.



1. Disconnect the negative battery cable.

2. Remove the belt. You don't have to take it off of all of the pulleys. Just slip it off of the alternator and position it out of the way. To remove the belt you use the square on a 3/8" ratchet. Insert it into the square slot located on the tensioner pulley. You can kind of see in the picture where the ratchet is inserted into the tensioner.



3. Drain the coolant. I'm not sure about other years but my Envoy doesn't have a petcock at the bottom of the radiator. I removed the lower radiator hose where it goes into the bottom of the radiator. Be sure to put the hose and clamp back on after it drains so you don't forget later on.

4. Remove the right engine lift hook. There are a total of 4 bolts. One is a 10mm that bolts to the a/c line mounting bracket. There are two bolts in the front and another on the backside. A 7 1/2" wobble extension comes in handy for the rear bolt.



5. Remove the 3 alternator mounting bolts. All 3 are 15mm. There are 2 towards the top and one on the bottom. The bottom one is much easier to remove if you use a 15mm flex head gear wrench.



6. Gently lay the alternator on its side and remove the positive cable nut and wiring harness. According to the manual this is one of the first steps it says to do but it's much easier waiting until you can get to them. There is plenty of play in the wires but still be careful so you aren't tugging on them.



7. If you're replacing the alternator go ahead and pull it out of the engine compartment. If you're just doing the thermostat I recommend moving it up towards the fan or someplace out of the way. It's a really tight fit when removing it from the engine compartment and can be tough to get in and out because of the fan shroud. If you do pull it out pay attention to how you had it positioned when you wiggled it up and out so you can try and get it back through the same way.

8. Remove the hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.



9. Remove the two thermostat housing bolts and remove the thermostat housing. There's one bolt on top and one on the bottom. Be sure to have a drain pan under the vehicle because there will be some coolant that will come out once it's loose.



10. Clean the mating surface on the engine. There is usually some leftover residue from the old o-ring. What works really well on aluminum is a 3M Roloc Bristle Disc.



11. Install the new thermostat. Don't forget to install the new o-ring that should have came with the thermostat. If you forget the o-ring it will leak. Install and tighten the thermostat housing bolts to 96 inch pounds.

12. Install the outlet hose and hose clamp.

13. Install the alternator cable and harness to alternator.

14. Install the alternator mounting bolts and torque to 37 foot pounds.

15. Install the engine lift hook. Torque the lift hook to engine bolts to 37 foot pounds and a/c line mount bolt to 89 inch pounds.

16. Install drive belt.

17. Connect negative battery cable.

18. Fill coolant to correct level.


I believe that covers everything. If anyone notices a mistake, or that I left something out, please let me know so I can edit it. Also, if you have any tips or tricks that you can add please do. I will also list them in the steps.

 

[coolasice]

Excellent write up, how much coolant is lost/replaced for the job?

 

[marinegrunt]

Thanks.....I didn't really pay much attention. I had a bunch of partly full jugs of coolant I refilled with. If I had to guess I'd say I drained out about 2 to 2.5 gallons.

 

[coolasice]

OK, I think I need to do this, but its too damn cold out right now (-14f this morning)... Gotta get the thermostat and wait for a decent 40f day..

 

[marinegrunt]

Hopefully warmer weather is heading your way. We hit -12 last week here in IL but are now in the low 40's during the day.

There was one time I had to pull a tranny outside in the winter. I draped a tarp over the hood and angled it towards the ground. I then used one of those Mr. Heaters and it kept it like 50 or 60 degrees under it.

When you remove the lift hook be careful when you remove the back bolt. I ended up dropping the bolt and lost it somewhere on the frame. Maybe remove it last and keep pressure on the bolt with the extension so it stays in the bracket hole. You can then lift the bracket and bolt out together at the same time. There's just no room to get your hand in there to get a hold of that rear bolt.

 

[coolasice]

its 30 out today, but working all weekend. i did my ball joints this fall in drenching rain, lots-o-fun

 

[kkeo211]

Very good write up (wish I had this when doing mine). I don't know about you, but the worst part of this job was the thermostat housing lower bolt. I took me a good 10 minutes to remove it, because you are sort of going in blind and just doing things by feel.

 

[Merc50323]

When you tightened the thermostat bolts, was it 96 in.-lbs. or should it be 96ft-lbs.? The torque wrench I have measures ft-lb and I'd rather not buy an in.-lb. or can I convert the 96 inch to ft-lbs.? Thank you for your help.

 

[coolasice]

just divide in/lbs by 12 for ft/lbs

 

[coolasice]

i'm planning on doing this tomorrow morning in the yard... not going to be fun... supposed to be a high of 11F tomorrow...

 

[aero_soul]

A wonderful write up. I went all the way and am stuck at the lower/rear bolt of the thermostat housing. Two problems here.
One that the rear/lower bolt is too tight to open. any help on that.
Secondly the clamp on the hose is NOT screw type and looks like the original one (the hard steel type). Moreover its one ear or whtever u call it is broken and is at a very odd angle. Wont break whtsoever i do. Any help to break it or get it off from there will b great.
Thanks in advance.

 

[JarrettK]

Awesome write up, I just went through this.. twice. Well mostly twice.
If anyone is getting ready to do this, here are the details that might help you.

--Before you start, make sure you have 3" 6" and 10" extensions and a universal end for whatever socket set you're using.

--If you've never taken your fan belt off before, go to harbor freight and get a 3/8" breaker bar.. It's perfect for moving the tension arm.

--If you don't already have a set, go to harbor freight and get a set of stubbies ( short wrenches ) in metric, with the ratcheting box ends. That bottom bolt on the alternator is soooo much easier to get off with a short wrench rather than beating on the fan blades.

--step 4 above, there is one other attachment point for that hose on the other side. Take a deep well 10mm socket and remove that nut as well. Get the whole things lose, you'll figure it out. It makes it a ton easier to get the alternator all the way out ( if you do ) when you can push that hose back and out of the way.

--The bottom bolt on the alternator. On mine, the pipe coming off of the compressor may as well have been touching it. I don't recommend doing this, but I was able to ever so gently coax it over once I got my wrench on the end of the bolt, and used it to kind of pry it over enough to have room to work. You can even get the box end of it and ratchet for a while, but not all the way.. don't get it trapped.

--The spring clamps.. suck. Get a larger set of vice grips.. you can get them set so that they clamp the thing open. Just make sure you get a good grip.

--The spring clamp on the hose on the thermostat end. Mine was facing away, towards the firewall, and was a total pita to get the tool on. When you're putting things back together, it is tempting to leave that facing up so you can get to it. DON'T.. The 12v stud on the back of the alternator with hit it.. In my case I ended up with the hose leaking right there the next day.. thankfully.. or I wouldn't have noticed that the alternator was putting pressure on it. You can face it forward.. just make sure the tabs aren't pointing up.

--The alternator wire.. When you're putting the alternator back on, and you've taken it either all the way off, or loosened that bottom bolt a lot.. and you're cussing up a storm because the damned thing doesn't want to seat up against the engine.. it's because of how this wire is oriented. Loosen it up. point the thing far right ( you'll see what I mean ). It looks like you have slack until you try to put it on, then it starts fighting you.

--OH, and and if you don't like feeling around for the back nut on the thermostat, you can get one of those snake cameras and set it up so that you can see mostly what you're doing. I was about to give up when I thought of that one.

Thought I'd share and maybe save some pain.

 

[JayArr]

I did this on the weekend and one thing I did differently was to NOT try to empty the radiator at step #3. Instead I waited until I was about to pull the hose off the thermostat neck and I put a large container under the car. I pulled the hose off slowly and let the fluid drain down into the pan from there. This way I didn't have to drain all of the fluid or pull the lower hose. I managed to catch all the coolant with no driveway spill and I just filtered it and put it back into the rad when I was done.