How to: Changing thermostat and rad cap
08-27-07, 10:43 AM
#1
How to: Changing thermostat and rad cap
I know there's some excellent info out there, but figure you can never have enough threads and pictures out there when searching, so here it goes:
A couple of years ago I changed my thermostat and rad cap with non-OEM parts. I'm usually good about maintenance and use OEM parts, but this was an impulse buy while at the parts store, since I knew mine were old. I had been meaning to change these to Mazda for a while, but came across some threads here saying bad things about these non-OEM cooling system parts, so I put this on my priority list.
Anyways, on to the procedure:
Difficulty: Easy (about as easy as an oil change - but you still have to be careful)
Time: 30 min. (but give yourself an hour - more if you start cleaning things like me)
SAFETY: MAKE SURE YOUR ENGINE IS COLD, and that the system is not under pressure. Use common sense and a rag when removing rad cap. Some coolant WILL spill (about a cup or 250ml roughly), and you don't want it on a hot exhaust. Have rags or kitty litter/sand/etc.
1. Get inside, put the Logicon temp. slider on HOT (Might as well do it now, since later when you start the engine, the logicon will do its job and you won't have to worry about it).
2. Remove thermostat cover cap (not the completely round cap at the top of the rad, which is on some models).
3. Grap a clear hose (say, 1/4" or 3/8" I.D.) long enough to go down the side of the fender to a container lower than the thermostat. Put the hose as far down to the top of the thermostat as it will go.
4. Siphon as much coolant as you can. Squeeze the hose so that any coolant near the top goes to the end of your hose. Now would be a good time to have a look at your Rad, Heater and smaller coolant hoses to the rear engine iron and throttle body, BAC valve, and rear of water pump outlet.
5. Unhook the small hose from the nipple on the plastic neck where the cap goes on.
6. Loosen the Rad clamp near the coolant outlet neck and slide it back on the hose past the end of the aluminum neck.
7. Undo the thermostat cover neck bolts (12mm socket), and note the spring and flat washers and how they go. Once you break the seal, a little coolant will leak.
8. Note how the thermostat is positioned, but remember that it may not be right. See if there's a jiggle pin on the old one. Pull out the thermostat. Now a shitload (not really) of coolant will spill.
9. Remove the old gasket and clean the mating surfaces. If there was only silicone, for shame! The gasket flanges are aluminum, so be gentle and get as clean a surface as you can withough gouging or unnecessarily scratching the aluminum. I use a gasket scraper carefully, the kind with the single sided razor blade.
10. The mazda thermostat comes with a gasket (which you can also get separately). Seems to be made out of rubber impregnated paper, but I could be wrong. I didn't use some silicone on it, because it seems like a very good gasket, I hate the mess, and planned on torquing the bolts anyway.
11. When you get the thermostat/gasket, be careful, since I saw a couple of part numbers on the parts fiche at the dealer (I have links for the FSM and Parts fiche in my sig.)
12. Put the new thermostat in, orienting the jiggle pin (circled in my pic.) as per FSM and my picture within the two lines shown. Note that this is a bit misleading...because of the way the thermostat goes in the circular groove, the thermostat will not spin along the range - it will actually not even go in except in two narrow ranges - one is within, and you'll know the other one is well off the range. If this seems confusing, don't worry, you'll see what I mean. Just make sure the thermostat is in flat and in the groove with the jiggle pin as shown.
13. Put the thermostat cover on, with washers,bolts, and GASKET (I almost forgot)in place and thread them on finger tight. You don't want to cross thread them now. Tighten them snug with a ratchet, then torque them to 13-20ft-lb (I used about 17 ft-lb). It is highly recommended you torque these, because you want the gasket to be at the right pressure - beg borrow or steal a torque wrench.
14. Put the large and little hose back, tighten clamp, fill with coolant. Loosen the bleed screw at the rad, make sure all air is out, retighten.
15. Top up coolant. Keep the cap off!
16. Start engine. Make sure the cap is off (I know I said it already). Double check the heater is on HOT. Check for leaks. Keep an eye (or a trusty helpers') on the coolant gauge (if it's trusty). Sometimes, too much air near the underside of the thermostat causes it not to open initially - this happened to me once - so you want to make sure everythings ok and that the thermostat opens up at the right time. You'll see the coolant become hot if you place your finger into the hole. The air introduced into the system should be easily gone, unless you have/had air elsewhere in the system.
17. Once at operating temp, top up coolant, reinstall your new maza cap with the funny japanese characters on top, and put the cap on. Let it run for a bit more, keeping an eye on the coolant temp.
18. Enjoy.
I know 17 steps for a simple job like this seems a lot for a simple job, but I think it's better to explain the why's and how's so people have a better understanding and more confidence when doing this task.
WHY NOT TO REMOVE THERMOSTAT AND LEAVE OFF TO IMPROVE COOLING:
You will notice that the thermostat has a shiny disK at the bottom. When it opens, it closes off the bypass passage on the water pump. This ensures all coolant goes through the rad when the engine warms up. Learned this on a Mercedes W123 web site. The other reason is you want the engine to actually go to operating temp. as soon as relatively possible so you can have some fun.
A couple of years ago I changed my thermostat and rad cap with non-OEM parts. I'm usually good about maintenance and use OEM parts, but this was an impulse buy while at the parts store, since I knew mine were old. I had been meaning to change these to Mazda for a while, but came across some threads here saying bad things about these non-OEM cooling system parts, so I put this on my priority list.
Anyways, on to the procedure:
Difficulty: Easy (about as easy as an oil change - but you still have to be careful)
Time: 30 min. (but give yourself an hour - more if you start cleaning things like me)
SAFETY: MAKE SURE YOUR ENGINE IS COLD, and that the system is not under pressure. Use common sense and a rag when removing rad cap. Some coolant WILL spill (about a cup or 250ml roughly), and you don't want it on a hot exhaust. Have rags or kitty litter/sand/etc.
1. Get inside, put the Logicon temp. slider on HOT (Might as well do it now, since later when you start the engine, the logicon will do its job and you won't have to worry about it).
2. Remove thermostat cover cap (not the completely round cap at the top of the rad, which is on some models).
3. Grap a clear hose (say, 1/4" or 3/8" I.D.) long enough to go down the side of the fender to a container lower than the thermostat. Put the hose as far down to the top of the thermostat as it will go.
4. Siphon as much coolant as you can. Squeeze the hose so that any coolant near the top goes to the end of your hose. Now would be a good time to have a look at your Rad, Heater and smaller coolant hoses to the rear engine iron and throttle body, BAC valve, and rear of water pump outlet.
5. Unhook the small hose from the nipple on the plastic neck where the cap goes on.
6. Loosen the Rad clamp near the coolant outlet neck and slide it back on the hose past the end of the aluminum neck.
7. Undo the thermostat cover neck bolts (12mm socket), and note the spring and flat washers and how they go. Once you break the seal, a little coolant will leak.
8. Note how the thermostat is positioned, but remember that it may not be right. See if there's a jiggle pin on the old one. Pull out the thermostat. Now a shitload (not really) of coolant will spill.
9. Remove the old gasket and clean the mating surfaces. If there was only silicone, for shame! The gasket flanges are aluminum, so be gentle and get as clean a surface as you can withough gouging or unnecessarily scratching the aluminum. I use a gasket scraper carefully, the kind with the single sided razor blade.
10. The mazda thermostat comes with a gasket (which you can also get separately). Seems to be made out of rubber impregnated paper, but I could be wrong. I didn't use some silicone on it, because it seems like a very good gasket, I hate the mess, and planned on torquing the bolts anyway.
11. When you get the thermostat/gasket, be careful, since I saw a couple of part numbers on the parts fiche at the dealer (I have links for the FSM and Parts fiche in my sig.)
12. Put the new thermostat in, orienting the jiggle pin (circled in my pic.) as per FSM and my picture within the two lines shown. Note that this is a bit misleading...because of the way the thermostat goes in the circular groove, the thermostat will not spin along the range - it will actually not even go in except in two narrow ranges - one is within, and you'll know the other one is well off the range. If this seems confusing, don't worry, you'll see what I mean. Just make sure the thermostat is in flat and in the groove with the jiggle pin as shown.
13. Put the thermostat cover on, with washers,bolts, and GASKET (I almost forgot)in place and thread them on finger tight. You don't want to cross thread them now. Tighten them snug with a ratchet, then torque them to 13-20ft-lb (I used about 17 ft-lb). It is highly recommended you torque these, because you want the gasket to be at the right pressure - beg borrow or steal a torque wrench.
14. Put the large and little hose back, tighten clamp, fill with coolant. Loosen the bleed screw at the rad, make sure all air is out, retighten.
15. Top up coolant. Keep the cap off!
16. Start engine. Make sure the cap is off (I know I said it already). Double check the heater is on HOT. Check for leaks. Keep an eye (or a trusty helpers') on the coolant gauge (if it's trusty). Sometimes, too much air near the underside of the thermostat causes it not to open initially - this happened to me once - so you want to make sure everythings ok and that the thermostat opens up at the right time. You'll see the coolant become hot if you place your finger into the hole. The air introduced into the system should be easily gone, unless you have/had air elsewhere in the system.
17. Once at operating temp, top up coolant, reinstall your new maza cap with the funny japanese characters on top, and put the cap on. Let it run for a bit more, keeping an eye on the coolant temp.
18. Enjoy.
I know 17 steps for a simple job like this seems a lot for a simple job, but I think it's better to explain the why's and how's so people have a better understanding and more confidence when doing this task.
WHY NOT TO REMOVE THERMOSTAT AND LEAVE OFF TO IMPROVE COOLING:
You will notice that the thermostat has a shiny disK at the bottom. When it opens, it closes off the bypass passage on the water pump. This ensures all coolant goes through the rad when the engine warms up. Learned this on a Mercedes W123 web site. The other reason is you want the engine to actually go to operating temp. as soon as relatively possible so you can have some fun.
08-27-07, 03:00 PM
#4
I put my gasket in without silicone and it had a super slow leak. I tightened the bolts some more and it seemed to go away and the reservoir level hasn't moved significantly in months. But I think there's still a teeny bit leaking. Anyhoo, if you have it on hand or are going to the parts store anyway, I'd just put silicone on the gasket and be done with it.
I'd also think that this would be a good time to get the air out of the cooling system. And I'd like to mention that overheats are the most common cause of engine failure (in an N/A, at least). So use the OEM thermostat and change it often. It's cheaper than an engine.
I'd also think that this would be a good time to get the air out of the cooling system. And I'd like to mention that overheats are the most common cause of engine failure (in an N/A, at least). So use the OEM thermostat and change it often. It's cheaper than an engine.
10-19-07, 10:17 AM
#6
There have been lots of questions in the past days relating to cooling system problems, so I thought I'd send this one to the top. Let me know if it helps, and archive worthy, because I haven't found this specific info there.
Tip: If you're replacing the thermostat after a coolant change, remember to fill the engine with coolant as much as you can before you put the thermostat in, as it will speed things up and ensure the thermostat opens up.
Tip: If you're replacing the thermostat after a coolant change, remember to fill the engine with coolant as much as you can before you put the thermostat in, as it will speed things up and ensure the thermostat opens up.
Trending Topics
10-21-07, 02:01 AM
#10
Winter sucks
Join Date: Jan 2004
Location: Newberg, Oregon
Posts: 3,083
Likes: 0
Received 0 Likes
on
0 Posts
Copied to rotorwiki if thats acceptable.
http://www.rotorwiki.com/index.php/C...d_radiator_cap
Will fix the formatting later.
Oh.. and I already had this one..
http://www.rotorwiki.com/index.php/C...OEM_Thermostat
http://www.rotorwiki.com/index.php/C...d_radiator_cap
Will fix the formatting later.
Oh.. and I already had this one..
http://www.rotorwiki.com/index.php/C...OEM_Thermostat
Thread
Thread Starter
Forum
Replies
Last Post
24seven_dada
3rd Generation Specific (1993-2002)
20
11-10-18 12:03 PM
