How To:Thermostat

[torq]

A little bit of a tangent but all the thermostat fun is happening in this thread. Looking to put an AEM water temp gauge in as I hate my gen2 not having anything to tell me how hot I'm running without my AP plugged in.

All the threads I see have people installing the sender on the upper rad hose, is this really the best place to put it? (Without drilling into the engine).

I looked in the shop manual but it's not straightforward as to the coolant path.

Thanks

[a4tek]

very helpful i just did mine like they said not hard just a PITA

[roadkill88]

By any chance does anyone know a torque spec on the 3 housing bolts of the thermostat?
I got mine swapped without having to move the power steering pump.. No biggie lol

[Raider]

"Tight" is what we did. Because no torque wrench for inch pounds.

[Dizzy Turbo]

Prolly around 71 in/lb

[Vitamin M]

I did this the other day I just wanted to add that if you have long fingers and the right extensions you don't need to remove anything else. You can access all 3 bolts from the top. It tool me about 2 hours because I had a problem with the coolant line getting air in.

[Vansquish]

Originally Posted by Vitamin M I did this the other day I just wanted to add that if you have long fingers and the right extensions you don't need to remove anything else. You can access all 3 bolts from the top. It tool me about 2 hours because I had a problem with the coolant line getting air in.

I covered this in my write-up on earlier in this thread.

[Bujwazay]

Just did this today, thanks for the write up....what a PITA!!!! The bitch fought me the whole way today, but it seems better now. I think my thermostat was stuck closed...high coolant temps (210*-225*) and the fans running a lot. Swapped out the thermostat and flushed/filled with new coolant. Cruising temps are 185*-190 now and don't shoot up at idle.

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[Frequentflyer]

When I did mine I was able to disconnect the lines and pull everything out from underneath the car. IMO, it's easier than trying to get everything out from up top.

[stockms3]

Originally Posted by kidrabbit84 Correct T-Stat on top and wrong on bottom: Attachment 145234

I have bought this thermostat and ECT sensor from NAPA. ECT sensor is OEM and has FoMoCo stamped on it and they did have the correct thermostat.

Edit: Price for thermostat was about $30+ and ECT sensor was $28 if I'm not mistaken.

[Design]

The serpentine belt is definitely a PITT if replacing with a new one. The trick is rotating the crank pulley to ensure it mates along the groves. A new OEM Mazda belt is so damn tight to slip over the pulleys - even with the tensioner fully rotated.

This video has been shared before but appropriate for this thread. Talks about reinstallation around the 3:00 mark:
https://www.youtube.com/watch?v=4SWVlbyfCmg

[G1sdaname]

After changing thermostat I'm getting idling temps of 214-219. When I first started the car the thermostat didn't do a thing till the temperature got up to 229 this is when the fan also turned on, anyone else seeing this? 80* outside temperature. Running at 201-205 around town which is not much different than what I was getting before.

[Lex2007]

[Cheapspeed]

I'm going to second, that it's a royal pain in the ass, IF your hoses are as old as mine. They were cooked onto the thermostat real good. I used one of those flexible hose clamp pliers but still had a tough time.

I had all my hoses folded and twisted and ended up pulling the thermostat out of the bottom with both hoses still attached. Everything went back together in about 10 minutes though. Saved some dough, but wasted about 2 1/2 hours of my life and my fingers and arms are tore up.

[G1sdaname]

Turns out my thermostats was fine, the running temperature for the aftermarket Thermostat is something around 200-214...


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[Lex2007]

Originally Posted by Cheapspeed .... but wasted about 2 1/2 hours of my life and my fingers and arms are tore up.

DONT SAY THAT! Its not wasted time bro. Its how you learn and gain confidence in basic car repair and better yet, as to how your car works.

[Cheapspeed]

Originally Posted by Lex2007 DONT SAY THAT! Its not wasted time bro. Its how you learn and gain confidence in basic car repair and better yet, as to how your car works.

I already know my car is a bitch to work on. 143k and it spent a few years in the north, haha.

[Lex2007]

Originally Posted by Cheapspeed I already know my car is a bitch to work on. 143k and it spent a few years in the north, haha.

Well listen here MR.! I just dont like your attitude.

[dustinarden]

Used this thread to help me change out my thermostat today in my speed6.

Jesus - its not a hard job in theory, but the cramped ass space makes it a royal PITA.

The bottom fat hose was baked onto the connector it clamps to. I had to snake a small ass screwdriver around the hose and then muscle the shit out of it to break it free. I thought the 3 bolts were going to be real hard, but they were actually the easiest part.

The hardest part was the clamps on the hoses at the thermostat. I couldnt get them both back on there as one would get in the way of the other. Ended up replacing the smaller hose spring clamp with a screw tightened one.

The odd part was i dont think all the coolant made it out. I only put about 1.25 gallons back in the radiator even after burping the hose. I havent really ran it around the block yet either though .. figure i'll put a few miles on her tomorrow and double check levels.

All thats left to do now is spark plugs, clean intake valves and install the oil catch can kit I bought. Oh and the CP-e RMM, but I think i'm going to get a shop to do that. Next weekend to do all that and then give it a good wash and wax before it gets too cold.

[Cheapspeed]

Originally Posted by dustinarden Used this thread to help me change out my thermostat today in my speed6. Jesus - its not a hard job in theory, but the cramped ass space makes it a royal PITA. The bottom fat hose was baked onto the connector it clamps to. I had to snake a small ass screwdriver around the hose and then muscle the shit out of it to break it free. I thought the 3 bolts were going to be real hard, but they were actually the easiest part. The hardest part was the clamps on the hoses at the thermostat. I couldnt get them both back on there as one would get in the way of the other. Ended up replacing the smaller hose spring clamp with a screw tightened one. The odd part was i dont think all the coolant made it out. I only put about 1.25 gallons back in the radiator even after burping the hose. I havent really ran it around the block yet either though .. figure i'll put a few miles on her tomorrow and double check levels. All thats left to do now is spark plugs, clean intake valves and install the oil catch can kit I bought. Oh and the CP-e RMM, but I think i'm going to get a shop to do that. Next weekend to do all that and then give it a good wash and wax before it gets too cold.

Wut. Changing your thermostat is harder than an RMM by FAR.

Anyway, to stay relevant to topic. I gained 3 mpg's on E25. I was averaging 19mpg (on trip not hand calculated) in this cooler weather but I'm up to 21mpg now. I'm sad thinking of all the gas I was pissing away the past 2 years.

[dustinarden]

something about doing the RMM freaks me out ... not sure what. If it easier than the tstat I guess i should give it a go.

[Cheapspeed]

Originally Posted by dustinarden something about doing the RMM freaks me out ... not sure what. If it easier than the tstat I guess i should give it a go.

The motor is still being held by two other mounts. I did mine with minimal tools in an apartment parking lot.

[dustinarden]

Interesting.

[Lex2007]

Originally Posted by dustinarden Used this thread to help me change out my thermostat today in my speed6. The odd part was i don't think all the coolant made it out. I only put about 1.25 gallons back in the radiator even after burping the hose. I haven't really ran it around the block yet either though .. figure i'll put a few miles on her tomorrow and double check levels. .

It never all drains out. That's why a true flush consists of multiple drain/refills.

[dustinarden]

yeah. I kind of want to get on of those flush hose adapter kits from the parts store. Hook it up to the garden hose and just let it run for a while, but i dont want antifreeze sparying out all over my driveway / lawn.

[Lex2007]

The problem with that is that you "contaminate" your cooling system with tap water which may be mineral rich. And yes the mess of coolant going into the ground and stormsewer and possibly poisoning your pets.

Its better to drain, then use distilled water, run it. cool it. Repeat with distilled. cool, drain, add pure coolant then distilled to correct ratio.

[Prallell6]

Followed Vansquish's step-by-step on page 1 for my 6 this past Wednesday and went fairly smooth minus the chunk of thumb I'm missing from trying to bust a hose clamp loose. About 2 hours total from system drain to refill.

All I needed to get that thermostat out was a 1/4" Drive Ratchet, 6" extension bar, 8mm standard socket, needle nose pliers and some of Minnesota's finest.

[MortalMechanica]

Ms3 here. Followed @Vansquish; 's guide to doing this without removing the power steering pump. It's a pain if you have larger hands but I am blessed with normal non titan hands.

I did have some trouble with the hoses though, strongly suggest that you pick up a set of picks from Harbor Freight, or any kind of coolant pick with enough reach to get up and into the thermostat hoses. I would not have been able to do this job without them.

Also make sure (if it wasn't obvious) that you remove the original gasket from the block. The old one seized onto mine so I had to gently scrape it off. Cleaned the rest off with a plastic scraper.

Done and done, Let's hope that p0126 doesn't come back.

[G1sdaname]

I done it twice now without removing the PSP, it's much easier to do if you buy a hose click remover. I'm in GA if you need to borrow it!


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[Jdab]

Just did the thermostat tonight, solved my lower than normal temp issues. I HIGHLY suggest just pulling the PSP, if you have a second pair of hands to help you out especially. Takes an extra 5 minutes, lowers stress level significantly. My hoses were also cooked on, used some Harbor Freight picks to remove them; be prepared for extra coolant coming out of the top hose and the thermostat when you finally remove it.

[noobinacan]

thanks for the write up.
took me a while...ended up removing part of the belt and moving power steering assembly out of the way.
Don't let the belt drop in the bay...

Looks like the OEM one from factory has some plastic pieces by the new one has metal.
Also stuff that helped was

1) small vice grips
2) flex head type ratchet wrench
3) wish I had one of those small thumb drive ratchet.

[brand0llaz]

high way cruising or just driving, I sit around 174, in traffic, 200+ should i replace it? No codes.

[MortalMechanica]

Originally Posted by brand0llaz high way cruising or just driving, I sit around 174, in traffic, 200+ should i replace it? No codes.

Hmm I usually sit at over 180. Closer to 190 on 50*F weather days. Sitting in traffic I'll see the temps rise to 210 give or take a couple of degrees.

I've been told that the OEM thermostat likes to slowly edge colder as it starts to fail and give you a p0126.

Honestly, if you don't have a CEL for it, I don't see why you should. Have you been servicing your cooling system regularly?

[brand0llaz]

Originally Posted by MortalMechanica Hmm I usually sit at over 180. Closer to 190 on 50*F weather days. Sitting in traffic I'll see the temps rise to 210 give or take a couple of degrees. I've been told that the OEM thermostat likes to slowly edge colder as it starts to fail and give you a p0126. Honestly, if you don't have a CEL for it, I don't see why you should. Have you been servicing your cooling system regularly?

Flushed it pretty much twice the last six months lol, was gonna get one from oreily but since u said it would be fine. Ill change it if it ever goes under 169. Hopefully its not going to ruin the engine while sitting at 171-174

[noobinacan]

get one of them ODB2 bluetooth readers. and get the app for your phone
then watch it.
after replacing high cruising at 3k, I am at 200.

When thermostat was bad, It was on the colder side of things..

[brand0llaz]

I got the ap

[furinax]

Just did this job this weekend. Yes, it is a PITA. I would say 5/10 difficulty but in retrospect it wasn't really that hard.... just cramped spaces and stuck hoses.

A few notes though.... 14mm wrench did not fit my tensioner pulley's hex head. I needed to use an adjustable wrench because I had nothing between a 14mm and 17mm at the time. I just jammed a screwdriver into the end of the wrench and stuck it into the chassis to prevent it from tightening again.

Each time you remove a hose, the thermostat, drain the coolant... expect the coolant to wildly splash everywhere. Have a pan beneath the car whenever something that holds coolant is removed.

Start to finish time for me was 3.5 hrs about. If I could pay someone $100 to do it I would though.... but it is nice to have the experience.

[brand0llaz]

It took u 3 hrs? Holy shit, first time took me 30 mins lol

[Lex2007]

No doubt bro. The worst part of any cooling system job is the mess from the coolant and disposal. Especially if you do it right and flush multiple times.

[RalliartRsX]

Just did this on the MS6.

Word of advice: Unbolt the 3 bolts necessary to dismount the PS pump and allow you to slide it to fender well (all hydraulics should NOT be removed mind you. There is enough length to allow this). You don't even have to completely remove the top bolt from the housing. Takes me about 3 mins to do it and worth the extra effort in the end. Spring clips were nary an issue (use of locking pliers made the job much much easier of course).

EDIT: In addition, when tightening or removing the lower bolt for the PS pump, do not lean too much on the PS reservoir. It is only held in by a rubber grommet and any movement WILL cause a leak from that port. It does not take much to pull the reservoir away from the pump, so keep that in mind.

Job took me about 1.5 hours start to finish. This included the 5 mins it took to get the serpentine belt on by myself and drain the coolant and having to walk back to my house for the part (took about 10 mins). The key to this (like any other mechanical work): Have the correct tools. Simple.

Bought a genuine Mazda part. No sense in saving $20 on a potential incorrect part or incorrect casting, etc. The part was $5x from my local dealer. Didn't even bother searching online for an aftermarket as the price point was so cheap. The coolant and drain pan cost me more........

Difficult: 2/10.

Thanks for the writeup folks!