Coolant Leak
 

I posted this a good while back but I haven't had any chance to work on the car & it isn't fully diagnosed but I have been given some pointers. Is there a temperature sensor on the back of the engine on a 1.6 miata? I was told there is and that the seal on it commonly fails. My car is not keeping pressure in the coolant system & is allowing coolant to leak out from the back of the engine on the passenger side. If this is the problem, I want to make sure I get or ask for the right part so if anyone can steer me in the right direction there I would really appreciate it. Really need to get this bad boy back on the road so I can take my truck out of service & fix it. Thanks in advance.

Yes, there are two CLT sensors on the back of the head. They are not leaking, but they are right next to the rubber cap which is.

It's the one labelled "cursed water plug":

http://www.rivercityroad.com/garage/...u_sensor_2.jpg

The guys at mazda cursed it for a reason - unfortunately, the last guy who knew that reason mysteriously disappeared in the vicinity of Rider's backyard about a year and a half ago...???

If you want to replace it with another OEM part (guaranteed to start leaking again no later than the year 2029) it's FEA7-13-104: http://www.finishlineperformance.com...cat=319&page=3

Joe...that's the culprit. Once I put the car up in the air I could see it coming out of that very spot. First I will ask if there is any permanent fix this problem and second I would like to request if there is a link to a procedure on how to get to this POS to replace it. That thing is in the worst spot ever & I can't figure out how the heck I'm going to R&R that bad boy without having to pull the engine. Thanks again, guys, your helping a ton!

It's cursed - there isn't an easy way to get to it - every way to get to it is difficult.

I took the transmission out to get to it...but I was also replacing the transmission...
Attachment 190907
Attachment 190908
It just so happened that I decided to replace the rubber bits while I had the opportunity

If you put the stock piece in there, it should last you another 15 years or so... :giggle:

Alternatively, you could tap the hole and put a bolt in there.

Make sure to drain coolant before you get underneath and start prying at that rubber plug!!!

Great. I was afraid that I was going to have to do major surgery just to fix this problem. Why the snickering after saying the OEM part will last 15 years? Is this the line of the bull the manufacturer likes to lay on but it really lasts only about 2 years or so? I really don't feel like dealing with this problem every couple of years.

You should just do a reroute while you are in there.

Mazda would have you believe that it lasts forever.

A new cap will give you 15 years + or - a few. Replace it whenever you do a clutch job.

You might be able to get to it easier by taking the cam sensor off of the back of the head. 2 12mm bolts and it slides out. Make sure you mark the exact position with a paint marker first (by cleaning and then drawing a single line across the joint at two different locations), or else make sure you can adjust it with a timing light when you put it back. The sensor slides out but you will likely have to do some wiggling to get it all the way off and out from between the engine/firewall. The spinny piece only goes back in one way, so you don't have to worry about it going in 180 degrees off. Get a new o-ring for this piece while you have it out - doesn't have to be an OEM part, a NAPA 49 cent special does the job just fine. Put a little bit of oil on the o-ring before you put it back into place so it slides in nice and sexy like. If it doesn't go in all the way, you'll need to twist it a little bit and eventually you'll get it lined up with the camshaft. If all else fails as far as removing/replacing it, removing the valve cover is your next option, and that is not exactly a painful process either. By removing the valve cover, you'll get access to an aluminum cover over the camshaft/sensor joint and you'll be able to lift the sensor straight up instead of back towards the firewall - you'll also be able to directly manipulate the spinny thing with your fingers, so there's no guesswork involved in getting it back in.

Thanks, man. I am tackling this project on Tuesday with a buddy's help. Sounds like coming in from the top & trying to work down to it will be the route of choice. I will let you know how it goes. Any idea what size o-ring so I will have all parts on hand when we start working? Hate having to stop & make parts runs...especially since I don't live near parts places @ all.

lol. mine failed twice, just had to remove the CAS. easy fix.

No idea on o-ring size. When I needed one, I took the CAS to NAPA and said "I need an o-ring for this"

Yeah, no problem...one parts run it is. You've been a great help for sure. My first buddy put a pressure tester on the coolant system & said I had blown the head gasket. Glad I did some further investigation before jumping in and changing that for no reason.

If you would have done that you would have been flamed for you name even more than I'm sure you already have.

Make your girlfriend/kid do it, small hands help a lot, seriously. I spent probably 30 minutes trying to swap the thing on my old car, my girlfriend ended up swapping it for me in 30 seconds.

watts?

Yes, I know. :D

When I did mine, step was was "remove head", although the head was already coming off for unrelated reasons. I've heard that they're pretty easy to reach if you have the transmission out as well, so some folks make it a part of their clutch-job routine. It's one of those things that's just not easy to do, like convincing the judge that the 14-year-old looked 21, or convincing your father that the same 14-year-old looked like a girl (and that it's really his fault anyway for not providing a positive male role-model.)

No, in all seriousness, if you replace it with an OEM part and don't damage it, I would realistically expect the replacement to last for 15 years. That seems to be about the age at which the OEM ones started hitting the tail end of the bathtub curve the first time around.

Which word didn't you understand?

For many reasons I have to say that my screen name was formulated long before the movies and that it was originated on a motorcycle forum so it wouldn't even make sense for me to lie about it. These miatas have nothing on the 137 rwhp 515 lbs Yamaha FZ1 that is my pride and joy. It is super modified & bad ass so this miata is just a fun way for me to enjoy myself when four wheels are necessary. When gas mileage is king, which seems to be the case lately, I will ride my bike because 40 MPG is impossible to come by even with a miata. Anyway, sometimes I need a little room & the bike can't provide that so I would love to get the miata in working order so I can use it in place of the bike when bad weather comes around. Thanks again, my friends, you have been such a great help indeed. Keep the advice coming.

Great idea. My son should be able to get in there once I get some of the parts out of the way. Went ahead & got an o-ring, the cursed water plug, and a valve cover gasket. Tuesday got canceled so maybe tomorrow I can knock this job out. Then I gotta try to get the emissions place to dumb down the Miata Link Engine Management System in order to get it to pass. Then, restore the old settings & get my dang tag. Drive & enjoy. :)

Thanks again for all of your help here, fellas. I changed that thing out on Friday. If you take off the valve cover as described & then remove the CAS it isn't really too hard to get to & swap out. You guys saved me a bundle.