Is it true that this stat doesn't work for our cars. Sound odd to me, but I have put two in and it keeps over heating. I've replaced the stat before, not sure what stat I used at the time. Thanks for any input.

Sounds like you've proven it doesnt work.. unless you've got a busted headgasket.

choose your poison

I'd say the same. Whats the mileage on the water pump? Are you bleeding the air really well/properly?
Nice to see you around again, back for your 6 month check-in? lol... ;)

Thanks Icarus, I put the first stat in and it didn't work. So I went back to O'Reillys to get another one, same problem. I got on here and in the search results, I found the guy that stated the Murray 4089 doesn't work. I went to Advanced Auto and got a Stant 14089. It even looks totally different. I'll reinstall it in the morning and post the results.

welcome back kc!!! see ya in a year or so lol

welcome back kc!!! see ya in a year or so lol

lol! I feel the love!

i remembered you painted your car than a few other posts here and there but that seems like it

You need to come around more!!

Not to get heavy, but I went through stage 4 throat Cancer 5 1/2 years ago. In the last 6 months I haven't been feeling good. It got so bad I thought I was losing my mind. It was like having a constant panic attack. My Adrenalin was pumping 100 miles an hour. They figured out it was my thyroid. Normal Thyroid readings should be between 0.40 and 4.50 Mine was 40.56. We got that taken care of finally and now I'm have issues on the opposite side of my throat that's making it hard to swallow and painful. So I'm pretty concerned that it (Cancer) might be back. I don't want sympathy. I've been blessed with a great life already. All I can say is really try and enjoy every day you get. When i was first diagnosed 5 1/2 years ago all of my friends felt sorry for me and as of today I have lost to of them and I'm still here. You never know what tomorrow will bring. Again, be thankful for everyday you get!

Anyway, enough of that crap. As for the thermostat I put the new one in and it looks like that was the problem. We need to make sure everyone knows about this so they don't go through the trouble it made. The Murray 4089 Definitely doesn't work. I will try to be on here a little more. I haven't even been on the computer for the last 2 months at all. Looking this up was the first time I actually got on and of course it was a great help.

Why not just put in an OEM one??

First of all, it my be difficult for someone to get to a dealership. On the other hand it just my be easier or closer to get on from a auto parts store. I would bet that the majority of people buy their replacement parts from an auto parts store. This is really just to hopefully help someone from having to go through the same problem. I'm sure that as in my situation, it was more convenient to just run down to the local auto parts store. I called around and found out that O'Rilley's was the only place that carried the Murray brand around Kansas City.

If you notice, there are many threads on here about people who replaced their thermostats and the car was still over heating. I've read many threads myself the last couple days. If I hadn't read that one thread pointing this out, I still would be racking my brain trying to figure out what was going on. I'm going to post a few threads with title's relating to this so it may be easier for people to learn about this information.

Oreily's carries Motorcraft parts...

Oreily's carries Motorcraft parts...

I'm not sure what your point is, but that's (O'Reilly's) where I bought the Murray thermostat. They said that is the only stat they had for the Mark VIII.

My point is that the OEM unit works very well... so if it available it is a very good choice...

I'm not sure what your point is.

his point is.. the OEM works..there are often issues with aftermarket crap.

I use a stant 13396 which is a 160 thermostat

by and large I try to stick with tried and true OEM parts, to prevent BS issues.

I see KK's point...

You can also try asking for a mustang t-stat to see if a wider selection is available. I forget what years are the same but many 4.6 t-stats are the same. maybe a little different temp.

^ +1
the stant thermostat I mentioned above, the listing in the stant catalog says.

4.6- all except dohc

but I can assure you it fits and works.. I put over 200K on my car with that thermostat.
Tiff runs one in her car as well...

i run a hyptertech motorad 160 degree in mine, runs nice and cool and had no problems with it, you can get them from summitracing.com

Thats the same one I use Lux. The temps are the same as with a stock T-stat when in trafiic or idleing. The damn fans don't come on until like 214-216 Last time I data logged.

I'm putting my 160 in when I pull my car out in the spring lol... :q:q:q:qing winter...

My shop manual states that the stock units are supposed to start opening at 183-190 degrees and be fully open by 210 degrees.

Thats the same one I use Lux. The temps are the same as with a stock T-stat when in trafiic or idleing. The damn fans don't come on until like 214-216 Last time I data logged.

ive noticed that with mine as well, once i start beating on it or sit in traffic, the temp goes up. stupid sniper tuning program doesnt control the fan either, suppose to, but it doesnt. i'm going to be selling it and buy sct.

Yeah I had the same problem with the Murray t-stat. Went back and got a Motocraft one and the problem was fixed.

KC has one of the sweetest marks I have ever seen in person. And it is a daily driver not a garage baby, I see him all over town.:cool:

Wished I had read this yesterday. Just replace my waterpump and still tring to figuar out why its still overheating after working hard to get the air out.

I always order mine from Max and get the ones for the Lightning ...

Well, got the new Stant T-stat in and looks like were in business. I guess there is something to the Murry not working. It's running hotter than it used to, but it cools down when you go down the road, so that is a major improvement. It seems to hold at half way when its idling and at 1/3 when driving. Its kind of hard to tell what normal is supposed to be because my old one was stuck open until recently where it started going back and forth. It rarely got past a quarter. If I ever put another in, I'll get a Motorcraft and probably drop it a few degrees, although, 160 seems a little too low. I had a 72 Ranchero 351c and I put a 160 in because I read in a book it was the thing to do horsepowerwise. But after years of not ever getting warm enough to heat the car, my brother finally changed it and it gets warm now in the winter and it actually drives better when its cold out. Quite refreshing. Anyways, what temp does the lightning open.