So far i was able to do everything by myself on my truck. But this time, i have to ask for help. I have 2001, 3.5L montero and few month ago my temp gage started to go to max. I assumed it's the gage or sensor, since engine did not seem to be dengerously hot, and because of weired bahaviour of gage arm. Temp would be in it's med position and then within 5 s it would go up to max, and sometives go up and down and you could see it moving. usually yo don't see sucha a sudden changes. After a while i had some small leaks on my hoses (that extra loop from heating core that loops down on the side of tranny) and it did appear as pressure build up. But then in my coolant reservoir i realized dark brown mud. (my local mechanic said it's normal it's sand form casting core just got loose and washed after few years?!) i washed it , put fresh coolant and after a week same thing. So i replaced the thermostat, did not help, i put that rad flush stuff since it seems like there is some hot spot in the system that does not circulate the fluid. i did not help either. i disconected some hoses, and tryied to flush it wiht hose, and same problem. I checked the temp sender unit works fine.
Is there anything else? could that be water pump? (but no leaks and no noises) would proffesional rad flush be much better?
any help appreciated

Thanks
Tomek

 

W/ the right equipment you should be able to tell exactly what the engine temp is. Any shop should have this. If you want your local parts place may have it available for you to use.

Also, what I've been told is if you're low on coolant, the up down gauge behavior is normal because you will have pockets of steam that are much hotter than your coolant and that's why you get the temp spike's.

IIRC, muddy coolant means oil contamination but my memory's never been super accurate. Regardless I would think that the casting sand theory is not normal on a 5 year old vehicle. I would expect sand from the casting to be gone a long time ago since you should have flushed your cooling system numerous times by now.

 

yes you right air pockets most definatelly could cause that, but i tried to bleed the system using 2 screws in the thermostat area, and it seems like never ending process; do i fill fluid, let engin run, let it expand for few minutes, let the air escape, tighten and it should be ok? Or should it be repeated it like 10 times? does anybody has proper bleeding procedure? i am looking to get original mitsu repair manual, but maybe somebody has it handy?

thanks

Tomek

 

According to the info at alldatadiy.com, the bleeder screws must be opened during filling process. The water will come out there first befor overfilling the radiator. I just did a h2o pump change, and no air entrapment.