mjr46

when does it overheat?? sitting still at idle or at cruise down the road?? after replacing t-stat you did bleed cooling system/purge of all air by running it with heat on until heat was good and hot right??

1mustang

it does it at idle and after a 15-20 min ride...and yes i bled the system

mjr46

so no overheat while cruising down the road right?? just after a drive and sitting still?? if so make sure condensor in front of radiator and radiator fins are all free of any dirt/ debris and it most likely in such instances is a bad clutch fan..= replace an restest and cheap insurance is a new radiator cap also

1mustang

it did do it once going down the road...what concerns me is a lack of fluid...or i cant feel the fluid going threw the top hose as well as seeing no cerculation in the radiator

thunderjet429

i say it's a fan clutch... also a bad fan clutch can cause a water pump to fail... i would replace both.

1mustang

ok...im really confused about the whole fan clutch thing....ive checked for loosness and there is none..it seems to work as it should

mustang86cars

Sorry I missed your message, just got back online. I also noticed that you have undersized pulleys, I've heard this can be an issue. Also, you could have a air pocket in the system, this will prevent the fluid from flowing. I would stick to the basics, I would start with a flush and refill.

1mustang

hey mustang 86...no underdrive pullies...that was on my 91...i bled or burped the system....no air pockets...leaning towards water pump now...as there is no flow that i can see and i dont feel any rushing threw the upper hose when its running

mjr46

^^^^^you can't feel it rush through the hose only a temp change[&:]..make sure t-stat is in correctly and operational...if for some reason t-stat won't open = no flow occurs ..don't assume cause a part is new it works.....I have 10 + cases to prove such assumption wrong

brentloftis

I would like to add my 2 cents as well.

Belt tension and condition is aitemto check but from the sounds you probably already checked.
I hate clutch fans,fan blade does not spin at the same rate as pully unlessthe by bi-metalexpands with heatbringing it toclose to 1 to 1. One way to "check" it although I don't know if it is accurate is see how freely you can spin it by hand after the engine has run hot. (ENGINE OFF OF COURSE)It should not spin veryeasy. May want to invest in a flex fan.

Other points, and I know I have done this before, are you sure you installed the tstat correctly?..... as in not backwards. If you are worried about flow and not seeing the swirl, pull the tstat out and bolt back up the housing with the tstat out, start the engine and look in therad. You will see flow now, hopefully......Witht he tstat out let it run for a while, past the 15 - 20min mark to seeif it is overheating.... if so the issue is somewhere else, if notreplace tstat. Also if the new tstat does not have a air hole already in it, drill one, it helps.