Afternoon all....I am new to the forum, but have been reading this forum for some time now. I purchased a 85 f150 - 5.0 (2 whl drive) and really enjoy the truck. The engine locked up on me a couple months ago and we replaced it with a 87 f150 block which we found used for $175 from a friend. By the way the engine did turn over this we knew before we bought it. To make a long story short we dropped the engine hooked it all up and it started right up. It was a great! Well after let some tuning up and running the truck we have discovered a one issue. The engine is over heating or running hot.

What we have done...
1) Replaced the thermostat
2) Replaced the water pump
3) Took the water pump off and ran wanter via a hose into the block to make sure it came out the other side. Also did this with air. Both of which worked.
4) Check all the gaskets
5) Checked the temp gauge.......
6) Pressure tested the engine for leaks. Which worked out fine.
6) Bought the book about the truck and did all the reading on the cooling system
7) Checked the heater core
8) The radiator seems to look very new and it worked perfectly with the old engine.

The team I have working on the trunk is my brother a mechanic by trade, a friend who is an mechanical engineer, another friend who is very hand with motorcycles and boats.....then myself (I am bascially the researcher and still learning). Basically a pretty solid crew....

I even had a local shop look at the truck and they said it was fine. Which turned out not to be true.....

Would you guys have any idea of what we should try next??? Or have you have had an issue like this one in the past. I am sure it's something so obvious and we might just be over thinking the issue.

Many thanks!

 

Take out the thermostat and run it without one. See if it still overheats. If it does, maybe either a head gasket or an old clogged radiator

 

You have 2 choices of how to fix it; either way will be time-consuming & probably expensive.

1) Remove the timing cover & install the '85-86 5.0L EFI timing cover & water pump.

2) Remove ALL the pullies, belts, accessories, & their brackets & convert to the serpentine ('87-up) belt system.

Your '87 water pump is spinning backward because you're using an '85 V-belt. So is your fan.

 

It actually can b/c no thermostat could let the water flow too quickly and not pick up enough heat to take to the rad.

Welcome to the forum bigT, like steve said, what combo of parts did you end up using?

Adrianspeeder

 

One thing you dont mention is airflow through the rad. Is it overheating while moving or standing still...or both.

Fan clutch maybe.. if it has one,.. or blocked rad as previously mentioned

 

On older vehicles (car or truck) the radiators can get clogged. I almost always replace the radiator with larger one. One with more cores. If you take out the thermostat and are getting good flow thru the block and it still overheats, then you might want to consider replacing it.

 

a dealor said air bubbles get trapped in the engine i was gonna replace all kinds of parts for nothing my f150 4.6L GOT HOT every 5 miles it was getting up to hot id pull over cool it and go 5 more miles late at night 1000 miles from home i was not gonna trust those shaddy machanics telling me it was this or that nobody gave me stait talk no leaks nothing obvios i changed the thermostat still hot then i read about a guy who replaces everything and it still got hot he had air bubbles just sqeeze the top hose run it 2ooo rpm in park heater on repeat my truck hasnt got hot in a week go figure,, air bubbles

 

Dude, this thread has been dead for over 4 years.

 

Huh? What? Mumified a long time ago.

 

thank you for your way late post. My ex has had the same problem with his 87 f150 truck and because of that way late post it saved me a lot of time and him a lot of money. who would've thunk it, air bubbles! lol ty!!

sincerely,
Fee

 

ty crazysnake!!