my friend truck keeps overheating new thermostat new water pump.
his father thinks its a pinhole in freeze plug

 

ok lets start with the basics...
year and kind of truck it is...

what motor is in it?

 

is his coolant system being over pressurized if so it could be a blown head gasket

 

almost forgot, maybe a bad water pump

 

no symtoms of blow head gasket
1999 jeep cherokee sport
he thinks its a freeze plug could that be it

 

Need way more info. Year, engine size, etc......

Or I could say.......... low coolant level. See what I mean?

 

4.0 motor everything else is in post before

 

Do a compression test for starters... are there any visable leaks? is it smoking?

 

not that he told me
and he dont no how to do a compression test neither did i never had to do 1

 

What kind of radiator, and last time it was serviced/rodded out?

Color of the fluid?

As Rooster asked....any steam out the tailpipe?

Any oil in the coolant or coolant in the oil? Have your friend join here. It will take less time, rather than going thru a middle man.

 

i belive its a stock radiator

 

no steam out tailpipe

 

Cracked head? Plugged radiator?
I just changed my radiator, pulled the end off the old one to find the bottom 1/4 was plugged up.

 

does his dad know how to do a compression test? and if no one knows how to do it... its time to learn

 

has he ever used any of that stop leak crap, maybe it has clogged up some if the coolant channels running threw the block itself. sorry about the water pump post i didnt see that till after i posted