What are your coolant temps?

[Armada]

They come on when it's too late.

 

[motormayhem]

They come on when it's too late.

That seems pointless. "Just in case you wanted to know...your engine is now crap"

 

[Armada]

Exactly. That's why they're called 'idiot lights'.

 

[motormayhem]

Mine is now doing the same thing!!! Small trailer = 210* normal driving and it is running 190-200 with a 180 stat. Radiator was just done by a shop, new water pump, t stat is 3 months old, new fan clutch. 90* outside

WTF?

 

[Barrman]

A clogged radiator won't move coolant through it. A good way to check is to get the truck warmed up and them use an infrared thermometer to follow each coolant pipe across the radiator. Constant temperature from end to end will mean it is flowing. Hot spots and especially cool spots mean nothing is flowing. Of course, the temps should be hotter at the top and cooler at the bottom too.

 

[JAsher45]

I have had this on my own engine. after i replaced the heads with some newer 6.5 cylinder heads I hooked a temp guage in the head and one in the cross over. the temps in the cross over where 10-15 degrees higher then in the head. so all in all i just went with the one on the cross over and marked my high level temp according on that guage at 225, that is where the cylinder head was at 215. there was a something in PM magazine a year or two ago about the 6.5's being safe to operate under normal conditions upto 230 degrees do to the heat in middle east.

 

[motormayhem]

Going back to the original question what did you do to fix it?