A few months ago I was losing coolant and constant temperature fluctuation. Very noticeable when pulling a trailer, temp needle rode 1/4'' or more over half when going up hills. So I pulled my head off and had it planed down by the local machine shop. He told me he found warpage in the head above cylinders 3 and 4. I put the engine back together with ofcourse a new gasket and ARP head studs. I am now no longer losing coolant but the temperature fluctuation keeps on. when im pulling it gets hot and when im goin easy it goes back down to half (190F). Any ideas? im kinda stumped. thanks.

 

is your radiator clean?

the puke bottles on these things are notorious for making a huge mess all over the radiator

puke bottle = pill bottle on the end of the PCV hose attached to the front timing cover...

they are supposed to be emptied every oil change, but nobody ever does it. I took the thing off and ran a long hose from the pcv down to the front axle.

radiator ends up getting caked up in oil and dirt as the cooling fan slings all of that oil mist from the PCV around and makes a huge mess...that mess ends up blocking a lot of the radiator.

thermostat can be another possibility. if the tstat isn't opening and closing fast enough it can cause some pretty steep temp changes.

I would check your radiator first...if it is nasty, then go to one of those do it yourself car washes with the pressure washers and go when they aren't busy or really paying attention...

set the pressure washer to tire and wheel mode, and pressure wash the outside of the radiator under the hood...

tire/wheel mode = simple green mixed in with the water.

they kinda frown on degreasing your engine these days, so try not to get caught doing it, or just play dumb and act like you didn't know

bout the best way to clean it short of replacing it.

also make sure your overflow bottle is filled to the proper level and your radiator cap seal is not messed up.

 

I don't know how common this is, but I recently found that one side of my thermostat was broken causing temperature fluctuations,

 

Yea I replaced my thermostat also so I'm sure that's not the problem but I do not have a blow by bottle on my truck so it does have a leaky oil mess. So that is good advice spraying out that rad. Will do thanks jigabop!

 

ECT's are going to rise on a prolonged grade with heavy weight and higher ambient temperatures, especially with those 150 HP sticks and a stock turbo. You don't have enough air to keep egt's down which in turn makes ECT rise.

 

Ok that is a good point and it has crossed my mind but I've had these injectors in for 1 year and the temp gauge was always on half. Never fluctuated until a couple months ago