Overheating Issue

I'm running out of options.

I put in a 34" radiator.

I put in a TBSS waterpump with t-stat.

I put Virgils reservoir cap on to make sure my cap wasn't faulty.

Filled it with coolant and ensured there were no air pockets.

The gauge is all over the place. The PLX gauge reads similar to the cluster gauge, so I don't think it's a gauge problem.

Examples of what it's doing:

I can be driving home from work and everything is fine. Temp will be right at 210 or so. This can be on a hot HOT day. Maintains temp. All of the sudden it will spike. 240...250...Then all of the sudden it will drop back to 210ish. That's what makes me think it's the temp sensor.

I just started it up, cranked the AC and let it idle for a few minutes. Checked it and it was fine - right at about 210. Put it in drive to take it around the block and it spiked to about 230 almost immediately. Stopped, revved it a couple of times, and it climbed to about 240 and then kept climbing to 260.

:nutz:

Like I said, about the only thing left I can figure is the coolant temperature sensor. So the plan is to put in Virgil's sensor and see if that fixes it.

Any other ideas?

sorry but sounds like air to me.did you burp it?

belts slipping?and ive had a loose wire on the temp sensor do it also.wiggled it from under the fender never did it again.

When I filled it, I filled it through the drivers side radiator hose. Had the hose from the drivers side head off. Filled it til coolant came out of the head. So if it's air, I'm not sure how to tell or what to do.

Belt isn't slipping.

The wire from the sensor is all in loom, so I think it would be fine. Not saying there's 0 chance it's nicked somewhere along the line...just doesn't seem likely.

Have you tried replacing the tbss t-stat with a new one? If not you might want to I know that was the prob on my dads 454. With same issues.

Well prior to putting the TBSS waterpump and tstat on today, I had a new 160 degree tstat in there. So the chances of both being bad are pretty slim.

Ohh, good point.

guage all over the place is because of Air.. Next ... our trucks hold 2 gallons of water/coolant give or take in a 28" radiator..... so keep that in mind.. if your starting over the first thing i allways do is... pour as much water in the tank as possible.. I know your truck has had an engine swap a few times and such.. does it have the coolant cross over lines on the head?... or are they bolth blocked off?... also there is a small line that runs from that cross over to the radiator about half way up on the passangers side.. make sure thats on there.. that would help bleed air from the heads... next up you have the heater hoses... 210 is a bit much for my taste but whatever you feel is ok in your book.. just not much room for Error.. also there is a bleed from the plastic resivior to the same passanger side of the radiator that must be used... Pour all you can in the tank starting over.. most times just over a gallon... Fire the truck up and Turn on the Heater with blower speed on full blast... and let the truck idle once its running it should tank another 1/2 gallon watching to keep coolant in the bottom of the tank.. I will allways check the heater hose and lines by hand esp if i am having a known problem.. as the system warms you will be able to top it off with engine temps 180-190... heater blowing very well and top hose very warm to the touch... if your look you will see the coolant flowing back into the tank as you top it off... 160 stat and 210 degree temps is not Acceptable... maybe 180s... what type of Fan system do you have? or do you run a stock clutch?... :confused: 210 at idle then goes up as you drive it acts like air flow problem..... best way to the rule out bolth is turn on the heater on HIGH !! if the motor cools off and gets to a normal level its because your cooling fans are NOT doing there job and the blower motor acts as test tool to prove that... I have seen this problem alot of times and the 160 degree stats dont help of the fans come on at 185... the water is flowing to fast and never has enough time to cool in the radiator...

Did you put in a new water pump? I never ever use a used water pump. I had a TA and a Caprice that both had water pump replacements that were from Vatozone and in months both pumps started overheating. I got frustrated and sold both cars. The guy that bought the first one a day later told me I had bad waterpump. Same thing on the caprice. Also once the seals are wet with water and antifreeze and then dry out they will die.

Sounds like air to me. These engines are very easy to trap air in the cooling system. See if you can borrow vacuum fill machine or beg a dealer buddy for a vacuum fill. I see this all the time when someone has a F*** dealer or something do a cooling system repair on one of these and then gets an overheating condition and fluctuating gauge.

If you have driven more than once it should have leveled off by now showing low level but it is possible the trapped air never came to the top.

Does it have a functional level sensor?

Does the low coolant message ever come on?

What type of fan controls do you have?

If they operate by temp, feel of the air coming off them when the gauge shows 240+ and see if the air is hot. If it is, it's likely that you are actually overheating and the gauge is correct. If the air off the fans is cool, there's lots of air in the system or the tstat is stuck.

Now the bad possibility. I'd go to AutoZone etc. and buy a block tester to ensure you haven't lifted a head or popped a head gasket.