Temperature delima ..

[grillen85]

OK here is the deal , some of you may have seen/read my tstat thread.
Well anyways the tstat an gaskets are new , the truck when putting water back in it the guage did not go crazy at all while sitting and running an letting the new tstat cycle to add water and what not ..

Well tonight is the first night I have driven it SINCE putting the new tstat in , well needless to say I get about half way to where I was going my my temp guage in the truck starts jumping around all crazy agian ..

180* - 240* - 180* - 240* - 180* - 240*
(mind you it is factory guage an these are estimates.)

But the weird thing is , it only jumps for like MAYBE 5 - 10 second and its back down to normal agian , like steady going up and down up and down like in SECONDS... Like if the truck was really running this hot I would think it wouldnt jump and down like this ..

needless to say , I do not think the truck is running warm .. it has no symptoms of running warm , its not making any bubbling noises and I can hold my hand on the radiator for 10-20 seconds without feeling like I am getting burnt. Like if it was really running that hot I doubt I would be able to touch the radiator or the rad. hoses .



Anyways , does anyone else have any suggestions ?

I am now leaning towards the temp. sensor being bad.

[lesterl]

Temp Sensor in the back of the head on drivers side. The one in the Tstat neck is for the ECM.

[grillen85]

OK cool , thanks !

[grillen85]

Hrmmmmm..... ok so ...

Today I decided to mess with it again an well I just let it idle in my drive way an the temp. does climb to like 220-230 for a few second (30 or so) an then it drops BACK down to 180* it will stay around there for awhile an go back up to 200-230 for a few seconds and then drop back down again..

Yet I can still hold onto the rad. and the rad hose after it has been running an also the overflow is not bubbling.

Still sound like the sensor to you guys ? The waterpump isnt leaking out the Pee Hole , like 99% of the WPs that I have replaced have been right before the took a complete dump ..


TIA ,
Eddie

[bansheeair]

Sounds like the temp sensor on the back of the head to me. Sending out pulses.

[Shaddix]

99% of bad waterpumps do melt/corrode the core plug and they start to weep out and leak. I however, have heard of pump impellers on the inside being the cause of a pump going bad and not leaking outside the block at all, just spinning nothing.

Being that it is so rapid, ,maybe yah got an air bubble in the coolant system, or that your gauge is just flat out lying =)

[grillen85]

See that is the thing with the pump not pee'ing that was odd to me , an like if the truck WERE running that hot I would think the overflow resi. would be bubbling NO ?


I also thought possible air bubble , but the truck started doing it after 2 yrs of me owning it , so that kinda ruled it out for me .. No ? I am going to replace the sensor and see what happens.

[wi11ie]

I have had impellers on the pump on my duke rust the hell off even in a clean system and not push shit thru the radiator...
Just a note..

[grillen85]

Well a little up ...

New temp switch (back of head),T stat, Water pump ...

an the guage is still going crazy , I do not think the truck is over heating..
But this guage is about to drive me up the wall..

Any Idea's ???

[Shaddix]

Quote: Originally Posted by grillen85

Well a little up ...

New temp switch (back of head),T stat, Water pump ...

an the guage is still going crazy , I do not think the truck is over heating..
But this guage is about to drive me up the wall..

Any Idea's ???

If you have absolutly a 100% working cooling system, then I would assume you have a wiring problem. Probably grounding out on something or pinched.

When you fill your cooling system up, do you run the engine until it gets the thermostat to open with the radiator cap off? If not, then you may have a large air bubble in the coolant neck. Make sure its all the way warmed up to 180 and then put the cap on.

[lesterl]

Try another Tstat, switch brands, OEM is good.

[grillen85]

Quote: Originally Posted by Shaddix

If you have absolutly a 100% working cooling system, then I would assume you have a wiring problem. Probably grounding out on something or pinched.

When you fill your cooling system up, do you run the engine until it gets the thermostat to open with the radiator cap off? If not, then you may have a large air bubble in the coolant neck. Make sure its all the way warmed up to 180 and then put the cap on.

Yes , I ran the truck for a good 30 mins at idle after getting everything back together to let the coolant cycle through out the engine. I was also thinking an air bubble .. I drove the truck to a show this past saturday and the temp guage was going up and down like explained , But the truck did not seem to be overheating in any way ..

I am going to put an aftermarket mechanical gauge in it just to make sure.

[Blkwdw86]

I suspect the gauge, particularly if 240 is it's limit. If it was a shorted wire, the gauge would jump from 180 to zero, not 240. Check the voltage from the coolant sensor AT the back of the gauge assembly connector with the engine running/vibrating for consistency. If the voltage holds steady (as I suspect), the gauge is fubar'd, get another one or have it rebuilt.

[grillen85]

Eff my truck ...

New Water pump , Tstat , all gaskets + now after market gauge ..

And there is def. something going on with the temperature. Like at idle it will go to about 190* give or take an you can see when the tstat opens(temp drop).BUT when you're doing anything BESIDES idling sometimes it goes to 190* sometime it goes to 230* ......

I has me pretty much stumped as to what could be wrong now .. I am going to try and take the tstat out and see what it does.. An if that fixes the problem I will get another one , from napa.
If that doesnt work maybe try a chemical rad. flush. just for piece of mind.

[grillen85]

Any idea's ?

[firstgenon24s]

Bump 4 u

[lesterl]

Dont really need to bump in this forum, like 5 posts a day....

Have you checked flow through the radiator, Tried a new thermostat of another brand AC is a good one.

[Steady Eddie]

Ok, going back to your original issue...temperature reading jumping.

And jumping FAST, like within 30 seconds...

My 2 cents: Given the volume of coolant, this seems a physical impossibility...the gauge is junk..

Then, you put on a mechanical gauge, and THAT gauge jumps too (?)...where is the sender located??

Remove the t-stat and check it's operation, on a stove (kitchen range), in a pan of water, slowly heated to boiling (212* F.),,use a kitchen thermometer and note the temperature (point) of when it begins to open and once again when it reaches fully open..a good t-stat will have about a ten * span between closed and wide open and will operate smoothly and NOT snap open or shut...new t-stats (regardless of brand) are notorious for being bad, right out of the box..don't "ass"ume it is OK, just because it is new...test it.

[grillen85]

Yep , I put a mechanical gauge in the truck and it still rapidly jumps it is located in the factory location , I really did not plan on leaving it in there unless the factory gauge was the issue..

I never ruled out , it being a bad tstat from the start ( i have had that issue before) .But I did notice these tstat do not have the "pin hole" on them , this is the first I have seen without a pinhole so I am for sure going to drill my own... We used to drill a series of them in our old roundy round cars , I plan to drill 1 or 2 .

But I did notice today that my upper radiator hose collapsed and it feels week , so when I get the time to work on it again I will replace it for piece of mind.Along with the lower possibly ( depending on fund).

[Steady Eddie]

Here is the t-stat that I used:

http://www.autozone.com/autozone/cat...estid=12109 5

It does have the "jiggle valve" or "hole" already in it, to equalize pressure above and below the t-stat body....it is a "Motorad" t-stat, sold in an Autozone box..100% stainless steel and copper.

It was/is the best 8 dollars I ever spent on my truck. It is a 180* F. t-stat...

[grillen85]

I have the duralast 192* in there now an it didnt come with any holes.
I think it had a 160* in there when i got it ( if the gauge was right) .

The one I have now is not the fail safe one.But it is the same brand just not the same temp * .

[Steady Eddie]

Quote: Originally Posted by grillen85

I have the duralast 192* in there now an it didnt come with any holes.
I think it had a 160* in there when i got it ( if the gauge was right).

The one I have now is not the fail safe one.But it is the same brand just not the same temp * .

=====================
grill--

You were smart to have not purchased the fail safe t-stat...true, they DO fail wide open, but not until the coolant becomes too hot for the Iron Duke. The fail safe (wide open) occurs at about 240*/260*---which will, on the Duke, cause head gasket blow outs, head cracking, and head warping, not good things.

About your t-stat not having a jiggle valve or a hole in it: drill one..a single 1/32" hole will work.

It maybe that Motorad eliminated this hole or valve as a cost savings move..but I agree it needs one.

*IF* you decide to flush out the radiator, be aware that the chemical (acidic) flushes available have caused the seals in the water pump to begin to leak, usually with in a week of using them.
I used distilled water, 79 cents per gallon at Walmart, and kept flushing it until it drained clear..then I used Prestone Yellow 50-50 premix.

[grillen85]

What do you think about the hose collapsing ? The tstat seemed to open at about the right temp ( my temp gauge I had only went to 180*) and the water was just comming to a very slight bubble.. I think the hose is weak and Plan to replace it , It is gonna really suck if I replaced all of this stuff due to a hose being bad.

[grillen85]

I messed with it some more today , I just haven't been in the mood to mess with it .. Ppl keep telling me it sounds like a clogged passage in the radiator , I am no rocket scientist but it just doesn't seem like it ...

I took the Tstat out complete I am going to run it for a day or so to see if the hose still collapses if it doesnt I will buy another tstat.

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[wi11ie]

sounds like someone put a radiator cap on there with the little handle instead of a coolant recovery cap.. flattened hoses are usually the result of system NEEDING more coolant that it is not able to pull from the overflow tank...
But that's just me..
wi11ie

[lesterl]

Good point Willie!

[grillen85]

I am unsure of what your saying about the cap , the truck has been fine for 2+ years since I have had it .. An it just recently started with the over heating issue. Im not sure about the system not being able to pull from the overflow .. The system has has very minimal coolant in it since I have owned it (florida).

I pulled the tstat and drove the truck it seemed to be fine , so I am going to replace the tstat ( as mentioned ) and see what it does then. If that does not work I will buy new hoses .. and if that doesnt work I will take the radiator to the repair shop to have it cleaned.

[wi11ie]

Caps go bad.. When they do the coolant recovery tank gets all the overflow and the system gets low. Caps are relatively cheap compared to the time you have spent effing with this damn thing.
You have replaced everything but that cap so fire it up,fill it up and replace the damn cap.You did keep the coolant recovery tank on the truck didn't you?
Ask for the correct cap at the local parts house.. it is probably a 13-16 pound coolant recovery cap.

[wi11ie]

These systems NEED pressure to keep the coolant in the block to insure cooling. The fact that the water could be sloshing back and forth would account for the readings fluctuating.
No Coolant touching a GM sensor shows low temps..
Thus the need for a pressure ,coolant recovery cap!

[grillen85]

I will do a new cap , its cheap no reason not to give it a shot.

[wi11ie]

No update?
WTF?
Must have been the fix..

[firstgenon24s]

I think its been ok since he took the thermo out.

[wi11ie]

Removal of the thermostat is just not a fix....
Proper repairs require the system to be as it was when it was working properly.(IE. new)
Rigging the t-stat to not work properly will result in low temps, shitty heater function and if it is a ECM controlled system, crappy fuel mileage.
But if you are not interested in it working properly, carry on..

[lesterl]

Quote: Originally Posted by wi11ie

Removal of the thermostat is just not a fix....
Proper repairs require the system to be as it was when it was working properly.(IE. new)
Rigging the t-stat to not work properly will result in low temps, shitty heater function and if it is a ECM controlled system, crappy fuel mileage.
But if you are not interested in it working properly, carry on..

I agree with the old fart.... :-)

[firstgenon24s]

Well Im sure hes going to replace the tstat,its not a daily so hes not that worried about it,as I wouldnt be either,my v8 blazer already gets 10mpg and low temps is a good thing here in florida lol.

[grillen85]

Well actually I havent messed/drove the trucks since like the 10th untill today with the tstat out an both times its wasnt more than a couple of miles max , I do not plan to leave the tstat out by anymeans ( read post #28 ). I just wanted to see if the truck has the same symptoms with the hose collapsing with the tstat out to try and rule out a bad tstat.

I really havent tried to rush messing with it very much , even though I really dont need to I should stop putting it off and work on it .

I could tell tonight just by driving it a mile that the low temps are effecting the way it is running due to it being so cool.

[grillen85]

OK so I am pretty much stumped ..
The only thing left is either the hoses or the rad. itself.

Blah.. so over this truck !

[wi11ie]

Refill and change the cap to a recovery cap !
And make sure the recovery tank is 3/4 full

[grillen85]

what is a recovery cap ?

the cap is new , an the over flow is roughly 3/4 full .
The system is pressurized , probably a dumb move but I checked that today while it was warm with a towel over the cap.

[lesterl]

The radiator Cap is either a recovery type that will allow the system to expell and suck coolant in as the water expands (heats) or contract (cools). Some caps wont let this happen propperly (not the correct cap, or bad cap.)

[grillen85]

gotcha , i will have to see which one mine is .

[grillen85]

New radiator cap on .. still doing the same thing.

Both hoses are collapsing , I am going to replace the hoses and then if that doesnt work the radiator. Man this has become a PITA !

[my_nightmare]

Mind if i join in on this discussion.
1) Since you got hoses a loose from radiator. Shoot water thru it to see how fast it comes out the inlet and outlet pipes. If it slow..,(it should come out 1/2 second after you start adding water).., suspect radiator clogged up. or partially clogged..(depending on the flow of the water thru outlet holes..)
2) (let it drain as much as it can now..)Now block off upper hole and test the bottom flow as well... if it takes longer than a second to get there..,it definetly got a clog.
3) hole in thermostat - definite must have to remove air in system. 2.5 are nortorious for air in system. Although the bad.., the hole will cut down a little on the output of the heat.., it something I imagine you can deal with.
4) After all the above is checked, hook all up and add antifreeze. Watch the return /drain bottle-tank. If bubbles start appearing after 8-12 mins.., suspect head gasket or head issues. 2.5's are also notorious for head issues. I've ran into several oddball issues on 2.5's. If possible.., grab an inspection mirror and flashlight and check all around where the head meets the block. Make definete sure there aint any leaks.
5) to check for any leaks.., you will need to borrow a coolant pressure tester. (oriely,advance, etc.. rent them) Pinch off return line to resivoir tank. hook up tester and pump it up the same amount of pressure that is listed on your radiator cap ..(e.g. about 12-14 pounds) using the flashlight and inspection mirror cheack for any leaks. If any is found, fix it if possible.. Make sure motor is somewhat warm (midway temp.., not scalding warm.) before testing for leaks.
6) you wrote something about the hose sqeezing together after it got warm or after thermostat. IF this was the upper hose.., That would leaqd me to suspect the radiator clogged, a blockage in system, or something to that effect. If this was the lower hose.., This would lead me to believe that either the thermostat not opening up quick enuff or all the way.., or a massive amount of air in the system. Check the system for these issues as well.

7) I know all of the above is ALOT to take into account.., but if you have replaced all of the stuff on the engine.., AND installed an aftermarket temp gauge.., The above steps should narrow it down quite abit. If it turns out to be the radiator.., either carry it to a radiator shop and let them clean it.., or replace it. From where I am from.., it about the same price on your year model vehicle.

Hope all this helps..
Allen

[grillen85]

Quote: Originally Posted by my_nightmare

6) you wrote something about the hose sqeezing together after it got warm or after thermostat. IF this was the upper hose.., That would leaqd me to suspect the radiator clogged, a blockage in system, or something to that effect. If this was the lower hose.., This would lead me to believe that either the thermostat not opening up quick enuff or all the way.., or a massive amount of air in the system. Check the system for these issues as well.

7) I know all of the above is ALOT to take into account.., but if you have replaced all of the stuff on the engine.., AND installed an aftermarket temp gauge.., The above steps should narrow it down quite abit. If it turns out to be the radiator.., either carry it to a radiator shop and let them clean it.., or replace it. From where I am from.., it about the same price on your year model vehicle.

Hope all this helps..
Allen

Hey , thanks alot .. Basically BOTH of my hoses are collapsing , I have ruled out it being a issue with the head/head gasket only do the fact at idle the truck doesnt go any higher then 200* w/ a 195* t stat. I am waiting for some money to come in and Im gonna get a new radiator an hoses.

[grillen85]

**** this truck ! new radiator and hoses ..

Still the same shit.