4.0 heating and cooling troubles

[sledneck07]

first off my engine temp severly flucuates. ill get on the road and my temp will rise up to about 240 then drop off to 170. then it will go back up to anywhere between 210 and 230 and bounce around for a bit (rise and drop about 5 degrees). then drop back down to 190 and stay there as long as i dont accelerate or decelerate, as soon as i do that it will start bouncing agian. i got a lever lock rad. cap on it and if i releave the pressure a bit of air goes to the res. also i dont get crap for heat but both heater hoses feel the same temp. any one got any ideas??

 

[Nhaz]

the bouncing temp sounds just like a normal thermostat operation during cold months.

when its cold it stays closed to let the coolant in the engine get hot and then it pops open to let all the hot coolant into the rad and sucks in all the cold coolant from the rad at the same time. then it snaps shut again when the engine temp starts to drop too low.

thats the bouncing. if its staying in the normal range then i wouldn't worry about it.

Its when it stops bouncing and stays cold or gets super hot you have a real problem.

 

[AllanD]

Actually it sounds more like an intermittent instrument ground.

Check the ground wire between the bach of the drivers side cylinder head and the wiper motor.

Tha ground wire if loose or corroded seems to cause issues with the temp guage.

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[sledneck07]

i drilled and tapped a mechanical temp gauge into my intake right next to the stock one so i hardly look at look at the temp on the cluster but it seems to read along with my mech. one. but whats with the air in the system and the lack of heat. i did a compression check bout a month ago and it was good. and i dont have excessive water or steam comming out of the tail pipe.

 

[trail B2]

You know theres a kit that checks for combustion gases in your radiator.It's like thirty some dollars but then you know and you can get to fixen or move to the next problem.

 

[sledneck07]

yep ive heard of the kit whrn i was doing a lil research. whats the kit called?

 

[calypso93]

Slightly off topic - I wonder if a common CO detector over the capless radiator would show CO hits if you have exhaust gases in the coolant?

 

[AllanD]

Yeah, my telling you to check the ground presumed you were depending on the stock instrument AND that it had an issue.

If you have a mechanical temp guage you've ruled out an instrumentation issue.

Me? I have mechanical guages on BOTH sides of my radiator.
(thermal probes between the front and back core)
but I need to open the hood to read them



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