overheating when heater is on

[TOYJOETA]

Hey guys, I have a 85 sr5 xtracab  and when ever I turn on my heater after a while the temp gauge starts to go up.  I have already replaced the t-stat with a toyota dual stage and still does the same.  if anyone has an idea of what to do it would be much apreciated

Thanx Joe.

Hey guys, have an 85 xtra cab that when ever I turn on the heater the temp gauge starts to go up,   then when I turn it off it goes down.  I have already replaced it with a toyota daul stage t-stat but it still does the same. any hel would be awsome.

Thanx Joe

[Mike D]

naturally your engine should run cooler with the heater on. there may be a possibility that there is a clogged line?

[TOYJOETA]

Ya but which line they all feel about the same temp.

[Mike D]

take it apart the only way to tell

[BigMike]

are your heater lines on backwards? Marlin told me about a time he had a car come in (when he was a mechanic / before the Crawler) and the car would run cold with the heater on. It turned out that with it backwards, it put a restriction and caused more water to pass through the engine+radiator and it would drop the temp. Possibly the 4cyl is likewise in an opposite manner?

[TOYJOETA]

No the lines are on right I already check that , the sensor on top of the t-stat housing has a broken connector but I don't think that has anything to do with it.

[brainlessfool]

maybe it's an in dash elect. problem?  are you sure that it's realy getting hot and not just reading hot with the fan on?  you could try to trun on  fan with the truck off to see if the gage moves up any? at all.
do you have a thermomitor (spelling?) that you could put in the cap opening on the rad. to see if the water is getting hoter with the heater on.

this is a good one.   

[79coyotefrg]

  as much as i hate to agree with brainless,  it does sound like an electrical problem,,  you said "on top of the thermo housing"  you should use a temp sender installed befor the themostat,   should be several places to put your sender,  check and make sure your connections are solid,  the bad connection with the extra amp draw of the fan can give a false hot reading,  make sure using a handheld thermometer

[brainlessfool]

as much as i hate to agree with brainless, 

kinda stings, don't it?   

[DontStall Rockcrwl]

yeah my truck does the same thin sometimes.. for me its the gauges. the gauge reads as if the damn motor is on fire... then goes down to reg. temperature.  soo who knows. hopefully thats all it is for ya

[PurpleYotaGirl]

Have enough coolent in there?

[Fireimp141]

My truck does some random stuff... i was driving down the road just a little while ago and it was at the top of the red... 30 seconds later it was down to cold 

[SWAMPER]

that happens to me but with the dayum oil level...it will sink all the way down but i check it and its aaaaiiiight!

[TOYJOETA]

that happens to me but with the dayum oil level...it will sink all the way down but i check it and its aaaaiiiight!

I have plenty of coolant.  I am really starting to think that it may be electrical,, the only problem is that I went to every junkyard in town and nobody had the connector I needed, and toyota told me that I would have to buy a new harness. .  About the themometer  Would one of those infer red ones work on it

That happened to me before then I installed a new t-stat and it fixed it, just make sure you buy a Toyota one because the ones a auto zone and checker suck.

[TOYJOETA]

sorry my hands are cold and hit the wrong quote

My truck does some random stuff... i was driving down the road just a little while ago and it was at the top of the red... 30 seconds later it was down to cold

I replaced the t-stat and that fixed that

[brainlessfool]

does you mom have a "cooking" thermomerter? you know in the knife drawer? used for telling when the turkeys done? if so it will work! (just don't tell mom where you've stuck it!)

[SWAMPER]

Make sure you wash it though...might make you sweet though it taste good

[BigMike]

a huge air bubble?

[79coyotefrg]

fireimp,  go to your local dealer and get a new thermo stat

um toyjoe,   go to a junk yard and get the connector you need,  if its just the plug that attached to the sender, you can make one, or just strip the wire back stick it thru the little hole on the sender and tape it


swampy,  how low is your oil pressure going??    you may be in for a new motor

let me guess you have great oil pressure when its cold, but drops when your driving aways the come to a stop

[SWAMPER]

No it only went down like 2 times and it was some time ago...it just went all the way down so i stoped turned it off checked it..it was fine and took off...never has done it again...