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98 chev 1500 low oper temps


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tylermc44
Novice

Nov 25, 2012, 4:32 PM

Post #1 of 18 (1471 views)
98 chev 1500 low oper temps Sign In

i have a 98 chev 1500 5.7L and it wont come up to operating temp it sits around 70 deg celcius, i changed thermostat thinking it might have been stuck open, but then i realized the rad cap and lower rad hose remain cold no matter how long i drive the truck for, ? thanks


Discretesignals
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Nov 25, 2012, 5:05 PM

Post #2 of 18 (1460 views)
Re: 98 chev 1500 low oper temps Sign In

You got to be having problem with T stat itself or it is being bypassed somehow. Are the heater hoses hot? What rated T stat did you put in it?





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(This post was edited by Discretesignals on Nov 25, 2012, 5:08 PM)


Hammer Time
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Nov 25, 2012, 5:08 PM

Post #3 of 18 (1453 views)
Re: 98 chev 1500 low oper temps Sign In

He's way up in Canada. It's probably just too damn cold out.

He may also have a fan clutch fully engaged.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 25, 2012, 5:09 PM)


Discretesignals
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Nov 25, 2012, 5:10 PM

Post #4 of 18 (1447 views)
Re: 98 chev 1500 low oper temps Sign In

Wonder how cold it is...





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Hammer Time
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Nov 25, 2012, 5:14 PM

Post #5 of 18 (1442 views)
Re: 98 chev 1500 low oper temps Sign In

He ain't hanging out at the beach.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Nov 25, 2012, 5:16 PM

Post #6 of 18 (1439 views)
Re: 98 chev 1500 low oper temps Sign In

I bet he wish he were.





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tylermc44
Novice

Nov 25, 2012, 7:15 PM

Post #7 of 18 (1428 views)
Re: 98 chev 1500 low oper temps Sign In

i jus put in a 95 deg C therm and i traced the heat its all the way from the therm housing to the rad and down the one side of the rad, to me i feel it could be plugged rad because the other side is stone cold. and i was having this problem even in the summer, lately temps been around 0 deg celcius. the heater hoses are hot , heater works great still.


Hammer Time
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Nov 25, 2012, 7:41 PM

Post #8 of 18 (1424 views)
Re: 98 chev 1500 low oper temps Sign In

Sounds like the radiator is just doing the job it was designed to, maybe a little too good.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tylermc44
Novice

Nov 25, 2012, 7:53 PM

Post #9 of 18 (1419 views)
Re: 98 chev 1500 low oper temps Sign In

ya way to good , its killing my feul mileage the truck drives in warm up (rich fuel) mode all day. i was jus looking for some input before i go spending $ on parts.


Hammer Time
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Nov 25, 2012, 7:57 PM

Post #10 of 18 (1415 views)
Re: 98 chev 1500 low oper temps Sign In

And what parts do you think you are going to change to make it run warmer? The radiator? That certainly isn't going to make it run any hotter.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tylermc44
Novice

Nov 25, 2012, 8:01 PM

Post #11 of 18 (1404 views)
Re: 98 chev 1500 low oper temps Sign In

and thats where im confused, i dont understand why the lower rad hose and rad cap are cold not mildly warm, but cold as if the truck wasnt running.


Sidom
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Nov 25, 2012, 8:32 PM

Post #12 of 18 (1397 views)
Re: 98 chev 1500 low oper temps Sign In

What sensors are u looking at? You need to look at a datastream and see what temp the ECT (temp sensor)is reporting to the pcm. If the datastream temp is at 195 or higher then you need to look else where for your mpg problem. If it's lower than 195 then you are correct & the pcm will be adding more fuel.....

You can't go by the gauge in the dash

As far as the temps go HT did bring up a good point about it being cold up there. If your rad was as restricted as you think it is, then in the summer time you would've been experiencing overheating problems under load (going up a hill, towing, high speeds). If you weren't getting any of that this summer then your rad is doing its job






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(This post was edited by Sidom on Nov 25, 2012, 8:35 PM)


Discretesignals
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Nov 25, 2012, 8:53 PM

Post #13 of 18 (1390 views)
Re: 98 chev 1500 low oper temps Sign In

And this is where I become confused. If the thermostat is rated for 195 F, that means it shouldn't start opening until around that temperature. Until it opens there is no coolant flow through the radiator. If the coolant temperature was only around 170, the heater wouldn't be performing very well and the heater hoses would be luke warm. Sid is right. You need to compare the ECT sensor reading to the gauge sender and see if they jive. You can also measure the temperature at the ECT sensor using a laser thermometer.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 25, 2012, 8:54 PM)


Tom Greenleaf
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Nov 26, 2012, 2:52 AM

Post #14 of 18 (1376 views)
Re: 98 chev 1500 low oper temps Sign In

Notes: It doesn't much matter how cold it is out or how well radiator works. Heck - same basic block runs raw unlimited water thru marine engines and maintain temps.

T-stat is probably just opening or allowing some flow when it should be shut tight. How cold is too cold for ambient temps? IDK for sure but way below zero Fahrenheit. Heater core will slow warm ups but at full blast with even a window open it should still warm up, just slower.

I suggest getting some actual temp readings. For actual engine temp at the thermostat housing. If gauge reads steady at a normal spot and always should get there and stay hot or cold weather then floor vents for heater if measured are pretty close to actual engine coolant temp minus some for ductwork.

Some thermostats come with a cut wedge to help bleed out air and allow minute flow or a jiggle valve for the same purpose never noted by me to let too much pass thru to matter.

Use only OE thermostat. If need be check old one (pan of water on stove thing) if not bent or damaged but think this is basic thermostat problem,

T

Ps: Happens - I've seen multiple inaccurate new thermostats too?


tylermc44
Novice

Nov 26, 2012, 8:36 PM

Post #15 of 18 (1356 views)
Re: 98 chev 1500 low oper temps Sign In

i priced out a temp sensor today and its relatively cheap and easy to change, im gonna try that cause i believe my truck is runnning at a normal temp now by using infared gun 96 degs at therm housing (celcius) but guage in dash reads around 70 celcius so thats what probably telling my engine to run rich all the time. thanks guys for the input ill let you know how it works out :)


Tom Greenleaf
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Nov 27, 2012, 1:09 AM

Post #16 of 18 (1348 views)
Re: 98 chev 1500 low oper temps Sign In

Infrared real temp rocks. Didn't re-read whole thing again but you thought it was stuck in cold mode which would make it more of a pig than they are anyway. Own a '97 and have had countless "350s" of my own never mind others. Temp sensors near thermostat can be done/changed without draining all the coolant.

Need to go look but it's cold out right now (smile) but waterpump is the bypass 'hose' not requiring a separate hose. Pump is always pumping to keep all coolant temp uniform is the idea. Once at rated temp will let t-stat trickle out some to radiator and same in from bottom.

Again - heater is stealing some heat and really can help if you are stressing the thing out in hot temps, A/C blasting, hauling a load but shouldn't need to do that. Fan clutches come in light, medium and OMG this thing is pulling itself by the fan!

Knock on wood but for the few I deal with the connector for the temp sensor(s) can be a problem. Pigtails available to solder in a new one.

In short - temp gauge should get up to it's norm spot and stay there even in extremes. If that deviates while running once warmed up find out why,

T


Hammer Time
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Nov 27, 2012, 5:27 AM

Post #17 of 18 (1335 views)
Re: 98 chev 1500 low oper temps Sign In

Your theory would make sense except for one problem................................

The gauge and the computer use different sensors so there is no relationship between a faulty gauge and your fuel mixture.

The gauge works off the "temp sender" and the computer works off the "temp sensor"







~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Nov 27, 2012, 5:57 AM

Post #18 of 18 (1329 views)
Re: 98 chev 1500 low oper temps Sign In

Two senders and chances are nothing really wrong with the engine coolant sensor one (I think yellow + black wire) but the other is suspect. Poor fuel economy goes with longer warm ups in cold weather alone plus possible fuel formulations wreck it more. If it was stuck in rich mode for cold a CEL would light near certainly.

Both connectors are subject to corrode more than others especially with road salts if used as it gets all over the engine tooUnsure

T






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