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2002 Sentra has 2 ECT sensors


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tractorboy
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Jul 14, 2021, 7:34 PM

Post #1 of 18 (652 views)
post icon 2002 Sentra has 2 ECT sensors Sign In

is one the ECT and the other for the fans ??? 4 pictures scroll down. if you go to rock auto shows two different coolant temp sensors like the ones i have pictured










(This post was edited by tractorboy on Jul 14, 2021, 7:44 PM)


Tom Greenleaf
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Jul 14, 2021, 10:05 PM

Post #2 of 18 (621 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

There may be yet another. What are you trying to fix on it?
If for lack of fans and other for it running rich unplug one see if it thinks engine is cold, should send a code.
What does this have for a gauge at dash. That will spike or do nothing like the others if not working.
Most have worked for my tenure at this the problems were not switches rather wiring to them.
It's important all the time don't allow an overheat now about a 20 year old car it's warm or hot in many places is quick and real hard on cars too.
*****
Noted for seasons and temps: Heat is harder on electrical anything than cold seasons, any extremes bring out the weak link problems,


Tom



Hammer Time
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Jul 15, 2021, 3:28 AM

Post #3 of 18 (614 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

The car has 2 sensors. The single wire sensor is for the dash gauge and is called a thermal transmitter.

The 2 wire sensor is for the computer and determines fuel mixture, fan operation and other functions.



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Tom Greenleaf
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Jul 15, 2021, 6:28 AM

Post #4 of 18 (607 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

Thanks Hammer. Tractorboy - what is/was the problem? Do another parts look up see if the parts look identical to yours AND if they come with pigtail wire ends.


Nice pics BTW, those types are really measuring resistance which will change with temp to send that almighty signal for the next item to do what it should.
No fan - no engine if you run it too hot, over fueled - flooded out, may not run or serious fuel unburned. Gauge would be just plain wrong, nice if all are on target,


Tom



tractorboy
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Jul 15, 2021, 6:52 PM

Post #5 of 18 (585 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

Thanks HT and TG
...a clue is the cylinder head is on a table Laugh. I am replacing the head gasket. I did one of those tests where you sample the radiator fumes for combustion gases. It failed the test. Luckily the head is not warped. should i check for cracks? or anything else you both can think of while i have the top end off. the car has 178k was thinking maybe doing the timing chain. The Hyvo chain looks great as the cam sprockets. the tensioner for the cam chain was full of sludge. the screen on the IVT solenoid had a fair amount of little black flecks which were also in the recesses in the head which were the spark plug tube seals that completely dried out and crumbled. I wanted to actually look at the oil pick up tube, i think to remove the oil pan i have to remove the timing cover. This car would have been so exotic back when i was in High School..DOHC, FI, EI, VVT, Bucket tappets, HEMI, ULEV, disk brakes all the way around. now adays just a moderate old car.Smile also i am rplacing the valve guide seals, amazingly when this car ran it did not use a drop of oil, the seals though are starting to dry out. Something else, there are some "O" rings in the gasket set have no idea where they go looked at Nissan online dealers exploded views have no idea where they go unless the set is for an all encompassing models, like for example this is a GXE so it has an EGR where as a model S would not and the EGR gasket would be a puzzle for the S model owner.. will post a picture of the gasket set tomorrow


(This post was edited by tractorboy on Jul 15, 2021, 7:16 PM)


Tom Greenleaf
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Jul 15, 2021, 7:30 PM

Post #6 of 18 (569 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

"The failed 'gasses' test for head gaskets?"
I don't trust those so much but bad sure isn't good.
Sludge! That's neglect somewhere or a wrong oil used. Personally like synthetics resist that sludge can be a fatal problem you may never clear all oil passages of it.
If you test head for warpage and want to try just a gasket job, any and all timing parts done right OE rated should be fine - careful on ones that claim better than OE?
I think you know the risks so in general am not going to suggest just that but try hard to check that all signs are right that it can work the old parts off should show how it leaked if not all bets off,


Tom



Hammer Time
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Jul 16, 2021, 3:36 AM

Post #7 of 18 (555 views)
Re: 2002 Sentra has 2 ECT sensors Sign In


Quote
It failed the test. Luckily the head is not warped. should i check for cracks?


You sure about that? I have never seen an aluminum head with a blown head gasket that wasn't warped to some degree, especially if the failure was bad enough to show positive with a chemical test. Those tests are notoriously hard to get a positive test unless it is really severely blown.

I would have advised you not to do this at all with that kind of mileage. Repairing the top end on an engine that worn really puts a lot of stress on the lower end due to the increased compression after the repair. Many don't survive long after.



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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.



Tom Greenleaf
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Jul 16, 2021, 7:14 AM

Post #8 of 18 (547 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

S-L-U-D-G-E! It could have failed test just from that, any care engines don't do that. Oil must return.
Head gasket job of just gasket? I've done a few that worked IDK how long whole car lasted they were horrible.
How did you determine even if cracked head was true? Not wood nor regular metal a straight edge AFTER you clean off any yuk.
The time to verify is right when removed. Where did the problem SHOW up in gasket or stains? Cracks can show with diluted magic marker ink diluted and wiped off. Look for even a spider web thin line connecting where it could blow gasses into cooling system.
Felpro by brand made a pretty forgiving gasket I think still does buy you a chance.
If it ran well before you suspected anything as HT said redoing head is hard on lower ends.
If time and can accept risk it's your call. The ports that return oil still must be cleared if sludge can fill a flat head screwdriver and pull it out like crust or stuck paste. Flakes block return if out of control bad valve covers pour oil out and pressure in crankcase also a problem.
Up to you it can work for a while or lost time and shorter $$ for trying.
If other things good sell off parts and cut loses that "S" {sludge} word just isn't very forgiving,


T



tractorboy
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Jul 16, 2021, 2:00 PM

Post #9 of 18 (522 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

they did not change their oil often. the sludge was only in the cam chain tensioner. I did the test first, then i used one of those chemical head gasket repairs. Part of the process was to remove the thermostat. At some point someone had used the copper head gasket repair that Advance auto sells. the whole thermostat was copper colored. So the repair was a two part epoxy process. i followed the instructions. I tested again and the Sentra passed the test. The Sentra ran great for several months then back to using coolant and running bad. I tested and it showed that combustion gases were again present. I used a machinists straight edge and feeler gauge ( piece of wood Smile ) . the head was cleaned, will clean again. There was no sludge in the top end just pieces of the spark plug tube oil seals that had completely dried out, see the picture. all the bearing surfaces look good, bucket tappets no wear. Plus the valves seem to have zero play.



(This post was edited by tractorboy on Jul 16, 2021, 2:15 PM)


Hammer Time
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Jul 16, 2021, 3:39 PM

Post #10 of 18 (502 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

You should definitely have it pressure tested for cracks.



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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.



tractorboy
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Jul 18, 2021, 7:38 AM

Post #11 of 18 (431 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

no warp








(This post was edited by tractorboy on Jul 18, 2021, 7:52 AM)


Hammer Time
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Jul 18, 2021, 7:43 AM

Post #12 of 18 (425 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

If you are confident with the surface measurement, then that makes the pressure test that more important.

You had leakage severe enough to fail one of those chemical tests which usually means a large leak. It had to come from somewhere.



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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.



tractorboy
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Jul 18, 2021, 7:55 AM

Post #13 of 18 (419 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

i know and that worries me there is a crack in the head, could it just be the gasket?


Hammer Time
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Jul 18, 2021, 8:00 AM

Post #14 of 18 (414 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

I've done a lot of head gasket jobs and NEVER saw one that was "just a gasket". It's usually either aluminum warpage that leads to a gasket failure or a crack that develops from the heat.

Was there an obvious bad spot in the gasket?



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

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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Jul 18, 2021, 10:54 AM

Post #15 of 18 (404 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

? Other reasons: Was run on plain water too long at some point? Gaskets (the few I did just gaskets + clean ups) showed the flaw clearly by eye in the OE gasket.
The maybe is fooled by the test or it's the block instead not to be passed over.
What other possible thing could put exhaust fumes in coolant? Look - is EGR or something close for a flaw to wait since 2002?
Any freeing chance this thing froze from lack of antifreeze protection those "freeze" plugs so called are really NOT to protect it rather in the making of cast parts in the first place.
I'm not testing it but was told protection to +15/20F (an Ethylene Glycol) or so that mix will not expand but still freeze or make slush,
T



tractorboy
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Jul 19, 2021, 7:18 AM

Post #16 of 18 (374 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

i looked at the gasket briefly it is still on the block. i looked at all the fire rings, they need a closer look was getting ready to rain. it looked like coolant maybe was seeping between the block and gasket. it was a quick look
cast iron never warps right ? Sly yeah i was thinking about the block, definitely needs checking and cleaning.


(This post was edited by tractorboy on Jul 19, 2021, 7:20 AM)


Tom Greenleaf
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Jul 19, 2021, 8:20 AM

Post #17 of 18 (367 views)
Re: 2002 Sentra has 2 ECT sensors Sign In

Just on cast iron: Warp? Not so much but can and still has possible flaws, rusts and can crack. Use of "dissimilar" metals affixed to it is the challenge of years on end they expand and contract at different rates with wild temp changes.
Blocks are line bored for shafts, cylinders AFTER the shape is there for the parts it will have. Flaws can be bubbles hidden in it, a metal or something that didn't belong when the iron was made (usually shows up right away) and the harder metal bits/cutting machines for surfaces isn't the same for one to the other yet visually can't see that.
Like a plain drill it isn't making the same size hole twice (my luck) so need to know how many you can make that will work for block of an engine.
Quality of the raw cast iron IMO has taken a serious decline perhaps for the speed of making it?


T



tractorboy
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Nov 5, 2021, 5:42 PM

Post #18 of 18 (131 views)
post icon Re: 2002 Sentra has 2 ECT sensors Sign In

I finished the Sentra. Actually has been finished for awhile. Have been driving the sentra around especially with high gas prices. The sentra get around 33 - 45 MPG

What we talked about tested for cracks



Replaced the vale guide seals



and cleaned the block gasket surface








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