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Engine not reaching operating temp

That's what the SES 15 test says? Although I've never experienced it.

Looking at the disassembled code in the chip I'm not really sure that is the case...
 
Sorry for the lag in replies, I was at the hospital with my mother and father. She has stage 4 Peritoneal Cancer and had to have 4 quarts of fluid removed from her abdomen.

Anyway,

  1. I don't know that there isn't anything in the seat area. I guess I was just hopeful.
  2. The engine is NOT blowing black smoke, at any time.
  3. I went and bought an infrared thermometer from chinafreight and took a measurement at the thermostat housing and the temp sensor at the side if the engine, its 170 to 175 and the fan is DEFINITELY surging. The dash gauge reads about the same.
How do you drain the coolant without making a mess. I know Eagle said to drain it into a clean bucket, but my petcock doesn't have a place to attach a hose or anything.
Please keep throwing out ideas, maybe we can figure this out. Thanks.
 
I take the radiator cap off (cold of course) use a 1/4" rubber hose, stick it into the radiator past the trans cooler (if present) and start a siphon into a 5 gallon bucket. I just let it drain until the hose runs dry. Still end up leaking a bit of fluid around the thermostat housing.

FWIW I intend to put a ball valve on the radiator drain, so that I can easily open it, and hook a hose up so it doesn't go all over the place. Not like I need to drain it often, but when I do, the factory setup is worthless unless you want to make a mess.

I checked the 1991 manual, and it says below -27* the code will set, but -22 vs -27 is inconsequential.

Most evidence seems to point away from a problem with the CTS (no issues with how it runs mainly) but if the code operates as GM says it does, the CTS has to be the problem. Not that I'm saying it IS the problem, just that the GM manual is wrong if the CTS isn't reading below -22/27*. But you have to know what the ECM is seeing for CTS temp. You can measure resistance on the CTS terminals and check that against the service manual temp chart, but I don't have that handy. I can get it though.
 
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If you don't like the pet-cock method, you could use a squeeze ball siphon hose (like for a boat) and pull it from the top.
*Don't use your mouth antifreeze can kill you. *

You can also replace the plastic petcock (plug) with a ball valve that has a hose fitting. Then you just push the hose on, twist the valve, and you get a clean catch.

Doorman makes a cheap plastic version for around. $5, part number 61123.
You will have to verify your thread size but that should give you an idea of where to start.

*edit*
Ok someone beat me to posting it, so I second the valve or siphon*
:)
 
Dorian,
If you can find the chart I'd appreciate it. I'll take the resistance tomorrow afternoon. If it doesn't match, I guess I'll be buying a new CTS, a siphon and a ball valve. I'll replace it and double check the thermostat seat and go from there.
 
tRustyK5 said:
When my CTS was bad it'd start cold, then after a few minutes puke black smoke and die...unable to re-start til it was cold again.

What is this with setting a code when ambient is below -22 F? Not that we get that cold that often, but probably at least twice a year...so I can expect a SES light and a code set when it does get that cold? :confused:
Click to expand...

We had a few mornings of -25 here this year (highs around 0 deg though) I had several tbi trucks here that were started, and no codes. With scan tool on them though, cts showed -15. I wonder how long it would take at -25 or colder to get the engine to that temp of flagging a code?
 
Even if the CTS is off? It won't raise your engine temp!

You have to have a bad T stat! Or it's stuck or not seated properly... you just proved that with the IR heat gun temps! I've seen more then one T stat stamped 195 open at 160-180... still at 170 you should have decent heat. So maybe the heater core is plugged? The fan surging on and off is normal... well it is on mine anyway until the clutch get's warmed up and driven a little, then it stays off. Usually when it's that cold it is locked on at cold start and as it warms a little kicks off/free spins.

Coolant sensor approximate resistance specifications:
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.
 
Slade001 said:
Dorian,
If you can find the chart I'd appreciate it. I'll take the resistance tomorrow afternoon. If it doesn't match, I guess I'll be buying a new CTS, a siphon and a ball valve. I'll replace it and double check the thermostat seat and go from there.
Click to expand...

It would be well worth your time to solder on some new ecm ground connections while you are at it.
 
I'm not sure how the CTS sensor even got in conversation as there is no engine issues indicating a faulty CTS?
 
eagle mark said:
That code could be old as well? Didn't he have a bad CTS? Usually when the CTS goes bad it reads -40*c and the person is complaining of RICH, Black Smoke, bad running, bad MPG etc...
Click to expand...
Has the code ever been cleared?
 
Slade001 said:
Dorian,
If you can find the chart I'd appreciate it. I'll take the resistance tomorrow afternoon. If it doesn't match, I guess I'll be buying a new CTS, a siphon and a ball valve. I'll replace it and double check the thermostat seat and go from there.
Click to expand...

It's kind of an either/or thing, you won't need a siphon AND and petcock valve, one will do. Just decide if you want to make one final coolant mess (because you will) to install the new valve, OR siphon it about half way down from the top, do you thing, and refill. You don't need both unless you want to siphon it all to install the valve.
 
Lets run down the list.

  1. No, I have not "cleared" the codes.
  2. I really don't want the mess. I can get a cheapo siphon and drain as much of the coolant as I can and pull the petcock from there.
I'll clear the codes this weekend and see what happens. But as I have all but verified the engine temp and the dash gauge are close enough to the real temp, shouldn't we accept the engine ISN'T getting to temp so the code "should" be legit. Right?

NOT trying to be argumentative, just asking a point.
 
eagle mark said:
Error Code 15 can set even if there is nothing wrong! :dunno:

Code 15 will set if
1. Engine runs for 30 seconds
2. Engine tempresture is less then -22*f for 3 seconds.

So it can set at cold start if outside ambient temps are below -22*f when first started...

Now if you clear the code when temps are above -22*f it should not come back. If it does? The CTS sensor is faulty... which will make it run extremely rich all the time.
Click to expand...

code 15 wont set from engine not reaching expected operating temp, will only set if above conditions are met
 
1) Pull ECM fuse, reinsert. If the problem is with the CTS (or CTS wiring/connectors) the code will come back.

2) You'll never get all the fluid out of the radiator by siphoning. No reason to get a fancy siphon thing, just a hose long enough to reach to bottom of radiator and the bucket, and start the siphon like most people do. Don't drink the crap. Use a long enough piece of tubing, and you won't have a problem.
 
dyeager535 said:
1) Pull ECM fuse, reinsert. If the problem is with the CTS (or CTS wiring/connectors) the code will come back.

2) You'll never get all the fluid out of the radiator by siphoning. No reason to get a fancy siphon thing, just a hose long enough to reach to bottom of radiator and the bucket, and start the siphon like most people do. Don't drink the crap. Use a long enough piece of tubing, and you won't have a problem.
Click to expand...

What ever you do, don't do ^ that.
Ethylene glycol is some nasty stuff, accidentally swallowing one mouthful can kill you. Keep it in a container, and out of you.

I may be a dumb redneck from small town Arkansas but I definitely know better than to suck on a straw with antifreeze at the other end.

* I wonder how many innocent women are sitting in prison for murder because their husbands tried a bad idea they read about on the internet?
 
I have learned when siphoning anything like gas,coolant,etc,that could be deadly--I use 2 hoses--one long enough to insert into the container to reach the bottom,and another one I insert into the opening,but do not submerge in the liquid...then I wrap a rag around both hoses to seal them,and blow into the second hose that isn't submerged--this creates a slight pressure in the vessel and forces the liquid out the longer siphon hose,with no danger of getting a mouthfull...you can use a compressed air source to do it too,just be careful ,you only need a little "puff",too much pressure will risk making a mess or rupturing the container..

I've gotten more than my share of gasoline in my mouth trying to siphon it the "old" way...now this is the only way I'd try it..
 
You need about 7.5oz of 50/50 antifreeze to kill you. If you can ingest that much through a 1/4 hose in one gulp, you've got a professional calling.
 
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