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Does anyone know how to check calibration on a temperature gauge? I have now replaced: radiator (aftermarket, 3 row, from a shop in Laramie, so quality unknown), fan, fan shroud, fan clutch X 2 (mechanic here said fan was not engaging at any temp so I got the clutch Toyota sells), water pump, thermostat, timing belt. At 63 mph on a level or a little bit of an uphill on an 85-degree day the temp gauge needle is 1/4 inch from the red line. I've tried burping the system (may or may not be doing it very effectively) and after $2800 I'm kind of at the end of my patience, and concerned about heading out on a long trip through the mountains in July. Can I measure the temperature of the coolant and learn anything from that? Really stumped and frustrated... (yes, the gauge panel lens is screwed up, looking for a replacement). 

IMG_20160603_142024765.jpg

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Temperature gauge and sensor can be picked up fairly cheap.  If I were having issues I would just go buy an aftermarket setup and install.  Now before I did that I would ask the forum if it would affect the computer.  If it would I would not replace the OE, but add the aftermarket one.  

Not a mechanic, just what I would do in that situation. 

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Different sensors.Where your temp gauge is reading is normal it is not hot until it's on the red mark. Stick a meat thermometer in the radiator they are reasonably accurate that will give you some ideal.

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13 minutes ago, Maineah said:

Different sensors.Where your temp gauge is reading is normal it is not hot until it's on the red mark. Stick a meat thermometer in the radiator they are reasonably accurate that will give you some ideal.

What should the temperature of the coolant be, or what should it be below? Thanks.

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harbor freight cheap tool

http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465.html

Check the temp where the upper hose goes into the radiator.

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I am a big fan of temperature guns, I have one and use it regularly.  They do have some limitations, I have never been able to get a reading off glass and other surfaces will sometimes skew the readings.  So when using multiple readings at different temperatures have to be taken to get feel for what is right.  If wanting to check the sensor, check the temp cool and as it rises, several times to make sure of getting an accurate reading.  Also a bit of flat black paint on some surfaces will help with a reading.

Then how do you know the gun is accurate?   

http://www.thermoworks.com/learning/infrared_tips_icebath_to_calibrate_infrared

I have thought about the HF instrument cluster,  not sure of the quality or if I would trust it, price sure is right.    Anyone using it?             

 

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18 hours ago, DanRT66 said:

Does anyone know how to check calibration on a temperature gauge? I have now replaced: radiator (aftermarket, 3 row, from a shop in Laramie, so quality unknown), fan, fan shroud, fan clutch X 2 (mechanic here said fan was not engaging at any temp so I got the clutch Toyota sells), water pump, thermostat, timing belt. At 63 mph on a level or a little bit of an uphill on an 85-degree day the temp gauge needle is 1/4 inch from the red line. I've tried burping the system (may or may not be doing it very effectively) and after $2800 I'm kind of at the end of my patience, and concerned about heading out on a long trip through the mountains in July. Can I measure the temperature of the coolant and learn anything from that? Really stumped and frustrated... (yes, the gauge panel lens is screwed up, looking for a replacement). 

IMG_20160603_142024765.jpg

Your needle position is probably suppposed to reflect around 240 degrees F.  If you take your sensor out and stick it in a cup of boiling water - it ought to read in the middle of the scale.

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the VZ3E has several sending units on the back of the engine block on an add on part.  If you look way over the top of your engine, behind the phelum (spelling?) - the "top" of the engine- the air from the intake enters it on the drivers side, you can see what I am referring too.

 

I believe one of those senders feed the gauge on the dash.

 

It seems logical to go straight to the engine cooling system thermostat and test that, but I don;t think that is what you are asking. 

 

btw, there are other things that can cause an engine to run hot,   like timing (easy to check) ,  also a head gasket leak can put hot air directly into the cooling system.

but back to your sending unit, I presume it should put out different voltage at different temperatures, so if one removed it and put in a pot of water and raised the temp, one could check calibration and vice versa , with a some sort of resistor apply varies current in the desired range to see if the gauge indash is ok.

 

never thought of it before, but if one put a thermometer on the cooling body (where the sending units are) one could see how hot it is right there without having to dissas

mble anything

Edited by DanAatTheCape
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Thanks, Dan. I just found the sensor/sending unit (crowded neighborhood back there) and verified that it's the right one by unplugging it and turning on the already-warm engine: no movement of the gauge until I plugged it back in. I have ordered an IR temperature gun and will do readings at various points after I take it back on the road and get it hot again, and proceed from there. Seems like, if the gauge is accurate, it could be time to visit a specialty radiator place for diagnosis. If it's not, I'll replace the sensor first and see where that gets me.

I got it warm enough for the fan to kick in today (heater on full), and the level in the overflow canister didn't deviate from "full" line, either then or after it cooled a bit. While it was running, I loosened the flush-kit cap enough to release any air - seems like the highest point of the system - but all that came out was coolant. So I think I don't have an air-pocket issue, other than the ones in my brain. Well, I didn't have anything to do this weekend anyway :-) 

Thanks again for the suggestions. This forum is great, and the folks here very kind. 

Dan in Albuquerque 

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as to  desired temp, the purpose of the cooling system is to keep the coolant from boiling.  Adding antifreeze raises the boiling point allowing an engine to run above 212 degrees.  

I think the specs on our thermostats is 82 c  which is  180 f.

I have attached a chart I found in the service manual with specs for the resistance the sending unit should be creating over the operating range.  I noted that the chart ends at 180 which seems odd to me.  I googled around the internet and their are numerous charts  to be found.

I think their are multiple sending unit with separate ones feeding the in-dash gauge. Hence not sure which sender the chart refers to. 

 

If you get a new one, would be interesting to put it in a pot of water along with a thermometer and record the resistance as the temp rises,

 

I was just looking at parts on rockauto.com.  They show a bunch of them - some are green and some are black with different connectors.  Did you happen to notice the color of yours?   maybe a pic of the connector?

Also saw one with the flat blade type of connector.

 

 

 

  http://www.rockauto.com/en/catalog/toyota,1993,pickup,3.0l+v6,1277995,cooling+system,temperature+sender+/+sensor,4748

 

 

tempspecs.pdf

Edited by DanAatTheCape
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Here is a pic of the water manifold (not sure of correct name). I can say the connector on the far left is involved with evap - the charcoal canister. when the engine warms up that valve allows gas fumes to enter the intake system

P1040444.JPG

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On 2016-06-04 at 6:28 AM, jjrbus said:

I am a big fan of temperature guns, I have one and use it regularly.  They do have some limitations, I have never been able to get a reading off glass and other surfaces will sometimes skew the readings.  So when using multiple readings at different temperatures have to be taken to get feel for what is right.  If wanting to check the sensor, check the temp cool and as it rises, several times to make sure of getting an accurate reading.  Also a bit of flat black paint on some surfaces will help with a reading.

Then how do you know the gun is accurate?   

http://www.thermoworks.com/learning/infrared_tips_icebath_to_calibrate_infrared

I have thought about the HF instrument cluster,  not sure of the quality or if I would trust it, price sure is right.    Anyone using it?             

 

don't have one, never used one, but it seems one could take readings on known items.  For instance the ice test, or reading in the freezer compared to a thermometer.  Also maybe boiling a pot of water and as it reaches boiling (sea level = 212 f) and such tactics

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I find IR temp guns to be kind of useless when it comes to getting coolant temps on an engine.  Readings can vary wildly by the surface, color, reflectivity, etc.

Since the temp gauge has no actual numbers on it - I think it can be safely assumed that anything up the the "unsafe/too hot" area is going to be temps up to 220-230 F.  Toyota system probably starts to boil at 260-270 F. F.  Even if it had just pure water in it, it would still have a boiling point of 259 degrees F.

Seems knowing what the sending unit is supposed to do isn't going to help in telling you if the engine is hot.  What counts is the final reading on the gauge. If you put your sender in 220 degree water while still hooked to the gauge - it ought to be a getting close to the "hot" range but not there yet.

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Due to many overheating issue this thread has my interest.  I was looking around for the proper name for the "water manifold" and cannot find it. It might be cross over water passage?  To further confuse things I did find that the design changed between 91 and 92 models. Jim

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Plenum of some sort? I've seen that name in use.

DanAatTheCape, Here's a truly crappy photo I took. I've drawn a red circle around the sending unit: simple flat-blade connector is the one. Amazon has one for sale: http://smile.amazon.com/dp/B000IYZ0KS/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=G7GEGNY01IGE&coliid=I2LVRQEY7H1F3D and they're available about everywhere. 

temp_sender.jpg

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The gauge sensor only has one wire. The red zone is hot any thing else is not. With the wire disconnected is should read dead cold with the wire grounded to the engine it should read full scale hot that pretty much is the test of the gauge. Yes it is possible the sensor is bad but they are pretty linear and generally just don't work or read full scale. Many years ago they removed all numbers from temp gauges because of the confusion involved modern engines run a lot hotter than the old engines did. 

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Would it be a difficult project to switch over to a gauge with numbers on it?  Might be comforting to know that the temp is XXX instead of half way or almost to the red.   Jim

 

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22 hours ago, jjrbus said:

Due to many overheating issue this thread has my interest.  I was looking around for the proper name for the "water manifold" and cannot find it. It might be cross over water passage?  To further confuse things I did find that the design changed between 91 and 92 models. Jim

I looked in the service manual and found "water by-pass outlet"  --see excerpt from manual attached PDF

wateroutlet.pdf

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22 hours ago, DanRT66 said:

Plenum of some sort? I've seen that name in use.

DanAatTheCape, Here's a truly crappy photo I took. I've drawn a red circle around the sending unit: simple flat-blade connector is the one. Amazon has one for sale: http://smile.amazon.com/dp/B000IYZ0KS/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=G7GEGNY01IGE&coliid=I2LVRQEY7H1F3D and they're available about everywhere. 

temp_sender.jpg

I ran the check on that part on the amazon page and it says "does not fit" ????     I suspect it might well fit.   The price is a little high compared to rockauto.    I am rather curious about a conversion to digital, 

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4 hours ago, jjrbus said:

Would it be a difficult project to switch over to a gauge with numbers on it?  Might be comforting to know that the temp is XXX instead of half way or almost to the red.   Jim

 

Not at all.  Pretty easy to add a mechanical gauge (my preference).  Red zone is 260 because that is where coolant often starts to boil in a car or truck.

gauge.JPG

gauge2.JPG

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28 minutes ago, jdemaris said:

Not at all.  Pretty easy to add a mechanical gauge (my preference).  Red zone is 260 because that is where coolant often starts to boil in a car or truck.

gauge.JPG

gauge2.JPG

I'm surprised, you have an automatic transmission!

You like those pre computer Toy's.  What about the newer ones with computers?       Jim

 

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48 minutes ago, jjrbus said:

I'm surprised, you have an automatic transmission!

You like those pre computer Toy's.  What about the newer ones with computers?       Jim

 

I hate having an automatic.  Just happens to be the way it came for $1800.  It's a 1988 and certainly has a computer.  In fact,  I had two (had a spare) but sold my extra to someone on this forum for $50.  After seeing your problems, I wish I'd kept it.  I had a 1983 Datsun Minicruiser and that had no computer, a 5 speed man. trans, etc.  Also had a full-floater rear with a 4.30 ratio.  In retrospect, I wish I'd kept it and sold my Toyota. I think I paid $1200 for it and the truck part was like new. Not a sign of rust anywhere.  I did not want to use it until I put it in my shop and checked it all over.  Then some guy stopped by and offered me somewhere around $2500 for it. In a weak moment - I sold it to him, figuring I'd pretty much doubled my money with little effort.  It also then took a mental burden off of me, worrying about getting it all done over.  That was my 4th micromini at the time and I was feeling a little overwhelmed. Now - I suffer from "grass is greener on the other side of the fence" syndrome. I have two Chinooks and the Toyota Minicruiser.  Yet I sit here thinking how that Datsun would of been better then all the rest.  

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24 minutes ago, jdemaris said:

I hate having an automatic.  Just happens to be the way it came for $1800.  It's a 1988 and certainly has a computer.  In fact,  I had two (had a spare) but sold my extra to someone on this forum for $50.  After seeing your problems, I wish I'd kept it.  I had a 1983 Datsun Minicruiser and that had no computer, a 5 speed man. trans, etc.  Also had a full-floater rear with a 4.30 ratio.  In retrospect, I wish I'd kept it and sold my Toyota. I think I paid $1200 for it and the truck part was like new. Not a sign of rust anywhere.  I did not want to use it until I put it in my shop and checked it all over.  Then some guy stopped by and offered me somewhere around $2500 for it. In a weak moment - I sold it to him, figuring I'd pretty much doubled my money with little effort.  It also then took a mental burden off of me, worrying about getting it all done over.  That was my 4th micromini at the time and I was feeling a little overwhelmed. Now - I suffer from "grass is greener on the other side of the fence" syndrome. I have two Chinooks and the Toyota Minicruiser.  Yet I sit here thinking how that Datsun would of been better then all the rest.  

I did not realize yours had a computer.   Most of my problems were caused by I don't know what I am doing and people insisting that it is almost never the computer!   It got to the point where I had no options but to get the computer checked.      

I am keeping an eye peeled for someone parting a 93,  I will grab the computer and ignitor and such if I can.  There are not many computers available for the C&C.

Only 4 micromini's?   I'm glad I do not have any room so I will not be tempted to become a Toy hoarder!    Jim

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I think you are over thinking the temp gauge. Check it with a thermometer at various readings then you will know what the temp is as how it relates to the gauge this is one reason they quit putting degrees on the gauge face.

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Well, that's the thing. If I get high temp readings (like 240+) I'll assume the sensor and gauge are okay and will look elsewhere. If the temps look normalish despite what the gauge is reporting, I'll change out the sender, and see where that leaves me. I have to get this solved - won't take it on the road like this. 

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My gauge is running the other way.  Waiting to get my new rig back from tire shop and then will use my thermal gun to see what the truth is.

As for finding the parts, frankly I think I am going to give this guy most of my business.  Planning on putting in an order this week after I inspect and see what I need.  He pretty much carries everything we need and what a useful resource.  I just think anyone that has all that put together is worth giving my business to. That said I have yet to do so.

http://www.22reperformance.com/22RE_Performance_-_Installation_Parts.html

Going through the engine, including cooling, is my next step and being as I am going to be doing it myself I was thrilled to read such a write up.  When I was actually able to talk to the guy who wrote it I was hooked. 

 

Wade

 

 

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A local club contacted an AC company because of AC comfort level issues, they wanted to have a humidistat installed.   The AC company told them before doing anything to install a wall thermometer next to the thermostat and check the accuracy of the thermostat.   Inaccurate thermostats must be more common than I knew.    Jim

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13 hours ago, jjrbus said:

 Most of my problems were caused by I don't know what I am doing and people insisting that it is almost never the computer!    Jim

Last year, a Dolphin owner on this forum with a 1987 22RE said his engine was running badly and was suspecting his computer.  That's when I offered him my extra for $50.  He posted here after installing it and said his was Dolphin ran great afterwards.  So, who the heck knows?  Running like crap did not surprise me.  But in your case with an absolute no-run situation?  THAT does surprise me .  Computer-controlled systems usually have "default" modes to keep the engine running if main system fails.  Now you've got me thinking Toyota does not have one?

I've got two Dodge Grand Caravans.  A 1998 AWD and a 2001 FWD.  Both have had computer problems all the time I've owned them.  Charging system will stop working once in awhile. After some panic parts changing while away from home (new alternator and battery) - I found out that all I have to do is "reboot" the computer when it stops charging.  I.e. just shut the engine off, and restart and then all is fine - sometimes for months.   So, now knowing that - I refuse to get to computers fixed on old vans.  These Dodges are kind of odd because the alternators have no discrete voltage-regulator.  It is built into the main ECM.

Jim - what you did with diagnostics is what I need to do with my 1988 some day.  I just don't have the patience and not as motivated since it runs fine.  Fuel mileage has gone from 14.5 to 12 MPG and I ought to sit down and do a complete diagnostics on all the electrical components.  What irks me is the system is supposed to throw an error code if something is amiss and I have no code.

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