After running my Metric conversions. I find your situation the same as mine was. I tried the cardboard in front of the radiator trick. It improved the temp. It also if not placed properly would overheat my engine. I then went and bought a Stant Super Stat thermostat. Installed the same, and had an immediate improvement in both performance as well as MPG. Idle temp will not be as high as operating temp, but will be very close. Give it a shot, it's only about $14.00 bucks US. Hope this helps, Jim.

 

Hello,

have you had the van read for codes lately? Anyone number of those codes could indicate problems that will affect the overall temperature of the van.

when was the last time you had a tune-up? What kind of replacement parts did you use?

does the van have a smooth idle?

 

Thanks. The last time I used an AC delco replacement thermostat. The engine doesn't run perfectly smoothly all the time as well and I was thinking of replacing the distributor since replacing the cap,rotor, and plugs doesn't solve the issue. A while ago the water pump went out which might have also affected thermostat performance. I'm also planning to replace the thermostat again because of this, but I'm still not sure if this will get the temp back around 91C. Is it the type of thermostats that I've been using that are keeping the temp lower all the time or is there something else keeping the temperature lower than usual?

 

When was the last tune-up performed? And were the plug wires also replaced?

Really, I spend more time diagnosing the problem instead of throwing parts at it. Verify that there are no codes stored and go from there.

 

Tune up and plugs were done about two years ago, but although it ran more smoother then...it still wasn't perfectly smooth. No Service engine light ever comes on so I guess there aren't any codes (when I plug in an OBDII reader I get no codes). Both of these issues affect the average MPG, but what exactly is affecting the temperature that is usually lower than 91C. Is it they type of brand thermostat I install?

 

Tune up and plugs were done about two years ago, but although it ran more smoother then...it still wasn't perfectly smooth. No Service engine light ever comes on so I guess there aren't any codes (when I plug in an OBDII reader I get no codes). Both of these issues affect the average MPG, but what exactly is affecting the temperature that is usually lower than 91C. Is it they type of brand thermostat I install?

If your ignition system is not up to par, the spark in the cylinder will not be as strong as it should meaning the explosion of the compressed air/fuel gas will not be as strong. Besides this affecting your fuel mileage, it will absolutely affect the amount of heat being generated in the engine being if the explosion in each cylinder is less, a less amount of heat is created. This happens alot. Since less heat is expelled by each cylinder, the cooling system will have too easy of a job cooling the engine. The easiest way to check for this would be to remove the spark plugs and examine them for color, deposits, etc.

Unless you have a new van or have platinum spark plugs, the tune-up should be done every 30,000 miles or once a year. The tune-up would consist of changing all of the plugs, the plug wires, cap and rotor.

 

Verify actual operating temperature. Take a temp reading at the sensor location and compare. Using a scan tool, look at CTS temp. This is what the computer is seeing.

91C

=196 F
Normal operating temperature. The thermostat should maintain this temperature once the engine has warmed up.

60-70C

=140 F to 158 F
Check thermostat for stuck open.

40C-50C

=104 F to 122 F
This is what I would expect from an engine missing a thermostat.
Also take a look at the fan clutch. A locked up(bad bearing) fan clutch robs horsepower and km/L. When you get the thermostat out, see what the temp rating is. It might be stamped on the bottom. When you get the new thermostat, check the rating.

 

Thanks for the advise-I'll double check the ratings on the next thermostat I replace. I think my temperature stays really low now because of the water pump failure I had a while ago that affected the thermostat through overheating. So replacing the thermostat again is a good place to start keeping in mind the temperature specifications on the next one I put in. Speaking of the fan clutch, is it usually supposed to engage when the engine is cold after starting. In the owners manual it says that it's normal to hear the fan after starting. Usually after starting in mild temperatures, I can hear the fan working and under acceleration it gets louder. After you get to second gear the fan noise goes away and stays quiet for the rest of the time driving. Maybe the fan has something to do with keeping the temperature lower all the time (almost around 90C but usually lower around 60-70C), or maybe it was the thermostat I had inside. About the fan, Isn't it usually supposed to engage only when the engine is hot? I rarely ever hear it running loud when the engine is warm. Maybe it always runs but quietly. How do you know if the fan clutch is "locked"?

 

i say thermostat. like the others. had it happen in my 92, i would drive for 25-30min before i got heat, put a new thermostat in and with in 5 min had good heat, and within 10 min engine was easily up to temp (190F) in the winter. with a good thermostat the engine will warm up fully and stay there regardless of how it runs or the load. if the engine is never fully warm then the computer makes the van run rich (like a half choke on a carb engine) so this could explain any low fuel mileage. though i tune up my be a good idea when the problem is fixed but i don't think that is the cause of the low temp.

 

Hi!
I have found that thermostats often fail to close properly after an overheat.
Also, the temp gauge might not be 100% accurate.
My temp gauge never goes higher than like 155 F and the thermostat is changed, checked and tested again and again. Cardboard is all over the radiator. I checked the temp via OBD and it shows somewhere round 200 F.
My conclusion is that my gauge must be off.

 

thermostats often fail to close properly after an overheat

Excellent point!

my gauge must be off

Keep in mind the gauge sender is located on the drivers' cylinder head.
Might be worth a shot.

 

How do you know if the fan clutch is "locked"?

Your fan clutch is fine. If it were locked, it would make a tremendous fan noise all the time.

Speaking of the fan clutch, is it usually supposed to engage when the engine is cold after starting. In the owners manual it says that it's normal to hear the fan after starting.

Yes. On a cold engine, even a brand new one will start in partial lockup and freewheel within a matter of seconds.

 

How hot is the heat inside the cabin?

 

The temperature gets really warm after the heating has turned on and after/during driving around 10 or more minutes from a cold engine. In the cold weather now, I noticed even after driving for more than a while, when I stop and put the Gear into Park, I can hear the RPM increase ever so slightly than what the RPM is when the gear is in Drive with the foot on the brake-and stay constantly at that slightly increased speed. It doesn't do this all the time, but in colder weather I've noticed it. Then when I shift to drive, the RPM goes down to normal and when I shift back to Park it goes back up SLIGHTLY and stays at that speed. I also noticed that when I shut the engine of then I start it back up right away, NOW the RPM is normal in Park. I guess the RPM increases back up in Park after driving for a while. ( Is this all because the engine temperature is usually around 60C (on average)-making it seem the engine is cold and therefore it increases RPM SLIGHTLY to keep it warm? Also, sometimes when I shift from Park to Drive or Reverse, it shifts fine into Drive or Reverse and then a second or two later the RPM increases (really slightly-for a second or two), and then goes back down to normal. Is this because the engine is still cold-not fully warmed up? I still didn't replace the thermostat since the last water pump went and am speculating that a partially open thermostat valve may be the cause of all of this.

 

While you are replacing the thermostat, take a look at the throttle body where the throttle plate meets the bore and clean if necessary. The idle air control valve (IAC) may be hunting trying to maintain RPM.

 

I checked my report/receipt for when the water pump was changed and found out that they actually did replace the thermostat. But, I've also noticed that the fan works all the time too, and am not sure if that is normal? It's not as loud when the hood is closed, but I can still here it running and it's louder when I look under the hood. It seems like the fan is running all the time no matter when I look under the hood. Is the fan supposed to work all the time? Probably that's why it's cooling constantly and keeping the temp around 60C.

 

The cooling fan is always going to spin unless the engine is off.

After you get to second gear the fan noise goes away and stays quiet for the rest of the time driving.

When you said this, I thought we were OK. The fan is not locked up.
Listen to the fan over a period of 15-20 minutes once the engine is 'warmed up'.
You should be able to hear the fan noise increase and decrease a couple of times during this time period. Ambient temp and whatever your vans' problem is may affect this test method. If so, try covering the front of the grille with a blanket or something and see if by blocking airflow you can get it to heat up more than normal. Then listen for the fan. Even if you have a part number on the receipt and can find out the temp rating, we're still not sure if the stat in the van is stuck open.

 

hi guys i just changed my rad cap and my operating temp has gone higher than ever before.

For the past year my temp would never go past 2 lines past the 40 mark now it went 1/2 way between 40 and 100 is this normal?

A pic of my gauge is here its in Celcius

Even while towing 3000lbs last summer the gauge never really went that high.

thanks :ty:

 

I think it should be higher. How old is your thermostat? What is your mpg at?

 

hey there well the rad cap i remove looked like the original cap so i'm going maybe guess the thermo could original too maybe.

Well my other car is a civic so I assume the shity milage is just part of the package? no? :lol: I never really fill it up because I freak out when the pump keeps going past 50 bucks lol.

 

hey there well the rad cap i remove looked like the original cap so i'm going maybe guess the thermo could original too maybe.

Well my other car is a civic so I assume the **** milage is just part of the package? no? :lol: I never really fill it up because I freak out when the pump keeps going past 50 bucks lol.

Yes, Over fifty bucks, I feel your pain. I think your engine temp should be very close to 195 degrees f. You can pull your thermostat and inspect it. But at about 12 bucks I would replace it. Proper temp rating is 195 degrees f. Jim

 

hey jim thanks so that is just a tick under the 100 mark i would guess, maybe this explains why the heater was so weak and the milage was not great....i mean it was really poor.

the original owner is a mechanic i was thinking maybe there wasn't even a thermostat ...to hide some other problem :shrug: ....but it tows strong without any problems untill now with the coolant smell in the other topic i posted in.

I just drove it around in traffic for 15 min and it was just starting to go higher so i thought i would ask. I will go for a drive now and report back.
thanks :ty:

 

The temp gauge will sit at one tick below 100C on the metric dash.. Roughly of course, it will go up and down slightly when the thermostat opens and closes.

Scott

 

As in the picture on page 2 posted by barqz, I have the exact same temperature (in Celcius) all the time. It never goes even close to 100 C, and I don't think it ever has in a long time. If it is the thermostat that needs to be replaced, is there a specific type or brand that I should get, or should I get the AC Delco original part?

 

Stant Super Stat for the win...

With the proper temp rating for your van of course.

Jim