Daymon66

okay. when i first got the car i got a check coolant message. added about 2 cups or so to the resevoir and no issues for a week or so. still kinda smell hot coolant from time to time. got the coolant light on my run today so i pulled over and all was well. got home and let her cool off for an hour or two. ran around in it again and when i pulled in driveway i got the coolant message. popped the hood and the upper left hose was VERY hot and hard (pressure) and the right upper hose was nice and cool and didn't feel as hard?????

why do i think my thermostat was/is stuck closed or something. i see no fluid leaks anywhere at all. is the hose being hot like that and the other side so cool normal???

thanks in advance for your advice

Dwayne

Hi Daymon66,
I was checking my cooling system a while back and bought an infrared temperature sensor so I could tell exactly how warm the hoses were getting. The upper (left) hose should be very warm (maybe even hot) to the touch but should register about 185-190 degrees when the car reaches normal operating temeratures with a 180 degree thermostat. The lower (right) hose brings cooled water to the engine and should be noticeably cooler but definitely warm to the touch. Here's a couple of pics of temperature readings after the engine attained operating temperature. The first picture is of the upper hose. I am using a 180 degree thermostat.


And here's the temp for the lower hose at operating temp for my '84...


If the lower (right) hose is still cool (i.e., ambient temperature or the same as before the car reached operating temperature), then something is wrong. What is your engine temperature guage reading after you drive it?

Daymon66

thanks dwayne.
temp gauge in the car reads about mid way? halfway between the second and third line.
where did you get that infrared digital temp gauge?

Dwayne

OK....your temperature guage is normal at the mid way. When I took these readings with the infrared, my guage was about mid way as well. Unless you are seeing the temp guage at or above the upper white mark, it doesn't sound like your car has a cooling problem.

If you are smelling coolant after reaching operating temperature, my guess is you have a leak somewhere (especially if you are adding coolant regularly). I smell coolant with my 96 Ford Bronco after it reaches temp but I know it has a leak and I know where it is.

As far as the IR Temp Sensor, the one pictured is a Craftsman 1000 degree model sold at Sears for about $75. My wife liked it so much she wanted one too but didn't need the 1000 degree one. I got her a 500 degree IR sensor at Harbor Freight Tools for about $40.

Daymon66

dwayne thanks brother. i was at sears yesterday picking up some more metric tools for the chest.
i'm heading back to get one now. too cool not to have.

i'll dig into it some and see if i can see a spot where it may be leaking a little. it hasn't left a spot in the shop or in the driveway yet..

good luck on all your projects... YOU DA' MAN...

Bill Ball

That sounds bassackwards. The right hose (passenger side) is the inlet to the radiator. It should be hotter than the left hose (driver side). Both should be firm once the T-stat closes off the bypass passage and water begins circulating through the radiator.

Your observation would be consistent with the radiator being plugged up.

Mrmerlin

The IR reader is the first thing to get, so you dont have to guess, for some quick leak checks look at the top of the pass side rad tank this is usually where it starts leaking. (This is the hottest coolant)
Also remove the lower aircleaner housing and check the pass side rear of the cylinder head this is where the heater control valve is connected, the short hose is usually the one that fails and also if the HCV looks old it is wise to replace the short hose and the vavle at the same time, Also see if the coolant bottle cap is looking old check its seals this shoulod also be replaced if it looks old
Check the coolant bottle it should be white, if its getting a to be a lite brown color it is time to replace it as well as the windshield washer fill spout (it will also turn the same color and crumble) and while your there remove both of the metal collars inside your new fill spout and also the one inside the top of the washer tank ( this task removes rusted metal from entering your washer system, and thus removes the possibility that your washers will spray rusty water/fluid on the paint and possibly staining the paint)

Daymon66

Bill, i agree but my perspective is to call it like i see it. thus looking at what i am working on whatever is left is left.....

passenger side to me is left when i am looking at the motor from the front of the vehicle..

sorry for the ignorance on my part.

Mrmerlin,

thanks for the advice. i'll follow up.

Bill Ball

OK, although the temperature observations sound consistent with a working radiator, the outlet (driver side) hose should still be quite warm/hot to the touch if the water is circulating (engine on, temp up enough to close the T-stat) and should be about as stiff as the inlet (passenger side). If the T-stat is not closing off the bypass, then the inlet hose should not be full/stiff. So, the radiator may still be obstructed, causing the inlet pressure to be much higher than the outlet. With the T-stat in cold/bypass mode, neither hose should full/stiff. Maybe this is normal. Check the temps as Dwayne has shown. That should be more helpful.

What is your gauge reading? Note - the gauge readings are generally suspect.

If you are slowly losing fluid, you have leak somwhere, although it may be hard to locate if it is slow. I don't have to add any fluid to the system during the 2 years between changes.

Daymon66

got it. similar readings to dwayne 183 and 147. gauge is in the middle of the second and third line.

i think i got a slow leak somewhere. will nail it down tomorrow.

the flyin' scotsman

As well as all the rubber hoses check around the water bridge (T.stat housing). There's a few O rings that may be weeping fluid.

Dwayne has a great write up: https://rennlist.com/forums/diy-928/406743-oil-filler-gasket-and-thermostat-housing-r-and-r.html

Daymon66

malcolm..... that is the deal there buddy.
i noticed some oil i think behind the t-housing down in the "pits"..
looks like i need to dive in.. may be coolant but not sure.

jpitman2

Interesting data on radiator inlet vs outlet temps. Think about this - if the outlet is 40F/22C lower than inlet, what temp setting should the fan switch at the outlet be to maintain a stable temperature via electric fans? Seems from all I have read the stable core temp should be around 90C/195F. I suspect the differential across the radiator will decrease with higher ambient temps, but even so, it would indicate that a switch located in front of the outlet should be set for at least 10C below the core temp,or around 80C/175F.
Anybody have anymore data on radiator outlet temps under high loads please?

jp 83 Euro S AT 52k