-----1997 DODGE B3500 SLT EXTENDED PASSANGER ---- 186,000 miles 5.9L

When its cold outside the temp needle stays below that 1/3rd mark, ( lets call it 30%) nearly on it but never over it.
In the summertime when temps increase it reaches Halfway past the 1/3rd mark. about 50/50 position.
There's a surprise here though. WHEN I TURN MY A/C ON IT REACHES 2/3rds NEEDLE! ( 65% )close to the last heat zone. before reaching (H).... HOT
The only thing i can do to cool it back down to 1/3rd is to turn the heat on max and let it vent thru the cab ( come on guys its getting in the 90's this week )
It has a new radiator cap, Thermostat, just did COOLANT flush thru Valvoline few months ago. hoses get rock solid , so with that said I maybe guessing wrong here but would assume that my water pump is working fine? correct me if wrong.
what could be my issue here? there's not a chunky coating of bugs and trash on the radiators fins, but there's a considerable amount. don't seem to have any leaks since i replaced my radiator cap.
Should I mention that I have NOT repaired the plenum plate yet and there is a very slight bit coating the upper intake.
oil changed Although I have noticed my oil pressure be pretty inconsistent. I'm not sure if its supposed to go from 28% needle up to 60% difference in the span of 15min. which one is better? low or high? are both bad? should it be 50% needle?
I think i have covered everything that i know about my situation.
any advice is much appreciated as i will be a boiling lobster in the drivers seat trying to stay alive on these hot days to go to work. it seems like i have 2 options here. be cold while driving eventually detonating my engine or face the heat with the heat on.

 

get a nascar radiator

 

You might try some water wetter in the radiator and the other thing to check is your fan clutch. Another thing to do would be to blow out or wash out the radiator. Be surprised how much dirt and sand gets lodged in the fins. I washed out my cars radiator lying flat on the garage floor and when I got done there was literally a layer of mud on the floor.

 

So I did remove the radiator and clean it really good. I can see thru 99.9% of the fins. Held it up to a street light and seen no cloggs when I was done. It is also running cooler. Any how, i was curious since my temp guage does not show temperature in degrees, it only shows hot and cold with a needle that fluxuates between the 2, how do i know what temp zone the needle is in? could someone tell me what temperature these markings represent? I heard running between190 ( cooler days ) and 220 ( hotter days) is normal operating temp. I'll upload a picture of my guage. Notice the 3 (1/3) markings. You have cold, 1/3 , 2/3 and then 3/3 which is Hot. At night My van normally runs right under the 1/3 mark. What temp is that? Then in daytime during summer it reaches little over 1/3 - sometimes into the halfway point. What temperature does the halfway point represent? Here are some pics. Trying to get an idea if I'm actually overheating or just paranoid from running hot on hot days.

Temp zones? No numbers just 1/3rd markers.

 

Get a scan gauge and plug it into your obd port. There are a number of options as to what you can monitor.

 

Theoretically, if the needle is between the marks connected by the solid line, it's all good.... And temp vs. needle position? Only real way to check that would be with a scanner, or, as mention above, scan gauge..... I have noticed that Dodge gauges are NOT linear.... I changed the thermostat in my truck, because I though it was running too cool, only to find that when the engine is up to temp, the needle was in the same place.... Shoulda checked that FIRST.

 

I'm going to assume these temperature issues are while driving and not while idling. If that's the case, you can rule out the fan and fan clutch. What I'm a bit puzzled over is how it seems to run cool in the cold and hot in the heat. The temperature should be fairly consistent, even while using the AC. It's acting as though the thermostat is stuck in the slightly open position, or it's installed upside down. If you're confident the t-stat is okay then I would replace the radiator, because the symptoms indicate it is partially clogged.

 

So while it's idling at night it stays cooler. While idling in hot summer daylight it idles hotter. But while driving with the AC on is when I get the hottest Temps. I can run night Temps during the day with my heat on full blast driving and sitting idle. Next thing I'll try is replacing the radiator.

 

It would be cheaper to find a radiator shop and have it boiled out. They are a bit rarer these days, but if you can find one they should be able to help you out.

 

What do they charge for that service these days?