I recently purchased an '85 4+3. After I have driven it long enough to reach normal operating temperature, I check the readouts. The oil says it's @ 235-240 degrees and the coolant still says "Lo."

Is this normal? What could be going on here?

Thanks!
-Kyle

 

If your oil temp is 235-240 then your coolant temp is likely about 220. The coolant readout says Lo until the engine reaches a minimum temp of 100. As I doubt your engine coolant is under 100 while your oil is 235, I would say check your temp sensor and wiring.

If you haven't been hot-footing it any to reach those oil temps, seems a tad bit warm to me. I run 190 water with 201 oil on a hot day (90 plus) just cruising. More agressive street driving brings water up to 210 and oil to 225. I do have some cooling mods but no coolers. Maybe you will want to check the whole cooling system out, clean out the rad, change fluids

 

Sounds like the temp sender is disconnected. Should be on the right head between #6 & #8, though for the '85, it may be on the left between #1 & #2. Find the wire and make sure it has a good connection to the sender. Test by grounding the wire against the block - gage should read 300 or so. If the the connection is good and the gage reads ok when the wire is grounded, you need a new sender. NAPA should have it.

 

Your car will run cooler because it's an LT1.

Another vote for disconnected sensor, or a bad sensor.

 

Thanks for the help. I was initially told that the dash was bad, since the fan would still turn on. I suspected a sensor, but thought I'd be best to double-check.

I just bought this particular '85 with 65k. I already swapped out the Diehard for an Optima, replaced the fuel filter, new K&N air filter, and valve cover gaskets.

Here's my Minnesota Winter plan:
-Remove the hood (It's just easier!)
-Change every fluid & filter (Oil, trans, coolant)
-160 degree thermostat
-2.5" SST Manifold-back exhaust (Should I wrap the front y pipe?)
-Coil thru plugs tune-up (No MSD box)
-Test every sensor and replace as necessary
-Inspect and clean cooling system areas
-Replace broken antenna mast w/ Harada style and bypass switch
-Install adjustable fuel pressure regulator
-Possible chip replacement
-Troubleshoot why I don't always get hot air out of vents

While I have it all apart, is there anything else I should consider replacing? Any tips? Any simple ideas to increase HP/Torque? It looks like everything is original equipment on this. Anything I should look for? The future will be working on suspension, brakes & tires. For now, they're good enough. In time, I want to tastefully restore this vehicle to 'better than the original' performance without going overboard.

Thanks again!
-Kyle
A humble neophyte

 

heck, if you're gonna go the extra step and remove the hood, might as well just yank the motor out and replace it - i mean, the hood will already be off!
i would say to do the throttle body coolant bypass - but you are in a colder climate, it's probably best you leave it like it is.

how about an electric water pump to free up a few horses?

while you are into it - you might as well remove the radiator "cover" and see what garbage has made it's way in between the condensor and the radiator - this could be causing some of the high temps - as mentioned before, these C4s are magnificient garbage collectors - everything from cigarette butts to plastic grocery bags and everything in between!

other than that, i don't know exactly - you look like you are going way above and beyone what i did on my '85

 

That's my grand future plan: Build a new engine and swap it out. We'll see if the wife lets me.

Electric water pump? I must be quite the fool, because I have not heard of this. Where would you suggest I look? I imagine that would require a change in the belts as well?

Thanks for the help.

 

not exactly sure about where to find the pump - i think meizere (sp?) makes one, there is another manufacturer out there too - if you search this tech forum for waterpump, i'm sure you will undoubtedly find several posts about them.

also i just noticed - you plan on a 160 stat - you might get a lot of boos and hisses for this - the reasoning to keep stock temp tstat is to help boil off condensation in the oil to prevent the innards from rusting - and besides you are in minnesota - how hot does it actuall get there?
i'm in AZ - so my c4 has a 160 stat in it - and let me tell you - it gets HOTT here - and i'd rather be able to use my A/C in the summer rather than the winter so i'll stick with my 160.
but if i were you - i'd start with removing debris in front of the radiator to help lower those temps - and replace that coolant temp sensor to get an accurate reading.