Engine getting hot but not overheating

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Engine getting hot but not overheating

June 19, 2007, 06:47:56 PM

So thanks to the hot weather I have a fun little problem. When I'm driving with the A/C on on a warm day (~90* or a little more) the T-bird gets warmer than normal. Last year the car would go up to 5 bars on the digi dash in city traffic with the A/C on (ie go 45 for a bit, stop sit at a red light, drive again ect) and now it'll go up to 6. Now that's the last bar in the normal range which has me worried. It does this if I'm driving on the highway at 70 mph or in city traffic but it comes on quicker in city traffic. I've checked the fan clutch and with the engine warmed up I can grab it and then spin it about 1/2 way around before it stops (I'm not holding it and spinning it. If I did that it'll just keep going around and around:hick: ). I believe that's normal. My guess is it's either the fan clutch or the radiator. The radiator is the one that's always been with the car (I didn't change it with the HO swap) and it's pretty clean inside. Any ideas? The car runs just fine if I drive around with the A/C off in 90* weather. It goes to 4 bars and stays there. The only difference between this year and last year I can think of is that I had two bottles of Redline water wetter in the cooling system and didn't put it back in. Perhaps this would have happened last year if I didn't have that in there. Sorry for the rant but if you guys have any ideas let me know:hick:

Engine getting hot but not overheating

Reply #1 – June 19, 2007, 10:02:54 PM

it still sounds like the fan clutch. here in florida's insane heat we get cars in the shop all the time with symptoms similar to yours. even if the clutch tests within the loose side of specs we replace it and the temps come down. there is a possibility of clogged tubes in your rad. look for cool spots in the core. a digital laser thermometer is good for this or be extremely careful and use your hand. engine not running of course. also could be a partially stuck thermostat. if it doesn't open fully could cause your symptoms. also if every thing else checks out look at your waterpump impellar. i have seen the impellar rotted away and the pump not leak. well that should keep you busy for a while.

Engine getting hot but not overheating

Reply #2 – June 20, 2007, 10:17:37 AM

A half turn on the fan clutch should be fine, but you never know. Hotter heads and cam will run warmer regardless. I'd step up to a 3 row radiator. Autozone sells the Visteon (OEM manufacturer and VERY reliable) in a 3 row application for a little over $200.

I'd also check the voltage at the water temp sender.

Also, what temp t-stat are you running?

Engine getting hot but not overheating

Reply #3 – June 20, 2007, 11:13:29 AM

did you check that fan clutch with the engine cold?

if so,, sounds good to me
-----------------------------------------------
ECT sensor test
Resistance test pin to pin of the sensor (this is a variable resister proportional to temperature including outside air temp if the motor is cold)
at 50degF=58K ohms
at 65degF=40K ohms
at 180degF=3.6K ohms
at 220degF=1.8K ohms

next clean the end of the sensor with scotch brite ect and retest
if high temps persist, replace coolant temp sensor and ECT as a matched set.
if that does not work, start looking at your coolant system parts.

------------------------------------------------------------
Coolant Temp sensor (1 wire)feeds the dash display in parallel with dash resistor.
resistance measurements are taken from the threaded stud to the housing
With a bone cold motor the resistance should be high or open
First , remove the single wire and ground it with key on
you needle or guage should max out
next unhook your oil presure switch and reconect temp sensor and retest
next , with a hot motor, unhook the single wire
your resistance should be very low approaching a short
next clean the end of the sensor with scotch brite ect and retest
if high temps persist, replace coolant temp sensor and ECT as a matched set.
if that does not work, start looking at your coolant system parts.

Engine getting hot but not overheating

Reply #4 – June 20, 2007, 11:26:10 AM

Overheating (or just running warm) in the city and on the highway makes the radiator suspect.

While cruising on the freeway, the cooling system doesn't need any assistance from the fan.

But, only the fan is ruled out by this symptom. You still could have a faulty thermostat or a borderline pump.

Engine getting hot but not overheating

Reply #5 – June 20, 2007, 12:40:23 PM

"Overheating (or just running warm) in the city and on the highway makes the radiator suspect.

While cruising on the freeway, the cooling system doesn't need any assistance from the fan."

I totally agree with Jeremy. Ram air through the rad should be enough to keep the engine cool at 70mph. The fan should be in free spin at that speed. The a/c condenser does add a lot of heat load to the rad and so does your extra HP. Your 20yo rad has served you well, you could either get it flushed out professionally or just by a new one. You'd be surprised how well a new single row aluminum rad will perform.

Engine getting hot but not overheating

Reply #6 – June 20, 2007, 06:19:45 PM

Ok first off I wrote something wrong:hick: . On the highway/constantly moving it's fine. It's stop and go traffic where it heats up. It also only does this on days above 85*. The water pump and thermostate (180*) were just changed when I did the engine. The radiator moves coolant good and the thermostate opens fine. I also noticed no cold spots on the radiator.

Quote

did you check that fan clutch with the engine cold?

if so,, sounds good to me

No that was with it hot. I checked today again with it cold and noticed it spins the same ammount. So hot or cold it spins 1/2 way around. I'm guessing my clutch is going bad slowly. I ordered a new one today from Summit so I'll change it and see if it solves my problem.

Quote

A half turn on the fan clutch should be fine, but you never know. Hotter heads and cam will run warmer regardless. I'd step up to a 3 row radiator. Autozone sells the Visteon (OEM manufacturer and VERY reliable) in a 3 row application for a little over $200.

3 row is a winter project:D

Engine getting hot but not overheating

Reply #7 – June 22, 2007, 07:48:36 AM

Quote

3 row is a winter project

I would imagine you would need it most now. The sooner the better.

Engine getting hot but not overheating

Reply #8 – June 23, 2007, 02:34:58 PM

Quote from: V8Demon;156201

I would imagine you would need it most now. The sooner the better.

I got a new fan clutch and it solved the problem. It is a heavy duty (5.0 Mustang Police spec) clutch and it moves a LOT more air at idle. Hell with the A/C on when it's 90* out it stays at 4 bars, at idle:D . The fan only moves at most 1/4 of the way around when cold vs. a little over 1/2 way that the old fan went. Now I bet with a 3 core it would run even better. I'll have to get on that when I get some free time.

Engine getting hot but not overheating

Reply #9 – June 23, 2007, 10:39:48 PM

Ijust upgraded my cooling system to the 3 row core rad and a new fan clutch due to the rediculous traffic I sit in on the way homw from work. Made a huge difference. The cat stays cool in traffic while I slowly smoke myself to death:hick:

Engine getting hot but not overheating

Reply #10 – June 30, 2007, 01:18:23 AM

Well now it running too cool:hick: . It was 62* out tonight and I went for a 35 mile drive and the guage went to 4 bars once and then dropped back down to 3 bars. So I drove 35 miles barly in the normal range. It has a 180* thermostate and I think I need to go to a 195 to let it run a little hotter.......and this is with the stock 20 year old 2 core radiator.

Engine getting hot but not overheating

Reply #11 – July 05, 2007, 07:22:33 PM

WEIRD----Recently I replaced the thermostat (no change) and then the fan clutch on our '88 TBird. No change for engine operating temp. The radiator is only 3 years old and the antifreeze is pristine. The waterpump is indeed over 10 years old. I replaced a waterpump on a '95 Pontiac a couple years ago and compared the replacement to the old one. The old one virtually had no impeller blade surface area left--they had been eaten away. The car had been running hot. As I am not particularly thrilled about ripped out a TBird waterpump, I have stopped the process for now.
Funny----now the AC in the T-Bird is ice cold, and for the first time in years I have to redirect the vents away from me to keep from freezing to death. Wish I changed the fan clutch years ago.