overheating problem (and some questions)

[81SPIDERMATT]

I think that the fan has power all the time and the temp switch when working creates the ground as it activates to complete the circuit ... if I am correct than yes jumping the terminals of the switch would work .. but I would also check to make sure you have power going to the fan

[btoran]

last night i verified i have power to the fan when the ignition is in the on position.

[TX82FIAT]

The dash temp gauge can be off a few degrees as well. notice if the car runs hotter when you turn the lights on...It is not really running hotter you just changed the distrabution of power in the system. On my car it runs all day at 178 on the highway at 178 per the temp gauge signal running through a megasquirt ECU that I can monitor on my phone. Yet the dash gauge reads about 185. The fan kicks on at about 195 on the gauge but it is really about 189 on my phone.

One of the items I carry in the tool box in the trunk is a four inch long wire with aligator clips on each end. This can come in handy if you think your switch to turn on the fan is not working. just jump the connection at the bottom left of your rad on the drivers side to complete the circuit and run the fan as mentioned previously. I would not by new sending units or other parts until you know exactly what the temp is. if the car is running too hot you should almost immediatly more coolant than normal starting to fill your overflow tank as it expands from heat.

Good luck, once you have the cooling system functioning it helps prevent other potential issues.

[spidernut]

Disconnect the radiator fan switch. Jump the two terminals on the wiring harness side and your fan should start running immediately. If it runs, you have a good fan.

[btoran]

interesting results...... it turns out the fan works and the car is not overheating.

the gauge on the dash is off by a bit, but not too badly. at about 190 degrees (as measured with a heat gun on the top of the engine), the fan does turn on but there is a problem because the whole fan/radiator shakes violently. this is what happened yesterday and i thought it was overheating, so i shut it down waited and then drove it home. i was close to home so the issue did not reoccur.

tonight, i shut the car down and had a good look at the fan. one of the fan blades cracked off and is missing, so the fan is terribly out of balance. what i thought was the car overheating was just an unbalanced fan shaking me around a bit.

it looks like just a few bolts hold the fan to the radiator. can i remove the fan without having to disconnect the radiator? and can i simply change the fan blade assembly instead of the entire fan?

[azruss]

you can remove the fan without removing the radiator or any hoses. Getting the fan of the motor is another thing. I've never been able to do it without ruining the blade.

[4uall]

i have 2 fans with mounts if needed

[btoran]

Jay - PM sent.

Everyone - A question while I sort out a replacement fan..... my engine doesn't seem to be overheating and from everything i've read, it is operating close to the "normal" operating temperature. at approx 190 degrees, the fan does kick on and cools the engine just enough that the fan turns off, then it cycles on/off again. however, 190 degrees is measured at the bottom of the radiator, while the top gets significantly hotter. not sure what temp the top of the radiator is exactly, but i'll find out today. what i do know is that it's hot, real hot. the hood gets hot to the touch on the outside and inside, you can barely touch the hood pads. even the fenders noticeably warm and stays that ways for hours after the car is shut down. i'll test the temp on the inside and outside of the hood today, but is this normal?

[4uall]

I can only speak from my own experiences and I would say "no" this is not normal

There are fan temperature sensors that are set for to activate at lower temperatures however, we should try to identify your cause first.

pm enroute

[spidernut]

Your hood and fenders should not be getting hot to the touch apart from the sun beating on them. Is your exhaust manifold heat shield still in place? That's where most of the heat will come from.

There will be a difference in engine temperatures at multiple points on the car including the top and bottom of the radiator. It normally won't be a huge difference, but it will vary. If the thermostat is closed, there will be a significant difference in temp between the block and the radiator. Once it opens up, it should be much closer in temperature.

If there is a huge difference in temperature between the upper and lower radiator, the radiator may need to be rodded out if it isn't flowing correctly. It is a simple procedure to remove the radiator and not expensive at all to have the radiator rodded out and pressure tested if this is the case. Measure the temp at the top and bottom of the radiator when the engine is fully warmed up.

The only source of extreme heat I've ever seen under the hood of a Spider is the exhaust manifold. The rest of the motor gets hot but not hot enough to make the hood and fenders too hot to touch. I'd check for a heat shield first.

[btoran]

I ran some additional tests by letting the car warm up with the hood closed. i checked before running the car and oil / coolant was full. the fan kicks on at around 190 and cools it off. a little while later, the fan cycles back on. the duration between cycles is reduced each time and the temp on the outside of the hood (and presumably inside) increases each time as well.

here are the temps with the car running for 30 mins after the fan first cycled on:

outside air: 75
outside of hood: 100
hood padding: 110
top of air cleaner 130
top of block 206
top of radiator 205
bottom of radiator: 145

i have no doubt that the temps would have continued increasing until the hood (and everything under it) was very hot, but i didn't want to push it because a) with the fan missing a blade, the car shakes something fierce each time the fan kicks on, and b) i didn't want to damage anything when the engine actually overheated.

do the temp diffs at the top/bottom of the radiator indicate a blockage and/or thermostat problem?

i'm sure the fan isn't moving air very efficiently since it's missing one of its four blades. could this account for heat not being cleared from the engine compartment?

Not sure what the exhaust manifold heat shield looks like, but it should probably go somewhere in here?

[81SPIDERMATT]

you will be surprised how much of a difference it will make when you have that heat shield ..let me say that again ... it makes a big difference ... .. I do not have a temp gun to shoot temps around the bay .... but I bet a properly cooled engine it is possible to find hot spots and "create" worry where there might not be a problem .... I have faith in the work I have done and trust my gauge to tell me what is up ...and I keep a watchful eye on it ..... past present and future I have and will think that my engine seems hot when all is fine .....

as for the shield .. I would source one and install .. did I mention it will make a big difference .. especially on the hood and that fender area .... mine is a different header but if you want I will go take a pic

[btoran]

does it look like i have the original type header? any idea where i can buy the heat shield? i checked the usual places (autoricambi and iap), but neither have it listed on their website.

[majicwrench]

This is close to "Good Grief" why are we measuring, and worried about, the temp of the hood?? If the fan cycles, the system is under control, fan can remove enough heat to reduce temp. And a fan with all four blades will work even better!!

YES hood will get hot!!!!! Don't go looking for problems.

"Heat shield" over exhaust, heat is still there, still gonna get out, is not going to go anywhere else just cause you have a piece of tin over it. Most of those are designed, not to reduce heat, but to direct heat into the air cleaner.

Keith

[btoran]

when the outside of the hood gets too hot to touch, and the fenders are very warm, i get worried. if that's normal for these cars, i'll stop worrying. so far, no one has said it's normal.