Temperature Climbs When in Stop & Go Traffic

[DieselSpider]

This is a good reminder to flush the coolant on my cars in particular the Spider

It is funny how blurry the line can be on a Spider having an overheating issue or not. Add to this that cars made over the last 20 years rarely stray from the perfect operating temperature "on the gauge" once they are warmed up. For example you know the modern day car is running hot as you sit at a stop light and the fan cycles on and off and you pick up on the slight change in engine operation/idle. However, the temp gauge never moves. On our cars the needle looks like it moves quickly and between 188 and 205. We already know they can have overheating issues and nobody wants to blow a head gasket. Again, something that rarely happens on modern cars. So...we sit in traffic and look at the temp gauge. Even the most confident of Fiat spider owners looks at the temp gauge for that remote possibility that today, despite our best efforts, could be the day she overheats.

So true. On current fuel injected computer controlled engines the computer starts the fan and if thats not enough starts resetting timing and fuel mixtures to maintain a pretty constant temperature. The old mechanical fan switch in the radiator compared to a modern computer controlled engine has a pretty large range between the temperature at which it cycles the fan on and off again with the set points shifting as the parts start to wear out.

Will today be the day it fails? I put in an override switch that I can flip on when the days are hot and I want a little more cool down after the fan cycles off along with an adjustable external fan thermostat.

Less than $20 at Advance Auto Parts:


http://shop.advanceautoparts.com/p/impe ... hermostat#

[georgeramos]

I think my problem with this same issue was (is) a small leak, or several over the past few years, that was small enough not to notice at routine inspection. Once i climbed under the car with a light i could see the lower rad hose had some moisture seeping past the clamp. So when id burp the system thw car was fine for 2 or 3 drives until the air "bubble" became large enough to block the stat...then id have overheating issues. Fixed the hose clamp then it happens again and i notice water pump flange dribble so toghten the bolts, fixed again, great for 2 to 3 drives, then again, small "squirt" every now and then from the coolant tee i put on the heater hose so i changed it...so far fine. Now im checking coolant level before every drive...

[joelittel]

"Now im checking coolant level before every drive..."

I know exactly how this feels and I never want to be in that position again. Good luck with yours George.

After further inspection of my new fan I'm not convinced it's as nice as the stock one was so I'm tempted to find a better one. Any suggestions or opinions?

[georgeramos]

it may not be as nice but if it keeps the temps where you want em I say keep it!

[DieselSpider]

it may not be as nice but if it keeps the temps where you want em I say keep it!

Some of the aftermarket fans tend to be not as nice in that they vibrate an awful lot putting a lot of additional stress on the radiator core. Best to replace one of those with something smoother running before it does any collateral damage. If its not as pretty then that's another matter as I would say function trumps form in this instance.

[joelittel]

I should have been more clear. By not as nice I meant that my new fan doesn't pull as much air through the radiator as my stock one did.

I wish I had looked at the statistics before purchasing the new fan. I had assumed it would work as well as or better than the old one but I was wrong.

It's a curved blade fan, and in another post some of the guys were saying that they've read curved blade fans don't move as much air as a straight bladed fan does.

It is, however, much quieter than the stock unit.

[DieselSpider]

It does have to move enough air to cool the engine. I bought one high volume fan that did move alot of air but it also vibrated so badly that it would make your coffee splash out of the cup and make your side and rear view mirrors vibrate so badly that you could not see what was being reflected. The fan wasn't cheap either coming from a respected local supplier.

[joelittel]

Over the weekend I was able to put my fan to the test, and unfortunately my suspicions are true. While stuck in gridlock for about 20 minutes my fan struggled to keep the temp at a reasonable level. The fan was fighting a losing battle and it was only a matter of time before it became a situation. If I had been stuck in traffic during July at high noon I would probably be writing a very different type of post today.

I think the cooler air temperatures have helped my current fan do it's job, but I'm not willing to roll the dice once the summer heat starts up.

I'm replacing it with a straight blade Spal as soon as I can. However, my fingers are crossed, because I don't want to trade up for a vibration problem either.

[vandor]

When the cooling system is working properly the stock fan has no trouble keeping the engine cool even at 100 F (38 C).
If it does not the fan may not be getting enough voltage, the fan motor may be worn out (I have never seen that, tho, usually they either work or they don't), or the radiator is semi-plugged up.
If it is the radiator one can tell by feeling the temperature of the air that the fan is pushing. It should be quite hot. If not, then even tho air is moving through the radiator, there is not enough water moving through the radiator.

[joelittel]

My setup is no longer stock. Not too long ago I had to replace my radiator so I "went big" and put in Vick's Texas Heat aluminum radiator. This unit is a bit deeper than the stock unit so my stock fan no longer fits the space. If I could use the stock fan I would, that thing is amazing when compared to my new aftermarket curved blade fan.

My current fan works but it seems to offer diminishing returns at best. Meaning over time, and in heavy stop and go traffic, the temperature will rise. If I'm moving at all the temp quickly comes back down, which I assume is due to the larger radiator.

My wife loves to drive this car so I need it to be sorted before I can feel good about letting her use it as her daily driver. She knows to watch the gauges and listen for new noises, she even knows what to do if the temp starts to rise, but her commute is nothing but stop and go traffic so I need to get this fix done before giving her the all clear.

[DieselSpider]

The DieselSpider barely has enough room for the waterpump shaft to clear the radiator so the stock fan was moved to in front of the radiator and now blows through it.

[joelittel]

Any chance you could post a couple pictures of your diesel spider fan setup?

[vandor]

Something is wrong - either it's a really poor fan, it's not sealed well, it's not getting enough voltage or somesuch. I bought a cheap 14" fan ~10 years ago and it has no trouble cooling the mild 2-liter with a smallish radiator.

How high does the temp climb when the fan is running? Would it overheat (~210F+) if you'd let it?

[joelittel]

It's a 12" fan, curved blades.

The cooling system seems to hold pressure, I assume this because when I open it a splash of coolant either "pops" out and/or I hear a sound like pressure being released.

If I were to let it go my feeling is that it would slowly creep it's way into the red zone on my temp gauge. So slowly that while idling in the driveway two cycles of the fan aren't enough to indicate a problem. But if I let it idle while I wash it before I'm done the temp is well above where it should be.

Idling in the driveway takes some time before it overheats, but it will eventually get there. On the other hand, being stuck in stop and go traffic helps the process along much faster.

[joelittel]

The new fan went in this morning. Spal # 30100400 16" Low Profile - Straight Blade - Pull. Even though it has 6 additional inches on my old fan's diameter it fit much better than both the stock and the generic fan I just took out. My first impression was that this will make it a lot easier to see the timing marks going forward.

I let the car idle in the driveway while watching the fan cycle on and off many, many times. The needle would move between it's highest and lowest readings over and over again, never really deviating much in it's range. I let this go on until I felt satisfied that the temp wasn't going to creep up on me like last time. I think my mistake with the 12" fan was that I only waited two fan cycles before proclaiming victory over my climbing temperature dilemma and driving around town all weekend.

While watching the gauge ping pong I noticed that my idle speed was way up, as in 2k+. Then I remember last year, while in for some brake work, my mechanic told me he had to adjust the idle speed because the car was running either rich or lean, I can't recall which. I trust this guy (because my car always comes back running smoother than when I left it with him) so I didn't think much of it and I didn't write in my notebook what he told me. I knew 2k to be the wrong idle rpms but winter came and I went from driving mode to maintenance mode and didn't do anything about it. I guess I thought with my recent header and exhaust mods this might be the new norm.

Then I remembered that the very first thing I did to the car, the month I bought it, was to adjust the spring on the AFM to trick the ecu into sending a little more fuel according to "Greg's Bosch L-Jetronic Fuel Injection Idle Adjustment, Diagnostic and Tune Up Page."

So I put the AFM spring/gear back to it's stock position and set the idle as close to 850 rms as I could. I'll have to go back to my mechanic and have him test for a lean/rich mixture again but for now I believe this can't make anything worse.

I can't help but to wonder if the faster idle speed and the tweaked AFM, combined with other recent mods all contributed to my issue.

Just to feel more confident about "fixing" the problem, I let the car cool down and ran the same test again later, meaning while idling in the driveway I let the fan cycle on and off many, many times while keeping an eye on the temp gauge. The photos below show the high and low levels.