348 Thermostat Switch Locations

Possibilities, in no particular order:

1. Failed/clogged catalytic converter
2. Failed thermocouple
3. Failed cat ECU
4. Overrich running condition

If your cat is really overheating (glowing red), stop driving and get the thing properly diagnosed.

Options 1, 2, 3 can be easily verified at home by swapping components from 1/4 to 5/8, and vice-versa.


What is that other black wire and band-clamp in the picture? (The wire which is NOT the thermocouple) Is it a grounding strap?

 

Proceed with caution. You are describing conditions that mimic a failed water pump.

Do you have coolant?

 

Or perhaps a thermostat that was put in backwards? I plan to replace my thermostat during the major I'm doing on my 348, but haven't looked closely at it yet to see how possible that would be. But I'd recommend doublechecking it!

 

If you have a failed waterpump, your coolant won't circulate...resulting in your temp gages showing cold while your engine is actually overheating (an easy way to warp your aluminum heads and blow a head gasket).

Presuming based on what you've said so far that you are going to start up your 348 again (which I do **NOT** recommend at this point in time), you can at least do a test to see if your gages start registering a temperature by turning off your A/C and turning your heater temp in the driver cockpit to "HI" with fan on low (on, but at lowest setting).

That will trigger your electric heater pump, which on 348s pumps several gallons per hour...possibly enough to give your motor the circulation required to show a temperature on your water temp gage.

Needless to say, I don't recommend the above, but if you are determined to drive the car anyway you might as well test your waterpump the easy way (examining the waterpump's weep hole for moisture and yanking on it to see if it wobbles would be the actual preferred way of seeing if it has failed).

 

If your car was reaching normal temperatures after changing the thermostat 3 mo. ago, and has more recently been acting up, then I agree it must not be the thermostat being in wrong. There's not enough info or dimensions in the manual to say for sure that the thermostat couldn't go in backwards, but since it's very non-symmetric looking, it would probably not be likely. Good luck with the diagnosis.

 

what do you mean by running very cold...? Like the guage doesn't move?
It takes a long time for my 348 to come up to operating temp.

 

WTH!!! You obviously don't understand how an engine cooling system or water pumps work. The 348 water pump is a direct drive concept the impeller is on shaft sitting in a bearing set and driven(in this case) by the timing belt. It rotates and pumps when the engine runs. It can not run independently of the engine. If it stops that means it's bearings have seized and the timing belt just went too. If the engine is running the water pump will always be turning with it, the seals may leak but it won't stop until it seizes up.
Hypothetically if you were to remove the water pump from the engine picture and still had coolant the gauge would NOT show a cold reading it would over heat very quickly and the gauge would read accordingly with what the water temp was. The only time a proper functioning gauge and sender would be pegged on 0 would be if there was no coolant touching it. The coolant sender does not read air temp. You need to study up on mechanical skills before spewing nonsense.

 

Man! I hope that you weren't holding your breath and pounding your little fist while you were typing that!


Look, here's what happens when a waterpump fails: there's no coolant circulation. Shocking, I realize!

In 348s, which have multiple water temp sensors at the very top of the engine, this means that coolant won't push an air pocket away from a sensor (because there's no circulation), and it means that the coolant temp sensors won't report the correct coolant temp. So your gage can show "cold" even though your engine is overheating. Might show hot. Might show normal temp.

Drive 15 minutes and your water temp gage says "0" or low temp...stop the car, get out, and heat waves are eminating from your engine bonnet! WTH?!


But...you can run the electric heater water pump in the front of a 348 (and 355, for that matter) by simply turning the heater temp to "HI" in the driver's cockpit. That will move a little coolant, which may or may not be useful.



It's also worth noting that 348s use the smooth *back* side of the timing belt to turn the waterpump...so your engine will run even with a seized water pump. Further, a water pump can fail without seizing (e.g. impeller breaks into pieces or spins freely on water pump shaft).




(oh, you can breathe now!)

 

In my own humble opinion, this thread should be erased and started over with. It's unneccessarily confusing.

The OP seems to be suggesting that his engine is overheating because it's hot under the engine lid. Well, of course it's hot! Open the lid after driving, and what do you find? A hot engine, two hot headers, two hot catalytic converters, one or two hot mufflers, two hot radiators, a hot oil tank, hot coolant and oil lines. Sorry, but that does not mean that the engine is overheating. It just means that a lot of hot components are located in the same area.

So - is there any actual evidence that the engine is OVERheating? What does the water temp gauge say? What does the oil temp gauge say? Do the radiator fans come on normally?

In answer to the questions. There is one switch, located at the upper left corner of the right radiator, which reads the temperature of the coolant IN THAT RADIATOR and tells the cooling fans to come on when the temperature reaches a certain level. There are two switches on the top of the engine, below the intake plenum, which operate the water temperature gauge and the water temperature warning light. Are they easy to get to? NO!

You need to read your "check engine" light codes.

ND, I'm sure you are aware that a 348 timing belt will fail within seconds if the water pump is actually seized. The belt will scream, it will smoke, it will break.

 

Braahaaahaaa.. You truly are an idiot aren't you. You get so defensive when you wrong about something. I would love for someone to step up here and defend your 1st sentence in post #6. You need to reread my post you might learn something.

First I have forgotten more about the 348 than you will ever understand. 2nd if your water pump seizes that tinming belt will be so hot in a matter of minutes if would fail almost immediately and lastly in this application the correct word use/spelling is gauge not gage

 

Incorrect.

Here's TMobileGuy's (now PassionisFerrari) thread when his timing belt finally came off after months of driving (March of 2006) with a seized tensioner bearing: http://www.ferrarichat.com/forum/showthread.php?p=135615492#post135615492

Here's where his tensioner started making a "very high pitched whistle" in July of 2005: http://www.ferrarichat.com/forum/showpost.php?p=135039183&postcount=1


You see, on 348s, the smooth, untoothed backside of the timing belt turns the waterpump and tensioners.

Because only the smooth side of the timing belt touches the water pump and tensioners (which are likewise smooth), a tensioner or water pump failure (even a full blown seizure) isn't fatal to a 348 engine for some great length of time.

In fact, every 348 motor has 2 guide shoe sleds (ostensibly to prevent belt backlash) that are often misadjusted such that they rub the smooth backside of the 348's timing belt for thousands of miles.



In contrast, the front toothed side of the belt has vastly more friction/grip, after all, and can continue to be turned by the toothed crank pulley.


Keep posting. Keep reading. You'll catch on.

 

I'm not going to go back and read TMobile's thread. If his engine had a SEIZED tensioner bearing, the belt did NOT last for months. It's not possible.

Let's get this thread back on track.

 

You should read the threads...it happened.

Likewise, you yourself are familiar with the smooth guide shoe sleds on top of the 348's timing belt. Many of those are misadjusted such that they rub the timing belt for thousands of miles.

In the first pic, see parts numbered 46:
2nd pic is part #46 as installed on a 348.
In the 3rd pic is Pap's 348 belt guide sled after 3.5 years of Aussie driving from his prior owner.


(the point being that a seized water pump or seized tensioner acts on the 348's belt a lot like a misadjusted belt guide shoe)
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ND, the tensioners and the water pump deflect the course of the timing belt by 90 degrees or more. The shoe doesn't deflect the belt at all, and the minimal contact with the belt damages both the belt and the shoe!

If those bearings are SEIZED (meaning they are not turning) the belt isn't just sliding along on a nice smooth surface with no friction, it's being dragged over a stationary surface a HIGH speed.

Imagine it this way. Take a nice smooth-surfaced object like a screwdriver handle, and push it up HARD against the nice smooth backside of a fan belt on a running engine. Try to deflect the course of the belt by even a few degrees. The belt AND the screwdriver will get enormously hot in no time at all.
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I agree that the angle of deflection by the waterpump and tensioner bearings will cause more heat when seized than will misadjusted belt guide sleds, but in both examples that I cited above (TMobileGuy's tensioner seizure and Pap's misadjusted guide shoe sleds), the 348's were driven for months and thousands of miles before either saw a belt failure.

So I use those experiences to say that a water pump seizure won't be instantly fatal to a 348's timing belt.

Obviously there will be a failure eventually, there's no disputing that, but the examples above are plural...not isolated cases...showing that belt failure isn't immediate.

 

Also, to get more in line with the topic for this thread, it's worth repeating that a 348's water pump can fail **without** seizing.

If the impeller breaks up or spins free of its shaft, then the waterpump itself will turn with the timing belt (no heat increase to note of any worth, perhaps even less heat), yet coolant won't circulate.

 

OK, I went back to post #13 and read the two links from TMobile's history.

ND, your second link (from TMobile's thread of July 2005), item #3, sounds NOTHING like a failure of a tensioner, or water pump, or a timing belt problem of any kind. Sorry. Not from the symptoms described.

Your first link (from TMobile's thread of March 2006), indicates that his belt failed almost INSTANTLY after he "all of a sudden heard a high-pitched sound like a turbo", with catastrophic results.

Ain't no way he had a seized tensioner for 8 months. No way. No way. No way.

 

It wouldn't even matter. See post #18.

 

LOL...Man you are really grasping to find some way in hell to convince yourself and the unaware that you are right. I sure hope the guys reading this don't listen too close to you. At least the ones that know anything about the mechanical side of life are getting a good chuckle out of this.
The probability of a 348 water pump falling apart inside is slim and if it did the driver not knowing/hearing it would be even less. But leaving that part alone and back to the fact: If the pump is out of the equation in an engine it would over heat fairly quickly and your temp gauge will rise accordingly, NOT show a cold reading. There would not be any air pockets that would develop in the coolant passages just because the pump seized. If there was air in the system you have an overheating problem, this can happen when you change the coolant and don't properly bleed the system. After the system is bleed properly there is no chance you will ever get enough air back in the system to cause a big enough air pocket that just happens to sit around the temp sensor to show a pegged on cold reading. Engines can slowly gain air(my 308 did this occasionally) in the system and the usual result is a rising of the water temp(it doesn't take much air to do this) not a cold reading, after the system is bleed again the temp goes back to normal. Thats is why a good temp gauge is important and why you need to pay attention to it as it can show very subtle changes in the coolant temp.
Oh.. and please read this carefully as YOU may learn something hahahaha

 

Just quoting you on this for later. I'll need a laugh one day, I'm sure!

 

I'm curious about overheated cat glowing red..anyone here have a photo? just a precaution to look out for...

 

Are you still getting the above conditions, or are you getting different behavior now?