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Using an infrared engine temperature gauge

Posted by rkj 
rkj
December 24, 2012 05:10PM
Hey Guys (and Kelly), but this is more for the guys. I'm having a few issues with the 5er and the cooling system. I've never used one of these tools but I hear they're pretty good at finding where problems might be.

Has anybody used these things, and know of a good brand or model to get. I don't mind spending real money for good tools but I'm finding cheap ones that might do the job (I'm not against that either). one cheap example, or a more expensive one.

I'm trying new stuff on this post so if it comes out totally haywire I'll try again, but the first tool goes for 16 bucks and the other, more expensive one goes for 100. There must be differences in capability etc. but I don't have a clue...

Thanks for any direction, Rick



perseverance furthers
Is it leaking or just overheating? Plugged radiator?

alan
rkj
Alan, I've been over this car 20 ways from Sunday, everything checks out. It does act like a temp gauge, or it's sensor, going south or a pocket of air (around the sensor) making the gauge run hot. The car is my 1998 528 and it has never given me a true sign of overheating but has, twice now, gone right over to hot (the needle) and turned on that nasty little red lamp on the right of the gauge. When that happens I throw the defrost button on and all's well for the time being. The last time it happened I bled the system, it has two bleeders, and it was good for 1500 miles. Now, just the other day, after a trip to the VA 150 trip, it did it again. I bled it again, this time a little more throughly.

I've had the pump out, it's a later style metal impeller, and it has a new thermostat. The fan clutch is fine and the electric fans are working as they should. It's never lost any coolant and passes a leak test.

The wierd part is that this car looks like a normal engine temp gauge but it's not; it's more an idiot light that looks like a normal set-up!

Thanks Bmw, nice move!

Anyway, this has me stumped but good and it has been sitting in the driveway for the last month or so waiting for me to figure what's up.

Thanks, Rick
One problem with the temp gages is that they are not telling you what the temp really is. It tells you that it is in that normal range. When the overheat occurs, the gage will go from normal range to hot very quickly. If the thermostat is computer controlled like the E38 is it could be malfunctioning.

The infrared temp sensor type instrument would be a big help to tell what the actual temp is.

The problem you will have is that the spot the infrared sensor "sees" can be pretty large in the less expensive ones. If you can get really close to the spot you want to sense it will be more accurate.

Bob in Everett
rkj
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Bob in Everett
One problem with the temp gages is that they are not telling you what the temp really is. It tells you that it is in that normal range. When the overheat occurs, the gage will go from normal range to hot very quickly. If the thermostat is computer controlled like the E38 is it could be malfunctioning.

The infrared temp sensor type instrument would be a big help to tell what the actual temp is.

The problem you will have is that the spot the infrared sensor "sees" can be pretty large in the less expensive ones. If you can get really close to the spot you want to sense it will be more accurate.

Thanks Bob, I figured the more expensive one would be better in some regard but didn't have a clue to what. I hope I can point this thing at different parts; thermostat, water hoses, and various parts to get a hint as to what is really going on with my lulu e39. Up till now it's been all guess work, Peter and I hate that!

Do you know when they started these fake temp gauge set-up's?

Thanks, Rick
Just keep in mind you will be reading surface temp, not inside water temp. Depends on the size and shape and material itself what the surface temperature will be.

My 2003 E46 still has a true temp gauge, I can see it go up and down depending on load, weather, cooling etc...
Quickly googled, you might have seen this earlier, could be it's no use for you either...

Air lock at thermostat: [bimmerboard.com]
How to read true coolant temp:

What is interesting here is when you turn on the heater, the temp drops. When you bled it a second time, was there more air in the system? Possible head gasket issue? But you said it does hold pressure over time, right? You can get the coolant tested for combustion product presence.

alan
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alanrw
What is interesting here is when you turn on the heater, the temp drops. When you bled it a second time, was there more air in the system? Possible head gasket issue? But you said it does hold pressure over time, right? You can get the coolant tested for combustion product presence.

alan

This leads us back to the clogged radiator theory. All that the heater does is add extra cooling to the radiator. That tells me that the radiator and/or fans are not working properly.

We had the exact same problem on our old Honda. I eventually discovered that the electric fan was not working(an old oil filler cap had fallen into the fan casing and jambed the fan). Running the heater would almost immediately drop the temp gage back to normal and the car would be good again for a few more weeks or months.
rkj
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Michiel 318iS
Quickly googled, you might have seen this earlier, could be it's no use for you either...

Air lock at thermostat: [bimmerboard.com]
How to read true coolant temp:

Wow, low cluster. Never heard of this, thank you so much Michiel smileys with beer
rkj
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rkj
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Michiel 318iS
Quickly googled, you might have seen this earlier, could be it's no use for you either...

Air lock at thermostat: [bimmerboard.com]
How to read true coolant temp:

Wow, low cluster. Never heard of this, thank you so much Michiel smileys with beer

The air-lock piece is golden too. Thanks again Michiel thumbs up I'll have to print that out.
rkj
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Archeo-peteriX
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alanrw
What is interesting here is when you turn on the heater, the temp drops. When you bled it a second time, was there more air in the system? Possible head gasket issue? But you said it does hold pressure over time, right? You can get the coolant tested for combustion product presence.

alan

This leads us back to the clogged radiator theory. All that the heater does is add extra cooling to the radiator. That tells me that the radiator and/or fans are not working properly.

We had the exact same problem on our old Honda. I eventually discovered that the electric fan was not working(an old oil filler cap had fallen into the fan casing and jambed the fan). Running the heater would almost immediately drop the temp gage back to normal and the car would be good again for a few more weeks or months.

I don't know if the radator has ever been replaced, I doubt it, but the car runs nice and runs cool up-stairs on the highway, it'll run all day at 100 mph +. A clogged radator would start to show up at highway speeds. All of my "overheat events" have been after long trips making short stops by the house on the way home (quick store runs). Totally weird. The aux fans in front of the radator were working just right but I'm going to recheck those now that I'm up and around a little more. (I had a week stay in the (hospital) but that's another story. Right now I'm having a money scramble so I'd like to see if I could just make this issue go away and sink some real money in to her later; radator, Tstat, hoses and belt tensioners. I've got the new waterpump and belts so far but I'd like to do everything at once.

Through out all these few "overheat events" the car has never lost any coolant or given any signs, other than the gauge showings, of a true overheated motor. I'm so careful about this; the M52 is even more sensitive to overheating than the M20's, and it's the only thing with this car that is freaking me out confused smiley

Thanks Archie
Wonder what they do at the factory or dealership, they can't keep having the car back to bleed the air. And what was that deal with drilling a hole in the thermostat to allow air to escape, why isn't the hole there in the first place?

I wonder if they apply a vacuum to the cooling system as they fill it in order to pull the air out of the system as it is being filled?

alan
rkj
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alanrw
Wonder what they do at the factory or dealership, they can't keep having the car back to bleed the air. And what was that deal with drilling a hole in the thermostat to allow air to escape, why isn't the hole there in the first place?

I wonder if they apply a vacuum to the cooling system as they fill it in order to pull the air out of the system as it is being filled?

alan

That hole started me thinking though... When the car they're working on they stood the top tank above the radator too, that also got me ....

When I bled mine the second time I couldn't get anything to happen for awhile, I had to take the car for a ride to build up the pressure and then it was still a while before I got any real coolant through the bleeders. Then, it took awhile to get clear coolant to flow confused smiley at both bleeders
It seems curious that they would design an engine with obvious air traps which make bleeding the system not so easy, eh?

alan



Edited 2 time(s). Last edit at 12/26/2012 11:38PM by alanrw.
Factory fills are usually on a vacuum
Do you think so? My VW Transporter was one air trap. I had to park it on a ramp nose up to get the air bled.
Have you replaced the thermostat at some point? If yes, are you sure it is in the right way (in case it has a hole, is it on top)?
December 27, 2012 10:58AM
The thermostat needs to have a small flow of coolant going through it to be able to accurately respond to the engine generating heat during warm up. If there is no flow, the engine can overheat before the thermostat senses it. I have a damaged engine from an aftermarket replacement that did not have a hole. It had only a small nick in the edge that was supposed to provide the flow but it was too small. The engine would get to 240 before the thermostat would open then it would go wide open flooding the engine with cpld water causing a thermal shock. Now I have exhaust gas leaking into my coolant .

The vent hole does need to be near the top to let the air out more effectively but when the hot water hits it the air will be let out anyway.

The manufacturing technique these days seems to be just to put a nick or notch in the edge of the disc by hand with a grinder instead of having the stamping that forms the disc make the hole at the same time. There will be the normal quality control issues with hand work and production quotas....

Bob in Everett
December 28, 2012 09:47PM
So you could rig up a vacuum system using a MityVac. Harbor Freight sells their version of the MityVac. They also sell an infared temp sensor.

alan
rkj
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Michiel 318iS
Have you replaced the thermostat at some point? If yes, are you sure it is in the right way (in case it has a hole, is it on top)?

It did get a new thermostat right before I took the car but I'm sure it was not drilled first, and I have no idea what the temp the stat is. I think I might have found the real source of the problem though; the aux fan in front of the radiator does not seem to be working all and could be my issue with the car running hot when not moving or moving very slowly.

I'm going to see if there's a way to jump out the temp sensor for the fans, just to know if the fan itself works. This car seems to have a complicated system for the aux fan system.

Regards, Rick
Hey Rick, did your car came with some sort of louvers in front of the radiator, like the e46? If it has, do they open as intended?
Just thinking out loud...confused smiley
On the E30, you just short the connector to get the fans going. Would guess it is the same on the 5?

alan
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