Temp question

[Dave L]

sadly, my e9 has been underutilized for a few years now. Happily, I have been taking the time to correct all the little issues that put her into storage.
One of the issues is she had started overheating without warning. Recently I replaced the water pump and thermostat, flushed out the system, replaced coolant. Now after warming up the temp gauge goes to about 3/4 toward red. So far has held there on a few drives. Where does other cars temp gauge operate at? Anybody had temp sensor issues?

 

[Sven]

It should be close to the 3:00 o'clock position. A bit lower when at speed and a tad higher on a hot day idling on the freeway.

 

[bluecoupe30!]

I have observed higher than "comfortable" temp reading after a coolant flush when I did not get all the air out of the system. Re-bled and temp reading much better.

 

[deQuincey]

sadly, my e9 has been underutilized for a few years now. Happily, I have been taking the time to correct all the little issues that put her into storage.
One of the issues is she had started overheating without warning. Recently I replaced the water pump and thermostat, flushed out the system, replaced coolant. Now after warming up the temp gauge goes to about 3/4 toward red. So far has held there on a few drives. Where does other cars temp gauge operate at? Anybody had temp sensor issues?

well, many possible causes,

including,

a new thermostat can be faulty, so do not necesarily trust on it, check it in a pan with warm water before installing, at 80 deg it should strat opening
but tstat is a double effect, it opens one side and blocks the other
additionally first make sure you are using the right thermostat, thermostat housings are at least of two types each one needs a different thermostat, your VIN will probably not help, as your tstat housing might have been changed, you will require a geometrical check of housing and tstat to make sure that the rear end of tstat makes the job

bleeding is essential, a hole in the tsat helps out the air bubbles

check sender and gauge, good earth is important

try to contrast what the gauge is saying and the real water temp using a thermometer

finally make sure that ignition timing and mixture is correct, reatard and lean makes engine hotter

 

[autowerks]

My temp reading is usually between 3:30 and 4:00 and it gets to 3:00 in traffic
nine blade fan, new thermostat and new Water Pump

 

[Dave L]

I think re- bleeding the system may be in order as was suggested. I'm fairly certain all parts are correct and installed properly. That sounds logical. I was happy that it was only going to just under the 3/4 mark and holding. That was a major victory compared to what it had been doing. Which reminds me....I need to change my oil!

 

[Bmachine]

You haven't said anything about your radiator. Is it the original one?

Lots of crud and/or rust can accumulate in there and strangle the water circulation. A through check of its inner functioning would be time well spent.

 

[Dave L]

It'd be a good idea to check the radiator, and I will. It's not original I don't think. My car mechanicals were all restored by Coupe king around 2004. I probably have less than a couple thousand miles on her since.

 

[lloyd]

sadly, my e9 has been underutilized for a few years now. Happily, I have been taking the time to correct all the little issues that put her into storage.
One of the issues is she had started overheating without warning. Recently I replaced the water pump and thermostat, flushed out the system, replaced coolant. Now after warming up the temp gauge goes to about 3/4 toward red. So far has held there on a few drives. Where does other cars temp gauge operate at? Anybody had temp sensor issues?

With respect, I think you may be chasing your tail. As deQuincey suggested, why not determine that your engine is actually overheating before attempting to fix something that is not broken. Who can vouch for the reliability/accuracy your temperature gauge? I once looked at an E3 for parts. The engine had blown a head gasket. The owner said he could not understand how it could happen "since the gauge never moved out of the blue."

Your gauge or the sender may be extremely accurate as-is, or it may be way off due to any number of possibilities, including poor grounds, loose or poor wiring, etc. Consider obtaining a reliable aftermarket thermometer or a point-and-shoot thermometer and take some readings. Even without a secondary gauge, does turning on the heater have any effect on the temp gauge? Hint: even a wee bit 'o corrosion on that coolant temperature sender and/or the attached wiring can render it unreliable and make some gauges mimic a wiper blade.

Not a slight against your prior mechanic, but even excellent work performed thirteen years ago, does not guarantee perfection in perpetuity. Some metal corrodes, rubber deteriorates, silt can compress into immovable sludge creating unforeseen arterial blockage and ossification. Unless you are using a special waterless-coolant, e.g., "Evans waterless coolant", flushing the cooling system and replacing the coolant is standard maintenance whether the car is stored or operated, even occasionally.

What was wrong with the waterpump that required its replacement? Are you using the upgraded fan and viscous fan clutch?

What was wrong with the thermostat? Did you test the thermostat, even the new one, to determine that it functions properly? What was the temperature rating for the new t'stat?

What type of coolant did you remove and/or install? Not certain, but some types are evidently disfavored due to an alleged proclivity to congeal under the wrong circumstances. http://www.sancarlosradiator.com/dex-cool.htm

I generally would not go to this length. But if I suspected a cooling issue - and had a radiator sitting for a long time - I would seriously consider removing the radiator from the car and (carefully) flushing it from all angles with water. IF the radiator had sludge at the bottom of the tank, a typical flushing, in situ, might be ineffective and blockage or potential blockage might remain despite a clear running stream.

 

[deQuincey]

With respect, I think you may be chasing your tail. As deQuincey suggested, why not determine that your engine is actually overheating before attempting to fix something that is not broken. Who can vouch for the reliability/accuracy your temperature gauge? I once looked at an E3 for parts. The engine had blown a head gasket. The owner said he could not understand how it could happen "since the gauge never moved out of the blue."

Your gauge or the sender may be extremely accurate as-is, or it may be way off due to any number of possibilities, including poor grounds, loose or poor wiring, etc. Consider obtaining a reliable aftermarket thermometer or a point-and-shoot thermometer and take some readings. Even without a secondary gauge, does turning on the heater have any effect on the temp gauge? Hint: even a wee bit 'o corrosion on that coolant temperature sender and/or the attached wiring can render it unreliable and make some gauges mimic a wiper blade.

Not a slight against your prior mechanic, but even excellent work performed thirteen years ago, does not guarantee perfection in perpetuity. Some metal corrodes, rubber deteriorates, silt can compress into immovable sludge creating unforeseen arterial blockage and ossification. Unless you are using a special waterless-coolant, e.g., "Evans waterless coolant", flushing the cooling system and replacing the coolant is standard maintenance whether the car is stored or operated, even occasionally.

What was wrong with the waterpump that required its replacement? Are you using the upgraded fan and viscous fan clutch?

What was wrong with the thermostat? Did you test the thermostat, even the new one, to determine that it functions properly? What was the temperature rating for the new t'stat?

What type of coolant did you remove and/or install? Not certain, but some types are evidently disfavored due to an alleged proclivity to congeal under the wrong circumstances. http://www.sancarlosradiator.com/dex-cool.htm

I generally would not go to this length. But if I suspected a cooling issue - and had a radiator sitting for a long time - I would seriously consider removing the radiator from the car and (carefully) flushing it from all angles with water. IF the radiator had sludge at the bottom of the tank, a typical flushing, in situ, might be ineffective and blockage or potential blockage might remain despite a clear running stream.

it seems that not everybody listens to the advices, seat and wait said the bard !
well said lloyd

 

[Ohmess]

Dave -- given what is posted here, my suggestion is to use the following bleed procedure.

Run the car up to normal operating temperature (which will read warm on the gauge) and make sure you turn on the heat fully (including turning on the fan to max) and leave it on throughout the process. Then shut the car down (without changing the heater controls) and let it cool.

Once cool, obtain a small section of hose similar in size to the small hose running from the expansion tank and a shop rag. Remove the end of the existing expansion tank hose from the expansion tank, wrap the shop rag around it and hold it in the air above the engine (not the paint). Connect the section of hose not previously connected to your car to the expansion tank. Now comes the fun part -- blow gently into the new section of hose, holding the end of the disconnected hose up so that the end of the disconnected hose is the highest point in the entire cooling system (including the part of the system you are blowing into). In other words, hold the end of the disconnected hose above the level of your head. Blow gently until all air is expelled and you get a light steady flow of coolant onto the shop rag. You only need to expel a tiny amount of coolant -- enough to ensure there are no air bubbles. Maintain the pressure exerted by blowing until you cover the top of the disconnected hose with your thumb to prevent air from being drawn back in. Then remove the new hose from the expansion tank and reconnect the disconnected hose using the rag to catch the small amount of fluid that will spill in the process of reconnecting the hose.

This process has worked for me without fail every time I have used it.

 

[deQuincey]

on bleeding and so on,

a couple of considerations,

1- heater must be on . ...may i ask why ?, AFAIK the e9 heater has no bypass or valves, so to my humble understanding it makes no difference to have it on or off, not to mention the fan blowing. any comment ?

2- all those magic tricks ar probably good, but i will tell you what i do ( last week in fact)

tstat has a 2mm diameter hole at 12oclock
first pour coolant 11 to 12 liters aprox
then close and start the engine
once is warm bleed at iddle, then accel engine a bit and bleed again, you will see how pressur drops
you will not do much if pressure does not build up again so
let car cool down,
next day add coolant with cold engine
and close cap
start engine and go for a spin,
when warm stop and bleed again
another drive
stop and bleed
come back home you are done

 

[Ohmess]

My understanding is that heat is on to ensure that the tstat opens. The bleed may not expel all the air if it does not.

 

[deQuincey]

My understanding is that heat is on to ensure that the tstat opens. The bleed may not expel all the air if it does not.

dear chris, i do not think it makes any difference, you tstat will open for sure if you let the engine warm up, over 83 deg the stat will be open letting the air trapped in the other part of the circuit and this will be done no matter what the heater selection you have, IMHO

 

[Dave L]

Yesterday I flushed the system over and over till only clear water came out. Refilled (using coolant mixture), bled the system, went for a short drive. It operated in normal range. Couldn't test further as I had an entirely new problem arise. I'm addressing that issue in a new thread "brake conversion". I've spent too many years away from my e9 that now I have to ask lots of questions to get back up to speed. Pardon my forgetting what may be simple things. I much appreciate the collective memory of this group.