Coolant Overheating Issues

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TimU
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Coolant Overheating Issues

Post by TimU »

I'd love some feedback on what might be causing a really annoying engine cooling issue, or perhaps what I've missed in my troubleshooting.
Please :)

Symptoms:
After driving for some distance without any issues, then idling in traffic, the engine temperature starts to raise well beyond 12 o'clock into the danger zone.

Information/Circumstances:
* Engine warms up normally (~15mins), temp needle stays nicely at the 12 o'clock position for as long as it wants. Have left it idling for 30mins without issue.
* Engine temp stays perfectly at 12 when driving at speed for any distance or time. I've driven for 2 hours (200km) without issue.
* After driving for some distance, then idling in traffic, the engine temperature starts to raise beyond 12 o'clock.
* If left idling long enough, it will move into the danger zone.
* Then, when decent travel (air) speed can resume, the needle moves away from the "danger zone" a bit.
* However, the needle does not come all the way back to 12.
* This results in a cumulative "hotter and hotter" effect, until it gets to the point where I have to shut off the car.

Recent Changes:
* Car has been off the road for ~8 years, recently completed a restoration and overhaul.
(^ I mention this because I can't confirm the cooling system function before the restoration)
* Coolant Clean, Flush and Refresh performed 2 weeks ago. Drained from the block and back-flushed the whole system.
* New Fan Clutch installed
* New Thermostat (80C) and housing installed.
* New AC Parallel Flow Condenser and SPAL high-flow pusher fan installed (Part of the AC system rebuild)
* Fresh engine oil and filter, 5W40 mineral oil.

Attempted Corrective Actions:
* Bled system really well (I think), multiple times; If I open the bleeder screw when under pressure there is just coolant coming; no air bubbles. Followed this "Coolant Flush Guide.
* Confirmed the overflow tank hose and radiator port is wide open and clear of obstructions.
* Replaced parts as above.

Unconfirmed (just thought of these now):
- Do the electric fan's High & Low speed thermo switches work?
- Water pump function
- Radiator blockages
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Jubilados
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Re: Coolant Overheating Issues

Post by Jubilados »

Since you’ve replaced the fan clutch and thermostat, and since the radiator has sat unflushed for 8 years (and is likely many years older than that), a new radiator is the next step.
plip1953
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Re: Coolant Overheating Issues

Post by plip1953 »

Jubilados wrote: Tue Oct 04, 2022 2:23 pm Since you’ve replaced the fan clutch and thermostat, and since the radiator has sat unflushed for 8 years (and is likely many years older than that), a new radiator is the next step.
I understand this suggestion, but why wouldn't a blockage cause overheating issues constantly rather than just as and when described?

But I guess it might be a good to remove the current radiator an ensure it will flush out/through without issue?

Edited to add: I see this thread has just been posted - looks like it could be useful in this particular context
viewtopic.php?t=33239.
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Jubilados
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Re: Coolant Overheating Issues

Post by Jubilados »

No, a blockage doesn’t necessarily cause overheating issues constantly.
It is likely partially blocked, so it no longer operates at full capacity and efficiency.
It still works enough to cool sufficiently under most circumstances, as described.
But the engine is is getting to other circumstances where it is creating more heat than the compromised radiator can cool. That’s when the temps are rising.
A radiator sitting for a long time can get very corroded. Esp with old coolant and/or an improper mixture (too much water, not enough coolant - coolant is not only anti freeze, it also has anti corrosion in it).
Radiators also commonly get clogged to a point where a flush isn’t going to bring it back.
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Ralph in Socal
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Re: Coolant Overheating Issues

Post by Ralph in Socal »

Jubilados wrote: Tue Oct 04, 2022 3:43 pm No, a blockage doesn’t necessarily cause overheating issues constantly.
It is likely partially blocked, so it no longer operates at full capacity and efficiency.
It still works enough to cool sufficiently under most circumstances, as described.
But the engine is is getting to other circumstances where it is creating more heat than the compromised radiator can cool. That’s when the temps are rising.
A radiator sitting for a long time can get very corroded. Esp with old coolant and/or an improper mixture (too much water, not enough coolant - coolant is not only anti freeze, it also has anti corrosion in it).
Radiators also commonly get clogged to a point where a flush isn’t going to bring it back.
Agreed. A new radiator was less than $200. Maybe higher now but still peanuts compared to a warped head and gasket repair

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TimU
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Re: Coolant Overheating Issues

Post by TimU »

Jubilados wrote: Tue Oct 04, 2022 2:23 pm Since you’ve replaced the fan clutch and thermostat, and since the radiator has sat unflushed for 8 years (and is likely many years older than that), a new radiator is the next step.
Thanks, yeah I think so too. I have a brand new OEM radiator in the shed that I picked up cheap a few years ago.
I was saving it for when it came due, but I guess it's time to test it out.
plip1953 wrote: Tue Oct 04, 2022 2:35 pm I understand this suggestion, but why wouldn't a blockage cause overheating issues constantly rather than just as and when described?
A blocked rad makes sense with the symptoms - High airflow provides enough cooling while driving, but not enough liquid can flow through the core when stationary to cool the block down.
plip1953 wrote: Tue Oct 04, 2022 2:35 pm Edited to add: I see this thread has just been posted - looks like it could be useful in this particular context
viewtopic.php?t=33239.
Thanks, I wrote that post 😊
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Re: Coolant Overheating Issues

Post by 86_6series »

I have to ask, what's the scoop on the mineral oil?
What are the advantages?
Do you change from the 20w50 to 5w40 because it's mineral?

thanks
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TimU
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Re: Coolant Overheating Issues

Post by TimU »

86_6series wrote: Wed Oct 05, 2022 10:35 am I have to ask, what's the scoop on the mineral oil?
What are the advantages?
Do you change from the 20w50 to 5w40 because it's mineral?

thanks
Sorry, that was a typo - Should have been 15W40.

Only used mineral oil for the thickness, because I was worried about a thinner synthetic oil seeping out of old rubber seals.
Mind you, I don't any evidence behind that thought, just my thinking at the time.
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Re: Coolant Overheating Issues

Post by 86_6series »

I tried synthetic, but the smaller molecules would definitely
seep through the pan gasket. Dinosaur oil stopped the seeping.

Let us know the results with the new radiator.

Bob V
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Re: Coolant Overheating Issues

Post by TimU »

Update: This weekend I resolved the issue.

1) replaced the radiator with a new OEM one.
2) cleaned the calcium off the temp switches.
3) confirmed the radiator temperature switches work. 91C & 99C.
4) confirmed the fan relays, resistor and wiring all works.

Took it for a ~50km drive and the temp gauge never left 12 o'clock, even when idling in traffic or parking.

Thanks for everyone's suggestions and advice! 🫶
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emac
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Re: Coolant Overheating Issues

Post by emac »

Glad you got it solved, that could have been bad!

Years ago when Al radiators first came out they gave a lot of trouble because people used a phosphate antifreeze in them. It would react and cause AL/phosphate deposits. I only use BMW antifreeze (phosphate free) mixed with distilled water. For some reason BMW's seem to be finicky about antifreeze.
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Re: Coolant Overheating Issues

Post by TimU »

There's a new twist to this saga.

It's currently peak summer here in Australia, and the ambient temps are up in the mid 30C range pretty regularly.

While the car is moving, there is no problem with the engine temps.
However when idling in traffic, the temp guage really starts to cook.

So I replaced the water pump with a brand new unit over the weekend.
On inspection, the old pump seemed to be very serviceable still.

And yeah, that wasn't it - still overheating.

So I went though THE WHOLE system again, piece by piece and guess what I found...

The new condenser fan on the front is a PULLER fan, not a PUSHER.

How does that happen, you may ask?

I refurbed my AC system earlier last year.
I supplied a brand new SPAL Curved Blade Pusher Fan for the AC guy to mount on the new universal condenser after he made up some new lines and gassed the car.

The fan that got installed to my car is a totally different model to the one I gave him to fit.

It's should have been this curved blade Pusher:
Screenshot_20230208-164225_Amazon Shopping~2.png
Screenshot_20230208-164225_Amazon Shopping~2.png (864.52 KiB) Viewed 1442 times
But instead, I got this straight blade Puller:
Screenshot_20230209-000831_Firefox Nightly~2.png
Screenshot_20230209-000831_Firefox Nightly~2.png (584.72 KiB) Viewed 1442 times

I gave them a call this arvo asking if they could have accidentally switched mine with another job, and they said "yeah it's possible, we use the SPAL fans for lots of jobs".
Calling back tomorrow morning to have a chat with the boss to hopefully sort it out.


At least this explains my problems!
This fan is trying to pull air out of the condenser towards the front of the car, rather than push it through past the radiator.

No wonder it's overheating, the two fans are fighting each other for airflow!

In the end, a piece of paper confirmed it.

I jumpered the fan to run on high without the engine running and stuck a bit of paper behind the radiator to see if it sucked or blowed.

The paper got sucked towards the front of the car, obviously the wrong way.
PXL_20230208_164021947~2.jpg
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PXL_20230208_164018416.jpg
PXL_20230208_164018416.jpg (1.58 MiB) Viewed 1442 times

Maybe someone has my Pusher Fan on their car and is having the same problem!
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Re: Coolant Overheating Issues

Post by Slownrusty »

Tim - glad you figured it out.

An overheating car is an unhappy car (and owner too).

Yasin
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Re: Coolant Overheating Issues

Post by GRNSHRK »

Agreed, glad to hear that you got it sorted, or are about to, but that's really not cool [-X

Hopefully your shop will make good and pay more attention in the future :roll:
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TimU
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Re: Coolant Overheating Issues

Post by TimU »

Today was proving day.

35C ambient.
Long drive to properly heat-soak the engine.
Idling in traffic for 15mins.
Air conditioning cranked.

Success! 😎
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Re: Coolant Overheating Issues

Post by GazM3 »

yes an incorrect fan direction is often hard to detect as air is still moving. Had this issue with my 540i and dual thermos where 1 was pushing into the radiator and one working properly and couldnt understand why it was running warm all the time. The simple tissue test conformed the issue.

With the fan trigger, you can use the lower temp switch off the e36 318i manual non AC version as this triggers the fans 8degC earlier. U will have to fiddle with the plug to make it work. I have these lower thermo switches on all my bmw's and they work nice
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