Overheated

Overheated

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Discussion

Dave85chim

Original Poster:

447 posts

85 months

Tuesday 20th April 2021
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Morning Folks

So 1st real trip out doing more than a spin around the block - revs up and fell in love!

However, ended up cooking! Steam and rumbling as the water temp hit around 110 with no fans.

However, once I stopped and turned engine off - the fans kicked in! any ideas why not when in motion?

I have had a recent Emerald install so not the otter - maybe thermostat?



[url]

|https://thumbsnap.com/PrpSD1m7[/url]



gruffalo

7,509 posts

225 months

Tuesday 20th April 2021
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Possibly had an air lock.

Steve_D

13,737 posts

257 months

Tuesday 20th April 2021
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A few mixed messages there.
'Not the otter' implies the fans are now switched by the ECU. In which case you need to be looking at the ECU data to see if the fan temp is set correctly plus is the ECU reading the correct temp.
A large air lock could be leaving the ECU temp sender in air so giving the wrong reading.

Thermostat could cause an overheat but would have the fans on even earlier so if they were not working then the issue is not the stat.

Steve

bobfather

11,171 posts

254 months

Tuesday 20th April 2021
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If the expansion pot is allowed to run empty the coolant system will draw air in. Due to the position of the expansion pot (low down) air has difficulty getting back out. A slug of air can become entrained and find its way to the pump, when that happens the circulation stalls and coolant boils at the cylinder liners.

If the expansion pot is too full it will eject coolant when the car is hot giving the false appearance of overheating.

Coolant level when cold should be around 1/3 full, any more and you risk blowing coolant out when it gets hot

Dave85chim

Original Poster:

447 posts

85 months

Tuesday 20th April 2021
quotequote all
Thanks guys huge help - so 1st point of call - bleed system and refill?

failing that check ecu setting as per Steve's comments.

Is this a full drain of system or is the a specific way of topping up exhausting the airlock?>

Zener

18,928 posts

220 months

Tuesday 20th April 2021
quotequote all
Only way to create air in the cooling system is coolant loss (disregarding HG failure etc for the moment) this is especially accurate if all was well before lay-up , and seeing as we re not talking initial filling of cooling system either scratchchin engines dont just randomly develop air locks no more than brake hydraulics , could also be a sticking thermostat there are some Mickey Mouse units around personally I only use the OE Wahler brand, like mentioned check level your software data and fan cut-in temps etc then take for another shake down

Dave85chim

Original Poster:

447 posts

85 months

Tuesday 20th April 2021
quotequote all
Thanks for that. To be honest I have only ran it a handful of times around the block since having all the fluids filled up since emptied - so this would of been the 1st time the system was properly brought up to to temp. So I will drain and refill. and go from there!

Shed TVR

138 posts

73 months

Tuesday 20th April 2021
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As others have said it's unusual that the fans didn't kick in. If you have the software for the Emerald I would take a look and try to find the settings for the fans, or if you know who did the conversion it could be worth contacting them.

Again think it's already been covered but I'd use the "Bible" method to fill and bleed the system. Run the car up to temp on idle and check both of the rad hoses are hot preferably with a temperature gun if you have one.

Classic Chim

12,424 posts

148 months

Tuesday 20th April 2021
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It’s worth making up a length of pipe and adaptor so you can connect it to bleed outlet in manifold and then into your filling jug so keeping that jug half filled with coolant as it comes upto to temps heater on hot the water can circulate into the jug as well as fill the system as the air expells.
A lot of air/ tiny bubbles came through that little pipe when I did mine over a good few mins. I put a clear piece of pipe in a section of it so I can watch the nice blue liquid coming through.
I’ve faffed about before without that set up!
This is the simplest most effective way I believe.
Don’t let it boil though.
It all has to be done not long after stat opens and before it gets hot.
My feeling is fill your expansion bottle half full as when it cools down it might draw quite a bit back in.
I check it when it’s gone cold and often it’s nearly bone dry. It’s better to push a bit out than draw more air in.

Top it upto 1/3 and it’s normally static after that.




Dave85chim

Original Poster:

447 posts

85 months

Tuesday 20th April 2021
quotequote all
Thanks Guys! This is Saturdays job booked!

Steve_D

13,737 posts

257 months

Tuesday 20th April 2021
quotequote all
Many owners find a plastic funnel that screws tightly into the swirl pot. If you keep a little coolant in the funnel then as the air comes through it can escape and and be replaced by coolant. As the air comes through the coolant will push up into the funnel then drop back as the air escapes.
When you have a bit of temp. hold the revs well up for 5 mins which will help drive the air out.

This is OK but being an engineer I had to have something different.



The lid helps stop coolant going all over the engine when it 'burps'.

Steve

s p a c e m a n

10,752 posts

147 months

Tuesday 20th April 2021
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Fan connections are ok aren't they?

Dave85chim

Original Poster:

447 posts

85 months

Tuesday 20th April 2021
quotequote all
Steve_D said:
Many owners find a plastic funnel that screws tightly into the swirl pot. If you keep a little coolant in the funnel then as the air comes through it can escape and and be replaced by coolant. As the air comes through the coolant will push up into the funnel then drop back as the air escapes.
When you have a bit of temp. hold the revs well up for 5 mins which will help drive the air out.

This is OK but being an engineer I had to have something different.



The lid helps stop coolant going all over the engine when it 'burps'.

Steve
I like this idea! Will definitely be trying this!!! Thanks Steve.

TarquinMX5

1,918 posts

79 months

Tuesday 20th April 2021
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Steve D

That looks like a good idea; I can't see on my screen but does that isolator valve screw into the swirl pot?

QBee

20,903 posts

143 months

Tuesday 20th April 2021
quotequote all
It seems more simple to me - your fans didn't come on, so check the fan and otter switch wiring.

So first, engine cold but ignition on, pull the two wires off the otter switch and connect them together (or pull them back a bit until you can see bare terminals and bridge across the two terminals with a screwdriver blade) and see if the fans come on. If they do your wiring is ok. If one comes on you have a problem in the wiring under the rad. If they both don't, then start looking at the connectors under the radiator. Wiggle them. I have had both be corroded so that I had neither fan working.

Once you have proved you have working fans then start the engine and see if the fans come on at 90 degrees. If not, do the same test as above, bridging the wires at the otter switch. If that makes the fans now come on, you have a faulty otter switch.

If all that fails to get you working fans at the right temperature, then your problem could be related to how the fan control is set up in the emerald. I have an emerald and will check in the morning if my otter switch is still connected or not.

I had too little coolant in a couple of weeks ago. Drove 20 miles and noticed the car was overheating and the fans were going flat out. Slowed down, temperature dropped, sped up, temperature rose. I stopped and allowed it all to cool down and took the brass filling screw out - it took over a litre of water to fill it. That was my problem. But that doesn't explain why your fans weren't working.

indigochim

1,501 posts

129 months

Tuesday 20th April 2021
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Steve_D said:


The lid helps stop coolant going all over the engine when it 'burps'.

Steve
Great idea, is it a 1/2" valve? how have you secured/sealed the container to the pipe?

indigochim

1,501 posts

129 months

Tuesday 20th April 2021
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Worth checking the fan relays too they can stick. Mine did fortunately whilst the fans where on, unfortunately while the French border police wanted to search my engine bay for stowaways.

Zener

18,928 posts

220 months

Tuesday 20th April 2021
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indigochim said:
Steve_D said:


The lid helps stop coolant going all over the engine when it 'burps'.

Steve
Great idea, is it a 1/2" valve? how have you secured/sealed the container to the pipe?
It will be 1/2 BSP I did something similar but used a stainless Champagne bucket biggrin Cos I'm Posh laugh No really

Steve_D

13,737 posts

257 months

Wednesday 21st April 2021
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indigochim said:
Great idea, is it a 1/2" valve? how have you secured/sealed the container to the pipe?
15mm compression fitting used to connect to a water tank.

Steve

Zener

18,928 posts

220 months

Wednesday 21st April 2021
quotequote all
Sorry Steve should of read his question properly but you have given him the answer biggrin