Cooling issues on 92 SE

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MetBlue
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Model: Elite 74 & Excel 92 (SEish))
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Re: Cooling issues on 92 SE

Post by MetBlue »

I've not been happy with the cooling on my car since the summer. - 3 Issues.
1 / I knew I had red coolant - assume OAT - Not good
2/ I knew from work in the summer the Otter switch wasn't
3/ And I'd been loosing water fairly consistently.
So with a longer journey looming and the cold nights, time to investigate.
I'd suspected the header tank might have been perforated, so removed, rigged up a way to pressurise it and held it in a bucket of water. Bubbles immediately out of the Filler cap ( Not the release valve). Long story short, I eventually got it to seal by wet 'n' dry on a piece of glass on the brass tank flap, and closing up the tabs on the filler cap so it was tighter to put on - Eventual result, all sealed, no leaks in tank and relief valve kicking in around 15 PSI.
Next to the temp sender. Dunked in boiling water with meter attached - Not switching. New Intermotor switch ordered (It's been modified in the past).

So rebuild all, fill with Blue antifreeze, test drive and ..... clear dripping leak from area of Switch - That was all on Sunday.

So today, drained, resealed, refilled --- and leaking. Then repeated and still leaking !!! - How difficult can it be to get a rubber pipe to seal on a clean Aluminium boss? . Began to think there must have been a hairline crack in the switch housing or damaged pipe. - Removed switch housing, with pipe to thermostat attached ( I thought that was the problem connection) stole some parts from teh Elite system and managed to seal up so I could pressurise and repeat the bucket test. Turns out all parts are good, just really struggling to get a seal, so cut the pipe bak slightly to get some new areas in contact.

Eventually rebuilt - Result - Got system warm and no drips or obvious leaks. - Very Happy

Then a transit van pulled up and handed me a parcel - Guess what was in it !!!! Yes, the new thermal switch !!!
It's still in the bag :lol: :lol: - It's winter and I have an over ride switch for the fan, so I'll stick with a sealed system for now.

Real test is tomorrow morning to see if tank level is still good after the test drive earlier.
Tony
What goes together.... Must come apart.

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Lotus-e-Clan
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Re: Cooling issues on 92 SE

Post by Lotus-e-Clan »

You could consider moving over to the dark side of cooling (ie Evans waterless coolant / EWP) and leave system pressure worries behind.

I know, I know, I'm pretty much ploughing my own furrow here ... but never say never!

Consider that my Evan's coolant system hasn't lost a microlitre of coolant since conversion (about six years ago? lost track!), due in-part to the near zero system pressure (no pressure cap fitted). And it doesn't overheat in the absolute sense of oil overheating at the piston ring level.
Overheated water systems under pressure breach head gasket seals (pressure + head warp(boiling)) and kills the engine when piston rings pick-up. The cause is uncontrolled metal expansion and LOCAL loss of oil film integrity at the liner/ piston ring interface.
Because Evan's coolant more faithfully tracks oil temperature without boiling/losing contact with the liner surfaces at high temperature (100C tends to be scary in a water system but not in a Evan's system) , the oil film within the liner/piston ring interface remains within grade. ...unlike water coolant systems where local steaming/boiling events prevents coolant contact with the liner resulting in ZERO oil cooling at the/piston ring interface - resulting in local oil overheating.

That said, I probably wouldn't have stuck with Evans without the flexible coolant flow that the DC EWP80 provides. Evans needs a higher coolant flow to quickly dump its heat compared to a water system. The problem is more at low engine speeds rather than high. All to do with Evans lower specific heat value compared to water.

I know I won't convince anybody on here ... not least because it's hamstrung by the initial outlay (Evan's coolant is about £20/litre and a DC EWP system will consume about £300-£400 by the time you've properly fettled it!) .
Peter K

TrevorK
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Re: Cooling issues on 92 SE

Post by TrevorK »

Lotus-e-Clan wrote:
Tue Dec 01, 2020 22:53
Because Evan's coolant more faithfully tracks oil temperature without boiling/losing contact with the liner surfaces at high temperature (100C tends to be scary in a water system but not in a Evan's system) , That's why the system is pressurised. It raises the boiling temperature. At 1.5bar it's over 110C the oil film within the liner/piston ring interface remains within grade. ...unlike water coolant systems where local steaming/boiling events prevents coolant contact with Not necessarily. Boiling the water removes a lot of heat. If the steam can be moved away and replaced with fresh coolant it can be very effective
Despite my comments in the quote above I can see the advantages of doing away with a pressurised system and the low freezing and high boiling points of the Waterless Coolant are a bonus as is the long life.

Could you not find a smaller water pump pulley to speed up the flow rather than go to an electric water pump?
What car is that?

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Lotus-e-Clan
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Re: Cooling issues on 92 SE

Post by Lotus-e-Clan »

Hello Trevor

Yes system pressure raises the boiling point, but a 100C temperature reading in the Excel is a gross remote reading taken at the thermostat and not at the liner surface/water jacket interface where small pockets of steam may form at higher local temperatures. And yes if cooler water is flowing well through the block then it is less likely to boil. Water wetters have been used in F1 to better keep the water in contact with the liner to prevent local steam pockets forming when at full chat - but hardly anyone uses them in a road car. Evan's however has better coolant-to-metal contact and a boiling point of 180C without any system pressure required so is better than a water system in that regard. It also cavitates a lot less than water too.

The weakness of Evans is the lower Specific Heat value. Water is a fantastic buffer of heat energy, - it heats more slowly (in terms of measurable temperature) compared to Evans which becomes hotter (in terms of measurable temperature) than water for the same heat energy input. Many moons ago I conducted a test to demonstrate this quite effectively.

Compare the behavior of Evans versus water for a measured heat energy input.
Image

You can see how well water absorbs the heat energy without rapidly raising its temperature reading. When the heat was switched-off after 5 minutes, water temp is only 74 C versus Evan's 104 C reading. Moreover Evan's temperature is still rising AFTER the heat is off - whereas water temp immediately plateaus (water's heat buffer effect.)

But when it comes to losing heat, water releases it's heat energy slowly (temperature readings are lower for a given input) that's why for water you don't want a rapid flow of coolant through the radiator. Evan's dumps its heat more quickly (temperature readings are higher for a given heat input) so a faster flow through the radiator is beneficial for cooling in an Evan's system.

A mechanical water pump running faster would absorb too much engine torque -the Excel needs more torque not less. The EWP is programmable so you get more flow when you want it to cool and less flow when you don't .. like at higher low-load cruising speeds (more air through the rad) and for short blasts when you want max power output (the EWP then flows faster to dump the heat after the event).

In a well maintained water system there's no cause for concern. But water systems tend to self destruct - corrosion, scaling, and high system pressures take their toll over time. Evan's systems are very stable over time....that's proved to be the case in both my Excel and Clan at least.
Peter K

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MetBlue
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Re: Cooling issues on 92 SE

Post by MetBlue »

Thanks for posting that Peter. I'd heard much about Waterless coolant, but confess to not knowing that much about it. I'm a lot better informed now.
I'll certainly be investigating further when the time is right.

Pleased to report that for the time being, my system seems good. 230 mile round trip today and no drama's on the cooling (Big thanks to suited and booted Richard for a push in the car park. At least it was down hill 👍👍).

The morning after I'd done the work, the level had dropped again which was initially a bit worrying, but I think it was just trapped air working through.

Tony
What goes together.... Must come apart.

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