Coolant & Otter switch
Discussion
I may have been a numpty!
As per my other thread, car seemed to be running a bit hot and the fans seemed to be kicking in very late based on the gauge, so decided to replace the otter switch first since it is cheap and fairly easy to access. Although I suspect it is actually the sender but we shall see, that’s a bit more faff to replace.
A reasonable amount of coolant came out, but I assume only what was in the swirl pot. At least it told me what coolant was in the car as it went down the drain.
Now for the numptiness, I wasn’t thinking and just topped it up via the expansion tank and not the swirl pot.
So, should I -
a) top up a bit into the swirl pot, massage the top pipe to get it to circulate, run the car, rinse repeat?
Or
b) run the car briefly and THEN top up the swirl pot? And I mean run the car for a minute or less.
I will also need to bleed it via the radiator as well, I expect.
I am leaning towards b as that in theory should get water flowing into the swirl pot and around the car and then I can check levels?
As per my other thread, car seemed to be running a bit hot and the fans seemed to be kicking in very late based on the gauge, so decided to replace the otter switch first since it is cheap and fairly easy to access. Although I suspect it is actually the sender but we shall see, that’s a bit more faff to replace.
A reasonable amount of coolant came out, but I assume only what was in the swirl pot. At least it told me what coolant was in the car as it went down the drain.
Now for the numptiness, I wasn’t thinking and just topped it up via the expansion tank and not the swirl pot.
So, should I -
a) top up a bit into the swirl pot, massage the top pipe to get it to circulate, run the car, rinse repeat?
Or
b) run the car briefly and THEN top up the swirl pot? And I mean run the car for a minute or less.
I will also need to bleed it via the radiator as well, I expect.
I am leaning towards b as that in theory should get water flowing into the swirl pot and around the car and then I can check levels?
Hi, you may have read Dave’s (COG’s) thread on Range Rover Sender Thread Size(?).
Well, despite the somewhat cryptic title our mate COG has sourced the correct temperature sender for our cars.
So it sits where it should do and not the TVR dead end.
I can see why people condemn all other cooling system items except the gauge and there are numerous companies out there who will sell you ‘fixes’ like different range thermostats and otter switches etc.
So unless you have an infrared thermometer, you’ll take the gauge as accurate.
The correct sender has totally restored my confidence in the Chimaera cooling system, and the gauge is now very accurate- it only takes 15 mins to change.
Just invest in a cranked 12/13mm combination ring spanner so all you have to do is move some HT leads out of the way.
However, topping up the swirl pot is easy and it often requires frequent checks in the course of a coolant change- until the level normalises at the bottom of the threads.
This is because it’s the highest point in the system and stubborn air pockets will eventually get themselves trapped there.
Naturally top up when cold, and keep the expansion tank cap on or coolant will symphon into it.
Good luck
Well, despite the somewhat cryptic title our mate COG has sourced the correct temperature sender for our cars.
So it sits where it should do and not the TVR dead end.
I can see why people condemn all other cooling system items except the gauge and there are numerous companies out there who will sell you ‘fixes’ like different range thermostats and otter switches etc.
So unless you have an infrared thermometer, you’ll take the gauge as accurate.
The correct sender has totally restored my confidence in the Chimaera cooling system, and the gauge is now very accurate- it only takes 15 mins to change.
Just invest in a cranked 12/13mm combination ring spanner so all you have to do is move some HT leads out of the way.
However, topping up the swirl pot is easy and it often requires frequent checks in the course of a coolant change- until the level normalises at the bottom of the threads.
This is because it’s the highest point in the system and stubborn air pockets will eventually get themselves trapped there.
Naturally top up when cold, and keep the expansion tank cap on or coolant will symphon into it.
Good luck
When I need to refill/top up my coolant I do the following to bleed the system.
Half fill the expansion tank,
Raise the front right of the car to get air out of the radiator then tighten the radiator cap,
I have a long neck funnel which I jam into the swirl put and tape to a piece of wood so the funnel is about a foot higher than the engine.
Fill with coolant and massage the hoses to bleed air out as much as possible whilst it’s cold.
Start the engine, heater on full hot.
Keep running until the thermostat opens and then keep going till the fans come on.
Rev a few times until bubbles stop coming back up to the funnel.
Engine off leave to cool then remove funnel and replace swirl pot cap.
Make sure the funnel is full all the time especially when leaving to cool.
I put some tape around the end of the funnel to get a good seal.
Half fill the expansion tank,
Raise the front right of the car to get air out of the radiator then tighten the radiator cap,
I have a long neck funnel which I jam into the swirl put and tape to a piece of wood so the funnel is about a foot higher than the engine.
Fill with coolant and massage the hoses to bleed air out as much as possible whilst it’s cold.
Start the engine, heater on full hot.
Keep running until the thermostat opens and then keep going till the fans come on.
Rev a few times until bubbles stop coming back up to the funnel.
Engine off leave to cool then remove funnel and replace swirl pot cap.
Make sure the funnel is full all the time especially when leaving to cool.
I put some tape around the end of the funnel to get a good seal.
I put a bleed screw in the swirl pot and a second one at the high point in the top hose, this is often where a bubble of air can get trapped and is difficult to purge out, so with bleed screws its easy to release it.
I also fitted bleed points to my in and out heater hoses and my in and out LPG vaporiser hoses, with the rad bleed screw I have 7 points in total, starting from the lowest bleed point working my way through to the highest bleed point I can quickly and easily chase out all remaing air.
And of course as always old school hose squeezing helps burp the system and speeds up the process
I have not seen this thread! I have read a few but one was talking about adding a resistor etc. Do you have a link to it or a link/part number of the sender?
Thank you for the bleeding instructions, useful and I shall try and do this tomorrow (wife permitting).
The bleed points look very helpful and will add them to my list of projects/upgrades!
Thank you for the bleeding instructions, useful and I shall try and do this tomorrow (wife permitting).
The bleed points look very helpful and will add them to my list of projects/upgrades!
It's been running since mid June! 8 pages to peruse here 
:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
:https://www.pistonheads.com/gassing/topic.asp?h=0&...
Assuming all levels are correct, one of the easiest ways of checking for air in the system is the heat coming from the heater. If it comes out extremely hot, then the heater matrix is getting hot water not air.
There is the potential for the matrix to be clogged or the awkward little valve not to open properly but you would have probably spotted a poor heater before you started doing things to the cooling system.
It can be a bit of a faff to bleed the car properly and I have had success jacking the front up! That was when I discovered how hot the heater can be..
There is the potential for the matrix to be clogged or the awkward little valve not to open properly but you would have probably spotted a poor heater before you started doing things to the cooling system.
It can be a bit of a faff to bleed the car properly and I have had success jacking the front up! That was when I discovered how hot the heater can be..
Jacked the car up and I think I've bleed it etc properly, thanks all! Might need to siphon out some of the expansion tank though.
Only question is, my drive is slightly inclined -
I assume the best way to do this, will be to have the car facing uphill while doing any work? The rear wheels will be chocked and left in gear etc.
Garage is temporarily full, so that isn't an option at the moment.
Only question is, my drive is slightly inclined -
I assume the best way to do this, will be to have the car facing uphill while doing any work? The rear wheels will be chocked and left in gear etc.
Garage is temporarily full, so that isn't an option at the moment.
Steve_D said:
Yes that's the one.
Steve
Brilliant, thanks!Steve
Hedgehopper said:
That is one on my list to add. While bleeding the coolant etc, I let the car run, and with the new otter switch, the fans didn't kick in until the gauge was reading about 100C, so I am currently assuming the temp sender is the likely culprit. Since I had the bonnet up, I could easily see both fans running as well.
Also waiting for a new Rover Gauge cable to show up, so will confirm once this arrives.
CoG and I concur on coolant bleed points. Those little 1/8"NPT Schrader valves you can buy for buttons are brilliant. Ive also installed one in the top of the swirlpot. Unless you get lucky, you will need a custom machined adapter boss to go in the swirlpot.
I can be persuaded to machine and anodise such things for beer tokens. Am furiously busy at the moment tho...
When I get round to it I shall machine up an M48*3 cap for the expansion tank with a pressurisation valve on it so I can properly purge all air.
I can be persuaded to machine and anodise such things for beer tokens. Am furiously busy at the moment tho...
When I get round to it I shall machine up an M48*3 cap for the expansion tank with a pressurisation valve on it so I can properly purge all air.
ed_crouch said:
CoG and I concur on coolant bleed points. Those little 1/8"NPT Schrader valves you can buy for buttons are brilliant. Ive also installed one in the top of the swirlpot. Unless you get lucky, you will need a custom machined adapter boss to go in the swirlpot.
I can be persuaded to machine and anodise such things for beer tokens. Am furiously busy at the moment tho...
When I get round to it I shall machine up an M48*3 cap for the expansion tank with a pressurisation valve on it so I can properly purge all air.
I can definitely supply ample beer tokens and much appreciation if you happened to find the time at some point to get one available. I can be persuaded to machine and anodise such things for beer tokens. Am furiously busy at the moment tho...
When I get round to it I shall machine up an M48*3 cap for the expansion tank with a pressurisation valve on it so I can properly purge all air.
I did find the other bleed point last night while trying to work out why the fuel pump wasn't working. Not as nicely done as the photo above though, so will be on the list of jobs to tackle and make nice/easier to use.
However the run did make me think the gauge is less wrong than I thought, and perhaps there was a lack of coolant in the system (before changing the otter). Even so, the new sender is definitely an upgrade (arrived today) so will be fitted in due course.
Even though I've already done and have more work to do to this car than the Boxster it replaced, I am fine with that. These are all little upgrades that are fun to do and just make life better. Not completely convinced the wife is in total agreement with that, but as long as she is out when most of the little packages arrive, it shall be fine.
Darned sight easier faffing about in the engine bay of the Chim than the Boxster as well!
QBee said:
I thought Boxsters were for non-smokers, because the engine has to come out to empty the ashtrays......or was my ex-Boxster-owning friend exaggerating? 
No, they were not! Pretty much the only thing easier to work on/replace on the Boxster compared to the Chimaera is the battery!I got the swirl pot plug off eBay, it was already drilled and threaded for the bleed valve which I purchase a couple of seperatly.
The heater hose bleed valves are sold for Caterhams and are just simple plastic knobs you fit in the hoses and twist open and closed by hand, but they work perfectly.
The heater hose bleed valves are sold for Caterhams and are just simple plastic knobs you fit in the hoses and twist open and closed by hand, but they work perfectly.
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