Hi all,
I'm in need of an opinion or some direction.
I recently changed my water pump and also thermostat and all was fine for about 600km.
Took the old girl out for a run the other day and temps started to rise. I got to where I was going and peaked at 95c
Other way home got to 98 then I turned on heater and it bought temps Down enough to make it home at 98.
I generally run at 78 to 82C.
Run a new PWR radiator. Have replaced hoses, has new coolant.
While trying to fault find I found a piece of rubber in my AST. See pic.
So have pulled water pump off and thermostat housing as I thought some how the seal gave way.
Water pump looks fine as did the seal on the thermostat.
Prior to that I thought an air lock , so with my funnel thingy I tried burping but nothing of substance.
No leaks I can see.
I have no idea where this bit of rubber came from.
Both caps are intact
Appreciate any thoughts.

 

IIRC, at least on the S6 cars, the stock fan sensor (thermoswitch) initiates at something like 96 C. so I don’t think you overheated.
What was ambient at the time? What ratio of coolant to water did you use after replacing the t-stat and WP? Were you careful to put the jiggle-pin on the t-stat at 12 o’clock? After complete cool down how’s the coolant level in the filler neck and on the overflow dipstick?

From the scale next to the coin, it’s hard to imagine that piece rubber seal making it thru the small lines to the AST from the rest of the system. I’d guess it’s a piece from an old spring cap that fell in…and not much cause for concern.

 

Thanks for the reply.....
I was aware of the 96c trigger point for fans and yeah maybe freaked out a little due to never have had it get to those temps since I have had the ability to gauge temps. ( most of its driving time I've had it ).
I was going to fit the FC or miata unit to get them on earlier but plugs are different so a task for a rainy day.
traditionally temps have been stable.
It just hit spring here so only 21c that day.
I run 30% coolant and also use distilled water.
I did see that jiggle pin but had no idea it had to be at 12 o'clock. Would love some insight into that.
I did start to see a rise in the overflow and a lowering in the system and when I pulled up could hear the pressure cap working. It's my understanding it sucks it back when cool ? I did however notice the neck had become brittle and a small hole on the overflow bottle so have ordered a new one.

Good point also on the rubber piece. I hadn't thought of previous caps.

i also will run it once I get some new bits in and check the fans kick in

 

That jiggle-pin is there to allow any air bubbles to pass and why you want it high (at 12:00 o’clock) in the housing.
And I mis-spoke earlier…the stock S6 thermoswitch in our cars initiates at around 105 C. It’s the S5 FC thermoswitch that initiates at 96 C. And unless the later series RHD FD’s we’re different, the S5 FC thermoswitch is PnP.
Applogies for any confusion.

The overflow bottle is NOT ever pressurized. I think the hole is suppose to be there. Just make sure that when the engine is completely cool, the level is at the “full” mark on the dipstick. As coolant in the engine’s system expands with heat, it enters that overflow. As the engine, and the coolant inside cool, a vacuum forms and draws coolant back out of the overflow.

 

The jiggle pin at 12 makes perfect sense, thank you.
I'll have to double check my part numbers on my thermo switch. I will also double check which sensor I was looking at but I did think it was the bottom one..
I have been doung some reading on that
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The overflow bottle is more my OCD kicking in. I understand that as long as the hose is submerged in coolant it can as you said draw back under vacuum.
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I'll poke about and may do a pressure test and or swap in my spare pressure cap. Something has changed as I've never seen temps in the high 90's.
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I haven't yet gone into panic mode worrying about damaged coolant seals. This is my first rotor since having rx2, rx3, S2 Rx7. I must admit while not a total novice, things were a lot simpler back in the day.
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I really appreciate your input

 

A little freak out is good. It keeps you on your toes.

With that said, if you have your fans set to a lower temp (which I suspect you do because 78 to 82C is barely operating temps), check to make sure both of your fans are coming on. I've had that happen to me before. All the sudden the car started running at 95-98C from an always stable temp of 85-88C due to one fan taking a dump.

 

That's not a bad thought at all. I will definitely check fans are doing there thing. Cheers

 

Is it possible the new thermostat you replaced to might be jammed/opening at the wrong temperature? If you've got the old one laying around, maybe swap it back and see if that makes a difference. Or put both in a boiling pot and see if they behave similarly.

 

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That was one of my original thoughts or that the rubber seal had broke and was fouling the thermostat.
I pulled everything out and I did pop new stat in boiling water and it did open OK.
Unfortunately I tossed the old one.
Thanks for the input, appreciated

 

Jiggle pin at 12 o'clock. You don't know what you don't know until you know it. This is why I read every thread...

 

I work Night shift so often have many hours sifting through threads and reading up on the millions of things I dont know

 

OK few things here.

- OEM thermostat ONLY. I've seen MANY parts store thermostats fail in a month or so. If you have aftermarket go get an OEM thermostat.
- Possible you just still have some air in the system. Use a Lisle funnel to get all the air out.

Also be certain there are no coolant leaks - loss of coolant will overheat the car, always.

Dale

 

Thanks Dale,

Im a huge fan of OEM, Especially critical stuff like sensors, solenoids ect.
Luckily I can get most of it from Japan at a decent price as Mazda AU rip off the general public.
Im just going through and checking out hoses and stuff now while I am waiting on a parts delivery from Japan.
The Lisle funnel was one of the best things I bought, so much easier doing coolant.
I am hoping there was an air pocket some place I missed.

 

And I recommend staying with the OEM .9 bar spring cap and OEM filler neck cap. If you continue having trouble with air in the system but a pressure test holds, new OEM caps would be my next move.

 

Thanks all who replied,
Just thought I would ping back witha follow up as I hate reading threads that leave you in suspense.
Finally got some new gaskets and stuff from Japan and put everything back together making sure jiggle pin was at 12 o'clock.
Went well for about 20 seconds then killed a belt. I knew it needed changing but that was one thing that didnt turn up, so waited for that then tried again.
Had my funnel burpie thing and run with heater on and filled overflow to correct level and run to temp,
Everything seemed ok so shut it down and capped the lot off.
Happy to say at this point, even with some 30C days temps have been back to normal 77 to 83 with the odd spike in high 80's if stuck in traffic.
So im hoping it was just the jiggle pin and an accumulated air pocket that built up over the 600km that I run.
I have a 75C Sard Thermosstat here if I feel the need but will keep it in the back pocket for now.

 

Your temps sound pretty normal to me…..you should be golden.

 

Yes, now all seems to be back to normal.
Still driving around not quite relaxed and monitoring but fine with that.
Both belts replaced and overall happy

 

I'm glad you got that sorted. The lingering feeling of being on watch for "is my problem still there?" really sucks. Take it out for a good spirited drive to build that trust up in your car again!

 

Thanks,
Definately a relief, I had horridle nightmares of water seals failing and rebuilds.
Ive had it out maybe half a dozen times, each for longer runs testing the waters ( no pun intended ) and it's held up so yes indeed building that trust up again and still enjoying.
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Car is looking good.

My S8 runs at 95 C most of the summer. In cooler temps the range is 85~90.

If I sit anywhere with the car idling for any length of time (or if stuck in slow moving traffic), it will range up to 107C

Sitting in line between autocross runs in 31C outside heat I got up to 117C because there was not enough time to let it cool between runs.

After a prior autocross, at the end of the day, I left the car running while I packed up then pulled over at the exit gate to read some texts.

The temp went up to 125C.

Fortunately I quickly got out on some open road and got it to drop (until I caught up to some traffiic.).

Had the car thoroughly checked over shortly thereafter, and there was no apparent damage.

 

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Thanks,
just glad I can drive it again.
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I always freak out when temps get into the 90's, I have read a lot and I understand high 90's is not uncommon and i suppose I wouldn't even know if I didn't have a digital temp gauge.OEM gauge just sits pretty.
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I think I would probably hyperventilate at 117c and possibly pass out if temps got to 125c.
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What radiator do you use ?
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I replaced the FEED one that come with the car for a PWR unit and it has been solid..

 

I had a generic "racing" metal rad put in early. I recently replaced my AST (and cap) with a new in box OEM. I think this has helped keep temps down. Previously I had a DIY one.

I have my Power FC commander set to show coolant temp, but also UIM intake air temp. I also have an AEM oil temp gauge.

I also installed the second oil cooler quite a while ago.

I had a temp gauge in my engine bay for a while.

The car would consistantly heat sink up to 107C just sitting in the car port after a run.

Accordingly I have a big industrual fan in my carport that I let wash over the engine bay for an hour or so after a drive.

 

I've got a completely stock cooling system and engine and I stay just below 100C on the hottest summer days in florida. I only get that hot when running the A/C. If I don't run A/C it's a solid 95C. I do have the radiator fans running full time.

 

Full time full time, or kicking in at a lower temp?

 

I've got a button that the original owner installed to turn them on or off, I just leave it on in Florida during the summer. No real reason to turn it off.