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Bigbird76

535d The Extra Thermostat fitting Guide.

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To bring up and old thread,, still not fitted mine!!

 

Going to though as my main stat seems a little lazy lately, and I mainly do short run journeys these days.

 

As the pics are down (photobucket!!) Which way round does the stat need to go in the hose??

 

Cheers. 

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Done it this morning. For reference, the upper hose on a 2007 320d is too small really to do this...

 

I managed to get the stat in  but only just far enough to get the hose back on to the rad Inlet. Not 100% happy with it, but will give it a try and see if it helps. Only 5 min job to whip it back out if it causes any issues. 

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Today i tried to put that small thermostat in it

 it went in but could not connect back to rad :/ ... its too tight or something, is there any smaller thermostat maybe, or with what did you pressed it in ?

 

thanks

Edited by vantsen

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I have just fitted the inline thermostat mod.  As a bit of background I put this on the FB page just before Christmas:

 

Need some thermostat advice please folks. 
I have an ‘05 E61 530D auto on 165k. Both my main and EGR (which is deleted) ‘stats were replaced 12000 miles ago. Check of temps recently showed that I’m only getting 85-86C at extended motorway cruise speeds with a single early read of 90C uphill. Takes about 20 min from start to get into 80s. Getting mid-30s fuel consumption. 
Have removed EGR stat and can blow through it with a bit of effort but it doesn’t appear wide open.
I’m t
hinking maybe it’s the transmission heat exchanger and am contemplating one of the in-line ‘stat mods discussed on the forums. 
For those in the know:
1. Which is the more effective online mod to address gearbox stat failure?
2. How can I get transmission fluid temps from either Carly or C110? Can’t see any obvious parameter. I have a Cable Shack cable with all the software but yet to load it.
3. What is the normal operating temperature for a ZF 6 speed autobox (serviced within 40k).

 

I got some good advice to have a go at the transmission heat exchanger 'stat inline mod on the lower transmission cooler, hose but I decided to go for the easy option first.  I've just been on a 60 miles motorway test drive and my results are inconclusive: 86-87C +/-1C (dependent upon incline), gearbox temp steady at 43C, although it took a good 35 min to get above 40C, which is still looks pretty low?  Fuel consumption looks good, albeit at 65mph on the motorway. 

 

Mindful that the engine design operating temps are in the low 90s, would I be right in thinking that the transmission cooler looks to be open and the extra cooling effect of that heat exchanger is dragging my coolant temp down by the crucial 5-6 deg C or so? One reason I want the transmission at the design temp is to rule out the low temps forcing my ZF box to remain in the warm-up cycle, as I am getting the classic Torque Converter failure symptoms of the transmission 'hunting' +/- 75rpm at 60-70mph with cruise in.

 

Appreciate any help offered.  Happy New Year all.
 

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The heat exchanger mod I put up on here separates it from the rest of the system, the 5 mod still allows some conduction through the system. Basically when the car is up to temp and the R5 stat opens with a duff gearbox heat exchanger you will start cooling the gearbox, the gearbox only really overheats in start stop traffic so it will overcool on the motorway.

 

Hence me not approving of the 5GT mod as it's just a general bodge.

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Ok, thanks mate. I think my ‘stats are good  to be honest, considering the R5 mod only gives me +1 deg C.

I’ll remove it and put the VAG stat in as you advise, otherwise it’ll all get a little confusing with different ‘stats and mods in the system.  Is it easier done from above or  below, once the under tray is removed?

Also, are those VAG clips essential or can you use Jubilee clips to secure either end.  I’ve already got the VAG ‘stat recommended from your DIY post.

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100% above, I lifted the pipe up and worked on it from above once clamped and released from the stat. 

 

I used those clips so it looked neat but others have used jubilee clips m8

 

Edited by GoNz0

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Just bought the Thermostat and clips. Going to do this as a fail safe. 

 

Haven't even checked temps but it seems like an easy and good thing to do. 

 

Edit: Completed simple task ! Thanks for the tutorial ! 

 

 

Edited by turbocrow

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I cannot for the love of me get that shizzle inside the hose far enough.

 

I have a wahler thermostat (like the guide says), and my car is a 525d, which has the same hose as a 535d has. And yes, i even looked it up that they have the same article number on the hose.

I have used everything that i can think of from my garage to lube that hose and stat. I've tried grease, engine oil, WD40, concetrated coolant etc..

I tried heating the hose up to about 90-100C if that would help it expand a bit. It didn't.

 

I fought with that shit for over 2 hours yesterday, and it wouldn't get further in then like 5mm.

 

Help a cold guy out with more tips. It is freaking cold here in sweden, and so is the car...

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3 hours ago, fredrikahonen said:

I have used everything that i can think of from my garage to lube that hose and stat. I've tried grease, engine oil, WD40, concetrated coolant etc..

I tried heating the hose up to about 90-100C if that would help it expand a bit. It didn't.

I don't have a diesel and have not tried the above conversion but have found that a spray of silicone lubricant works wonders with tight fitting rubber.

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You see this as a bodge?

A massive one, you're plugging up the only way to release heat from the engine with a stat nowhere near any of the 3 heat sources the original 3 stats are there for. All it takes is the egr to heat up and you have a hole in your inlet manifold. You're relying on blind luck the stat opens before something's damaged. It truly amazes me people still get away with this m8.

 

Sent from my SM-G920F using Tapatalk

 

 

 

 

 

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1 hour ago, GoNz0 said:

A massive one, you're plugging up the only way to release heat from the engine with a stat nowhere near any of the 3 heat sources the original 3 stats are there for. All it takes is the egr to heat up and you have a hole in your inlet manifold. You're relying on blind luck the stat opens before something's damaged. It truly amazes me people still get away with this m8.

 

Sent from my SM-G920F using Tapatalk

 

 

 

 

 

Good thing my EGR is long gone then!

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23 minutes ago, fredrikahonen said:

Good thing my EGR is long gone then!

No everyone who fit's this is gone though.

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3 hours ago, GoNz0 said:

A massive one, you're plugging up the only way to release heat from the engine with a stat nowhere near any of the 3 heat sources the original 3 stats are there for. All it takes is the egr to heat up and you have a hole in your inlet manifold. You're relying on blind luck the stat opens before something's damaged. It truly amazes me people still get away with this m8.

 

Sent from my SM-G920F using Tapatalk

 

 

 

 

 

Oh I get you. So how come the gearbox/Audi thermostat is such a good fix? What's the difference?

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Just now, iReaper1157 said:

Oh I get you. So how come the gearbox/Audi thermostat is such a good fix? What's the difference?

It is placed right after the heat exchanger and only blocks the gearbox cooler lines, it is also modeled exactly on basically every single VAG car from a polo to an R8 that all use this stat just after the gearbox heat exchanger as the VAG group figured they didn't need to over engineer a stat for every model like BMW did. It runs 15 degrees lower than the one it is replacing directly in the oil lines to account for the pinhole flow it introduces meaning the cold water from the rad mixing with the transfer plates in the heat exchanger  hit 95C the coolant hitting the stat is approximately 80C so the stat opens, this has been tried and tested in several situations with the box never exceeding 95C so a perfect solution to a problem BMW are not prepared to acknowledge.

 

 

If BMW/Behr sorted their shit out and made a gearbox heat exchanger that didn't fail I would happily fit one, but that isn't the case. Fit a new one and it will fail the 1st time it opens, I don't have enough fingers for people I know including myself who got through 7 before being forced to do this tried and found it failed.

 

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On 12/3/2019 at 9:34 PM, GoNz0 said:

It is placed right after the heat exchanger and only blocks the gearbox cooler lines, it is also modeled exactly on basically every single VAG car from a polo to an R8 that all use this stat just after the gearbox heat exchanger as the VAG group figured they didn't need to over engineer a stat for every model like BMW did. It runs 15 degrees lower than the one it is replacing directly in the oil lines to account for the pinhole flow it introduces meaning the cold water from the rad mixing with the transfer plates in the heat exchanger  hit 95C the coolant hitting the stat is approximately 80C so the stat opens, this has been tried and tested in several situations with the box never exceeding 95C so a perfect solution to a problem BMW are not prepared to acknowledge.

 

 

If BMW/Behr sorted their shit out and made a gearbox heat exchanger that didn't fail I would happily fit one, but that isn't the case. Fit a new one and it will fail the 1st time it opens, I don't have enough fingers for people I know including myself who got through 7 before being forced to do this tried and found it failed.

 

I've done the VAG mod myself after reading your post and its worked wonders but needed main stat as well. decided to go to BMW and bought a main and EGR at the same time deciding not to go for this inline mod. Just didn't sit right with me. Just wondered your thought for comparison. 

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Gonzo can reply on his behalf but I still give my thoughts. A thermostat on the top hose is a bodge compared to the original system where the main thermostat reacts on the coolant mixed from engine itself and all the return lines (heater core, oil heat exchanger, EGR cooler, gearbox heat exchanger and bleed path via expansion tank). A thermostat on top hose will only react on the coolant coming from the engine and for it to react it would need more bleed flow which would inevitably cause more flow to radiator. With a simple hose thermostat there will be more fluctuation on temperatures and it will always be a compromise. The original system is actually very clever and works great as long as the thermostats work correctly. Isolating a single circuit with separate thermostat like with the gearbox heat exchanger is a totally different thing compared to isolating the whole system. Same thing with EGR cooler if EGR is mapped out.

.

Edited by Clavurion

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7 hours ago, Clavurion said:

Gonzo can reply on his behalf but I still give my thoughts. A thermostat on the top hose is a bodge compared to the original system where the main thermostat reacts on the coolant mixed from engine itself and all the return lines (heater core, oil heat exchanger, EGR cooler, gearbox heat exchanger and bleed path via expansion tank). A thermostat on top hose will only react on the coolant coming from the engine and for it to react it would need more bleed flow which would inevitably cause more flow to radiator. With a simple hose thermostat there will be more fluctuation on temperatures and it will always be a compromise. The original system is actually very clever and works great as long as the thermostats work correctly. Isolating a single circuit with separate thermostat like with the gearbox heat exchanger is a totally different thing compared to isolating the whole system. Same thing with EGR cooler if EGR is mapped out.

.

Makes sense now. Thank you 

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And now for something completely different!

 

I will be undertaking the heat exchanger stat modification shortly.  Originally went for the top hose Renault 5 method and can confirm it is only a bodge.  My query is this.  Many of you have stated that you cannot get the Renault stat into the hose.  Will I be able to get the B.....d out again or is it new hose time?  Don't want to leave it in as well as the new one.

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5 hours ago, oldjohnny said:

And now for something completely different!

 

I will be undertaking the heat exchanger stat modification shortly.  Originally went for the top hose Renault 5 method and can confirm it is only a bodge.  My query is this.  Many of you have stated that you cannot get the Renault stat into the hose.  Will I be able to get the B.....d out again or is it new hose time?  Don't want to leave it in as well as the new one.

It will come out m8, if not used hoses are cheap enough.

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5 hours ago, oldjohnny said:

And now for something completely different!

 

I will be undertaking the heat exchanger stat modification shortly.  Originally went for the top hose Renault 5 method and can confirm it is only a bodge.  My query is this.  Many of you have stated that you cannot get the Renault stat into the hose.  Will I be able to get the B.....d out again or is it new hose time?  Don't want to leave it in as well as the new one.

And have you confirmed it is the heat exchanger?

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