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GoNz0

The old thermostat questions (again)

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Very interesting thread.  My 3.0 petrol doesn't seem to get warm, so was thinking of changing the stat. Do the petrol models have this gearbox heat exchanger this too?  Yes, mines an auto. 

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On 05/01/2018 at 2:46 PM, RightHandGoose said:

My recent E61 2007 purchase has the DPf flashing a lot now and I've just done cluster reading. That will probably explain why it will not regen..? Took the car for a 30 mile round trip and the temp peaked at 70 and fluctuated between 65-68.........should I buy the engine coolant sensor first or do the clamp thing first. As it happens I'm looking to get the autobox serviced too and there is some leakage to been seen from below on the pan.

 

The gearbox heat exchanger thermostat is the most unlikely thermostat to fail. The main thermostat is usually the one that goes. However sometimes it's the EGR thermostat.

 

Yes three thermostats to contend with.

 

The coolant temperature sensor very rarely fails but the main thermostat seems to wear out and is an extremely common cause of low temperatures then DPF blockage.

 

Change the EGR thermostat first because it's something like £30 and a 10 min job to change.

 

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Nice 1 Jason, thanks for the support. As it happens I've just bought the engine coolant sensor. But will buy the EGR sensor and do that first before I shell out for labour on the engine coolant sensor. Cheers

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EGR one takes about 10 minutes, really easy. If you have both I would get on and do it, while you have the rad hose off and thermostats you can unplug the gearbox one and see if you can blow through it, if you can it's buggered and will need swapping.

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Just tried my trusted Torque Pro App + ELM327...Freeze frame information:
------------------
Engine Load = 98.824 %
Engine Coolant Temperature = 54 °C
Intake Manifold Pressure = 32.779 psi
Engine RPM = 3,076 rpm
Speed (OBD) = 73.943 mph
Intake Air Temperature = 18 °C
Mass Air Flow Rate = 160.94 g/s

Plus P14A7 Powertrain

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48 minutes ago, GoNz0 said:

EGR one takes about 10 minutes, really easy. If you have both I would get on and do it, while you have the rad hose off and thermostats you can unplug the gearbox one and see if you can blow through it, if you can it's buggered and will need swapping.

 

Cheers buddy.....

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Seems I am back to where I started, temps are terrible again, between 65 and 80 if I am lucky. I need to get under the car and clamp the heat exchanger again in case it has gone south. Return pipes seem cool to the touch though, same can be said for the main pipe from the stat and the EGR.

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Can it be down to it being bloody cold and damp at the moment?  I'm leaving mine til it's a bit warmer and see if I actually do have a problem or not....

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Thing is I have a picture of the hidden temp after I had done the bloody heat exchanger, checked historical weather for nottingham 2pm on the 11th of december and it was 0 degrees, go figure it has been hovering around that all week. I will go clamp it off again later this week weather depending, I will be rather pissed if the new heat exchangers gone tits up.

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Thing is Dave, the heat exchanger has its own loop back to the rad, this is what allows the damn thing to take some of the engine heat and throw it into the rad bypassing the main stat as I found out last time. I guess when I get a bit of dry weather I will see if my 3 year old will behave for 20 mins while I get under it and clamp that pipe again!

 

I will be gutted if it is that and probably happy to have an answer again. 

 

I will let you know.

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As you said, it isn't that old and is pretty poor if it's failed already, but at least it could be an answer. And hopefully it'll be a warranty exchange, so no cost?

 

But...  you said the return pipe is cold, so.......

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I will have to buy it new then return the faulty one or the car could be off the road for weeks while they piss about, either they will just refund on return or play the long game as they will be unable to test and send it back to Hella/Behr for testing. Of course if I can blow through it I know its fubar.

 

Carparts4less don't have the best customer service.

Edited by GoNz0

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1 minute ago, DaveR said:

Tstill got your old one ? 

Hell no, dropped that in the bucket with coolant and gearbox oil and as I knew it was well fucked it went in the bin. No biggy I can stump up that much for a few weeks while they sort it, I will put off other repairs I had planned :lol:

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Oh well, I clamped off one of the cooler pipes and temps shot back up to 90 so it confirms the new ones jammed open within 6 weeks. New one ordered and RMA started for the old one as they are happy to refund that after it has been returned for testing.

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On 11/12/2017 at 7:19 AM, Wabby said:

100% gearbox heat exchanger mate.

 

Just pop an inline one in the top hose .... standard mod that I and many others on here have done with no detriment. Only costs a £5er as well.

Did that on mine and cured the issue, plus it gives better gearbox temps

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Thursday saw me swap the failed 6 week old Hella-Behr gearbox heat exchanger as the temps went to shit again, clamping off the return pipe confirmed the new unit had failed with the thermostat open. Prior to removal I clamped off both coolant lines, pulled one hose and released the clamp on the other, sure enough coolant flowed straight through the thermostat that was initially shut when new as I tried to blow through it again.

 

CP4L were reasonably helpful but I still had to buy a new one while I wait for them to return it to Hella for testing.

 

After I had done the work and bled the coolant I went for a drive, temps were up to 88 in 10 minutes, 5 miles of urban driving. Happy as it was working again and economy returned.

 

Sunday we went out for a drive and I noticed the economy was down so I brought up the temp menu and the bloody thing was hovering around 75 again, unbelievably the replacements failed open again within 48 hours.

 

Spent 20 minutes on the phone to the Hella UK product manager who is now waiting for Germany to get back to him to see if they have an answer or I just seem to have really bad luck with 2 failures in a row. He did lookup to see how many returns they had through and in the past couple of years the UK has had one, probably due to people not knowing they have a problem.

 

Cooling system is fine, no shit in it, new coolant (G48 BMW approved) so it can't be a foreign object getting stuck in the stat, new stats in November that were not needed as the heat exchanger was the cause.

 

I did notice both had half a sticker missing and lots of dremel work to remove what I assumed were the OE details, the product manager told me the same without me asking that this was in fact the OE unit BMW use with the branding removed so he is also stumped, we both know you expect the odd one to fail but 2 in a row could point to a bad batch CP4L had (had as they are OOS now)

 

Pissed off!

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Bloody ell..  That's not good at all!  Good job you're doing the work yourself and not getting a garage to change them! 

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Do the Renault 5 turbo top hose mod...cheap, fast and I never see less than 80 degrees now, even on a fast, steep, long descent. £5 on eBay and about 45 minutes to do.

worked for me...

kind regards,

ed

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2 hours ago, DaveR said:

Bloody ell..  That's not good at all!  Good job you're doing the work yourself and not getting a garage to change them! 

If I had paid a garage it would be covered under warranty and they would be claiming it back from CP4L as they did ask if I wanted to lodge a labour claim.

 

And I have no wish to do the top hose thermostat mod thanks, it is fair enough for a single stat car that requires engine mount removal and cam belt off to get to the housing but not a 50k when new BMW, I try not to bodge thing's "if" I can help it. Main reasons due to the 3 opening when needed.

Edited by GoNz0

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That’s fair enough and a good approach to things. I put new genuine thermostats in mine when I got her and they got her up to 80 degrees...for about three months and failed again. Top hose mod has been fine ever since but I like your thinking.

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