T-stat & control valve acting funky

[Magister88]

Hi everyone,

So about 1.5 years ago I replaced the t-stat as part of the cooling system refresh (hoses, sensors, rad, ET, WP etc..) and it was working fine engine temp around 93C.

1. Recently i started to observe the k-temp (my android unit shows the coolant temp all the time) and noticed that the engine reaches the 93C fairly quickly and stays there between 91 - 96 driving locally. However on highway driving while accelerating it can drop as low as 81 degrees. before slowly climbing back up, given i keep thing constant. it does take some time to go back to 93 and if i speed up it can drop back quickly to 88, 84 etc..
this t-stat is almost new from FCP Euro: Mahle Behr 11537509227. could it have started sticking open?

2. on another note seems my amazon heater control value acts up from time to time (also replaced it about 1 year ago). where the driver sides starts to blow really hot air while passenger side is normal. connected a scan tool and while the value shows as closed, the heater exchange on left shows 88-90C and right side shows closer to what the set point is. I guess it sticks open, did anyone of you replace it with the non oem version, seems OE it pretty expensive at $180 or is that the only way to go? rockauto has the gates and other brands for around $100. the amazon one was $40 (didn't think much of it when i got it).

Note: the t-stat temps still act the same way even of the heater value is working normally. so i do not believe its related.

Any input would be highly apricated.

than you.

[andrewwynn]

My rule for non OEM parts is when it's easy to access and not mission critical (you don't live where it's life threatening if heater valve breaks closed) and won't damage or prevent engine from operating it's fair game (bent my own rules a bit not realizing how hard it was to swap an aux fan geez BMW).


Sent from my iPhone using Tapatalk Pro

[80stech]

The coolant temp dropping at times is a function of the DME controlled thermostat heater and is normal and the reason why the dash guage is programmed to stay in the middle over that range.

[andrewwynn]

The reason for the non temp gauge on the dash pointing to noon from damaging levels of hot pot to damaging levels of cold is literally to prevent customers asking too many questions during warranty period. (as according to tech builtin). They don't think the average user can handle the truth (literally).

When the tstat fails open it will take longer to get up to temp and won't even reach temp when ambient is low.

[Clavurion]

Coolant temp should drop when you accelerate and warming element on thermostat is activated. But the basic temp seems a little low.

https://www.pss-autosoft.net/diagram...1214_M0KFK.htm

[workingonit]

The pointer of the coolant temperature gauge in the instrument cluster is located in the mid-position at coolant temperatures of 75oC - 113 o C in centre position.

I don't know much about the BMW M54 engine yet, but my experiences over 55 years with other

• 1) aluminum block/aluminum head engines,
• 2) iron block/aluminum head engines,
• 3) iron block/iron head engines

tell me that 113C (235.4F) is too high. I'd want the dash gauge to warn me about that temperature approaching, long before it was reached.

Operating temps, & over-temp and/or overheat experiences:
1) aluminum block & heads:

• a) '62 Olds F-85 with the 215c.i. V-8, that needed to be kept under 200F, or the head gaskets failed (2x),
• b) '08 Cobalt & '09 HHR with Ecotec all-aluminum engines, both run around 180F-217F (when the fan automatically kicks in)...the HHR experienced 245F, with no damage (1x, thru hose clamp failure), but never again, I hope.

2) iron block with aluminum heads:

• a) streetable engines always kept at gauge-displayed optimal running temps, no overheat experiences & no true temperatures known,
• b) race engine (427/441 c.i. 635 rwhp, was always temp-monitored and kept cooler than 200F, due to large alum. radiator, dual fans, separate transmission cooler/fan system, no T-stat (flow restrictor used instead), and a 55 gpm electric water pump. Goal was to run as cool as possible for higher horsepower, less chance of head gasket failure (14.1:1 compression ratio)

3) iron block with iron heads: the bulk of my experience comes with this combination. There were only two overheating instances overall, one survived it, the other engine didn't.

• a) '66 Chevelle had a mild 327-331c.i. (300hp) at first, and overheated badly (off scale), when its' first electric fan relay fried, far away from any parts store. I always carry a spare relay now, after electric fan conversions. I raced it later that day, and tore it down at home afterwards (decided to upgrade radiator, cam, lifters, manifold, carb), to check the head gaskets. They were OK. A survivor.
• b) '86 S-10 extended cab pickup, while driving to work, the temp gauge went off-scale suddenly in freeway traffic, and I pulled off the road. Don't know what happened, it was so sudden, but the head gaskets both failed, and I had the engine (2.8L V-6) replaced.

I've read a lot about BMW cooling problems, long before I ever thought of owning one. That's why I specifically asked my friend that acquired the X5 that he traded to me (for the '66 Chevelle drag-car) to be sure to repair/replace/restore the cooling system, which he did (except for the viscous clutch & fan, inexplicably). I observed much of his work being done....

Of course, I immediately put in a hi-power electric fan (3000 cfm), and thought it was good, until I was advised not to trust the BMW temp gauge. Since then, I've added an unused spare smartphone to my unused center ashtray, just to display the REAL coolant temperature at all times (via Torque Pro android app). I have it set to alarm me if I become distracted, and the temperature rises past 220F (104C). I figure that if my two Ecotec engines are Ok at, or below, that temperature, then my X5 should be OK too.

[Overboost]

Originally Posted by workingonit

The pointer of the coolant temperature gauge in the instrument cluster is located in the mid-position at coolant temperatures of 75oC - 113 o C in centre position.

I'd want the dash gauge to warn me about that temperature approaching, long before it was reached.

Run this hex code mod on your cluster. You need PA Soft 1.4 but my buffer is 10C.

https://xoutpost.com/1121333-post23.html

[workingonit]

Originally Posted by Overboost

Run this hex code mod on your cluster. You need PA Soft 1.4 but my buffer is 10C.

https://xoutpost.com/1121333-post23.html

Eventually, I'll get a cheap laptop with coding ability so I can get useful info on the display while driving. I'm not a programmer, but i'll give it a try. I already tried to use the BC programming trick, but it reverts back to ambient temperature.

So in the meantime, I'll use my Torque Pro App to monitor realtime coolant temps (I should've kept some gauges from my racecar!). Oil temp, oil pressure, transmission temp would be nice to have displayed as well. I can't find any BMW-specific PIDs to add to my TP app, either.

[Magister88]

@andrewwynn

My rule for non OEM parts is when it's easy to access and not mission critical (you don't live where it's life threatening if heater valve breaks closed) and won't damage or prevent engine from operating it's fair game (bent my own rules a bit not realizing how hard it was to swap an aux fan geez BMW).

Yeah i have been following similar rules for OEM/aftermarket parts, mission critical must be OEM or OE but with BMW logo scraped off.

@80stech

The coolant temp dropping at times is a function of the DME controlled thermostat heater and is normal and the reason why the dash guage is programmed to stay in the middle over that range.

@andrewwynn

The reason for the non temp gauge on the dash pointing to noon from damaging levels of hot pot to damaging levels of cold is literally to prevent customers asking too many questions during warranty period. (as according to tech builtin). They don't think the average user can handle the truth (literally).

@Clavurion

Coolant temp should drop when you accelerate and warming element on thermostat is activated. But the basic temp seems a little low.

Yeah i was under the impression it should stay fairly close to the set point temp. I think the stock t-stats is 95C for 3.0 and higher for the 4.4, 4.6 & 4.8. The one i got is 93C one. so the basic temp is inline i believe unless you are talking about drop to 81 not being normal. I know the idiot gauge does not change from 75 - 1?? hence why i was using the Test function in the cluster and the Ibus interface on the android unit. it is also more clear by reading the paper posted by Clavurion and it seems to be okay as far as operation goes unless i am misinterpreting what you are telling me


@andrewwynn

When the tstat fails open it will take longer to get up to temp and won't even reach temp when ambient is low.

Yeah it gest their quickly with < 10 minutes to 93C. so i guess its not going bad yet.

If your heater valve is stuck open you have an extra radiator running that is in the loop and cooling the engine even when tstat is closed. Logic dictates that will make the engine run a little cooler than the set point so your symptoms seem to match the conditions described.

Yeah this make sense, it would contribute to cooling the engine even more.

When it got stuck i believe (unless its electrical), the most noticeable is that the air of the driver vent starts to come in very hot when no other adj where made to climate controls and pass side is okay. connecting the scan tool:
Heat exchanger temp:
Left: 88 - 89C (190F) almost engine coolant temp.
Right: 22C (73f)

is that not enough evidence that the heater value is going bad?

[Magister88]

Originally Posted by workingonit

The pointer of the coolant temperature gauge in the instrument cluster is located in the mid-position at coolant temperatures of 75oC - 113 o C in centre position.

I don't know much about the BMW M54 engine yet, but my experiences over 55 years with other

• 1) aluminum block/aluminum head engines,
• 2) iron block/aluminum head engines,
• 3) iron block/iron head engines

tell me that 113C (235.4F) is too high. I'd want the dash gauge to warn me about that temperature approaching, long before it was reached.

Operating temps, & over-temp and/or overheat experiences:
1) aluminum block & heads:

• a) '62 Olds F-85 with the 215c.i. V-8, that needed to be kept under 200F, or the head gaskets failed (2x),
• b) '08 Cobalt & '09 HHR with Ecotec all-aluminum engines, both run around 180F-217F (when the fan automatically kicks in)...the HHR experienced 245F, with no damage (1x, thru hose clamp failure), but never again, I hope.

2) iron block with aluminum heads:

• a) streetable engines always kept at gauge-displayed optimal running temps, no overheat experiences & no true temperatures known,
• b) race engine (427/441 c.i. 635 rwhp, was always temp-monitored and kept cooler than 200F, due to large alum. radiator, dual fans, separate transmission cooler/fan system, no T-stat (flow restrictor used instead), and a 55 gpm electric water pump. Goal was to run as cool as possible for higher horsepower, less chance of head gasket failure (14.1:1 compression ratio)

3) iron block with iron heads: the bulk of my experience comes with this combination. There were only two overheating instances overall, one survived it, the other engine didn't.

• a) '66 Chevelle had a mild 327-331c.i. (300hp) at first, and overheated badly (off scale), when its' first electric fan relay fried, far away from any parts store. I always carry a spare relay now, after electric fan conversions. I raced it later that day, and tore it down at home afterwards (decided to upgrade radiator, cam, lifters, manifold, carb), to check the head gaskets. They were OK. A survivor.
• b) '86 S-10 extended cab pickup, while driving to work, the temp gauge went off-scale suddenly in freeway traffic, and I pulled off the road. Don't know what happened, it was so sudden, but the head gaskets both failed, and I had the engine (2.8L V-6) replaced.

I've read a lot about BMW cooling problems, long before I ever thought of owning one. That's why I specifically asked my friend that acquired the X5 that he traded to me (for the '66 Chevelle drag-car) to be sure to repair/replace/restore the cooling system, which he did (except for the viscous clutch & fan, inexplicably). I observed much of his work being done....

Of course, I immediately put in a hi-power electric fan (3000 cfm), and thought it was good, until I was advised not to trust the BMW temp gauge. Since then, I've added an unused spare smartphone to my unused center ashtray, just to display the REAL coolant temperature at all times (via Torque Pro android app). I have it set to alarm me if I become distracted, and the temperature rises past 220F (104C). I figure that if my two Ecotec engines are Ok at, or below, that temperature, then my X5 should be OK too.

I have the Ibus interface on my android head unit, it starts when the unit turns on and shows the temp of coolant. a bit slower than the cluster but quick enough. i don't use the 3 position gauge. also my temp never exceeded 97C when idle in traffic on hot day. I think i can setup an alert if temp goes above certain threshold.