First of all Hello and Happy Holidays to Everyone.

I am a 2008 X358 4.2 naturally aspirated owner and just ran into some problems right before the holidays.

There is no heating on either side unless the rpm is above around 2000.
To make it more clear the driver's side is all cold (even when revving) except for feet vents which on both sides give out the best heat (only when revving ).

Engine coolant is good, no leak, expansion tank pretty new.
Also have my OBDII bluetooth adapter connected constantly and have monitored the temperature fluctuations since this happened.
The coolant temp rises normally maybe a bit faster then usual and doesn't stop until the temp is over 100 - 104 c with the cooling fan kicking in.
The temp on the dashboard is in the normal 1/2 position and i wouldn't notice the rising temp without the OBDII scanner.
Now when the coolant temp is 95 and over and i rev the car to 2000 rpm and over the temperature drops within seconds to around 88 degrees and i also get warm air into the cabin.
Oh btw the driver's side wasn't getting heat for some time now.

Now I guess its one of the three or all of the below that are causing this:
1. blocked heater core
2. aux pump done
3. thermostat

The car has 162,000 km so i guess it wouldn't hurt to change all 3 parts.

Recent (within last month) check engine codes :

P2096 - Fuel trim system too lean bank 1 (had spark plugs changed, all 02 sensors changed, checked all rubber pipes for primary and secondary air and the code is gone)
P0128 - Coolant thermostat, coolant temperature below thermostat regulating temperature (this code comes up and goes since last winter but just once or twice)

and my last code that i don't think has any thing to do with this is:
P0430 - catalyst system efficiency below threshold (bank2) - 02 sensor change didn't help so i guess ill need a new cat.

Ok so right now I am not getting any MIL except the P0430 every test cycle.

Oh yeah two more things my rpm drops a bit to low when the engine is hot when coming to a stop and the car died 2 (seperate) times right after a start on a warm engine recently.

So back to the problem if anyone has any suggestions then i'd be glad to hear them out.

Thanks in advance.

 

Hi,

Definitely time to get the thermostat changed out, check all hoses and the thermostat housing and check your aux cooling pump for operation.

Based on your description you have the following issues in this order: bad thermostat, inoperative aux pump. Also your temps in excess of 100c is excessive and should be rectified (and gain heat at idle) once your thermostat and aux cooling pump are rectified.

With the aux pump, check relay, fuse and connector first and feel pump for operation when heater is selected to hi setting at idle.

 

Thanks Abonano,

I guess i'll start with the thermostat and aux pump and move on to the heater core if that doesn't solve the problem.

Had a lot of work done to the car this year small paint job, polishing, brake upgrade of all, fuel tank leak, front and rear park sensor check, tyre pressure sensors, tyres, alloy wheels,alignement, then a steering wobble that turned out to all new wishbones and joints which did need a change but also didn't solve the wobble that turned out to be the bearings with the axles so that too. Then the front left air shock bursted so had to change the front 2 as well. Was pretty happy for a month then had it for a all round inspection with all filters changed and turned out the gearbox filter is leaking so that had to be changed. The lean codes and the catalyst gave me a push to change all the O2 sensors last month. Also the heating on the driver's seat died and now this.
I guess the CAT is trying to tell me something.
Hopefully i'll have this sorted out next week and move onto an exhaust upgrade with new pipes and cats.

 

Well you're getting closer to owning a brand new car with all those new parts. My money's on the t-stat. good luck and let us know.

Merry Christmas.

 

Yes, you didn't have much luck with all these required repairs but as Sean says, you'll have soon a new car!
How many miles?

 

Tonight after shutting off engine noticed electric fans running fast. Restarted car and dash temp gauge normal middle and no trouble lamps, turned off engine and fans still running.

Was driving normal, air temp 65f, no low coolant lamp, no coolant smell, aircon off. Normally aspirated engine, don't have code reader yet.

This year already three dealer visits and spent over $4000 on thermostat and housing, water pump, belt, oil pan, tie rods, bushings, computer communication issue, etc. Sigh...

 

You have a cooling issue if fans are running after shutting car off.

Look for coolant leaks.. Expansion tank is the biggest offender. If you have the SC 4.2 you have to also investigate the hose under the supercharger. Do you have a scanner capable of monitoring coolant temps?

You will need to get to the bottom of the issue before resuming normal driving.

 

Hi,

Well haven't dealt with the problem yet (just ordered the thermostat and water pump).
I am more than certain that the heater core will need to be replaced as the driver's side is not getting any heat whatsoever.
Yes all these repairs will hopefully make the car like new at 162,000 km.

XJPurr
As Abonano said you have a cooling issue for sure, would say a bad thermostat as well but since you just changed it and the water pump then maybe you're leaking coolant.
Did You check the coolant level ? I know it should flash the warning lamp but if the sensor is bad might as well inspect it yourself.

So I am curious at what temp does the dashboard gauge go above normal 1/2 when the engine is overheating ?
As in my case with a hooked up OBD adapter as i stated before the temp reaches 103-105 c (gauge is at normal 1/2 way up maybe slightish over 1/2) and the cooling fans turn on.
Really wouldn't have noticed without the OBD that im getting temps of over 100.
Also why does revving the car get the coolant to cool down ? (BTW attached some pics of this) With a closed thermostat wouldn't that not make any difference or even get the coolant temp warmer ?

 

My money is on the simple things first.
The AC/ heater system is replete with vacuum actuated devices that open internal doors/vents and water control valves. The fact that high revs (low vacuum) starts to change things makes me focus on controls/vacuum/valves.

BTW When observing engine temp changes, just turning on the heater system will result in a small drop in water temp.

 

the temp gauge on an X350 is little more than a glorified warning light. It's not an accurate read.

I tend to use an IR thermometer and when the car reaches normal operating temps, I measure the temp on either side of thermostat in your case as well as the Auxiliary heat pump and incoming and outgoing lines to the heater core. This, for me, is the fastest way to determine root cause(s).
Since your parts are on order, give it a try if you have the IR thermometer.

 

the temp gauge on an X350 is little more than a glorified warning light. It's not an accurate read.

I tend to use an IR thermometer and when the car reaches normal operating temps, I measure the temp on either side of thermostat in your case as well as the Auxiliary heat pump and incoming and outgoing lines to the heater core. This, for me, is the fastest way to determine root cause(s).
Since your parts are on order, give it a try if you have the IR thermometer.

 

BTW When observing engine temp changes, just turning on the heater system will result in a small drop in water temp.[/QUOTE]


Turning the heater system on does not make any difference to the coolant temperature (i've tried all possible configurations, on/off, lo - high, ac on off etc etc..) Only raising the rpm above 2000 drops the coolant temp below 90.
Also keeping the rpm above 2000 doesn't keep the temp down on the long run it eventually starts to keep rising. While letting the car idle at this point or driving at a slow pace gets the temp to rise about 1 degree every 2 seconds giving me about 20 seconds of peace till i have over 100 degrees c and need to rev above 2000 to cool it back down to 90 (this is really frustrating to drive like this).
Well the CAT is going to the workshop on tuesday and its going to rest till then.

 

I think that rules out low coolant. Don't know what that ring/reflection is.

 

That looks like the metal clip that would go on the plastic hose beneath the expansion tank to keep the hose secured.

Just for kicks I would check to ensure you have that metal clip on the hose.

PS - you'll need to get a magnet and get that clip out of your tank...