35d worsening gas mileage - solved- thermostat/fan/EGR cooler - DIY with pics

[sgrice]

Woot, Woot!

Congrats and Well Done!

Stephen

[TriX5]

Thanks guys.

Unfortunately no beer....but 4 venti-sized coffees yes. Nevertheless, now that I have been in there and "mentally cataloged" the procedure I could repeat it in half the time. Putting it back together and testing, then reattaching the bottom engine cover took about 1.5 hours.

If one is doing this in a fully equipped shop this should be no more then 2 hours in all. Not sure where the 1000 dollar quote came from other than an unreliable Service manager.

[ZetaTre]

Since you're where it's very cold these days, you're feedback on the engine temperature would be extremely valuable. Let us know!!!

[TriX5]

It is my wife's daily driver but I will try to get some seat time and let you know. Yesterday it zipped right up to 87-89 on a short 1 mile trip to the Giant.

[London Lad]

Can I pick your brains please gents gents?

I have a UK spec, X5 E70 35d, 2009 build, 2010 registered car with about 40k miles on it.

At the moment ambient temp here is about 8C.

I have a Scangauge permanently connected to my OBD port and mounted on the dash so I can monitor engine temp and battery voltage.

When fully warm my engine temp runs at 84c +/-2degrees. At this time of the year getting fully warm takes a while, up to 5 miles on slow country roads, quicker if the starting ambient temp is less than 5C and the Webasto FBH comes on.

Now here is my question; if, fully warmed up, I cruse at say 50 MPH on a dual carriageway with temp showing 84C and then floor the throttle and let the box change down a couple of gears and let the revs climb towards max RPM, the temp immediately drops to around 75C, then as soon as I lift off and continue normal driving it returns to 85C with in 10 seconds or so. This is RPM related and not road speed related.

Seems strange to me, am I missing something?

BTW the car runs fine and shows no codes and returns reasonable fuel economy.

[TriX5]

-10 Celsius ambient last night. On Interstate at steady 65mph speed mine runs 83-84 C.

[ Snow coming down hard today. Very happy with winter tires on both X5s right now.... :-) ]

[neliconcept]

Originally Posted by London Lad

Can I pick your brains please gents gents?

I have a UK spec, X5 E70 35d, 2009 build, 2010 registered car with about 40k miles on it.

At the moment ambient temp here is about 8C.

I have a Scangauge permanently connected to my OBD port and mounted on the dash so I can monitor engine temp and battery voltage.

When fully warm my engine temp runs at 84c +/-2degrees. At this time of the year getting fully warm takes a while, up to 5 miles on slow country roads, quicker if the starting ambient temp is less than 5C and the Webasto FBH comes on.

Now here is my question; if, fully warmed up, I cruse at say 50 MPH on a dual carriageway with temp showing 84C and then floor the throttle and let the box change down a couple of gears and let the revs climb towards max RPM, the temp immediately drops to around 75C, then as soon as I lift off and continue normal driving it returns to 85C with in 10 seconds or so. This is RPM related and not road speed related.

Seems strange to me, am I missing something?

BTW the car runs fine and shows no codes and returns reasonable fuel economy.

Most likely when you open up the throttle, the throttle body throws in a lot of colder air and that is the reason for the temperature drop. However, if you stayed on it for a while it would start to heat up and probably surpass your cruising temps.

[josiahg52]

-11 to -18C outside today and I was running a solid 82 to 83C at highway speeds. I am very glad I put dedicated snow tires on the X5 this winter. I experienced DEF freeze for the first time this morning; it was -18.5C when I started her up according to the ambient temperature sensor.

[TriX5]

Curious, how do you know the DEF was frozen?

I park indoor (garage is part of the house) so I haven't experienced that yet.

[London Lad]

Originally Posted by neliconcept

Most likely when you open up the throttle, the throttle body throws in a lot of colder air and that is the reason for the temperature drop. However, if you stayed on it for a while it would start to heat up and probably surpass your cruising temps.

Thanks but I suspect the drop is too quick for that as it happens in seconds and I would have thought it would have taken longer for intake air to effect the water jacket especially in relatively mild weather. But who knows.

I'm going to change the ecg stat today as its a cheap and easy job and see if that helps