I have just bought a 1997 Omega CDX Estate with the 2.5TD BMW engine (Manual) .It has 70k on the clock. In general the car seems fine, (Dispite hitting a Deer 24hrs after purchasing it and ripping the near side mirror off).
My query is this:
I decided to see what the car could do.
However in 5th gear I was doing about 90-95mph at around 3000rpm only halfway up the scale of this 6 cylinder engine when there was a sudden power loss. The revs drop and obviously the speed drops to just under 90mph and then it picks up again. It is just like the cruise control was in control (if you know what I mean).
Also sometime if I need to set off sharpish from a T'junction there can be a lack of power as if the turbo isn't kicking in.
I don't know if these are related.
I have been told that turbos have an overpressure valve. I thought this was only found on supercharged engines.
Does the BMW 2.5TD have an over pressure valve?
And if so could it be the cause of this?
Could it be the engine management limiting the speed or revs? It is possible to go right through the rev range in lower gears, so it isn't limiting just he rev's.
Has anyone else noticed this, or does anyone have any clue as to where to start looking.
Cheers,
Charlie.
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This can be due to excessive temperatue of the engine, which may not show on the guage, if the guage sensor is in dead water.
Blocked radiators are also quite common, restricting cooling, but not giving a high guage reading.
Waterpump impeller failure is also common on these engines, the composite GRP impeller shears off the shaft .
Also, injector number 4 or 5? has a start of injection sensor (electrical connector) built in, these can fail and make the car lose most power, like you describe.
First, I would drain the water tap at the bottom of the fuel filter (or just replace the filter) and also, I would remove the viscous fan and shroud, and feel the radiator to make sure it is getting hot all the way down to the bottom.
One other thing, may be the EGR valve , to the right of the TURBODIESEL trunking at the front of engine, these can get sooty and oily and stick, it's only 4 nuts and two bolts to remove, may be worth cleaning in white spirit/petrol or whatever.
Eventually, the EML light might come on and a code will be stored.
Good luck!
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Thanks for the advice,
Looks like I have got quite a few things to be getting on with this weekend.
Charlie.
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