Ok, so this follows on from my bio diesel experiences..
its a long one...so get a coffee or something.
summary
I inadvertantly put bio-diesel in my td4.
and shortly after (less than 10 miles) it starts crackling and spitting..
so i assumed i was doing it in..
advice was given, dilute the bio-d with real diesel and changle fuel filter.
hadnt got round to the fuel filter yet, but diluted and drove it about.
still crackling and generally playing up.
new sypmtoms..
anyways..today coming back along the motor way..i notice the temp gauge had gone right up to the red line , thinking i had slipped a belt i pulled over to have a look.
as soon as i stopped even before i turned the engine off, the gauge drops back to normal (9oclock position)
opened bonnet, fans running highspeed, all belts ok. water low but still ok. no leaks. rad hoses feel ok, top one hot, bottom one cold.
got back in and reved it....seems ok...i drive alone the shoulder and when still ok pull back out into traffic.
after another halfmile...it does it again...temp in the red and no power.
once again when i stop....i goes back to normal.
basically i limped 4 miles along the hard shoulder, and got it off the motorway and into a layby.
each time i got it under load it red-lined and i lost most of the power.
checked everything again..all ok as far as i could tell.
gave up...called AA..
waited and hour. engine cools..
AA man arrives...and listens to my tale..
and gets me to start it up...
and gears up to do a cooling system diagnostic...
so he does something odd with the cooling water expansion tank...apparently a head gasket failure test...bubbling the air in the cooling tank through some blueish liquid..not sure what...but appearently
its not HGF.
next a pressure test...he blocks the expansion tank..and pressurises it..
we wait...no leak...we run the engine...no leak.
so now he gets me to run it at 2000rpm..for about 10-15 mins..
it warms up...but no redline.
all the whire he is using a laser/IR thermometer to check the coolant pipes temp. the rad temp and the engine block.
the determination after this is that he cannot find the fault..and its been running fine for 35-45 mins..AND hasn't crackled or spat once !!
he suggests he follow me home.
we start...and after 3 or four miles...it does it again, redline no power.
still no crackling or spitting though, i pull over pop the bonnet....the gauge goes back to normal....he checks the temps...Engine 68deg. Rad 56deg.
he reckons its a faulty sensor...and i should ignore the temp gauge
we drive off again....within half a mile the gauge goes up power drops off.
so i continue...waiting for it to go bang...it doesn't
2miles..
3miles..
4miles
but i get slower and slower till im doing 25 miles an hour with an AA truck and a huge queue of cars behind...
here comes a hill...only a slight incline...speed drops of to below 20mph.
i pull over. gauge goes back to the normal position..
again the temp is check with the laser/ir thermometer..
engine temp 79degs, rad67. and idling no problem
we wait a few mins....
again we drive off, i have all my power back...
up the hill, down the other side...up the start of the next...
gauge redlines...no power...
so we decide to give up and he tows me 30+ miles home..
all the way home, engine is running fine (to give me power steering and brakes.). no redlines. just sat on normal.
and its still not crackling or spitting.
(noticable be cause it has been spitting since the bio-D went in)
so ok , im home..
with a less than quarter of a tank of mixed bio-d and real Diesel.
but now i'm expecting it to lose power and redline the temp gauge after it gets up to normal temp.
the AA man reckons one of the sensors is telling fibs to the ECU..
as he can see the actual temp with his fancy laser/IR thermometer.
and its in a kind of limp home mode..but if so....its odd...cos no warning lights are on the dash...and its only a limp home if you live somewhere with no hills.
what do i need to look for now..could it still be MAF related power loss as was suggested in the bio diesel spluttering thread ?
where are the temp sensors..and are they easy to get at?
its odd, because now...the fuel seems to be buring ok.
so if something has failed completely now...cause the current symptoms..
could it have cause the misfiring when it was on the way out.
i guess what i'm trying to avoid is the garage spending an hour or three trying to reproduce the fault before trying to fix it as i'm guessing I have 15-20mins of driving time from cold before the fault will comeback.
all advice welcome...even the amusing flak from the boys with tratters.
cheers.
rich.
its a long one...so get a coffee or something.
summary
I inadvertantly put bio-diesel in my td4.
and shortly after (less than 10 miles) it starts crackling and spitting..
so i assumed i was doing it in..
advice was given, dilute the bio-d with real diesel and changle fuel filter.
hadnt got round to the fuel filter yet, but diluted and drove it about.
still crackling and generally playing up.
new sypmtoms..
anyways..today coming back along the motor way..i notice the temp gauge had gone right up to the red line , thinking i had slipped a belt i pulled over to have a look.
as soon as i stopped even before i turned the engine off, the gauge drops back to normal (9oclock position)
opened bonnet, fans running highspeed, all belts ok. water low but still ok. no leaks. rad hoses feel ok, top one hot, bottom one cold.
got back in and reved it....seems ok...i drive alone the shoulder and when still ok pull back out into traffic.
after another halfmile...it does it again...temp in the red and no power.
once again when i stop....i goes back to normal.
basically i limped 4 miles along the hard shoulder, and got it off the motorway and into a layby.
each time i got it under load it red-lined and i lost most of the power.
checked everything again..all ok as far as i could tell.
gave up...called AA..
waited and hour. engine cools..
AA man arrives...and listens to my tale..
and gets me to start it up...
and gears up to do a cooling system diagnostic...
so he does something odd with the cooling water expansion tank...apparently a head gasket failure test...bubbling the air in the cooling tank through some blueish liquid..not sure what...but appearently
its not HGF.
next a pressure test...he blocks the expansion tank..and pressurises it..
we wait...no leak...we run the engine...no leak.
so now he gets me to run it at 2000rpm..for about 10-15 mins..
it warms up...but no redline.
all the whire he is using a laser/IR thermometer to check the coolant pipes temp. the rad temp and the engine block.
the determination after this is that he cannot find the fault..and its been running fine for 35-45 mins..AND hasn't crackled or spat once !!
he suggests he follow me home.
we start...and after 3 or four miles...it does it again, redline no power.
still no crackling or spitting though, i pull over pop the bonnet....the gauge goes back to normal....he checks the temps...Engine 68deg. Rad 56deg.
he reckons its a faulty sensor...and i should ignore the temp gauge
we drive off again....within half a mile the gauge goes up power drops off.
so i continue...waiting for it to go bang...it doesn't
2miles..
3miles..
4miles
but i get slower and slower till im doing 25 miles an hour with an AA truck and a huge queue of cars behind...
here comes a hill...only a slight incline...speed drops of to below 20mph.
i pull over. gauge goes back to the normal position..
again the temp is check with the laser/ir thermometer..
engine temp 79degs, rad67. and idling no problem
we wait a few mins....
again we drive off, i have all my power back...
up the hill, down the other side...up the start of the next...
gauge redlines...no power...
so we decide to give up and he tows me 30+ miles home..
all the way home, engine is running fine (to give me power steering and brakes.). no redlines. just sat on normal.
and its still not crackling or spitting.
(noticable be cause it has been spitting since the bio-D went in)
so ok , im home..
with a less than quarter of a tank of mixed bio-d and real Diesel.
but now i'm expecting it to lose power and redline the temp gauge after it gets up to normal temp.
the AA man reckons one of the sensors is telling fibs to the ECU..
as he can see the actual temp with his fancy laser/IR thermometer.
and its in a kind of limp home mode..but if so....its odd...cos no warning lights are on the dash...and its only a limp home if you live somewhere with no hills.
what do i need to look for now..could it still be MAF related power loss as was suggested in the bio diesel spluttering thread ?
where are the temp sensors..and are they easy to get at?
its odd, because now...the fuel seems to be buring ok.
so if something has failed completely now...cause the current symptoms..
could it have cause the misfiring when it was on the way out.
i guess what i'm trying to avoid is the garage spending an hour or three trying to reproduce the fault before trying to fix it as i'm guessing I have 15-20mins of driving time from cold before the fault will comeback.
all advice welcome...even the amusing flak from the boys with tratters.
cheers.
rich.