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Old 12th March 2017, 14:42   #1
Don.Hasi
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Default Hot start problems with serviced Diesel

I think, I know what you think... Hooray another one ... But after reading many topics, mine is a bit different. So thought give it (another) try.

When buying the car, the thermostat was kaput. So I was driven with mostly a quarter on the water gauge. Sometimes even less. The 135bhp Diesel started ok when >5C. Beneath <5C I had to use the FBH for some seconds. Of course it was not very effective with the great water circle steady open, but it helped enough to start the machine.

Now with some more ambient temperatures I have done the top hose thermostat mod and finally get good water values. The engine pulls very nicely after a quick service of air filter, Pcv and cleaning the EGR and throwing in some silicone tubes and viton rings so far, so good. The year before she got a new diesel filter and I think a new pump (don't know which one). She has now 140k mls on her young legs...

Sadly with more temperature in the engine bay it doesn't start when the engine and water is hot. I have to crank over minutes, well, it feels so, to get it started. If it were a NA, I would say, there are hot fumes in the airbox which have to be cranked through... It is just this amount of time for it.

Of course if I let cool her down, it works also, but with enough patience and cranking she will do it herself.

I have read about injector leak backs, cam and crank sensors, HP-System etc. but nothing which could explain so far this behaviour. The cam sensor which is the usual suspect in case of hot start problems should come IMO to daylight as well when the engine itself is hot not only the water... The oil gets not that hot with only, say 40c water, but it still gets hot on the German Autobahn if it wants or not... And I could start her every time.

So, what do you think?
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Old 12th March 2017, 15:01   #2
FrenchMike
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Hi,if you want to progress ,make some measurements when at FAULT .

(i guess your plenum has not be flooded )

http://www.the75andztclub.co.uk/foru...d.php?t=109615

Good luck

Mike
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Old 12th March 2017, 15:28   #3
Don.Hasi
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Thanks.

Oh yes, the plenum is of course dry like a Martini
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Old 12th March 2017, 15:38   #4
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Quote:
Originally Posted by Don.Hasi View Post
Thanks.

Oh yes, the plenum is of course dry like a Martini
well,if you can start it with a sniff of easy strat ,carry out an injector leakback test first ...
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Old 20th April 2017, 10:03   #5
Don.Hasi
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I have used a can of LiquiMolly diesel injector cleaners. It has certainly improved the things but not cured it to all good. Will try another can and see where we will get to.
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Old 21st April 2017, 13:14   #6
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Quote:
Originally Posted by Don.Hasi View Post
The cam sensor which is the usual suspect in case of hot start problems should come to daylight as well when the engine itself is hot not only the water...
Do you mean when the coolant is warmed using the FBH rather than from the engine? Surely if the coolant is warmed by the FBH, the circulation will also warm up the engine? Isn't that what the FBH does? In other words, the cam sensor is warm in either case.

TC
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Old 3rd May 2017, 21:08   #7
Don.Hasi
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TC: yes, the cam sensor was hot also with the faulty stock thermostat alone and the car started with this. So, it was not the culprit, so my thought.


@all: it was the faulty inline thermostat which lead the engine to the hot starting problems. After the change, it starts now fine even after a hot Autobahn journey. Result :-)
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