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boiliebasher

Any M51 gurus about?!

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Hi all. My E36 TDS has started to suffer from the infamous "hot start" problem at just over 150k miles. 

When cold starts on the button from glow plugs and in tank fuel pump priming but anything over 1/4 on temp gauge this circuit is bypassed and so no plugs or pump activated. 

It then takes a few seconds longer of cranking to start. HOWEVER what I find curious is that as my drive is on an incline, I am able to "bump start" in 2nd when engine is warm and it starts instantly......

Im just a bit puzzled why when it's bumped started it fires straight away and why it's off the starter it can take anything up to 10 seconds to fire.......

Battery and starter are both in good order....

I'm probably just going to buy a "box of tricks" as a temporary measure off eBay but I'm perplexed as to why the difference in starting procedures can have such an effect on how and why it fires as in my mind, at the end of the day all your doing is just turning the engine over and I hasten to add, maybe even a little quicker in terms of rpms with the starter motor?! All replies welcome  :)

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Right made a tiny bit of progress this morning. 

I found out using a voltmeter that the fuel pump actually DOES prime every time the contact is turned regardless of if the engine is cold or not.

I don't know if this is the case with E34's but now I definitely know this is true with my 99' E36 TDS.

 

So that means from what I can work out anyway; it's only the glow plugs that don't come on when the engine is warm.....

Still can't explain why it bump starts immediately but won't off the starter...

 

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Just to add incase any one looks into this thread, on my 99' TDS the intank fuel pump primes for 10 secs every time the ignition is switched on regardless of engine temperature.

After 10 secs it then switches off unless the engine is started, then it stays on permanently until the engine is switched off again 

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Right then, fitted this eBay "hot start" fix gizmo and essentially it turns on the glow plugs every time you turn the ignition.

Do you know what, best 20 euros I ever spent on the car. Works a charm and more importantly no more embarrassing hot start problems! M51 engine now starts first time every time hot or cold. :)

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Oh and here's the link just in case any one might be interested. It comes from Poland and dead easy to fit. Well worth it imho :)

 

https://m.ebay.fr/itm/HOT-START-FIX-BMW-E34-E36-E32-E39-2-5-2-4-TD-2-5-TDS-STARTING-WARM-ENGINE-MODULE/201241774850?hash=item2edaf1cb02:g:6XgAAOSwGvhT28gk

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