240D intermittant starting problem
 

A colleague has an 81 240D stick shift with a strange starting problem. When cold in the morning and using the glowplugs it starts right up no problem. After having been driven for a while, normal commute, then switched off, will not start. After waiting about ten minutes it starts right up again. When she was leaving work today the car was idling in the parking bay. I came over and asked her to switch it off and see if it would start again. Switched off right away, no vacume problem apparent. Then started right up again no problem. She seems to think a new alternator is in order. This would be the second in a year. Car already has a brand new battery. I'm no mechanic but the thing that gets me is the cooling down period of ten minutes before starting normally. It sounds like a vapour lock problem that a friend's Porsche had some years ago but surely you dont get vapour lock in a Diesel? I told her I'd ask the forum if anybody could provide a suggestion. Any help would be appreciated. She's at the point of taking it to a Mercedes dealer...

- Peter.

I would start by checking the voltage at the glow plugs when it becomes hard to start. Wonder if the gp relay is starting to get tired and is only affected after it is warm from the under hood temps?

I am assuming that you are describing it cranking but not starting when the problem exists.. not that it will not turn over ????
If yes, then it really should have NOTHING to do with the alternator.... I don't know what it IS.. but it should NOT be the alternator....

If it cranks but won't start, check the fuel filters and fuel lines from tank to lift pump -- air leaks or plugged filters can cause fuel starvation at idle, resulting in starting problems until enough fuels seeps through.

Could also be a bad starter -- may have too much resistance hot to turn fast enough to start the engine. "Chevy starter disease", if anyone remembers 70's Chevy starters that someone left the heat shield off of!

Peter

Idiot
 

It occurs to me that I'm a complete idiot. After all this time on this forum I never thought to ask if the problem was that the engine cranked but didn't start, or just didn't even crank. I'll find out tomorrow and that should narrow it down a whole bunch!

- Peter.

-. Peter.

Try pumping the hand priming pump before you try to start it in that 10 minute period after stopping it. See if that makes any difference.

Finally got more detail
 

OK. So I spoke with the owner yesterday and it seems to be electrical in nature. When it wont start there's no activity under the hood at all. No cranking, not even a suggestion there's an engine down there. Almost like the battery died. Although all the dash lights light up like normal at the same time. Then after waiting ten minutes starts up no problem.

- Peter.

Probably the starter solenoid going bad.

I don't know if it can be replaced by it self.
If not you'll have to replace the whole starter.


Louis

"No cranking"

Clean the battery terminals and the connection where the ground cable attaches to the car.

I'd lay bets on the starter solenoid. Starter isn't that far behind, either, it it's original.

You can test by checking for battery voltage at the small connector on the starter solenoid when it won't crank -- if you have voltage, the solenoid is bad, if you don't, it's the key switch.

If it clicks, but nothing happens, the contacts at the solenoid for the starter motor windings are bad, replace solenoid. Might also be worn out brushes, in which case I would replace with a rebuilt starter.

Peter

While it could be cable connections, I just conquered a similar hot starting problem by replacing the starter. Bad connections are not usually heat sensitive.

Good luck!

"While it could be cable connections"

While this is not a fix for all not starting problems, its cheap and easy to do and it could be the problem.;)

btdt
 

when the phenomenon happens, try cycling the key a few times-usually that will work.