C250 TD Starting Problem - Help Please - - PeachParts Mercedes-Benz Forum

earlydoors · #1 09-29-2007, 06:18 AM

Hello everybody,

Any help with my problem greatly received... I am considering buying a (p) reg 1996 or 1997 C250 TD Estate this weekend at what seems a bargain price.
How ever it seems to have a problem sometimes in starting, sometimes it will fire straight away and other times you can be cranking the engine over for several minutes before it will eventually fire, in this case there is a strong smell of diesel from the exhaust so seems fuel is there.... it has covered 200,000 miles with no service history to see other than what has been done in the last 6 months, full service, including all filters, brakes etc.(just inspected car more fully, has new glow plugs fitted. 1 new metal pipe on the injector sytem, new radiator and waterpump..
I desperately would like the car but at the same time dont want to buy a sick pup that could cost ££££ to fix. if anyone can give me some guideance on diagnosing some possible causes would be fantastic, I am not familiar with working on modern cars, how ever I am a trained mechanic from from my youth but this was 20 + years ago
Owner informs me hes sick of spending money onit and just wants it gone, admits that sometimes takes for ever to start. help about to buy it blind and take a gamble its nothing Really serious

What could it be...it has obviously been looked at, and apparently from a specialist garage, they have fitted new glow plugs a pipe and a FULL service and still has the same problem

Thank you in advance

Best Regards Mike

TMAllison · #2 09-29-2007, 12:20 PM

There's not too many of us here with much expirience with the CDI's as they have just arrived here 2 years ago and are still under warranty, but.....it sounds as if it has a fuel leak somewhere that is allowing air to enter the fuel system causing hard starts. The CDI's still rely upon oring seals at plastic fuel lines feeding the fuel filters and IP that cause problems on the 606 engines. The 606 IP relied on oring seals at the delivery vlaves too. Your pump is considerably different so that may not apply on your engine. The above assumes the car runs good once started.

Is also possible is an electrical glitch controlling the shutoff valve or a sticking SOV.

earlydoors · #3 09-29-2007, 12:27 PM

Thank you for that, the car is a C250 TD 1997 i think, once the car starts it runs sweet as a nut, and also restarts fairly easily when warm. where shall I start bearing in mind somebody else has already had a go at fixing it, whats the next reccomended step. Thanks again for any help, going to buy it in the morning but i think its to cheap not to have a gamble on, its the esprit version as well which is quite nice

TMAllison · #4 09-29-2007, 12:33 PM

Is it a CDI? It's right on the cut off point I think.

Assuming its not CDI, every I said about fuel leaks is VERY applicable. In addition you should look for fuel leaks at the IP delivery valves too as they also have oring seals.

Keeping the tank more than 1/2 full and parking nose down hill will help with the first start of the day.

earlydoors · #5 09-29-2007, 12:55 PM

Just checked it was registered Feb 1998, so not sure what that means ?
Under the bonnet everything seems bone dry and no obvious leaks, thanks for the tip, healf full down hill, im 99% sure that will help, assuming I cant see any leaks do you reccomend getting a servce / overhaulk kit for the injection system, if there is such a thing, whats my next step? Thanks again. Regards Mike

TMAllison · #6 09-29-2007, 01:07 PM

I'm pretty sure its not a CDI engine. It also is not an engine we ever got in the USA.

You can purchase all new plastic fuel lines fairly cheaply. On the 606 engine it runs about USD$60 for all of them. Or, you could purchase the orings only and replace them yourself. Is an easy DIY job. This link pertains to the 606 again, but the sizes and counts should be very similar. http://www.peachparts.com/shopforum/showthread.php?t=177588

The fuel lines are clear when new, yellowed if aged. Is kind of nice to have new ones as you can see if any bubbles are present which helps one track down where they come from.

Fuel/Air leaks are fairly common, any MB "diesel" mech ought to have been able to figure that out???

If leaking at DV seals you might want to let a mech do that job as it is a lil bit technical if inexperienced and can cause irreparable damage if done incorrectly.

earlydoors · #7 09-29-2007, 01:23 PM

Thanks again, What are DV seals ? I will look into replacing all the pipes, i just cant believe the mechanic didnt do that 1st, When the engine is running there is clearly visible bubbles in the fuel line, is this normal ? and do you know of a good supplier of parts for the UK? im guessing genuine ones are expensive>

Thanks Mike

TMAllison · #8 09-29-2007, 01:27 PM

DV is delivery valves. On top of the IP (injection pump) where the metal fuel lines attach. The valve in the IP has an oring.

If you see ANY bubbles, therein lies the problem.

earlydoors · #9 09-29-2007, 01:27 PM

Just worked out what DV is, delivery valve, ok, what damage could I do, what is the danger ?

Thanks again

Mike

earlydoors · #10 09-29-2007, 01:30 PM

Bubbles hey, ok well at least I have some where to start, i guess now i have to find how they are getting in and where, would this make the car take 2 or 3 minutes of cranking in the morning to start ??? and then run lumpy for a few seconds

TMAllison · #11 09-29-2007, 01:32 PM

DV - beneath valve holder where the metal line attaches is a fuel element (ie: a tiny valve). If it is distrubed, knocked over, twisted, turned, etc the best case is the pump will come off and go to Boach to get recalibrated and if torqued down with element in worng orientation it will get replaced with a new pump.

TMAllison · #12 09-29-2007, 01:33 PM

Quote:

Originally Posted by earlydoors

Bubbles hey, ok well at least I have some where to start, i guess now i have to find how they are getting in and where, would this make the car take 2 or 3 minutes of cranking in the morning to start ??? and then run lumpy for a few seconds

Yep!

earlydoors · #13 09-29-2007, 01:35 PM

Right ok, thanks for that.... it does have 1 new metal pipe, im assuming its safe to replace all hoses pipes etc, just dont go any further than take the pipes off from the DV yes?

TMAllison · #14 09-29-2007, 01:42 PM

The metal lines should be fine unless someone ahs bent them such that they wont seal. They are simple compression fittings.

Just replace the plastic fuel lines, pre-filter and it oring and possibly the oring behind the shut off valve onthe side of the IP (black plastic valve).

earlydoors · #15 09-29-2007, 01:44 PM

do you know if there is such a thing as a service kit which would comtain all the hoses pipes o rings etc ?

You have been so helpfull, thank you, off in the morning to buy the car, assuming it starts i will get it home and no doubt be asking for some more help, hopefully i will fix it and be able to close the post with a happy ending.