My 240D, new issue.... - PeachParts Mercedes-Benz Forum

Marcan82 · #1 10-04-2022, 11:07 AM

Good Day friends.

My 240D 4-speed has 134000miles on it and I am experiencing a misfire/shaking and hesitation when I start to drive on a COLD engine only. This has been a slight issue in the summer, but as temps have gotten lower it has gotten quite a bit worse. I should mention that my car hasn't been driven much at all in the last >10 years aside from occasional drives around the block. I'm thinking it's injector related and I am wondering the best way forward regarding replacement/nozzle replacement.

Any thoughts?

Thanks.

Sugar Bear · #2 10-04-2022, 11:53 AM

If the fuel is fresh I'd check the glow plugs first.

What year is the car?

How long does the misfire persist?

Was it run on WVO?

Good luck!!!

Marcan82 · #3 10-04-2022, 11:57 AM

Thank you for the reply.

Fuel is very fresh with new filters as well.
Glow plugs were replaced with pencil style a while ago and have maybe 5-6000 miles on them. Never ever driven on WVO and misfire persists until driven MAYBE .5 a mile however during engine warmup there is quite a bit of injector noise/nailing.

JimSmith · #4 10-04-2022, 09:04 PM

Sounds like glow plugs should be OK, and fuel quality is likely OK from the tank. However, it may be that your injectors are not all "equal" and one may be either a bit dirty or otherwise not moving correctly when the injection pressure is reached. You might have them removed and checked. You used to be able to buy just the nozzle bits and pintel but I think you have to buy a fully assembled injector now. And they used to be about $80 as a fully assembled injector from MB....no idea how much they are now.

Jim

Sugar Bear · #5 10-04-2022, 09:13 PM

I would still confirm the glow plugs good and if good add injector cleaner e.g., Power Services.

Good luck!!!

Marcan82 · #6 10-05-2022, 06:43 AM

Thanks all. I use a fuel treatment in every tank is that sufficient or would a more concentrated 'diesel purge' be ideal?

Adam in IL · #7 10-05-2022, 07:47 AM

I'm still chasing the same issue on my 300d. Another thing to check after the basics of glow plugs, valve adjustment, filters, etc. would be compression.

Marcan82 · #8 10-05-2022, 10:21 AM

Has anyone here used a seafoam type product as an upper cylinder cleaner used through the intake? Could this lead to disaster?

Sugar Bear · #9 10-05-2022, 10:56 AM

I've not but wouldn't because if the cleaner became fuel which it likely would, the RPM's would become uncontrollable.

I'd choose a ring soak. Scope the intake, if it is clogged pull it and clean it out.

Good luck!!!

Marcan82 · #10 10-05-2022, 10:59 AM

Thanks, I've been thinking about doing a ring soak. Would it be done through the glow plug ports? What would be best to use as a soak?

Sugar Bear · #11 10-05-2022, 01:02 PM

It would be good if you could do a compression test first. You could then do a ring soak and measure the outcome.

I'd use Marvel Mystery Oil.

I don't see why it couldn't be introduced through the glow plug hole but would value the input of others if the injector ports would be better.

Good luck!!!

ah-kay · #12 10-05-2022, 01:19 PM

Ring soak is useless and a waste of time. Nothing will dissolve carbon, if that was your intention. You need to physically scrape carbon off so it is like an engine overhaul. However, if it makes you feel better then go ahead. It ain't going to do any harm nor good.

Do a compression test and it may give you a clue on the health of the cylinders.

Diesel911 · #13 10-08-2022, 11:11 PM

As has been said check the glow plugs.

I had some bad fuel that I got somewhere it did not run well till the engine was warmed up.

Air leaks in the fuel inlet hoses and the hand primer can cause misfiring. The fuel inlet hose between the fuel supply/lift pump and the fender well is cheap to replace from with hose from an Autoparts store. As long as it is fuel hose it will also be rated for Diesel Fuel. At least that is how it is out here.

If you pump your hand primer and it leaks fuel that is a likely source of an air leak.

240Ds often have M type fuel injection pumps that have O-rings in the delivery valve holders. If they leak people have said it can misfire.

The 240D fuel supply/lift pumps sometimes need to be rebuilt. There are kits for that.

There is a fuel pressure relief/overflow valve on the engine side of the fuel injecting pump that looks like a banjo bolt. It will have a piece in the center with a screwdriver slot of a ball bearing pressed into a hole in it. It is what controls the fuel supply pressure.

When old the spring inside loses tension, and they have trouble holding pressure at idle speed.
If you have the one with the screwdriver slot you can take it apart and look at the ball bearing inside that is used as a valve and see if it has rusted spots on it and you can measure the free length of the spring.
The free length is supposed to be 27mm. If not, you are allowed to carefully pull the spring till you get that free length and assemble it and see if that fixed the issue.

Also, if your idle speed is on the low side you may need to raise that.

Diesel911 · #14 10-08-2022, 11:13 PM

One of our members greezer used to rebuild injectors. You could contact him.