W115 240D starter motor removal - PeachParts Mercedes-Benz Forum

j-galap · #1 11-21-2020, 08:25 PM

Hi folks,

I did a search for this exact topic and found nothing (plenty of info on the W123, but not W114/5), so I thought it might prove useful for future generations to start a thread on starter motor removal on a W115 240D.

Reason being: I'm having trouble, so the car currently looks like this:

Seemingly, it's fairly straight-forward. Unless I've missed something, there's three steps to removing it:
- L-bracket that mounts the front of the starter to the motor mount
- Electrical connection
- Two hex bolts on the back of the starter that mount it to the transmission.

Of course, unhook the battery before doing this job.

L-Bracket removed from motor mount (two 10mm bolts and two 17mm nuts):

One tip for this step: use an offset wrench for the 17mm nuts. They're in a bit of a tight spot, so getting a socket/ratchet in there is nigh on impossible. Another tip, disconnect the throttle linkages in the area to give yourself more room to move. Easy enough to and makes life a lot easier.

The hex bolts:

Here's where I'm having trouble. The two hex bolts are pretty close in to the bulkhead, so getting enough torque on them to undo is proving difficult. Thus far I can't get them off, so I can't take the darn starter off. There's no room for a traditional impact gun, and the exhaust gets in the way of my breaker bar, so I'm a bit stuck.

So, anyone else done this job at any point and can provide some insight? I'm currently trying to avoid having to pay a mechanic to do this job for me because, well, it shouldn't be too difficult - and local classic MB techs here in Vancouver aren't cheap!

Any thoughts?

Thanks

Sugar Bear · #2 11-21-2020, 08:58 PM

Those bolts can be a nightmare.

Put penetrating oil such as Kroil or PB Blaster on each end of the bolts, both at the internal hex end and where they come through the starter. Clean the internal hex of the bolt well. When the fit of the hex driver is loose, I've epoxied the bit in place to prevent rounding.

Use long 24-30" extensions staying parallel to the transmission to get farther away from the exhaust pipe to get a breaker bar on the bit. The bar will have to be 1/2" drive, 3/8" won't do it. If at all possible, hit the bolt from both ends with a punch and hammer. It's even better if a helper can hit the bolts while torque is applied. Use a chisel on the outside of the hex striking it in the loosening direction. Once set-up to apply the torque use about 80% of the force you can apply then suddenly with a snapping motion apply the remaining 20%. Be prepared for a sudden release, watch where your hands will land to prevent cuts etc. when it breaks free.

Also it may be possible depending on the length of the hex bit to put a 10mm box wrench on it and still get the bit in all the way. If you can arrange this a helper can apply force to the wrench while you apply torque to the breaker bar.

MAKE CERTAIN that the car is safely supported with secondary blocking in addition to the jack stands while you are under it.

Good luck!!!

Alec300SD · #3 11-21-2020, 09:30 PM

Short end of long handled Allen key in the bolt
Tap the Allen key in place so it sits deep in the bolt head.

A). Combo box/open end wrench (same size as Allen key), with the box end on the Allen key (as close to the bolt head as possible).
If needed, use a second combo wrench nested into the open end of the wrench on the Allen key (increases your mechanical advantage).

B.) Long handled combo wrench (larger than the long handled Allen key) with boxed end (not open end) positioned on long arm of Allen key.

With one hand, press down on the Allen key to keep it in place securely, while applying force to the combo wrench(es) with the other hand until the clamping torque is released.

Diesel911 · #4 11-21-2020, 10:22 PM

Someone on another Benz forum made the wrench in the attached pic to get at the one between the back of the Engine and the fire wall. But it was on a gasoline engine.

I got tired of the failed attempts and drilled 2 holes in my Fire Wall and I now have easy access to those 2 bolts.

I could not tell from the picture but 3/8ths extensions can sometimes be too springy and you loose torque with them.

j-galap · #5 11-21-2020, 10:33 PM

Oh man, I was hoping I'd missed something obvious here but it turns out: yes, those bolts are a massive pain in the backside.

Thanks for the suggestions on how to do this. @Sugar Bear, funny you mention the extra safety aspect as I was very paranoid of this job and had all manner of extra jack stands strategically placed around the car when I was working on it earlier. Definitely don't fancy a transmission in the face...

vwnate1 · #6 11-22-2020, 12:15 AM

They're the same as W123's, the various comments here are all on target *except* never, EVER use an open end 10MM wrench on your Allen tool ! .

There are long cranked 10MM box end wrenches, I know buying a new tool for just one job sucks, maybe you can find one in a thrift / pawn shop or online at the "E' place .

Or at the local trailer rental place, when I were a young lad I'd often rent tools I didn't have from the local indie rental place .

I've done it many ways but my favorite is to use 4' (maybe longer) of 1/2" drive bits and extensions and a flex handle (misnomer : 'breaker bar') to get the top one loose first then go after the lower one as you have more room to work in .

Cleaning the Allen head of the bolt to ensure the bit fits as deeply in as possible is critical, by the time you discover your mistake it's far too late .

Good to hear you're taking safety seriously .

Alec300SD · #7 11-22-2020, 01:59 AM

Hi Nate,

My goof

Meant to say boxed end of large combo wrench in part B...prior post edited with correction in red print.

j-galap · #8 11-22-2020, 02:25 PM

Ordered a set of long crank box end wrenches. Let's see how that goes!

I'll report back with pictures and hopefully non-bloody knuckles

Sugar Bear · #9 11-22-2020, 03:18 PM

Apply penetrating oil (not WD-40) a couple of times to both ends of the bolts while waiting for the wrenches.

Good luck!!!

mabbonizio · #10 11-22-2020, 06:17 PM

I replaced the starter on both my w123 240d and w115 240d.

the nice thing about the 123 is that since the engine bar is bigger its pretty easy to reach the starter bolts from up top by the firewall.

On the 115 I had to go from underneath and use long extensions etc...

Something I did to save myself a lot of cursing and frustration was to remove the intake and exhaust manifolds. That way I could just pull the starter right out.

When I did the job on my 123 I had to get the starter out from below and it was really frustrating. doable - but frustrating!.

vwnate1 · #11 11-22-2020, 11:00 PM

When faced with a really tough bolt, I sometimes slip a box wrench over the bolt head and then use another longer box end wrench on the open end of the first wrench to gain serious torque .

Sadly I'm not allowed to post any attachments else I'd cobble one up for display .

I used this method to remove a rebuilt starter off a '77 W123 240D in the dirt in New Mexico once.....

Sadly the starter wasn't a BOSCH rebuild so I got hosed ~ the Bendix wasn't any good .

j-galap · #12 11-24-2020, 08:05 PM

I am really struggling with this one, not helped by the fact that it's been raining almost non-stop all day, all night (darn PNW!). Box end wrenches arrived yesterday night so today I found a window of time to put down a mat and climb under the soggy car. I had cleaned up and pre-soaked the bolts with PB Blaster so I had my hopes up.

Allen key in situ on the lower bolt (top one was proving too tricky to get on to and I was running out of light) but in the end I still didn't have enough torque. These things really do not want to come off it seems!

Getting close to throwing in the towel on this one and paying for the local MB specialist to do it. To show up at their place with the car on the back of a tow truck to undo two bolts is a troubling prospect for the mind though

I did come across this impact wrench after searching for other options though. Wonder if that might do the job. Would probably cost me as much as the labour to get the starter changed after all...

Alec300SD · #13 11-24-2020, 08:58 PM

I had a really stubborn upper starter bolt on my W116.
To get it to break loose, I had to orient the ratchet handle horizontally, then I used a trolley jack to lift on the handle.
There was a piece of scrap 2X4 wood between the ratchet handle and the jack to get the needed height.

The PS of the car lifted up about 3 inches and still didn't break the torque.
Suddenly adding my weight to the PS fender finally got it loose with a a loud cracking sound.
Note: vehicle was not on jack stands for this procedure.

vwnate1 · #14 11-26-2020, 06:38 AM

FWIW ;

You should always loosen the top bolt first .

When worrying about the vehicle falling off jack stands or simply don't have a trolley jack and safety stands, you can drive the right two wheels up on a curb using a driveway's drop curb.....

That impact wrench @ 220 Lb. Ft. looks good, be area you might shatter your Chinese 1/2" drive flex knuckle .

Impact sockets and extensions, knuckles etc. are BLACK never chromed .