Bolt Size Question - IP - PeachParts Mercedes-Benz Forum

Jmana · #1 12-01-2007, 05:23 PM

I am having one heck of a time locating a proper bolt for an 87 300D with a 6 cyl engine. The bolt is the one that goes through the timing sprocket. I was given a part number here before and ordered that bolt and the washer with spring, but it doesn't seem like the bolt is long enough. The washer seems to fit though, but what's weird is I don't remember removing this washer when I took the old pump out! So if anyone knows how long that bolt should be, or the right part number for it, please let me know. The only other thing is that the new pump is out of an 88 300SDL, but that should take the same size bolt, right? I attached a pic of the new pump and you'll see that it does not have a bolt, but I pulled this out (it wasn't screwed in, there is a bulb at one end which seems to be press fit in) and it is the same length, so I am really confused as to why the new bolt isn't long enough. Any help is appreciated!

sixto · #2 12-01-2007, 06:33 PM

The 300SDL was only sold in the US in 86 and 87.

I don't have the bolt in front of me but it wasn't long at all. Not even an inch of shank, IIRC.

Is the sprocket seated properly on the IP? Splines engaged and rotary cam facing the vacuum pump?

Sixto
87 300D

Jmana · #3 12-01-2007, 08:29 PM

Maybe it's not an 88, that's what the guy had listed it as, but he had bought the car for parts so maybe he didn't know the year. I think the sprocket is seated, at least the pump is in the right location and bolted in, but is it possible the sprocket moved forward? I know it was a pain to get the splined end to go into the sprocket. It seems like the splines are in the sprocket, because when I rotate the engine the pump cam rotates with it. What exactly did you mean about the rotary cam facing the vacuum pump?

sixto · #4 12-01-2007, 09:57 PM

Quote:

Originally Posted by Jmana

What exactly did you mean about the rotary cam facing the vacuum pump?

The roller coaster track the drive wheel of the vacuum pump rides on.

Sixto
87 300D

Jmana · #5 12-01-2007, 10:20 PM

Yeah, I never took that off, so it is still facing where the vacuum pump will go. Anything else I should look for?

gsxr · #6 12-01-2007, 10:48 PM

I have a pump taken apart on my workbench, with the bolt and washer in the front. The bolt measures 75mm long, the washer is 8mm thick, and the bolt is a left-hand thread. The bolt goes into the pump 40mm before it touches the threads inside the pump center shaft, leaving 35mm of bolt exposed. This is from a 1987 pump, and the bolt should be the same for all 1986/1987 OM603 engines. The washer is different depending on if you have the original timing device or the newer/different style. I don't know the difference between the two washers but I assume they are different thicknesses. (?) See the 3 attached photos below, sorry they are so small, but MBShop has *stupidly* small file & image size restrictions on this forum. C'mon, guys, buy some freakin' hard drives for your server...!

Also, here are two photos of the old & new timing devices (hosted on my website, so they're decent size) :

Jmana · #7 12-02-2007, 10:38 AM

I think the 300D and 300SDL pump must have some minor differences. I looked inside the hole in the splined end of the old and new pump, and on the old one the threads don't start for about an inch back inside the hole. On the new pump the threads start right away, and for some reason the bolt they gave me for a 300D will not thread in. The thing that still bothers me is that the bolt that shipped with the new pump was completely different than the old pump. I posted a pic of both below, and they are both lined up in the same direction that they go into the pump. The new pump one almost looks like the head was cut off the bolt, then pushed into the pump backwards. Is this the way the 300SDL was set up? One other thing is the sprocket has been pushed forward when I put the pump in, I don't know why but the spline did not want to fit into the sprocket, I hope the splines aren't different in size. I am hoping if I can find a bolt to fit the new pump that it will draw the sprocket back. So I guess what I now need to know is does anyone know if there is a different bolt for the 300SDL? And is the splined end for the 300SDL the same as the 300D?

gsxr · #8 12-02-2007, 10:43 AM

The pump is the same on all 1987 300D, 300TD, and 1986-87 300SDL. It's the same pump that I took photos of above. Your pump should have a nameplate with the SAME 603-070-10-01 part number on it.

All OM601/602/603 engines use that SAME bolt for the front of the IP. If you are having problems getting the new 601-990-04-01 bolt to thread in, the pump has screwed-up threads inside. Unless you can find a long, left-hand thread tap to fix the internal threads... you may need to get a different pump. You have the correct bolt, that is not the problem.

Jmana · #9 12-02-2007, 11:06 AM

But why was the bolt that came with it in with the bulbed end stuck inside the pump? And why are the threads inside located differently?

Jmana · #10 12-02-2007, 12:56 PM

After looking inside the hole on the shaft with a mirror, I realized the threads are in the same location as the old one, so I was wrong about that. It almost looks as if someone had broken off the bolt head, then hammered the bolt in the opposite way, which screwed up the threads inside. I don't know what the heck to do now, I am sure it would be nearly impossible to tap it out. At this point I just want to get the car running in order to sell it, but without this bolt being in there I am sure it wouldn't run properly. The bad thing is I need to have it out of the driveway in two weeks, because I am moving.

Jmana · #11 12-02-2007, 01:05 PM

I found some left hand taps online, if I was to go this route, what size would I order?

sixto · #12 12-02-2007, 02:37 PM

Pretty clear to me that someone didn't realize it's a left hand thread and snapped off the head trying to loosen it. I couldn't figure out why the shank is necked down close to the head. Could be that MB or Bosch was smart enough to foresee someone not using the manual and sacrificed the bolt rather than the threads of a very expensive IP main shaft.

Jmana, take the new bolt to any machine shop and they'll tell you what pitch and diameter tap to use.

Sixto
87 300D

Jmana · #13 12-02-2007, 02:53 PM

That actually makes a lot of sense about allowing the head to snap off. What I can't figure out is why someone would do that, then somehow get the bolt out, then put it in backwards, and they had to have hammered it in because it took a lot of effort for me to get it back out. One other question, I can't seem to get the sprocket to go all the way back onto the shaft, I have tried hitting it with a large socket to move it back but it seems stuck. Does anyone know approximately how far of a space is between the front of the sprocket and the front of the shaft? On mine there is exactly an inch, which seems too much, in fact with the washer installed the bolt doesn't even reach back to the threads. I had a hard time installing the pump and I think this is why. I am afraid that even if I do get the bolt in, that the sprocket still won't go back into place. Does anyone know why this could be happening? Is there something behind the sprocket that could have gotten out of place during install and be causing this? I remember I did look behind it but didn't notice anything out of the ordinary.

sixto · #14 12-02-2007, 03:17 PM

The splines in the sprocket sit on the splines in the shaft. If you can take depth measurements of the splines in the sprocket, you can determine how far onto the shaft the sprocket should go.

If you have time on your hands and keen eyes, count splines on the shaft and sprocket :/

Sixto
87 300D

gsxr · #15 12-02-2007, 06:46 PM

The pump must sit flush on the back side of the block, and pull easily into the splines inside the timing device. It should all go together with NO hammering, prying, pressing, or otherwise excess force. You may need to rotate the pump along the axis of the shaft to get the splines to engage. Assuming you are using the steel timing basket tool to hold the timer in place, the pump should fit up against the block by hand, while the basket holds the timer in place. It's a yes/no, black/white, go/no-go fitment. Once in place, the bolt & washer should connect with no problems. The washer is different depending on the version of the timing device... if your timer looks like the one on the left side of my photo, that is the new version. If it looks like the right side, that is the old/original version.

Bummer about the screwed-up threads... that is exactly what I suspected you would find. A competent machine shop might be able to fix it for you, if you are unsure about tackling this yourself. Hopefully there is enough material to tap into. I'm not sure if a Helicoil or TimeSert is an option here but it might be worth investigating (worst case scenario).