Failed Oil Pump Chain Replacement - HELP - PeachParts Mercedes-Benz Forum

Rob_Dietz · #1 04-14-2006, 01:28 PM

I lost the oil pump and chain in my '85 300D TD. After hearing a wierd pop immediately after startup a few weeks ago, the engine got really noisy and I initailly thought it was an exhaust leak. The oil pressure was low but there. Then the engine seized for a half a second and then oil pressure went to 0. I then realized what happened and immediately shut down. Restarted to confirm 0 oil pressure and shut back down. Dropped the lower oil pan and the chain was dangling and had been pulled apart. Upon closer inspection of the oil pump and bottom of lower oil pan knew it was not good. The oil pump shattered from the internal gear, bent the pump drive shaft and chewed up the teeth on the oil pump sprocket. I also found a shattered metal ring and two very long (@8") very small wind springs that I can't identify. Can anyone tell me what the ring is, what the springs are and if the oil pump chain can be replaced w/o 1) pulling the motor or 2) w/o having to pull the upper oil pan and crank pully's and seals off? Any help would be greatly appreciated.

Rob_Dietz · #2 04-14-2006, 11:23 PM

Well, I bit the bullet and started removing everything needed to get to the crankshaft gear. Found that the timing chain also was about to fail. The deeper I dig, the more I'm finding. I still haven't figured away to install the oil pump chain w/o dropping the upper oil pan. If anyone has any ideas, I would love to hear them. I just can't beleive that MB did not design the crankshaft seal opening big enough to fit the oil pump chain and crankshaft gear through w/o having to drop the upper.

Brian Carlton · #3 04-14-2006, 11:48 PM

There are several folks on here who have done the oil pump and chain and will advise you on this. However, it's not all that common so some patience is necessary until a proper reply is received.

I'll try and locate someone.

Pete Burton · #4 04-15-2006, 02:06 AM

From rebuilding my engine, I remember cheching to see if there was room to do this. I came to the conclusion that it was possible WITH the upper oil pan on, but it's not easy. You have to remove the oil pump sprocket from the pump, get it engaged with the chain, then bring the pump into place. Don't forget to torque the bolt that holds the sprocket, or it can loosen up and break a hole right through the upper pan. Don't ask how I know this

engatwork · #5 04-15-2006, 08:17 AM

I think there is enough room to put the new chain in place with the front crank seal out of the way although it is a tight fit.

The thing that raises red flags for me on your job is this:

Quote:

Found that the timing chain also was about to fail.

Sounds to me like you would probably be $$ ahead by biting the bullet and going through your timing chain/guides and replacing all of it.

One thing I would be concerned on this job is the fact that there may be metal particles in the oil passages just waiting to be pushed along after the new oil pump is in place. The spring thing you are asking about is the oil pump chain tensioner spring. I suspect that this item broke (or the oil pump chain tensioner rail) first followed by the chain and everything else. Every time I have torn one of these engines down I have found the more wear on the oil pump chain tensioner rail than any of the timing chain rails.

How many miles are on the car?

t walgamuth · #6 04-15-2006, 09:14 AM

is thinking what i am thinking ...that a full teardown might be a good idea.

metal particles floating around in a motor will end up in the bearings eventually. not good.

tom w

Rob_Dietz · #7 04-15-2006, 05:42 PM

Thanks for all the info. I figured out that the spring that I found was from the crankshaft seal. It's the spring that keeps the tight seal around the crank. A complete teardown is a bit beyond my experience level but I am obviously planning on running a new timing chain through and I'm thinking about putting a very large magnet down under the oilpan and using a magnetic drain plug. Interestingly, I also shattered the crankshaft seal ring when it let loose which is pretty burly. I'm assuming that the oil pump siezed/shattered which then took out the chain that then collected at the top of the crankshaft gear and then chunked the timing chain. If there is a silver lining to this, it's that it happened in the drive way and not at 80 mph on the highway. I'm going to drop and check the main bearing on the #1 and I've inspected the cam lobes which look fine so I think that there wasn't a whole lot of damage.