Thanks to the great posts on this forum, I felt ready to tackle some engine projects on our 1991 190E 2.3, which I had acquired parts for over the past couple weeks. A leaky water pump needed replacement, and as long as that much needed removal - motor mounts and belt tensioner shock were also planned. So far, the results are mixed, so I'll share, following with my questions.

First was water pump removal. Unclipping the shroud and laying it over the fan, removing the fan retention bolt was easy, then both lifted out together. I intended to remove the radiator, but that never was necessary. I drained it from its drain plug. Next loosened the four bolts attaching the wp pulley (torx), then loosened the belt tensioner, then removed the pulley and belt. With that removed, the three nuts securing the fan clutch electromagnet were also easy.

The battery cable was next, then the alternator. Top bolt was easy, but I couldn't get a purchase on the bottom. Then I discovered it was secured with a nut and lockwasher in the rear, which were easily removed. The alternator bracket removed easily, I disconnected the two bolts holding the thermostat housing to the engine, loosened all hose clamps leading to the pump (3), and pulled the hoses away. The remaining wp securing bolts were removed and carefully organized (lengths vary), and the water pump just lifted right away from the block. At this point about a relaxing hour had expired, and I was primed!

Next I carefully pried the plastic dust cover off the idler, and removed the allen-head bolt. With the idler off, I could see the retaining bolt for the tensioner shock, but misjudged it an allen (it's torx) and it rounded off. Removed shock by gripping its collet with visegrips to break it free, then bolt was free to turn out. The failure mode of these items was now apparent - the rubber molded between the metal bushes hardens and crumbles away, and the 'o-ring trick' cannot solve that problem.

Next the engine mounts. I supported the front off the ground with jack stands under each side of the crossmember, and the floor jack under the sump as needed (with a 2X4). The passenger's side was pretty easy, removing the 8mm allen bolt thru the crossmember access hole underneath, and plenty of room to break free the 17mm hex bolt on top. Jacking the engine a bit, it wasn't too hard to slip the new one in and juggle it to line up the hole on top, after loosely securing the bottom bolt. I spent most of the next 4 hrs trying unsuccessfully to remove the top bolt on the driver's side engine mount. By removing the bottom bolt and jacking up a LOT, I could get a box wrench on top, but no maneuvering room to break it free - I finally gave up and secured both mounts. Somehow, intake components must have to be removed to gain access.

Finishing up the wp replacement, I coated the gasket with 'ultra-blue RTV' and reassembled the pump bolts using anti-seize, torqing to spec. I reattached the components on the wp except the fan. I reattached the alternator bracket and alternator, attached the new tensioner shock and the idler. To install the belt, I had to remove the lower alternator bolt and loosen the top, then reattach. Belt retensioning worked fine, but left a question. Finally, I set the shroud over the wp, reattached the fan, and clipped the shroud back over the radiator.

So far no leaks, but some intermittant noises suggest I MUST replace the other motor mount to level the engine, somehow. So my questions finally:

HOW do I get access to that top motor mount bolt on the drivers side?

How do I set the tension on the fan belt correctly? Unlike other posts here which describe a set of marks, my indicator shows a triangle. After resetting the marker with the securing bolt loose, I adjusted to the middle of the range, then tightened. Is this adequate (it seems plenty tight)?

Thanks. Steve.

Well, I answered question #1 - I removed the fuel injection assembly including the mass-flow meter body and fuel distributor, as a unit. Not difficult, but involved - every fuel line connection had to be removed, the injector lines at both ends. This gave access to the 17mm bolt from directly above. With the engine jacked up, the mount was easily removed, but complete extrication was from underneath, tricky, and could only be accomplished with the steering linkage full left. New one attached easily once maneuvered into position. Engine is much smoother and quieter now with both mounts replaced.

Now I still need to determine the correct belt tension. Alternator bearing is making a racket most of the time, and previously it was only occasionally. Anyone know the correct tension?

Thanks. Steve.

To find out about adjusting the tensioner go to Tensioner help! or do a search on 'tensioner'

__________________
Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)

Thanks for the thread, Mick. I had read that, but it was the only reference I found. I was looking for a 'second opinion' to confirm.

Steve

A follow-up. New problem. Although engine now quieter, vibration less, and no more 'knocking' while starting - all due to the new motor mounts - there was a rattling noise, intermittent, that I could not localize. It appeared to be in the fan belt path. At one point today after pulling the car back out of the garage, I discovered a small bolt in the garage under where the front of the engine had been. I recognised it as the stripped-head torx bolt I had tried to re-use attaching the damper to the idler support.

By now it only took a few minutes to dissassemble to the point of replacing that bolt with a NEW allen-head one, but tragedy finally struck - the tensioner broke while resetting it for the umteenth time. The broken one came out with three bolts attaching bracket to engine, and the 17mm one through the middle, after pulling the power steering pulley for access. Hopefully the new one now on order from Phil will go in as easily.

Tensioner failure mode was as others have noted, where the rubber hardened and cracked, preventing normal tension from being possible. In addition, adjusting further I cracked the torque-lever that turns it from the adjustment screw.

Steve

Addendum. New idler kit came last night from FastLane, and I installed it. Of note, the included mounting bracket did not fit the engine - one hole did not line up quite right. Rather than try to bend it, I reused the filthy but functional old one. Although everythig else seemed to bolt in fine and the adjuster did its job, I could not get the indicator to work. It basically just did not move as I increased the tension.

Only a 16-mi drive to work so far, but none of the annoying noises I have been hearing for the past months. You can hear a little 4-cyl 'drone' under load, but muted, and overall a very quiet car.

Steve