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Old 01-18-2003, 12:53 PM
sbourg sbourg is offline
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Join Date: Jul 2001
Location: SoCal
Posts: 1,303
Water pump, engine mounts, tensioner shock 190E?

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.
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