alternator pivot bolt frozen. Driving w/o water pump - PeachParts Mercedes-Benz Forum

sun tortise · #1 10-08-2023, 04:01 PM

The alternator belts on my 1985 300D are very loose and screeching. Battery barely has enough charge to start.

Cannot loosen the pivot bolt, even using a 1/2" breaker bar, cheater pipe, and heating everything with a torch. So there is no way i can ever either adjust or change those belts.

I can charge the battery and try to avoid driving at night.

When i completely lose the water pump, how far can i drive in cool to cold autumn weather without the engine overheating to the point of damage?

Sugar Bear · #2 10-08-2023, 04:35 PM

Watch the temp gauge, don't overheat it the damage is permanent. Since it is the pivot bolt can you loosen the others and pry the alternator tight while the pivot is still tight? You may be able to install a slightly shorter belt by removing and reinstalling the water pump pulley.

May want to look for the alternator bracket from a used engine, cut yours off and replace it. Good luck, a single bolt can create such a headache.

vstech · #3 10-08-2023, 10:54 PM

Are you sure you aren’t turning the welded end of the bolt?

sun tortise · #4 10-09-2023, 12:57 AM

I think the adjustment bolt has a welded end, but not the pivot bolt. But i could be wrong.

shadetreemechan · #5 10-09-2023, 07:36 AM

Quote:

Originally Posted by vstech

Are you sure you aren’t turning the welded end of the bolt?

The front pivot bolt is not meant to move. That allows you to loosen the nut from the back with a single wrench......

86Merk · #6 10-09-2023, 08:15 AM

If the water pump fails I'm not sure you'll have flow past the sensor to get an accurate reading. Even if you do, the water in the head will boil in a matter of minutes at best.

tl;dr

Don't drive without a water pump.

Shern · #7 10-09-2023, 09:12 AM

Quote:

Originally Posted by vstech

Are you sure you aren’t turning the welded end of the bolt?

This exactly.

Anything else would have broken free or sheared off completely by now.

Diesel911 · #8 10-09-2023, 09:19 AM

In the picture there is 2 areas where there is a pivot bolt #2 at the bottom is the area where the lower pivot bolt is. And #1 is the top bolt.

The circled areas are where there could be blots holding the casting to the engine block.

Assuming it is the lower pivot blot that is the issue you can see in the picture there is areas to start spraying a penetrant like the PB Blaster with the penetrating catalyst (you need to see the word catalyst on the label). If you remove the #1 pivot bolt and loosen the large alternator adjustment bolt (see the 2nd pic) that should allow you to remove the sheet metal and to get something like a 2x4 to gently lever against the alternator housing.

Also, all of the large blots have nuts on the ends the nuts can be heated and can be removed or split with a nut splitter or a sharp chisel.

While the penatrant Kroil is supposed to be better PB Blaster with the catalyst is sold by Home Depot. I keep mentining the catalyst because PB blaster makes 2 products. One product that you don't want is the WD-40 like lubricant and it works the same as WD-40. For the job you want the penetrant and it has catalyst on the label.

vstech · #9 10-09-2023, 03:12 PM

Quote:

Originally Posted by shadetreemechan

The front pivot bolt is not meant to move. That allows you to loosen the nut from the back with a single wrench......

Yup, just making sure.

I’ve seen people cranking on the other end…

cmac2012 · #10 10-09-2023, 08:29 PM

Quote:

Originally Posted by 86Merk

If the water pump fails I'm not sure you'll have flow past the sensor to get an accurate reading. Even if you do, the water in the head will boil in a matter of minutes at best.

tl;dr

Don't drive without a water pump.

This. Way too much possible downside.

Is there anyway to get an angle grinder perhaps USA halfway worn down (smaller) skinny cutting wheel and cut through the old bolt? I haven’t looked at this exact bolt in a long time, could be next to impossible.

sun tortise · #11 10-09-2023, 10:47 PM

The adjustment bolt was no problem. the nut behind it readily loosened.

The bolt at the very bottom of the alternator has no nut, but screws into a threaded hole in (i guess) the housing. With PB blaster, WD39, and the propane torch, got it to where it would loosen 1/8 of a turn at a time, with great force, and it never broke loose. I thought for sure it was going to snap, but now i can swivel the alternator enough to where i can hopefully put on new belts. I'm not sure if there is a third bolt that is supposed to be loosened,but it seems like i can hopefully change out the belts with the pivot bolt loosened slightly, and the nut behind the adjuster loosened.

Thanks for the advice, and wish me luck!

sun tortise · #12 10-10-2023, 03:48 PM

Put on 2 "new" belts on (Conti belts from Pelican, with a 2005 date on them), also steering belt. Cut the a/c belt since that doesn't work anyway.

The pivot bolt is just as hard to retighten as it was to back it out 1/8 inch or so, and i am tempted to leave it, as i am still afraid it could snap. The plan is to check the adjustor frequently.

Can i get away with this? Also, tightening the 2 belts, even tho they are identical, one is slightly slacker than the other, even tho the alternator is pretty straight, if anything tilted very slightly in favor of the TIGHTER (outer) belt!

Appreciate any thoughts on the matter, and thanx again for the encouragement and advice. Peach folks always pull thru in the darkest hour!

Sugar Bear · #13 10-10-2023, 04:17 PM

IMO leaving the pivot bolt loose will be ok, but it is your call. If you leave it that way, check it periodically.

Belts used to be sold as matched sets but not anymore from what I can tell. Belts in '05 probably were sold in matched (identical length) sets. Were they a matched set? The shorter tighter belt will probably stretch to match the longer one.

sun tortise · #14 10-11-2023, 02:41 PM

Those '05 belts were bought together & have the same numbers on them. Drove about 40 miles, and they slacked a tiny bit, probably mostly normal stretching for belts that have been sleeping for 18 years.

Sugar Bear · #15 10-11-2023, 04:46 PM

"Matched Set" belts were supplied as a pair and were packaged together from the factory. It was more than being the same #, they were almost exactly the same length. As manufacturing tolerances became tighter "matched sets" were no longer offered.

Either way you'll be fine as the belts run-in.