Aternator Belt Tension

[Chief Engineer]

A torque wrench will make you stronger.

You must remember to always put it back to zero when you are done.

"Face it folks, you can't Torquemada anything" History of the World, Mel Brooks

[hellosailor]

Loctite will inhibit corrosion, simply because it prevents anything else from getting in. But unless I missed something (you know, guys and instructions <G>) it won't protect the way a real anti-seize will.

And if you're about to buy NeverSeize...the key word with that is SPARINGLY because that silver paste manages to get into everything and migrate everywhere. Does a very nice job on bolts that are subject to a lot of heat, like exhaust manifolds or exhaust clamps, where Loctite would just burn up also.

[nhschneider]

First, I don't recommend prying on an alternator housing to tighten a fan belt - they weren't designed to take that kind of stress. I use a belt jack, identical to the one purchased at JC Whitney and shown in an earlier post.

Second, fan belts should be tight. On my new Beta Marine engine, the specification is a half-inch deflection at 15 pounds of pressure - that's quite a bit of pressure. Tight fan belts actually last longer because it allows a more efficient heat transfer. They have to be very tight to cause premature bearing failure on either the water pump or alternator.

Fair winds and calm seas.

[Chief Engineer]

Reminds me of a story......

A DIY Yachtsman had the opportunity to meet the designer of his boat....world renowned XXXXXXXXX XXXXXXXXXX....he said " Every Screw I put in the hull is parallel to the waterline, what do you think of that?"

His reply was....Well 1/2 are too loose and the other half are too tight.

[Ocean Girl]

I just got home from work and looked into loctite info, here is what I think would be good to use Loctite Blue. I will use a turnbuckle thingy for alt belt adjustments, but first will buy a new belt (green stripe ribbed), some loctite blue, and a torque wrench. So my final question is: How much torque for the alt mounting arm bolts?

They say boats are like women, but I can say with absolute certainty that I am no where near as complicated as my Ocean Girl!

Cheers,
Erika

[nhschneider]

Check out:

Steel Bolt Torque Specifications Table - Engineer's Handbook

Good site for data on such things as torque.

[Ocean Girl]

Once again, you guys rock.
thanks,
Erika

[Laidback]

Erika,
Somewhere there is one statistic that tells us something and that is:-
"there are over 800,000,000 vehicles on the the worlds roads" if there is one single adjustment that is made to each of those vehicles in the vehicle's lifetime, (EXCLUDING adjusting the seat belt, or the tire pressure) it will be to adjust a drive belt's tension. No Gadgets will be used, No Loctite will be used.
Ordinary 'split locking washers' are the standard method of ensuring the alternator does NOT move once its nuts and bolts are tightened up. You can be sure that your Alternator is already secured using split locking washers. McMaster-Carr
There is no necessity to complicate a very simple everyday procedure. The KISS principle applies to tightening a drive belt.

[YourOldNemesis]

1. Use any kind of appropriate lever to hold the alternator in place while you tension it - you do NOT need to fork out for any special tools
2. If the lever won't move the alternator, the belt is either already too tight, or you haven't undone one of the bolts required to allow it to move for tensioning.
3. Always use a washer with a bolt. In this case a couple, to stop it vibrating free (as laidback said) if you want a belt & braces approach, use some threadlock too.
4. If you think that replacing a bolt that has fallen off and moving water hose out of the way is a 'project', you should see my cars.

[Ocean Girl]

Originally Posted by YourOldNemesis

4. If you think that replacing a bolt that has fallen off and moving water hose out of the way is a 'project', you should see my cars.

Ahhh, clearly you have yet to work on OG, it is never a simple replacement of a bolt, just like it wasn't a simple tightening of a belt. OG will lure you with that "simple" task, but in the end, two hundred dollars will be spent, at least two tools acquired, and I bet this will take about 6 hours total. (that is if all goes well with replacing the water hose that was chafed through from the bolt). So you hear the words of a broken woman (twitch twitch), who has given up on the mirage of anything simple when it comes to her beautiful boat. I dare ya to try to do ANY simple job aboard OG, she will break you too.

I will have a mechanic friend come check my work before I run the engine since I think the alignment of the belt pulleys are a bit wacky. But I want to do the work myself, I won't have a mechanic at the ready offshore if I end up single handing.

**Is this water hose a volvo thing? It looks "shaped" so I am thinking I need to relace it with a precut preshaped hose from volvo, correct? The bends look impossible to make.

Cheers
Erika

[Jetexas]

There is a good chance that it is a formed hose from Volvo. However, in a pinch you can take it to an auto parts store and have them try to match it with a car hose with a similar bend that you could cut to the length you need.

You can also find coiled wire made to fit inside a straight hose that will allow you to make bends without collapsing the hose.

[BubbleHeadMd]

Originally Posted by maxingout

I had trouble with slipping alternator belts on my Balmar 90 amp alternators, and for a period of time I went through lots of belts.

Then I discovered ribbed belts. Ribbed belts are magic on Exit Only. No more alternator belt squeal, and the belts last a very long time. Those transverse grooves in the ribbed belt work wonders. Until I used ribbed belts, I had the same problem as you. I fought to make the belt tight enough so that it would not slip and self-destruct.

It frequently comes down to one of two solutions. Either install dual pulleys and use non-ribbed belts, or stay with a single pulley and use a ribbed belt.

That's the way it is on Exit Only.

So what you're saying is, that they're ribbed for her pleasure?

[YourOldNemesis]

Originally Posted by Ocean Girl

Ahhh, clearly you have yet to work on OG, it is never a simple replacement of a bolt, just like it wasn't a simple tightening of a belt. OG will lure you with that "simple" task, but in the end, two hundred dollars will be spent, at least two tools acquired, and I bet this will take about 6 hours total. (that is if all goes well with replacing the water hose that was chafed through from the bolt). So you hear the words of a broken woman (twitch twitch), who has given up on the mirage of anything simple when it comes to her beautiful boat. I dare ya to try to do ANY simple job aboard OG, she will break you too.

I will have a mechanic friend come check my work before I run the engine since I think the alignment of the belt pulleys are a bit wacky. But I want to do the work myself, I won't have a mechanic at the ready offshore if I end up single handing.

**Is this water hose a volvo thing? It looks "shaped" so I am thinking I need to relace it with a precut preshaped hose from volvo, correct? The bends look impossible to make.

Cheers
Erika

And clearly you 'have yet to work' on my 3 cars. Car #1 was bought for £600 and is required to take me from London to Almaty (Kazakhstan) setting off next week, I single handedly replaced the engine in car #2 last weekend just to keep the thing running, and car #3 is being designed and built by me with a motorcycle engine: currently the engine is in, but there's no floor, transmission tunnel, plumbing, wiring, transmission or instruments.

[hellosailor]

"if there is one single adjustment that is made to each of those vehicles... it will be to adjust a drive belt's tension. "

And that's actually a FAILURE of maintenance. A v-belt (any belt that doesn't have an automatic tensioner, as cars probably all do these days) needs to be tensioned once when it is installed, and then a second time about a month later after it has stretched in. It may require retensioning every couple of years after that, and it requires replacing in the fifth year, in normal service. (Five year is what Gates, Goodyear, all the premium makers give for maximum service life.)

While you certainly can lever/pry directly on an alternator in order to tension it, prying on the WRONG PART of the alternator can damage it. Prying on the solid metal frame is OK, prying on the heat shield or other non-structural-frame parts of it is a very bad idea.

Using a tensioning bar AND a tension guage, so you can adjust it correctly the first time around, is not such a bad idea. If you've got enough room to stick either one of them in there, and if you've got the persistance needed to find a tension guage these days. With v-belts now obsoleted in automotive use, there's not much need for tension guages in the mass market either.

[Ex-Calif]

Originally Posted by Ocean Girl

I just got home from work and looked into loctite info, here is what I think would be good to use Loctite Blue. I will use a turnbuckle thingy for alt belt adjustments, but first will buy a new belt (green stripe ribbed), some loctite blue, and a torque wrench. So my final question is: How much torque for the alt mounting arm bolts?

They say boats are like women, but I can say with absolute certainty that I am no where near as complicated as my Ocean Girl!

Cheers,
Erika

Hi OG - I'm late to this thread but hope can add some value.

Your engine looks like the Volvo MD2010. That's the exact model I have. You need to find the sub-model of your engine to make sure you have the right parts going back together. I suspect you have the MD2010-B but there is a data plate On the right hand side of the engine near the top. Get the right model number.

You have 3 jobs - 1. Fix the stud that secures the inboard end of the alternator tension arm. 2. Replace the freshwater pump to heat exchanger hose and make sure it doesn't chafe again. 3. Tighten the alternator belt.

First off a stud is a rod with threads on both ends. A stud is mounted in a steel block more or less permanently and the other end receives a nut. Your nut is missing. It is possible the stud has also backed out of the engine block. You need to check that.

1. Stud Repair - Why did the stud (or nut) chafe the hose? The chafe could be from the nut as it backed off or from the stud backing out. If the stud backed out it would allow the nut to be loose. To fix it.

- Remove the alternator completely - tag the wires and be careful not to damage them.
- Remove the chafed water hose completely
- Find two nuts that fit the stud - install the first by hand until it bottoms. Install a second "jammer" until it comes up against the first. Using two wrenches tighten the second one and loosen the first one until they "jam" together. then with one wrench try to "loosen" the first nut with moderate pressure. If the stud moves, remove it completely. Check the threads and maybe wire brush them lightly to clean. Use "RED" locktite on the threads and reinstall it until it bottoms and then torque it. Red locktite is the "permanent" type and is appropriate for studs into blocks.


For the next repair you will need a new hose - I do not recommend trying to find one at an auto store that is close - the clearances are tight in this installation and you don't want this hose chaffing because it doesn't fit right.

I use this site for parts - Volvo Penta, Mercruiser and more - Marine Parts Express - engines, outdrives, propellers

From the home page click on "Volvo Penta Parts Schematics" - Click Diesel - Scroll down the big list of schematics and pick MD20A0B-MD2020B-MD2030B-MD2040B. (It's a quirk that the 2010B schematic is mislabeled.

Sroll to "Cooling System" Scroll to the first "Water Pump" entry and open the pdf. This is the schematic for the 2010B - It appears the part number for this hose is 861928. You can copy this number from the parts list and paste it directly into the search box at the top of the page. The part is $24.49. I have had excellent experience with their shipping. I have not had to return parts so can't comment.

IF YOU DON"T HAVE THE MD2010B THIS PART NUMBER IS WRONG. THERE ARE SEVERAL CONFIGURATIONS IN THE MD2010.

2. Water Hose - When you remove the band clamps check thier condition. If dodgy get new ones. Make a judgement call on the other hoses on the engine - raw water to exchanger, raw water inlet and heat exchanger boot. If they were "dry" and show any signs of cracking at the ends I would replace them while I had my head in the bilge. I would spray the old ones liberally with WD-40, or coat in vaseline and store them in separate zip-lock bags, and keep them as spares.

- Secure new hoses - tighten the band clamps well. My rule of thumb is that the new hose rubber will start to "squeeze" into the grooves of the band clamp when the tension is right. Remind yourself to retension these in about 10-15 hours of running as the rubber sets.
- Clearance - Sometimes you can "twist" the hose a bit on the water pipe flange to optimize clearance. You need clearance from the v-belt on one side and the stud/nut on the other. If you can twist the hose about, try to equalize the clearance and I guess you should be able to get a t least a pinkie finger on both sides. You may have to recheck this after reinstalling the alternator.

3 - Alternator Install - You can browse the parts schematics noted above by selecting Electrical system and alternator. There are three configurations for alternator brackets and hardware. I suspect you have option A. The idea here is to examine the hardware, bolts/nuts/washers. To see what the original configuration was. It looks like in this case

- Upper pivot point has a bolt, plain nut and spring washer. A spring washer or split washer is a basic retention device. It indicate no need for loctite but if it makes you feel better you could use some blue.
- Lower inboard. This indicates the stud and a flange nut and no washer. The flange nut has grooves on its mating surface like "teeth." it creates a mechanical retention and indicates no loctite required. Again some blue if it makes you happy.
- Lower outboard. Indicates a bolt, flat washer and flange nut in the original configuration. My replacement alternator has a threaded pivot at the outer end (which makes tensioning a lot easier) and the hardware is changed to a flat washer (against the pivot arm), a split washer and a bolt.


Ok - Probably a bit of a pedantic post but I hope you find the schematics useful. I have actually downloaded most of the schematics for my engine as pdf and have printed and bound some of them. This is the kind of resource on the internet that is useful but could disappear at any time.

If I ever sell my boat on I have a fairly good library of manuals that will add value for the new owner.