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Beta 38 - 70 Amp Alternator Belt Sizing


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I’m after some advice regarding the top mount 70amp top alternator belt fitted to Beta 38 engines. This is the one dedicated to the domestic battery bank. 
 

I bought my boat last year and the previous owner left several new spare belts for this alternator ranging in size from 6pk1295 to 6pk1305. The current belt a 6pk1300 failed yesterday. I’m pretty sure this was as a result of the belt wearing on the outside edge due to its perilously close proximity to the adjustment Allen bolt. If you have a Beta 38 you may well know what I mean by this. If the belt is on the loose side it can touch the adjustment bolt momentarily when the engine accelerates up, or at least it appears to on my engine.
 

Anyway I’ve replaced the belt but I’m starting to wonder if the previous owner had bought the correct size spares. A used one he left has the same ‘tell tale’ wear line. 

 

Beta part number is 214-02614 but predictably they don’t state the actual belt length! Can anyone tell me the length of the genuine Beta belt so I can confirm I’m using the correct size? It should be printed on the outside edge. 
 

If I am indeed using the correct size belt, I’m considering replacing the current Allen bolt with a regular hex bolt which my measurements indicate will provide much better clearance. Again, has anyone thought about doing this?

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1 hour ago, Withywindle said:

I’m after some advice regarding the top mount 70amp top alternator belt fitted to Beta 38 engines. This is the one dedicated to the domestic battery bank. 
 

I bought my boat last year and the previous owner left several new spare belts for this alternator ranging in size from 6pk1295 to 6pk1305. The current belt a 6pk1300 failed yesterday. I’m pretty sure this was as a result of the belt wearing on the outside edge due to its perilously close proximity to the adjustment Allen bolt. If you have a Beta 38 you may well know what I mean by this. If the belt is on the loose side it can touch the adjustment bolt momentarily when the engine accelerates up, or at least it appears to on my engine.
 

Anyway I’ve replaced the belt but I’m starting to wonder if the previous owner had bought the correct size spares. A used one he left has the same ‘tell tale’ wear line. 

 

Beta part number is 214-02614 but predictably they don’t state the actual belt length! Can anyone tell me the length of the genuine Beta belt so I can confirm I’m using the correct size? It should be printed on the outside edge. 
 

If I am indeed using the correct size belt, I’m considering replacing the current Allen bolt with a regular hex bolt which my measurements indicate will provide much better clearance. Again, has anyone thought about doing this?

My Beta B38 (or rather BV1505) is rather old and uses a single 70A Alt but I get no rubbing issues from contact with anything.  Have you looked at pully alignment?  Each pully centre should be in line with each other otherwise the belt can ride up a pully or make contact with something.  I used to have a problem with the belt getting worn too quickly and even breaking but shimming the pulley inline with the water pump and crank pulley solved that issue.

 

as above 1295mm should be fine.

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Beta BV 1505 in our boat runs a 6PK1238 with no problems. It was fitted when we bought her in July 2015, and that belt is still going strong - though it may be reaching end of life due to lack of further adjustment.

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11 hours ago, Col_T said:

Beta BV 1505 in our boat runs a 6PK1238 with no problems. It was fitted when we bought her in July 2015, and that belt is still going strong - though it may be reaching end of life due to lack 

Now that is interesting. Your belt is over 7cm shorter which reinforces my hunch that the belts in my service kit are wrongly sized.  I don’t suppose you have your original operator maintenance manual? If the Beta part listed in it is either 214-0613 or 214-0614 then that would confirm we have the same engine and I’m running the wrong belt size. If you see what I mean. Update: See my latest post below - I’ve been quoting incorrect part numbers. So unless you also have a Travel Power unit our belts will be a different length. 

14 hours ago, churchward said:

My Beta B38 (or rather BV1505) is rather old and uses a single 70A Alt but I get no rubbing issues from contact with anything.  Have you looked at pully alignment?  Each pully centre should be in line with each other otherwise the belt can ride up a pully or make contact with something.  I used to have a problem with the belt getting worn too quickly and even breaking but shimming the pulley inline with the water pump and crank pulley solved that issue.

 

as above 1295mm should be fine.

Thanks, it all looks to be in alignment. The previous owner a marine engineer had the belts running rather looser than I would have done, but they say better loose than over tight as that can prematurely wear the bearings. So I left them. I now think the belt may have jumped on the crankshaft pulley as a result which caused it to shred. You live and learn.  I’ve fitted the new one somewhat tighter but I’m still concerned how close it runs to the adjustment bolt hence trying to establish the correct sizing.

 

I’ve asked Beta for the correct belt length for my engine but haven’t had a reply yet. I suspect they may just say buy a Beta genuine belt for peace of mind. We’ll see. 

Edited by Withywindle
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Quick update. After further digging just realised my belt is an unusual one as I have a Dometic Travel power unit installed. Part number is 214-04218. Oh joy!
 

Still need to verify belt length but probably only Beta Themselves will be able to answer. Thanks for all of the help and sorry my original post was misleading. 

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4 hours ago, Withywindle said:

Quick update. After further digging just realised my belt is an unusual one as I have a Dometic Travel power unit installed. Part number is 214-04218. Oh joy!
 

Still need to verify belt length but probably only Beta Themselves will be able to answer. Thanks for all of the help and sorry my original post was misleading. 

Surly you can see from the adjustment you have if the belt length is suitable. if its too long you will be at one end of the adjustment and too short you will need a screwdriver to leaver it on

Edited by ditchcrawler
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If you take the belt to a belt stockist like Erik they will have a widget to measure the pitch  length of a belt. B other wise measure the outside length and subtract the constant which can be found online.  Try the Continental or Gates websites.

 

That said, there is little practical difference in a  1295 length belt and a 1305 length.  The 10mm pitch length difference will account for no more than 5 mm movement at the adjuster in a typical set up.  It is much more likely from what you say that the belts are being run under-tensioned and that is a problem with poly V (multi rib) belts.  Too loose is actually  worse than (just) too tight.  Poly V  are designed to run much tighter than  V or Wedge belts and should really be tensioned with a mechanical tensioner and checked with a special tool.

 

N

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21 minutes ago, ditchcrawler said:

Surly you can see from the adjustment you have if the belt length is suitable. if its too long you will be at one end of the adjustment and too short you will need a screwdriver to leaver it on

Well that’s true, you’re right of course and the belts I have do fit albeit they’re at the very maximum end of the adjustment.  It’s just the way they run too close to that Allen bolt that is bugging me.  I guess I just want to know the correct size, hopefully I’ll get a reply from Beta soon. 

Edited by Withywindle
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6 hours ago, Withywindle said:

Now that is interesting. Your belt is over 7cm shorter which reinforces my hunch that the belts in my service kit are wrongly sized.  I don’t suppose you have your original operator maintenance manual? If the Beta part listed in it is either 214-0613 or 214-0614 then that would confirm we have the same engine and I’m running the wrong belt size. If you see what I mean. Update: See my latest post below - I’ve been quoting incorrect part numbers. So unless you also have a Travel Power unit our belts will be a different length. 


Apologies for the delay replying. The operator maintenance manual is on the boat, where I shall be tomorrow, and I’ll try and find the part number then. We do not have a travel power, which is a shame as that would be useful on a number of fronts.

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12 minutes ago, Col_T said:


Apologies for the delay replying. The operator maintenance manual is on the boat, where I shall be tomorrow, and I’ll try and find the part number then. We do not have a travel power, which is a shame as that would be useful on a number of fronts.

That’s great thanks, although it now looks like my belt will be different to yours. The travel power is indeed a great bit of kit, not something I was looking for when we bought the boat, but it’s been a real bonus. 

Edited by Withywindle
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Just an update to conclude this.

 

I received a reply from Beta Marine who confirm that the 6PK1300 is indeed correct. My engine build is an unusual one for Colecraft with the Travel Power Generator and consequently the part number for the belt is not widely listed. 
 

Thanks to everyone who responded. As ever your advice and comments where very useful. 

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Just for completeness, the part number in my operator’s maintenance manual is 214-63090.

 

As far as I know, this is for a ‘standard’ BV1505 e.g. not a special for a particular builder / fitter-out.

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2 hours ago, MtB said:

Surely the root problem remains unresolved - that bolt head too close to the belt. Most curious as Beta engineering is usually well thought out. 

 

Any chance of a photo of it? 

 

Indeed, I’m going to replace the bolt with a low profile version or perhaps just a standard hex. 🤔 Current clearance is about 5mm. 
 

Will post a pic tomorrow all being well. 

9 hours ago, Col_T said:

Just for completeness, the part number in my operator’s maintenance manual is 214-63090.

 

As far as I know, this is for a ‘standard’ BV1505 e.g. not a special for a particular builder / fitter-out.

Beta have told me 214-02954 for my build. 

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39 minutes ago, Withywindle said:

Indeed, I’m going to replace the bolt with a low profile version or perhaps just a standard hex. 🤔 Current clearance is about 5mm. 
  

Maybe some one lost the original and fitted that one

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No I think it’s genuine Beta. It matches all of the others. In fairness the belt only just touches probably at high speed , but over time it’s going to wear as the one the previous owner left me bears testimony. I’m confident I can fix the problem using a lower profile bolt now I know It’s not the belt sizing that’s the issue. 

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