Beta 38 Heat Exchanger Replacement

  • May 06, 2023 8:12 PM
    Message # 13193833

    I thought I would share my experience. 

    I have finally completed the replacement of the heat exchanger on my Beta 38 from 2006 which has prevented any sailing the last few months. 

    The main take away is, service your H/E & tube stack and check/change the pencil zinc regularly!

    It was a bit of an ordeal that also included replacing the alternator, wiring and the alternator bracket. 

    The catalyst was finding the engine blocks small coolant drain petcock sitting all corroded in the bilge after checking the engine after a day of motoring. Not good. The threaded part was still in the block, so I was lucky that I didn’t lose all the coolant. 

    I had to get the remaining piece of the petcock out without doing any damage to the threads in the block. I removed the alternator for better access and drilled out the broken petcock without getting too close to the threads. 

    I had ordered from Beta a new petcock drain and oil sender but could not find a tap that matched the threads in the block or new petcock.

    I queried the San Francisco Beta dealer and Beta Marine home office in North Carolina on the tap size, but neither of the suggested sizes matched the thread of the drain. On my quest to find the proper tap, I found a small hardware store in South SF – Daly City Tool Mart - that took a look at the new petcock and recognized that I needed a 1/4” British Standard Pipe. (BSP) 

    “NPT and BSP threads are not interchangeable due to the differences in thread forms. NPT threads are pointed in the peaks and valleys, where BSPs are rounded.”

    Using the ¼” BSP tap, I was able to tap the threads in the engine block and install the new drain petcock.

    I proceeded to service the heat exchanger which I’ve been doing every 2 years. This involves removing the H/E end caps and removing the tube stack for cleaning. The aft end cap was easily removed but I could not get the forward end cap on the H/E to budge. I tried careful tapping on the tube stack from the aft end (the tube stack comes out either end) and it would not move to come out either end.

    I tried heating the H/E with a propane torch as well as cooling with Dust Off. Along with PB Blaster over a few days. I was finally able to get the forward end cap to dislodge by putting in a large Philips screwdriver in the end bolt hole and stepped on it with my full weight.

    I could see that there was a lot of corrosion around the H/E cap and where the brass tube stack sat inside the aluminum H/E and an aluminum ring that it fits into. These dissimilar metals caused serious corrosion. 

    The fun continued as the tube stack would not come out. I tried to knock it out with a mallet and block wood so as to not damage the tube stack, but it would just not move. This led to more days of the heat/cold PB Blaster cocktail. I could see that I was damaging the tube stack and had already messed up the end caps, so I went ahead and ordered new ones from Beta Marine inc. Not cheap, but at that point I knew I could not use them again. 

    I finally got the tube stack to move and break free using a socket extension and hammer. There are 2 aluminum sleeve O-rings that hold the tube stack in place inside the H/E and the aft one was very corroded and forward O-ring was essentially gone. 

    I did some sleuthing around the interwebs and found a few videos of some folks that had machined new aluminum o rings and tried to weld back the corroded parts of the H/E. While considerably cheaper, I’m not sure how long a repair like that would last. 

    After talking to the Beta folks in NC, I ended up sending back the parts I bought for the original H/E and ordering the redesigned entire new H/E unit which includes the tube stack and the new 3 bolt end caps. 

    The new larger H/E came unfinished aluminum, so I cleaned, primed and painted it red. I also got 8 new studs that screw into the block to secure the H/E in place and new gasket. 

    The original H/E had stud holes were just large enough for the studs, whereas the new H/E version has larger stud holes to hopefully to alleviate any corrosion between the steel studs and aluminum H/E. 

    The adventure continued with trying to remove the old H/E without damaging the engine block or anything else. It’s held on by 8 bolts (studs) with nuts. After removing the nuts, the H/E would not move at all, so I had to continue with the hot/cold/PB Blaster regimen. 

    Finally, I had to resort to driving chisels in between the block and the H/E all while trying not to do any damage. Little by little I got it to move until the H/E finally came loose. The studs had seized to the aluminum of the H/E and locking it to the studs. 

    Installing the new H/E was easy compared to getting the old one off. Now with the new H/E in place I could see that there was very little clearance between the alternator positive stud and the forward end cap on the H/E. Even shortening the positive stud didn’t allow the alternator to swing into place. 

    The only long term fix was to buy the new alternator and brackets to be able to have enough room for the alternator. A week later I receive the new alternator and I had to play around with the provided spacers for the pivot bolt to find the right combo. 

    Lucky, they sent me a few different sized spacers. 

    I used the pivot bolt and added a socket on the bolt to get it to pull the spacers into the “ear” on the engine for pivot access. I tightened it until the pivot spacer was pressed into place.

    Of course, the alternator belt was too small, so I had to get another flat belt and then play around with the adjustment.

    Before I put the Alternator back in place, I had to remove the H/E again to be able to run the new wiring for the alt from the starter and underneath the tank of the H/E. 

    There is no way I would have been able to see what was what in the wiring loom unless the H/E tank was out of the way. 

    The old alt was 100 amp and the new one is 120 amp. It was a crazy project, but I hopefully won’t have to do that ever again!

    Reading through the Beta forums etc., it seems the H/E is an Achilles heel of the Beta and you need to stay up on the pencil zinc on the aft end cap and I’ll be servicing the tube stack yearly from now on! 

    The cost of the project, not including the countless hours of me trying to get things to come apart was $2,077 for the new H/E tank with tube stack and new alternator. 

    19 files
    Last modified: May 06, 2023 8:35 PM | Anonymous member (Administrator)
  • May 10, 2023 7:48 PM
    Reply # 13199101 on 13193833

    Hi Randy , sorry I just noticed your post . Wow that was a bunch of work , but a job well done . I have done similar with our little Yanmar but nothing like you have done . OK like you need to worry about something else , Kevin Donahue did a Youtube video about his Beta exhaust . The tube  broke about 2 inches from the motor flange . I hope that is not your case . 

    Mark .  

  • May 12, 2023 4:27 PM
    Reply # 13200978 on 13193833

    Thanks Mark. The aluminum spacer rings that hold the tube stack were so badly corroded they were unusable (and they are no longer available) along with all the other corrosion, I ended up replacing the entire HE tank/tube stack and assembly. I don’t wish this project on anyone. :) 

  • May 20, 2023 1:16 PM
    Reply # 13204475 on 13193833

    Hi Randy

    Nice How To & Write Up With Pictures.

    My Beta 38 Is A 2015 Model,I’ve Had “Sparrow” 2 1/2 Years And That Was One Of The 

    Projects I Wanted To Tackle This Year, I Hope It’s Not As Involved As Yours.

    Good Job And Thank-You Posting


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