Upgrading my Universal/Westerbeke Heat Exchanger: The dumbest repair I’ve ever made

This is a tale of folly and failure. My lack of research and trust in manufacturers led me down a long path of woe.

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The Universal 5424 in our 1982 O’day 34 was overheating. The 3-cylinder diesel motor was rated to run at 2800 RPM. However, if we pushed it past 1900 RPM, the temp needle began rising and never stopped.

Decades ago, Universal/Westerbeke admitted that the 2″ diameter heat exchanger was too small for the 5424 and the M-25 and recommended upgrading to a 3″ heat exchanger. Despite our engine allegedly being rebuilt in 2008, that never happened.

At the very beginning of this debacle, a friend said I should just buy a cheap generic 3″ heat exchanger with screw-in bungs, so I could size them to my hoses and just do a quick swap. I decided against that because I wanted to keep the engine as OEM as possible with an “official” upgraded part, and I thought finding the barbed bronze bungs might be a pain. Oh, how foolish I was.

Catalina Direct had factory style replacements heat exchangers starting at $500, but I wasn’t ready to pay that much, so I searched eBay. One seller claimed he had a 3″ Universal heat exchanger. It looked very similar to the one I had. I made an offer at $150 (plus $20 shipping), and he accepted! I probably should have paid more attention to the last line in his auction that said, “measurements are not exact.”

A few days later the eBay exchanger arrived. It did look very much like the one on my boat — because it was the exact same 2″ diameter heat exchanger mounted on the back of my motor.

I contacted the eBay seller, and after a photo with a measuring tape showing that he had definitely listed this part incorrectly, he agreed to refund my money. Unfortunately, I had to spend another $20 to ship it back.

Before the project even started, I was down $40.

I browsed the Universal/Westerbeke options on Catalina Direct, and they all had the same hose inlets/outlets listed. I took that to mean they were standard sizes that would be the same as the heat exchanger I was removing. That was a terrible assumption.

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Approximately $550 later, I had this 3″ x 17″ behemoth that didn’t share a single intake or outlet size with my old unit. In fact, despite being the “factory” upgrade, some of the outlets didn’t even point the correct direction.

I slowly began the process of adapting the hose sizes and directions to make it fit.

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Why have four hoses and eight leak points when you can have 15 adapter pieces, nine hose sections and 63 leak points?

The worst part of it all was the 7/8″ raw water intake port. My oberdorfer pump had a 1/2″ barb and hose coming off of it. I found a 3/4″ barb, but a 3/4″ hose will not fit on the 7/8″ intake — even if you boil the hose first. There are no 7/8″ fittings available ANYWHERE.

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I ended up running the 1/2″ hose to a 3/4″ adapter and then triple clamping the 7/8″ hose onto that to keep it from leaking. However, since the soft 7/8″ inlet got slightly out of round as the heat exchanger was being moved around for three weekends, the 7/8″ hose doesn’t make a perfect seal on it, and I’ve now got an ever-so-slight drip of sea water leaking into my bilge for the rest of my life.

Another $500 in adapters and hoses later, I finally had the entire coolant system put back together.

Since I had to drain all the coolant anyway, I decided to replace my thermostat.

thermostat

That was an easy process, but you have to special order the molded hose that connects the thermostat housing to the water pump. Be aware of this fact ahead of time because if you’re not, you have to put the project on hold for another week while you wait on that hose to show up.

Once I finally got it all back together, I fired up the engine, and it promptly overheated.

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Yes, I had an airlock. I did not know that after filling the coolant system, you must remove the bolt in the top of the thermostat housing and then pour more coolant in there to remove the air pocket.

After overheating the engine twice dealing with the airlock, I finally got it running. We ran it in the slip long enough to verify the thermostat was opening correctly, and that she wouldn’t overheat anymore.

It took three weekends and about $1200 after the expense of the heat exchanger, hoses, adapters, clamps, thermostat, and impeller, but we can finally push into the wind at 2200 RPM without overheating.

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Our last time out in that type of wind we were running at 2 – 2.5 knots. Making trips down to Galveston in a strong headwind were completely out of the question. Now we should be able to plan trips at an average speed of at least 4 knots no matter what the weather is like.

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We still don’t have one of those speed demon sailboats that can motor at 6.5 knots, but four is twice as nice as two. However, if I could do this project again, I definitely wouldn’t be so freaking dumb.

Don’t be like me. Get the generic heat exchanger and screw in the barbs that fit your existing hoses. You can even get 90-degree nozzles and twist them to the exact direction required.

I’m going to apologize now to any future captain of Gimme Shelter. Projects like this are the reason people hate previous owners.

 

 

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