Heat Exchanger Securing Straps on the M35B engine.

[Kachina]

This post is to encourage owners to check the integrity of the mounting straps on their engine heat exchangers and to find out if others have experienced this failure. I have just completed a 2000 nm coastal trip off Australia's East Coast (Engine hours now = 682) and during a routine engine check I have found that BOTH the steel straps which hold the heat exchanger to the engine block have fractured. The heat exchanger is fortunately still supported underneath by what remains of the straps but moves around a lot. In the Westerbeke parts manual these straps are shown on the diagram, but not as replaceable items. I am addressing this issue directly with Westerbeke's Australian agent because it looks very much like a similar fabrication problem as occurred with the fuel filter mount (which also failed on my engine).

Trevor D'Alton
Kachina
#150

[RCMURPHY]

I had the same problem. Also had some hose wear-enough to cause it to be replaced. Engine at about 370 hours.

RC Murphy
SemperFi
#008

[Richard Thabit]

I have just replaced both Brackets which hold the heat exchanger securely to the engine block of my M-35B engine. Universal/Westerbeke referred me to Hansen Marine as my distributor in the northeast for the parts. They are shown on page 25 of the engine manual but not specifically named. Hansen Marine customer service knew of them and said that several others have been ordered. Part number is 46947. Each had fractured where they are bolted to the engine. Hansen said that it is most likely from vibration.

I noticed that the heat exchanger was loose when I was changing my pencil zinc in the engine. The entire assembly moved so I reached back and felt the loose brackets.

It is a difficult job because of location and if I were double jointed it would have been easier. I could not remove the old brackets without taking a lot apart so I moved them to the middle of the heat exchanger and was able to bend open the new brackets enough to slip them around the heat exchanger and then bolt them to the engine using the existing bolts.

The 2 brackest cost $21.80 and I paid an additional $35.00 for overnight shipping.

This should not be happening and mine may have been broken all last season for all I know. I had been having leakage of the engine antifreeze so I will carefully watch it to see if now that the heat exchanger is mounted correctly again, the leakage stops. The entire assembly had dropped down about an inch and was resting on the engine. I checked and tightened all hose fittings to the heat exchanger afterwards. I have 255 hours on my engine.

I ran the engine today and all seemed fine. I will do a sea trial Saturday when I take the boat for the first time this season.

This is the second fractured part I have replaced. The first was the right angle bracket holding the fuel filter about a year ago. That was free from Westerbeke because they issued a bulletin. These heat exchanger brackets are not yet covered by a service bulletin.

Please check your heat exchangers.

I would like to know of any others who have had this problem.

Richard
C350 # 111
Three Sheets

[pieterv]

Just came back from a 3 days trip and yes my heatexchager brackets are also broken!
I was told by my fellow boaters i should replace them with a copper bracket, more flexible.

I have 229 hours on my engine.
I will look for a standard 3" pipe straping that should do the job.

I have an other question: what is the average fuel use per hour of the Universal 35B engine?

Thanks
Pieter
Hull 36
Vancouver

[Richard Thabit]

I have the Autoprop on my boat and I average 0.67 gal. per hour.
I usually run up or down the Hudson River for hours at 2000-2300 rpm averaging 6.5-6.8 knots thru the water with SOG depending on current. The engine has 336 hours.
Richard
Three Sheets
C350 #111

[Air Mobility]

Ran down to Georgetown Md to check on things this morning. We had been out the week before Labor Day and was interested to see if I had problems with the heat exchanger brackets. We plan on leaving Sunday for another week on the bay and I did not want to be surprised by an engine problem. I am happy to report that the engine heat exchanger brackets are fine. About 500 hours on engine. I did have the problem with the fuel pump bracket last fall.

Air Mobility
hull 158

[vineyardsailor]

I also found both straps broken. Hull 265 with 271 engine hours. I called the distributor and he was "sure" one my engine mounts was broken. I intend to do a detailed failure analysis (I'm a mechanical engineer). I will post my opinion and will in all likleyhood follow up with the manufacturer. These mounting brackets should last for the life of the engine (as they did on my 21 year old M25). My distributor had the brackets in stock (my first hint they were bad) and when asked they offered that they had sold 16 last year.

[RCMURPHY]

I have experienced a second failure of the M-35 engine heat exchanger straps. I had them replaced several years ago, along with a damaged water hose. Now, at about 800 hours the straps are broken-again. My diesel mechanic states that in his experience of working on this engine-he has seen heat exchanger strap failure of about 40%.

[djones]

Hi All,
I was doing some of the normal maintenance on the engine, and saw that my brackets for the heat exchanger are broken as well.

Here's the question. Are these two brackets welded directly to the heat exchanger tube? On one bracket, it is broken just above the bolt hole at the end of the strap. The other strap looks like it has separated from the heat exchanger tube. The two straps do not go all the way around the heat exchanger. That's why I wonder about the weld.

I wonder if Universal/Westerbeke has an improvement kit for this? Sort of like they came up with to beef up the alternator mounting in the M25? Sounds like plenty of us are having problems.

Hope y'all had a good Memorial Day holiday.

Don Jones, "Onatop" C350 #13
Oak Island / Southport, NC

[Stu Jackson]

May I assume that you've all been regularly checking the Universal website for Bulletins?

http://c34.org/bbs/index.php/topic,4309.0.html

[Stu Jackson]

I had to go to Google and "Universal engine bulletins" on an advanced search. You could find the same for your engines this way: http://www.westerbeke.com/products/Prod ... .aspx?ID=7

Try service bulletins.

My M25 engine's so old it doesn't matter anymore.

[djones]

The bulletins noted are about the cracking fuel filter bracket, not the heat exchanger bracket. I haven't seen any Westerbeke/Universal bulletin about that yet.
-Don

[sailorbob]

This appears to be a common Universal problem. The way the heat exchanger was secured to the M25XP engine on my old Catalina 30 was with hose clamps. They both cracked from engine vibration and I did not discover it until holes were worn through the elbows on the exchanger, dumping the antifreeze in my bilge and overheating the engine. Fortunately, I caught the overheating before damage was done. Catalina replaced my heat exchanger. When I replaced the clamps, I wrapped the exchanger with cork gasket material, then the hose clamps. They lasted another 15 years after that. Is inserting some sort of shock absorbing material possible on the M35B? If the heat exchanger is allowed to move around, hoses or elbows may suffer as a result, with serious consequences. So far, the clamps on my M35B look fine after about 200 hours, but who knows when they will fail? This is a flawed design element.

[reinhardschumann]

We have 2100 hours on our M35B. We're on our third heat exchanger due to this problem. This is a stupid design, with a heavy heat exchanger strapped to a vibrating motor in the worst possible position. The best cure is probably to mount the heat exchanger on the bulkhead where it would not be constantly abused by the motor, but we have not yet done that. We've learned to keep an eye on the mounting. Check it each time you check the oil. Our latest heat exchanger was mounted with rubber pads (silicone?) between the straps and the heat exchanger, and it has lasted at least 500 hours. (Do not use a cheap hose clamp to attach it. It will fail in a few hours! Use the factory clamps.)