A few details about my installation: The Beta 16 was installed new in the summer of 2009 replacing a Volvo MD7A. The engine has a high-rise exhaust and I used the same waterlock muffler as was installed on the Volvo. In addition I used the same 3/4" Marelon Sea**** that was original to the boat, and it is connected to a 5/8" hose that is connected to a sea strainer. The outflow connection of the sea strainer to the engine's sea water pump is larger diameter, I believe 7/8", but I need to verify this.
The Beta 16 has the TMC 40 transmission and is turning 13" x 8" Michigan Wheel Prop (DJ355). With this arrangement the highest RPM I am normally able to reach is about 3100-3200. The boat tends to squat more under full power than with the previous engine, so much so that the exhaust will dip slightly under water.
The engine has very low hours (less than 150), although I do run it frequently.
The few heating issues I have had in the past have always been because of blockage in the sea water system that was easily remedied by removing the blockage. Once I had a piece of the pump's impeller break loose and I had to take the system apart to fish the piece out, and the engine seemed to run at normal temperature after that.
My current problems started during a trip several month's ago now. We were in calm, flat water conditions and about 1 hour into motoring towards our destination when my temperature alarm sounded. We had been running at close to full throttle. It appeared we had good water flow coming out of the muffler, but I stopped the engine and checked the pump impeller and all looked good. The sea strainer was clean and there did not appear to be any incoming blockage. The engine restarted fine, but when I placed the engine in gear and increased the throttle, the engine raced slightly and a white plume of smoke (or steam) came out of the exhaust. At this point I stopped the engine and called for a tow. One thing that came to mind too was that I had changed the oil very shortly before leaving on this trip. It is very difficult to read the oil dip stick with new oil and I thought that maybe it could have been overfilled some. I have read about overfilled engine oil becoming frothy when it becomes hot and causing problems, but not sure if that could have contributed to this.
Wondering if seawater had somehow entered the engine I checked the oil and it did not appear milky; however, as a precaution I changed the oil several times to remove any potential water, and measured the amount of oil carefully to not overfill the engine. I decided that an examination of my exhaust system was in order. My exhaust run is pretty short, but determined that my waterlock muffler could be lowered some and I was able to move it down about 2 to 3 more inches. I would like to have an anti-siphon loop installed, but the space is just too tight for one.
I also installed a new pump impeller and then restarted the engine again and it seemed to run great at the dock. Appeared to be good water flow out the exhaust (but still need to measure it), no smoke and all seemed normal. Now a sea trial was in order.
During the sea trial the engine exhibited much less power than previously (max RPM now only 2500-2600) and the engine overheats above about 2000 RPM.
Based on what I've read on the threads on the Forum there appears to be a few more things I can check, or change to help with the overheating. Maybe I need a 3/4" full flow valve that will connect to a 3/4" hose as I've seen recommended; however, it seemed to work fine in the past with the current arrangement. I will further investigate to see if I have blockage somewhere else and possibly remove and clean the heat exchanger. Perhaps my waterlock muffler is too small and cannot handle the water flow out the exhaust. Also, I've seen a couple of threads where the Heat Switch Sender could be faulty (is this worth replacing?).
I am concerned about what has caused the sudden loss of power compared to the previous performance. Any suggestions on what I can check would be greatly appreciated.
Thanks.
-- Edited by Islander on Friday 14th of July 2017 04:00:58 PM
I think that you have a few different issues all coming together so you need to check the following very carefully:
1) drain the coolant and clean the heat exchanger tube stack. You will need new O rings and M8 bonded seals for this. If you email me directly, I can email you the instructions to do this job but I cannot post a pdf file on the forum as it doesn't support pdf's .
2) dissassemble your exhaust system and check for any blockage. I am always suspicious of re-using old exhaust parts as they often cause some issues like excess back pressure. This could be caused by a de-laminating hose or waterlock muffler that is too small or by an exhaust thru-hull that is too restrictive
3) change the intake hose and strainer as the fittings that accept a 5/8" hose possibly have a opening that is less than 1/2"
4) you may have a blocked fuel filter which can cause the engine to run hot, especially if you have a less than 100% cooling system and prop that is oversized.
When you have gone through the above, check that you can rev the engine to 3,600 in neutral. This will help you to make sure that the throttle cable is properly adjusted.
Stanley
-- Edited by Stanley on Monday 17th of July 2017 10:33:29 AM
Thank you for the recommendations. I will send you an email for the cleaning instructions.
Do you have a recommended waterlock muffler for the Beta 16?
I'm not certain I fully understand your 3rd answer above. Do you think I need to go to a hose larger than 5/8" (and that would require a larger thru hull)? The sea strainer is a Bronze Perko, but I will have to measure the intake size. I see they do come in 1/2", 3/4", 1" and larger intake models.
Do you believe my prop is oversized? This was the model that was recommended when I purchased the engine based on my boats specifications. I've always thought it might be too large, but I've run the specifications by my local prop shop and they thought it should be a good choice.
Thank you for the recommendations. I will send you an email for the cleaning instructions.
Do you have a recommended waterlock muffler for the Beta 16? I don't know what boat you have or what space there is in the engine compartment so I cannot recommend a particular waterlock muffler. We have one waterlock muffler, Centek have a good number of vernalift mufflers and Vetus have a great selection as well.
I'm not certain I fully understand your 3rd answer above. Do you think I need to go to a hose larger than 5/8" (and that would require a larger thru hull)? The sea strainer is a Bronze Perko, but I will have to measure the intake size. I see they do come in 1/2", 3/4", 1" and larger intake models.Please change your intake hose to 3/4" with the correct fittings and strainer.
Do you believe my prop is oversized? This was the model that was recommended when I purchased the engine based on my boats specifications. I've always thought it might be too large, but I've run the specifications by my local prop shop and they thought it should be a good choice. Yes. If you can reach 3,600 in neutral but cannot in gear, the engine is held back on the propeller. If you have the propeller modified to lose 1" from the diameter or the pitch, this will make a big difference.
Thanks for the instructions for cleaning the heat exchanger core as it was quite clogged with scaling. The vinegar did the trick on getting it clean and hopefully that will help with the recent cooling issues.
I am now starting to troubleshoot the low power issue and I am concerned about too much back pressure. The installation manual indicates that the exhaust hose for the Beta 16 should have an inside diameter of 50mm (about 2 inches) and the it should match the exhaust bend diameter. I have a high rise exhaust and it seems to have about a 1 5/8" inside diameter and that is the size of the exhaust hose being used. I can make about 3200 rpm in neutral and 2600 in gear. When I initially installed the engine I could make 3200 in gear.
Should I install an exhaust hose with a 2 inch ID to my exhaust bend?
when i installed my new Beta, I was going to re-use the existing exhaust hose. It looked pristine on the outside. However, it was smaller than recommended for my engine so I replaces the entire exhaust system. I don't know what made me look inside the old hose, but it was delaminating and flaps were hanging down, probably one of the reasons the old engine was performing poorly. Also, when installing the new exhaust system, I upgraded it to current ABYC standards, a safety improvement .
If you can only reach 3,200 RPM in neutral, you must attend to this before you start having the propeller modified.
Look at the test certificate that was included with your engine's paperwork and you will see an "off load" speed achieved while the engine was on test at the factory. This is what you expect to achieve in neutral.
Your problem may be any one (or a combination of 2 or more) of the following:
1) incorrect throttle set up and adjustment
2) restrictive fuel supply or fuel return
3) restrictions in the exhaust system
4) blocked air filter
5) incorrect tacho reading.
Remember that if you cannot achieve full RPM in neutral, it is pointless to expect it to do so in gear. Once you have attended to this you can then re-test in gear to see what you get for performance.
Thank you for the information and I am planning to check each of these.
I would like to know the required size of the exhaust hose for this engine as the installation manual indicates a 50mm (2") exhaust bend for the Beta 16; however, it seems a 1 5/8" hose fits the exhaust bend perfectly.
1-5/8" is just fine for an exhaust run of up to about 8' as long as the outlet thruhull is not restrictive.
Anything over that, go up to 2". If you have this situation it is ok to have 1-5/8 from the engine to the waterlock muffler and 2" from the muffler aft.
I am back to troubleshooting the low power issue from last year.
Since my last reply I have worked on what I thought was a back pressure issue by going to a larger waterlock muffler and increasing the exhaust hose diameter to the previous recommendations. There is now a 1 5/8" hose from the exhaust outlet to the waterlock and the run is less than 2 feet. There is a 2" hose from the waterlock to a 2" exhaust thru-hull outlet.
Sadly, this modification had no impact on the engine's performance that I could measure.
My only thoughts moving forward would seem to indicate a fuel and/or air restriction. The air filter is not overly dirty, but I will replace soon.
I do have a concern with the fuel lift pump as the hand primer does not seem to move fuel any longer. I have used this a couple of times in the past to bleed the system and it worked find, but now does not seem to push fuel through when activating it.
The engine starts and runs fine, but still only able to reach 2600 RPM in gear and 3200 RPM in neutral. Again, when I first installed the engine and over several years of operation I could reach 3200-3300 RPM in gear. The factory test report indicates it reached 3650 in neutral and I have no doubt it probably reached that in neutral when I installed it, but I believe I am slightly overpropped.
Next steps I am considering working from the fuel tank to the each of the fuel filters removing each hose and determining there is not any fuel restriction that I am missing.
I do have a concern with the fuel lift pump as the hand primer does not seem to move fuel any longer. I have used this a couple of times in the past to bleed the system and it worked find, but now does not seem to push fuel through when activating it. When the stops the lift pump is in the pump position. You must turn the engine over to get the pump off the cam. Then you will be able to get fuel through when pumping by hand.
The engine starts and runs fine, but still only able to reach 2600 RPM in gear and 3200 RPM in neutral. Again, when I first installed the engine and over several years of operation I could reach 3200-3300 RPM in gear. The factory test report indicates it reached 3650 in neutral and I have no doubt it probably reached that in neutral when I installed it, but I believe I am slightly overpropped. We went through this last year. You must adjust the throttle control so that you can get 3,600 RPM in neutral. If you can only get to 3,200 in neutral, you will never get full power from the engine. You are over propped and need to correct this.
Next steps I am considering working from the fuel tank to the each of the fuel filters removing each hose and determining there is not any fuel restriction that I am missing.
I agree we went through this last year and the throttle cable is not the problem as it moves the throttle lever fully. I have even removed the throttle cable and engaged the throttle lever manually and still only reaches 3200 RPM in neutral.
Yes, I am aware I am over propped; however, there has been no change made to the prop and before I started having this issue it made 3200 RPM while running, but now only 2600RPM.
I stand corrected.....I think you may have something with the throttle cable.
I made some adjustments and can now reach 3600RPM in neutral. In gear I'm still only getting 2600RPM, but that is tied up at the dock and I haven't tried it underway. I'm hoping underway might increase this number some. Like I mentioned in my previous post it used to make 3200RPM underway.
I'm also going to have a diver clean my running gear and bottom to ensure it's all in good shape.
