How do you go about confirming that the coolant pump on the Universal MX25 engine is working correctly? To be clear, I'm referring to the 50/50 mixture coolant and not the raw water pump.
thanks
thanks
Testing coolant pump?
- Thread starter CowboyWay
- Start date
That is a reasonable question. I have not seen any surfire way of confirmation. There is some anecdotal evidence.
- The engine is not showing signs of over heating. Temp gauge reads normal. No steam in engine compartment.
- There is no noise from the pump
- The belt is turning the pump pully. No drips coming from the weep hole.
- If you circulate coolant through the water heater, the water should get hot. If not then there is no circulation.
I've seen intermittent brief surges in coolant temperature. I've replaced the impeller on the raw water pump and can even observe the flow momentarily on the output of the water pump to confirm its pumping. For the coolant pump, I've bypassed the hot water heater connections when I replaced it last year, so I can't confirm, but maybe I should reconnect that as it would make this easier to confirm. I don't believe there's air in the system as I bled it briefly. What I've observed is that the water temp comes up to around 170 and surges to around 180. It didn't use to do that. Possibly related, I've seen a handful of times when the tach drops to 0 when the engine is running. I'm thinking it may be a ground issue as well. Any tips on how best to connect the hot water heater coolant lines up and bleed the system?
thanks
thanks
Several things I pondered as I read your post.
I believe the setpoint for your thermostat is 180°F. I would not worry about it if the thermometer is not exceeding 180°F.
10°F is 5.5% of 180°F well within the error of accuracy of most commercial thermometers. I do HVAC testing and most of my specifications allow +/- 10% of the reading. In this case I would be held by 180°F on the high end and low end would be 162°F.
I wonder if the 10°F is just the thermostat regulating the water temperature. The thermostat opening at 180°F and opening just a little to much and the temperature drops to 170°F. The thermostat closes a little and it close back to 180°F. This could be caused by something as simple as the thermostat aging. Not sure I would be real worried about it as long as there are no other issues. You could try replacing the thermostat and see if that helps.
I would do some research and see if the Universal MX25 engine has a minimum temperature and if it does not I would not worry about it.
Normally is a cooling pump is not performing something over heats.
Good luck on troubleshooting your issues.
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Mine is reading 160 degrees at 1800 RPMs and 165 at 2200 RPMs. It was reading ~10 degrees higher when I purchased the boat, but I replaced the seals on each end of the heat exchanger (they were very deteriorated--both seals, the 0-ring for the bolt and the flat round seal for the end) and replaced the Zinc (clearing out the sludge from where the PO hadn't changed it in a season or two) and that dropped my temp ~10 degrees. I've been holding steady there for 5 years, replacing the zinc every year.
Oh, and is just the tach needle dropping, or is the engine actually starting to stall? If you have intermittent stalling, please read this post where I was experiencing that and what the solution was.
Couple weeks ago I got an early AM call from a friend, said they started out to Catalina when tachometer stopped and engine temp went up so got towed back to harbor. When we opened engine the belt had shredded at one spot. So I went for a shop vac while she went for a new belt. I turned the alternator and pump by hand and both spun free with no noise, so I put the new belt on. Started engine and at first tach wasn't reading, had her throttle up and the tach kicked in and started reading. Engine purred, no noise, no leaks, good temp and alternator was charging normally. The ONLY thing I could see was the water pump was MAYBE wobbling a little but could be optical illusion. I suggested putting it under a load and recreating the failure, but it would seem to be the pump. She opted to call her mechanic who replaced the water pump that afternoon. This was a Yanmar 3YM30 in a Cat320.
engine seems to run fine... just the instrument acting weird... dropping to zero... seems like its heat related... works fine for a while, then 0... next time i use it a day later its fine.
I have had similar issues with my tachometer , it needs a certain amount of voltage from the alternator before it will start reading. if the battery is fully charged the alternator will only put out a minimum amount of volts. I have a solar panel also, and I have to shut that off so when I am motoring so the alternator will continue to put out enough volts, I do not remember what the minimum volts is to activate the tachometer. Your description is very similar to my issue. I use an external regulator for my charging from the alternator.
The M25XPB in our 310 runs at 160 -170, pretty consistently.
A few months back the raw water pump failed, there is a thread on here about it. Not an impeller issue, the bearings and shaft seized up solid.
I changed both pumps and cleaned out the heat exchanger, even though the temps were fine right until the pump crapped out.
It doesn't sound as if your coolant pump is the problem, but if you do decide or need to change it, go to a Kubota dealer or industrial engine shop, much cheaper than the marine sources.
Of course the raw water pump won't be Kubota related part, their tractors don't use one.
A few months back the raw water pump failed, there is a thread on here about it. Not an impeller issue, the bearings and shaft seized up solid.
I changed both pumps and cleaned out the heat exchanger, even though the temps were fine right until the pump crapped out.
It doesn't sound as if your coolant pump is the problem, but if you do decide or need to change it, go to a Kubota dealer or industrial engine shop, much cheaper than the marine sources.
Of course the raw water pump won't be Kubota related part, their tractors don't use one.
Thanks all for the advice and tips. I replaced the raw water impeller again and ensured that both washers were in place on either side of it when installed. I had cleaned and replaced the zinc in the heat exchanger as well (not much in there to remove). Here's a video of what I observe with the temp gauge at low rpm. No the engine does not stall. Universal M-25XP - Overheating
Suggest a temperature indicator sticker on heat exchanger and an infrared thermometer to confirm if engine temp is high or it's an electrical problem with gauge or sender.
10 Point Non-Reversible Temperature Label | Omega Engineering
10 Point Non-Reversible Temperature Label | Omega Engineering
Thanks, I'll check the connections and see if that's the cause.
I'm also thinking it might be related to the thermostat? Anyone have experience diagnosing a bad thermostat? I do have an oem replacement part handy. Any tips on changing it out?
I'm also thinking it might be related to the thermostat? Anyone have experience diagnosing a bad thermostat? I do have an oem replacement part handy. Any tips on changing it out?
I don't think a faulty thermostat would cause the needle to jump around like it does in your video. As JoeWhite suggested probably wiring or a faulty sender. Maybe a bad gauge?
As Ralph Johnstone suggested an IR temperature gun is very useful for diagnosing heating and cooling issues and they are an inexpensive tool to have around. Here is one that is certainly not the best but should fit any budget. https://www.amazon.com/Thermometer-...07XG3P7R9/ref=cm_cr_arp_d_product_top?ie=UTF8
If I got that one I'd test it against a known temperature before relying in it.
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You can pull the thermostat. put water on the stove in a pan. Heat it up. Use a thermometer to test the temp of the water. At 150º the thermostat should open (depending on the unit). By 180º it should be fully open (again depending on the unit).
If it fails to open or opens too early, you can replace it.
If it fails to open or opens too early, you can replace it.
True but much easier to diagnose it with temperature gun readings from various points on the engine.
Where is the fun in that? Beside, you might miss the opening and closing temps of the thermostat.
Boiling a boat engine part on the wife's kitchen stove, and getting out of the house before she knows what happened. Now that is living on the edge.