I have a 1988, M 25 XP Universal. Memorable afternoon on Boston Harbor today. The "chance of showers" turned into an all out squall with a 50 kt gust and low 40s sustained for a few minutes. Seeing it coming, we reduced sail to minimally unfurled jib and started the engine a few minutes before it hit. Guests smelled something and engine temp was at max. (I think my high temp alarm is broken). After a nerve wracking 30' running and hove to, the wind died and we ghosted to our mooring. There was no squealing as I have read in other overheating posts. I found the impeller looked great and had free flowing water at the through hull. I restarted engine, saw perfect water flow in exhaust, saw nothing abnormal in the engine but after a few minutes the temp hit max again. The only other data is that the galley tap produced no hot water despite the engine temp. I assume there is a problem with the coolant pump. Any thoughts? Of course I'm supposed to take a big group out to see fireworks in two days which doesn't seem too likely right now but if there is a quick diagnosis and fix, I'd be thrilled. Thanks in advance for your help.
Hi Brian, not the way to end the day. You have good raw water flow out the exhaust and your coolant level is fine correct?
Have you done any work on or around the engine recently? Has the engine been running at normal temperature until this?
Unsaid is if coolant level was checked.
Check hoses to water heater. See Critical Upgrades topic.
@Brian
If you have good seawater flow out the exhaust obviously the issue has to be the Hx or the closed coolant system. It is a VERY slim chance that the coolant pump is bad (impeller can't move water.) Bearings could be bad (a squeal) but the pump will still turn. If the impeller is bound up you will burn up the engine belt.
If the HX is blocked, you won't see good flow out of the transom. But it might be worth removing/checking the end cap on the inlet (stbd) end of the Hx.
If the exhaust manifold is full of coolant then the situation I see is a stuck thermostat. However, that doesn't make sense because the WH should still make hot water (unless something else is going on with it) because with the TStat closed coolant will still flow to the WH.
If coolant is moving, the short hose from the TStat cap to the Exhaust Manifold inlet would be hot. And the long return hose between the Hx and the coolant pump will be cool. See for coolant flow directions:
https://groups.io/g/Catalina30/wiki/9626
My gut says "air lock" based on everything you describe.
Thanks for the quick replies. Coolant level is normal. Winter work included changing out coolant, new engine mounts, cleaning out heat exchanger with new gaskets, new impeller and new fan belt. Six weeks into my sailing season, the engine temperature has been about 140 consistently until now (our cold ocean water) and perfect hot water from the tap. I haven't touched anything since May launch.
Maybe it helps or not, but last week we had an air lock in the coolant system (I changed the hoses and had the HX cleaned). After a few minutes on the engine, the temperature gauge read over 200, but the engine was not particularly hot. Was that really the engine? The gauge? Finally we found that there was no coolant in the thermostat housing so the probe was taking the temperature of the air (which heats up faster than the liquid I imagine). Conclusion: I bought a laser thermometer to get a second opinion if my instruments tell me that the engine is too hot.
Brian,
I too suspect an air lock, not unusual when you change your coolant. Run the motor if the heat exchanger remains cold to the touch it's air locked also known as a big giant air bubble. It's easy to eliminate, run the motor with the radiator cap off, once it starts to warm blip the throttle a few times up to around 1500rpm that will drive any trapped air out the radiator opening. You may want to put some rags around the opening because when the air bubble hits that opening it's going to bubble up and take some coolant with it. The H/X should start to warm immediately indicating the air bubble has been cleared. You'll have to top up the coolant afterwards.
When you changed the coolant, did you follow the steps to "burp" the system? If coolant level in the reservoir is normal, raw water flow is good, no hot water at the tap, but temp gauge reading very high I suspect an air lock as well.
Engine Overheating 101 - How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462
Brian : It also sounds to me like an air lock in the internal coolant line. Burp the engine!!
A thought
So, important details to update and nothing is ever simple...I told you that I checked the coolant level. Well, the overflow tank showed coolant in the normal range but in the aftermath of the storm and the 240 degree temp reading, I didn't open the radiator cap. I naively thought the level was fine. Well, today I did and coolant was empty! I then found evidence of a leak where the hose to the water heater attaches and coolant in the bilge. I fixed this, BUT, nothing is ever simple. I filled up with fresh coolant, burped the system once, twice, three times following the different options recommended but in the end nothing worked. Temp still rapidly rose, coolant hoses to the heat exchanger remained cold as did hoses to the water heater, all the while with perfect raw water flow. So, does this mean a faulty thermostat? I wonder if having no coolant could damage/destroy the thermostat. Does anyone know if this can be opened and serviced/fixed or do I replace the thermostat? Is there anything else left to check? I'm saddened that my 20 year tradition of watching the best local fireworks from the boat will end but I don't see any other simple answers.
5% the TStat is stuck.
95% chance you still have an airlock. Probably in the coolant pump so the impeller is trying to move air, which it cannot. Fill Fill Fill thru the top of the coolant pump.
You could try to put a bypass hose between the Pump/TStat housing in place of the WH hoses and burp again. That might get you on the road for fireworks.
Well Hallelujah! We're back in the game, leaving for fireworks in 30'! Thank you Ken and everyone else. For my last attempt, I filled the water pump from above with coolant as Ken suggested and then repeated the coolant into the Tstat lower hose until it flowed out of the Tstat and everything is running perfectly! Of course, just to provide a little anxiety, as the engine heated up there was some light smoke coming off the engine blown by the alternator. I'm pretty sure it was spilled antifreeze evaporating because I couldn't locate a specific source and it ended after about 10'. So, thanks again and happy 4th to everyone in this great community!
Brian : Glad to hear that you finally got it!!
The way I "burp" the engine is - I disconnect the heater hose to the thermostat and take the cap off the reservoir. I have a small PAR hand pump the I put into the disconnected hose and pump the coolant into the reservoir until I get a steady stream of coolant. Then I reconnect the hose back to the thermostat and run the engine. You might have to open the butterfly valve on top of the thermostat till fluid comes out, but you should be good to go!!
A few thoughts
GREAT!!!
Dontcha love when a plan comes together? And without blood, cut fingers, and iodine.
Enjoy the light show and be safe.
Quote from: Ron Hill on July 03, 2024, 02:00:09 PM- disconnect the heater hose to the thermostat
- take the cap off the reservoir.
- I have a small PAR hand pump the I put into the disconnected hose and pump the coolant into the reservoir until I get a steady stream of coolant.
Ron
I am interested in your method -- it may work better on the C-30 mk-1 than "our" method. The mk-I has some unique challenges.
You pump into the heater hose (i.e., to the water heater)?
Which "reservoir cap" do you remove -- the exhaust manifold cap or the overflow tank cap?
What do you mean then "pump to the reservoir"? (keep pumping to the water heater?)
Where are you looking for the steady stream -- Out the Tstat nipple?
Thx
Ken
Hi Ken, wrote the following knowing folks of varying levels of experience use this forum. Not trying to be a wise guy. Except for the ball valve on the thermostat housing, I learned this method from Ron Hill, so credit goes to him.
The set up is a Par hand pump, and a short piece of (1/2" id I think) clear hose open on one end and reduced down to a hose barb to fit the water heater loop hose connected to the thermostat housing on the other end. Optional is a second short section of clear (1/2"id I think) hose to fit onto the discharge end of the Par hand pump. I found this piece of hose is not really needed.
Remove the coolant reservoir/tank "radiator" pressure cap. This is not the overflow tank.
Disconnect the hose in the water heater loop from the thermostat housing, and plug the hose barb into it. Connect the open end of the clear hose to the suction end of the Par hand pump. Optional add a short section of clear hose to the discharge end of the Par hand pump.
Put the discharge end of the pump into the coolant reservoir/tank (not the overflow tank). Begin hand pumping and you will draw coolant through the system and back into the reservoir/tank. Continue pumping until the stream of fluid into the reservoir/tank is a clear solid color indicating no air in the coolant loop. Reconnect the water heater loop hose to the thermostat housing, being careful not to loose any coolant. Put the "radiator" cap back on.
Start the engine and watch that the temperature stays in normal range. A simple no mess bleed/burp method.
I also replaced the OEM valve on the top of the thermostat housing with a ball valve. My final bleed step is to connect a clear 1/4" tube to the ball valve and tape it to the hand hold near the top of the companionway. Surprisingly the fluid will climb that high. With the engine running I open the ball valve. The coolant begins to fill the hose and remaining air bubbles in the system percolate out. When the air bubbles stop or slow to almost nothing, I close the ball valve.
FWIW - If the Par hand pump has been sitting a while, put some o-ring lubricant on the shaft and the internal rubber pump plunger. Otherwise the pump may be "sticky" and not operate smoothly.
Jon : You are right ON!! I wrote this up in the Mainsheet tech notes many years ago. I've done it for many years.
Ken : All you are doing is pumping a closed loop of internal coolant thru the water heater system to get any air out!!
A thought
Hey Jon/Ron
THANKS! Got it. What threw me was that I was envisioning Ron using the PAR to pump from a jug of 50-50 INTO/through the closed system. That method will work well for the issues on my mk-I -- the WH is high (in the cockpit sail locker) and that's where air in the closed system ends up.
So the PAR procedure sucks coolant from the closed system pump, thru the WH and depends on gravity for coolant to flow from the Exh Manifold, through the Hx, block, and back to the TSTat.
Since Brian's issue was that the airlock was located in the pump, have you ever found that the PAR method won't draw well on a recently drained/filled system because it can't pull from an empty pump? (yes I know that the recommendation is to fill the pump.)
Just asking, do you think that it would be effective to turn the PAR around and suck FROM the Exh Manifold and PUSH it through the WH? That would be using the PAR to push coolant into the pump.
Ken- the water heaters in the C34 are located under the galley sink just above the floorboards.
Guys : I believe that the way that Jon and I suck the internal coolant thru the water Heater is the best way to get all of the air out after a coolant change.
One other thing that I do is - Every couple of years I add some "Water Pump Lubricant" to the system!!
A thought
Hi Ken. In response to your question about draining and refilling, I just removed my HX. To do that I drained the coolant reservoir, and drained the coolant from the HX. Just shy of a gallon coolant in total, so think the block, coolant pump, and thermostat housing were empty. After replacing the HX, I filled the reservoir, then began pumping as described above. Added more coolant into the reservoir to top off. Put the "radiator" cap on, and started the engine. Ran for about 20 minutes in the slip and temperature stayed in the normal range. I plan to take the boat out and motor around for about an hour next week to put the system under load to verify all is good. Hope that answers your question.
Jon
"Yes." Thanks!
Quote from: Noah on July 07, 2024, 09:20:02 AMKen- the water heaters in the C34 are located under the galley sink just above the floorboards.
Yep I know that
Hi again. Alas, my problem isn't over unfortunately. I had no problem motoring home about 3 miles from the fireworks last week, engine temp stable at 140, so I figured problem was solved. Yesterday visiting the boat for the first time since, I again saw coolant in the bilge and the manifold ( if that's the right name) where it gets poured in was visually down about a third while the overflow container was half full where it usually is. I couldn't identify any leaks. A friend told me I might get a pressure tester on loan from an auto parts store-says you place it where the radiator cap goes, pump up the pressure and reveal the leak site hopefully. Does this sound right/possible? I'm not sure how old the hoses are going from the engine to the WH but the first crack I saw last week was right at one of the WH nipples and I cut off the bad area, shortened it by an inch and seemed to get a good seal when I replaced it with no weeping from that site now. I am supposed to leave on my one month trip to Maine in 10 days so I'm feeling the pressure. I could replace all these hoses which won't be fun and will be time consuming. There's a lot of hose out of site under the floor and I guess there's no other way to know if there is hidden trouble. If there's a better first step, I'm all ears. Does coolant ever leak from the WH itself? It's mounted on a plywood platform and not even sure how I would find out. The platform has lost its ? epoxy seal to the hull so there could be a little movement in rough conditions of the WH but with all the attached hoses and the low almost midline location, I don't think it can move too much. Thanks again for any guidance. Brian
Questions
Have you downloaded and read the parts manual for your engine? - It really helps when identifying engine parts.
Have you studied the coolant flow diagram (it shows seawater and closed) - it can help to ID every place that a hose connection could be loose.
What's your annual PM on the cooling systems on the engine?
****
If you post good pics of your engine it can often help to ID issues.
Help US to help YOU.
***
Coolant could be theoretically leaking from anywhere there is coolant, including if there (unlikely) a hole in the WH.
Coolant can be lost if there is a pinhole leak between the seawater and coolant sides of the Hx, although it should not show up in the bilge.
Coolant can also be lost if there is a pinhole leak between the potable HW vessel and coolant ("heatant") loop in the WH. It would depend on the relative pressures which way each fluid would be pushed. Obviously it would not be good, as (there is a very slight chance that) toxic coolant could be pushed into the potable water supply.
QuoteA friend told me I might get a pressure tester on loan from an auto parts store-says you place it where the radiator cap goes, pump up the pressure and reveal the leak site hopefully. Does this sound right/possible?
It's good trouble shooting. Much better than guessing at what to change.
Jim
Would you guess the amount of coolant in the bilge was about equal to the 1/3 missing from the coolant reservoir on the engine? If so, and you don't see coolant anywhere else, you're problem is most likely a leak from one or both of the hoses going to the water heater. If one hose was cracked at the WH nipple, odds are it's time to replace both hoses.
I agree the bilge amount seems about equal to the loss. I'll attack the hose replacement first thing tomorrow morning. My usual auto parts store doesn't have the radiator cap pressure tester to loan/rent.
Brian : Take a paper towel and wipe each of the hose connections and see if you can find the one that is leaking. Then you can change out the hoses that go under the galley floor.
A few thoughts
Quote from: Analgesic on July 12, 2024, 04:22:10 AMMy usual auto parts store doesn't have the radiator cap pressure tester to loan/rent.
Usually Advance Auto, Autozone, O'Reilly and sometimes NAPA rent them.
Harbor Freight sells a kit.
Or, buy a gauge, bicycle pump, and a couple pipe fittings and test thru the thermostat cap. You'll probably want a valve in line to isolate the pump once you pressurize the system because the pump might leak a little. You also need to know the pressure rating of your cap and not exceed that. I'd buy a high psi cap - like 20 psi - just for the test.
I rented a radiator pressure tester from a general large rental shop (many years ago).
Craig
All the local AutoZones near me have them for free loan. You buy it (used) and upon returning get a full refund. They're pretty generic kits with lots of adaptors for different radiators.
A few years ago I wasted a 3 hour trip to the boat because the AutoZone kit was missing the required adaptor, so I decided to buy my own for a coolant replacement.
https://www.amazon.com/gp/product/B0067UE6IY
Since then I've had no need to use it, so it's sat around unused. But it's there for when I need it.