4BY2 Overheating - air in sea chest at high RPM

While tracking down air leaks have you checker the toilet to sea strainer connections? If the line to the washdown pump can cause a leak so could the toilet (head) connections. Your air leak problem has me spooked enough that I am considering adding ball valves to both the wash down and head "feed " hoses. I f I do so I will be using AWAB umperforated 316 SS clamps.
 
Osprey,

The head on my R-25 is fresh water only. There was only one connection, the wash down pump, on the sea chest (not a sea strainer). I removed and capped the line to the wash down pump.

It is poor practice to tap more than one item of one thru hull - especially something as critical as engine cooling.

Now the engine heats to 220 and no longer sounds an overheat alarm. Still not perfect, but better.

Next project is to replace the crushed "O" ring on my raw water pump. Unlikely source of a leak, but some air may be sucked in at high speeds. We'll see.

And, the engine is sounding a CHECK ENGINE alarm plus the Yanmar display is re-booting every few minutes. No real idea, but the last time this happened, it was water in the fuel. I checked that.

Thanks for the idea.
 
See my entry entitled "Service", related to "Check Engine" light issue. It was restricted fuel flow due to gummed up filters.
 
Barry, the filters are clean and fairly new.

Restricted fuel flow has its own alarm code - I’m not seeing any code.

This is typical of a loose wire or short.

In the dark . . . /Stu


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796
 
Fixed! I hope.

Today the raw water stopped flowing at high RPM - and recovered at low RPM. Repeated the cycle several times - then it stopped flowing at any RPM. Sounded like a bad impeller - so we were towed in and I took the impeller out. Sure enough, the Run Dry rubber part slipped on the hub with little force. Clearly something that could cause the remaining symptoms.

I learned stuff that might help those of you who helped me:

1. The CAUSE was when the "pros" painted the bottom, they painted the inlet strainer so water was barely able to flow thru. Inlet strainers area a BAD idea, but if you must keep yours, be sure each vane of the strainer is sanded free of paint and a "proper" paint for bronze is sprayed on. When I finally dove the boat, there was about 10% flow.

2. The semi-clogged strainer caused overheat - and that likely caused the thermostat in the exhaust manifold to fail closed.

3. There never was anything wrong with the heat exchanger or the $4,000 worth of other parts that were removed, cleaned from their already fairly clean state, and put back in. This was just a diversion.

4. When the overheat caused by (1) occurred, I removed the impeller (guessed the most likely cause - and it was 2 years old), and replaced it with a spare RUN DRY - blue impeller. This compounded the problem because the RUN DRY was defective, slipping at high RPM originally and slipping at lower and lower RPM as the defect progressed.

5. The air we discovered in the Sea Strainer/Sea Chest was a diversion caused, in part, by the semi-clogged inlet strainer. If you don't use your wash down pump, remove and plug that opening in the strainer. It is not a seamanship was to connect the wash down pump and will cause you grief. The batch of hose clamps in the Ranger-supplied part of the boat was defective on my boat. I have replaced them all - but forgot about the wash down hose clamps - one was bad and leaking. Check your hose clamps every 6 months or replace them with higher quality hose clamps as I did.

This has been a frustrating and very expensive learning experience. I never tested the RUN DRY impeller when I installed, and the mechanic who removed/inspected/replaced it did not test it either - that error cost me about $8,000.

Thanks for everyone who helped e get going. Hopefully some of what I learned will help you.

1. If you have an inlet strainer, remove it or at lease clean it carefully after painting.
2. Remove and plug your wash down pump - if you need the pump, put in a dedicated thru hull.
3. Most important, Test your impeller by being sure you can't turn the pulley while holding the impeller firmly.

Sail safely /Stu
 
Yea! It was just a matter of time before this conundrum was solved! Perseverance prevailed! Glad you now have a working boat! I enjoyed the updates even though you obviously were frustrated to no end!

Seems there may be another lesson regarding using the “run dry” impellers?

Curt
 
Congratulations on getting this solved! Can’t imagine all the stress this has caused you over the past two months.
We have been using a blue Run Dry impeller for the past 80 engine hours with great temps. If we start getting high temps, that’s the first part I will replace based on your experience.
 
I don't know if all/any blue Run Dry impellers have the problem, but the person who sold me the impeller that goes in tomorrow (it was bought as a spare to replace the spare Run Dry) suggested that Run Dry impellers sometimes slip on their hubs.

This problem isn't entirely the impeller's fault - the inlet screen was partially clogged with paint when the problem started - and the extra work may have damaged an impeller that would have given good service otherwise.

It is hard to install an impeller with my fingers crossed, but I will try.
 
Well done Stuart!

At this point I'd say you have a very good handle on the systems and their current state; which should prevent further issues from happening.

Now you have fixed the problem are you still selling?
 
I had a blue dry run impellor fail after a couple of seasons use (about 200 hours). It would not draw any water from the strainer. On removal of the impellor, it appeared to be okay. I replaced the blue with a standard Yanmar (127610-42200) and the new impellor worked just fine.
 
Deleted duplicate
 
I had a similar overheating issue. Had the bottom painted this year, 2 weeks later started overheating. Temp got up tp 212 and was loosing coolant into the bilge. I changed the impeller myself, witch was a treat, stripped two bolts and ended up talking off the pump all together. To make a long story shorter I pressure tested the heat exchange with no problems. The pressure testing kit says you should test the radiator cap as well, I did and the cap did not hold pressure. Replaced the cap and no more leaks and temp stays at 199 degrees at 3300 rpms.
 
I removed the inlet screen that was painted closed partially.

Ranger installed a screen suitable for fresh or cold water not Florida. When they partially closed the strainer, two impellers were damaged. If your strainer is intact, it is mostly luck keeping your engine cool.

Remove the strainer or clean it often.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796
 
Yes, she is still for sale.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796
 
You must log in or register to reply here.

  • Tugnuts.com is the community hub for Ranger Tug, Cutwater, and Solara owners. Since its inception in 2008, the Tugnuts forum has grown into an active and thriving community of more than 9,000 members. It serves as both a meeting place for the best boating community online, and an invaluable archive of information.

  • User menu
Back
Top