30 Pilot II Yanmar 315 engine saved by the bell

I reported this event on boatdiesel.com and the Yahoo Mainship group but thought I would wait for more data before placing it all on the record here.

A couple of weeks back, we were cruising our single 6LPA-STP Yanmar 315-HP at 3400 RPM (a bit higher than our normal 3000) when my add-on alarm panel alarm sounded with both the engine coolant high temp and the aft bilge pump (mounted right aft of the engine) lights lit up. There was no guess work involved on my part as I instantly intuited that the seawater meant to enter the engine coolers was going into the bilge instead. Without even glancing at the temperature gauge, I shut the engine down after which the following wind pushed a whiff of burning rubber into the bridge deck. That was obviously exhaust hose being charred.

A quick assessment revealed the hose elbow coming out of the seawater cooling pump had burst wide open on the outside of its curve.

The coolant tank was full and had overflowed about an once into the bilge and the boiling noises inside the engine were forbidding to say the least. The temperature gauge was pegged. As it cooled, the engine recovered ALL of the coolant with the level returning to normal in the recovery bottle. Oil on the dipstick was normal, but I changed it and the filter anyway, even though it had only been 23 operating hours since the last change. I took a sample and sent it off to Blackstone Labs. Their comment received today is as follows:

"RICH: Thanks for the notes. It looks like you dodged a bullet by shutting the engine down so quickly. These results don't show poor wear or mechanical problems so despite the overheat situation, internal parts didn't leave excess metal behind. The oil was in good shape, physically. There wasn't any measurable contamination to point out and the viscosity was on target. Insolubles were low at 0.2% and the TBN was stout at 7.4 since 1.0 or less is considered low. All is well from here. Hopefully the hose stays put going
forward. Nice report at 676 hours!"

Testing the boat after hose replacement and system cleaning at 3400 RPM shows all is running at normal conditions.

I had been thinking about renewing the seawater system hoses on this 2005 boat because I assumed from the paint on them that they were all original, and I initially blamed aged hose as the causative factor. After all, the previous owner (about 5 years of ownership) and I both conducted freshwater rinses of the system after every run, and surely it would be clean inside. However, the responders on Boatdiesel.com were having none of it and insisted that clogging of the system raised the pressure at the pump which burst the hose.

I finally took their advice and looked into both ends of the oil cooler where I found tan-colored calcareous hard growth covering the surfaces. The tube nest was not completely clogged, but there was obviously some constriction of the passages and doubtless the same could be said for all five coolers on the engine. Running Barnacle Buster through the engine yielded a pretty mucky looking brown mess in the bucket; so they were right, at least partially. I dissected the offending hose elbow and found a curious narrow tan-colored streak running up the the outer radius of the hose's inner surface. So I think there was some actual erosion of the hose material which weakened that area, and my assessment is clogging 50% and old hose wear 50%.

So far I have replaced the burst elbow with a silicone elbow and renewed the next piece of hose downstream with a Yanmar hose because of its unique shape and the fact that it is 1.5" on one end and 1.75" opening on the other. I may eventually find a place which can custom make that piece in silicone. Other short sections of the seawater hoses will also be replaced in the near future with silicone wherever possible.

I have ordered a Borel exhaust hose temperature alarm which I will modify to also run through my added-on idiot light and audible alarm panel. Should a loss of seawater cooling happen in the future for any one of a number of reasons, I expect to hear from this alarm well before the engine begins to overheat. One wonders why all boats don't come equipped with such audible alarms as well as audible bilge alarms.

Another modification to the system will be the addition this week of a grating over the exterior through-hull mushroom for the main engine cooling, a thing, the lack of which, I find inexplicable.

It is my belief that instant reaction in seconds, not even tens of seconds, saved this engine and that the audible and VISUAL alarm combination (something this boat did not come to me equipped with) allowed me to have the information to react properly. There wasn't even time to think, "Duh, maybe I better look at the temperature gauge." The boat fell right off plane with my finger on the engine shutdown button - not normally advisable, but in this case warranted.

Great reaction and outcome to what could have become a disaster. But I have a hard time seeing how a 13 year old piece of hose could fail like that no matter how fouled the downstream was thus increasing the pressure.

But obviously it did.

I also wonder if silicone blue hose is any better than the black stuff at resisting long term deterioration. I realize it handles high heat better, but.....


The Borel alarm is a great addition and will give you an addition 30 seconds to react when it goes off.


David

I dunno about the silicone benefit either, but if you believe you get what you pay for, well, I'm getting a lot better product.

But a 13-year old hose did burst under pressure. So was it "rotten" hose? The tires on our cars are supposed to be changed after six years, regardless of tread wear. Why is that? These products all age. Had the hose been new, would the back pressure have burst it. I doubt it, but it might not have been very many years before it did because of the added pressure due to internal fouling.

All the same, I am glad the event also caused a closer look at the internal cleanliness of the system and a consequent cleaning of it.

Rich,
I had a similar situation last year. The long hose on thetop side of the fuel oil cooler blew off . I was not sure just thought the hosewas old and maybe the hose clamp let loose? I ordered every hose on both the sea water side and antifreeze side justto be safe. So this spring I replacedall the hoses I could get to without taking the coolers off. Those two smallones are still on the list. This season, believe or not had the same hose spliton me, 119775-49010. Running across bay see bilge alarm go off. Look down attemp gauge rising above 200 shut down motor. Restart motor for a couple secondsto see where all the water came from and found the split. I caught this within seconds to a minute or two so no realoverheating.
Now I just replaced this 90% degree hose with the small offset the year before due to the other hose popping off. I thought that I could have purchased an old,bad hose? I was extremely lucky to have another hose , 119775-49020 on theboat. The split was too large for duct tape so I replaced the hose with asimilar one and went on my way.
Now I’m worried? I guess I need to pull both ends of cooler?6LPA-STP, 435 hrs. on 2006 boat. Itdoesn’t look too hard just lack confidence? I guess I’ll plan on pulling thecooler or ends to confirm if obstruction is the problem?? Need to look into thebarnacle buster I guess?

I would not assume the new hose you put on between the fuel cooler and the inter-cooler was defective. That fact that it blew off on one end points to a lot of back pressure, probably due to clogging. I believe you have the same issue I did with fouling of all your coolers.

This engine pumps 35 gallons a MINUTE through the seawater cooling system at WOT. So imagine what kind of back pressure you are getting if all four of the downstream tube bundles (inter-cooler, oil cooler, tranny cooler and heat exchanger) are even slightly clogged with calcium-like deposits.

You had the opportunity to look into the fuel oil return cooler when you replaced that long hose. Was it clean or did it have a crusty light tan appearance indication calcareous fouling?

Another relatively easy place to look for this fouling is at the transmission cooler. Just pop off one end and take a peek. Anything other than clean metal is cause for a cleaning.

By the way, I am pretty handy, but when I wanted to reform a preventive maintenance service of the inter-cooler (which included pressure testing the tube bundle after cleaning), I was quite happy to watch a professional do that the first time.

My suggestion to you is for you to do as I did with the Barnacle Buster treatment. when you see that cruddy solution flowing into the bucket from your engine, you will know it was the right thing to do and that you have likely solved the problem of bursting and popped off hoses.

Let me know how it goes.

Rich,
Do you have a picture of how you jury rigged to recirculate buster fluid through engine? Did you take off 2" seawater intake hose and reduce down to 3/4" hose fitting? How about when it comes to 90 L ? Just clamp off trans and shaft hose?

No photo; so here's a thousand words. It was very simple.

First let me say that I made an adapter for connecting to the forward end of the loop which made connecting to the new silicone hose elbow coming out of the seawater pump quick and easy. It consists of a 1.5-inch-to-1.5-inch plastic barb-to-barb hose union stuck into one end of a 3-inch long section of silicone 1.5-inch diameter hose. The other end of this hose has a PVC pipe bushing (1 ¼ “ with a ¾ “ threaded hole in it) with a ¾” barb to ¾ “ threaded adapter. I used a heat gun to soften the silicone hose up a bit before forcing the slightly larger PVC bushing into the hose – no clamp required.

Then I removed all the zincs from the engine and plugged the holes with empty zinc holders.

Next disconnect the hose elbow at the output port of the seawater pump and insert the exposed hose barb of the adapter gizmo mentioned above into it and put a hose clamp on it. This is sooo much easier that dangling over the area with one hand trying to push something into the open end of the hose elbow because the plastic barb slips into the elbow rather easily. Pilot 30s suck for access.

Next use 8 feet of cheapo bilge pump hose pushed onto the ¾” barb of the adapter gizmo and run back to a bucket behind the engine where I pushed it onto the ¾” barb of the cheapest non-automatic 12-Volt bilge pump West Marine had. Connected the wires of the pump to a portable 12-volt power supply I have.

I then disconnected the 1.5” hose to the engine exhaust water injection point and pushed into it another 1 ¼” to ¾” PVC bushing with another plastic ¾” hose barb to ¾” threaded adapter and put a hose clamp on it. I had about 6-feet of ¾” hose attached to this end to be able to both get the solution back into the bucket but also to be able to put its end out in the cockpit to pump overboard when needed.

Lastly, I clamped shut the cooling hose running to the dripless shaft seal.

All this took about 15 minutes once the adapter gizmo was made up.

I ran some water into the bucket and switched on the bilge pump to fill the system and ensure it was flowing through from one end to the other. I used the Barnacle Buster CONCENTRATE (NOT the ready-to-use stuff) from West Marine ($79). With just enough water in the bucket to cover the pump, I put about 40-50 percent of the BB concentrate into the bucket, and within 20-30 seconds had what looked like French onion soup pouring out of the engine into the bucket. Ran for one hour and then laid the exhaust ¾” hose on deck, turned on the freshwater hose into the bucket, and continued pumping until it was clear. Next, to ensure the initial solution had not weakened to the point it could not remove any more growth, I added the rest of the BB into the bucket and continued for another hour. The bucket was clear after this last hour; so that was wasted BB. Pumped that out onto the deck until the soapy feel of the acidic solution was replaced by pure freshwater to thoroughly rinse the system.

Reconnected engine hoses, reinstalled zincs, unclamped shaft dripless seal cooling line, placed all wash hoses, pump, and adapters into the bucket and stored for the next time.

Took boat for a ride.

QED, as my Naval Academy calculus professor used to say.

Thanks Rich, just saved me hours of running back and forth to Home Depot. I was hoping I didn't need to take that sea water pump off. Forgot about the zincs. Sometime the small tid-bits of information save hours of grief. Thanks again.

It's nice to be able to give the precisely right information. Hope you get lots of gunk outa there!!!

Hi Rich, long time no see! I'm glad you avoided a catastrophe there. I also had a similar occurrence last year with the same hose while cruising on West Bay. My bilge alarm alerted me. I managed to tape up the hose with a lot of plastic wrap and duct tape and limp home at low speed with one eye on the road and the other on the temp gage. I replaced the hose and figured that I probably had flow problems through the intercooler. So, I took it over to Destin (talk about a long, nervous trip!) to get inspected/serviced and, sure enough, the passages were badly clogged. Lesson learned.


Hope to see you out there sometime soon. We're planning a trip down to Appalach in early Oct.

I remember you telling me or hearing about that incident. Was your engine rumbling from within after you shut it down like mine was?

I figured what the heck, with towing insurance, rather than risk trying to restart after a tape job (I do have duct tape aboard) I'd give ol' BoatUS a chance to shine. But I admire your resourcefulness!

I am hoping that now that the clogging has been acid cleaned away that my practice of freshwater rinsing the engine after every run will keep it clean and prevent any future accumulations, but I will inspect every year or so nonetheless. If you ever want to flush your system with Barnacle Barrier or Rydlime as a preventive measure, let me know, and I will run my bucket with ready made kit of pump and adapter pieces down there to you and help set it up.

Have fun on the run to Apalach, we went in May following my brother in his Grand Banks 42. Chris Smith says Saturday-week we could wake up to 60 degree weather in the AM; Fall is coming!