Intercooler hose

[Capt Ron]

I found what may be a chronic issue with the raw water feed hose that fits between the oil/fuel cooler and the intercooler. Mine blew off at the intercooler end while running a year or so ago. The first time I suspected the clamp so I replaced with two clamps. last weekend it blew off again. I found the cause while opening the engine cover just after running hard for awhile. The intercooler end of the hose was swollen to twice the size. With the engine off it goes back to normal. The reason I think it's a chronic issue is a friend with another Yanmar 300 HP had his wear through at the throttle linkage adjacent to the swollen area even though with the engine off it wasn't close enough to touch.

[sail410]

I just had a similar problem and it was due to a "plugged" cooler or coolers. You need to pull all of the coolers and have them cleaned before something major happens. When the coolers are removed you will be surprised at the crud in them. this causes a pressure build up which expands the hoses until they burst. Cleaned coolers solved the problem.

[Capt Ron]

Thanks.

[RobS]

Yes, sounds like clogging of the arteries downstream in your raw water cooling loop causing excessive back pressure.

Have you noticed the engine temp being a little higher than normal, especially as you run hard?

I would do a rydlyme flush now and then pull the coolers in the offseason so you avoid any downtime in this already shortened season of the northeast. I have a prior thread here on AOG regarding a rydlyme flush on my 6LP.

[Capt Ron]

The Rydlyme flush did it as you suggested. The hoses are now staying put and the temp. is down a few degrees. As a note to others, watch the exhaust steam. I had steam form the exhaust at cruise RPM prior to to flush. Now steam is gone. Also squeeze the hose going to the intercooler while running. If it's hard as a rock, it's time to do something.

[slimjim]

The Rydlyme flush did it as you suggested. The hoses are now staying put and the temp. is down a few degrees. As a note to others, watch the exhaust steam. I had steam form the exhaust at cruise RPM prior to to flush. Now steam is gone. Also squeeze the hose going to the intercooler while running. If it's hard as a rock, it's time to do something.

had same issue and now my temp is down 5 dgrees and less steam as well.

[Carl]

Did mine over the weekend as well. Biggest change was at WOT. Temp stayed at just a bit over 180. At cruise it now is staying put below the 180 mark. These are all gauge readings. There seemed to be a big difference of flow from when I first started the pump, to when I was done. At the end, the mixture was really swirling in the bucket.

[slimjim]

My engine runs at 170 at cruise, it was reading 175, I have never seen it at 180. My mech who is a yanmar dealer says the alarms go off at 200.

[Tree]

Can anyone tell me the part number for this hose - my buddy just had the same happen and yanmar in the UK appear to be pretty useless when it comes to getting the hose - or should he be talking to Hurth?

[Yearwood]

Last July 4 weekend my son and I blew the same raw water hose with 30 minutes of one another on two different Yanmars, mine 6LP STE. He went to the local auto supply store (U.S.) with the hose and bought one with a compound bend, cut it and used the part needed. He sent me a text message with a photo and I did the same. We were both back in service the same day at less than half the price.

[OldDemps]

I had a sudden overheat problem (shocking at WOT and alarms start blaring) and thought raw water impeller failure but impeller was perfect upon inspection Changed impeller anyway while RW pump was apart and had good raw water flow at exhaust after. My Mechanic then said coolant thermostat could be cause of sudden overheat. I Changed it w new OEM yanmar thermostat / new coolant and engine overheated again, this time quicker. then I did Rob's Rydlyme flush posting because I was too lazy to open all four~ coolers on my flush deck yanmar. The engine has been flawless for the last 10 hard running hours since Rydlyme flush. I was skeptical of Rydlyme claims and didn't see a lot of crud after flush but it must have worked! I'm very pleased for $80~ 2 gals in chemicals. Mechanic also said if I eventually open coolers the Rydlyme will have softened deposit for me to mechanically removing deposits if needed.
NOTABLE POINT. the new yanmar thermostat says 70C right on it. Same as the old thermostat that came out. 70 Celsius is only 158 Fahrenheit and my gauge runs about that at low speed and up to 175~ WOT now.