Re: [Amel Yacht Owners] OLDER MARAMU REPOWERING WITH YANMAR 4JH4-HTE WATER INGRESS EXHAUST
toggle quoted messageShow quoted text
This is the same upgrade that I am considering. Can
You tell if the new engine is a smaller footprint than the Perkins?
On to your flooding problem... The engine is of course below the waterline and since seawater is connected to the cooling system it wants to fill the engine. You protect it from doing this by looping the raw water as high as possible and providing a vent to prevent siphoning. It is quite common for a vented loop to get salt or something in the vent causing the vent to not function. If this happens during shutdown and there is a lot of water in loop it can siphon feed into the engine. I like to eliminate the vent vslve and run a small tube out the side of the boat so that when the engine is running you have a stream of water showing that the vent line is open. Watch out for dirt dobbers and other insects that can plug the hole... Another less likely issue is the larger hose size. You can figure with the engine running that the hose will be filled with about 50 percent water. Calculate the volume of the hose that is draining back to the muffler or pull the hose off the muffler after a shutdown to check the level visually...you need extra volume for safety. One final check if none of these help is to see if your muffler might have an air leak in the stand pipe which prevents if from blowing out the water properly.
Best of luck
Sent from Samsung Mobile
-------- Original message --------
From: "alex.paquin@... [amelyachtowners]" <amelyachtowners@...>
Date: 06-14-2016 10:42 AM (GMT-04:00)
Subject: [Amel Yacht Owners] OLDER MARAMU REPOWERING WITH YANMAR 4JH4-HTE WATER INGRESS EXHAUST
Good morning to all. We repowered our Older 1981 Maramu with a Yanmar 4JH4-HTE work completed 2 1/2 years ago. The engine now has less than 300 hours.Previous engine was a Perkins 4154. We have had two incidents.
1. Carter flooded with seawater from the exhaust from overcranking. Inadvertently the engine ran about 20 minutes in this condition. The engine had less then 100 hours when this ocurred. The engine was left like this for 30 days. When we realized what had happened we made 6 oil and filter changes to flush the engine. The engine started with some difficulty but operated normally when used for another 200 hours approx.in the course of 2 years.
2. Last week after being shut down one month, the engine would not turn. We decided to remove the valve cover and injectors and found cylinder No.1 with one cup of seawater. Water apparently entered when it was shut down. That cylinder was with the exhaust valve open.
We removed the water and flooded all cylinders with WD-40 and 15-W40 engine oil to attempt getting the pistons unstuck.
The raw water intake was left identical to the original arrangement which worked well with the Perkins. The diameter of the Yanmar Exhaust is 3" slightly larger than the Perkins´ and therefore modified the Amel supplied SS muffler which is in good condition for this diameter. The exhaust hose after the muffler was changed but is slighty less diameter than the 3" from the engine.
Also we had to relocate the muffler to the port side to adapt to the new Yanmar exhaust location.
Obviously there is a hydraulics problem I don´t understand very well. I posted some pics of the installation we have now. The 3" exhaust hose from the Yanmar does curve up before coupling to the muffler, that could be a problem.
I seek some advice from the group members regarding what should we do with the engine (first aid) and second the hydraulics of the exhaust system, where did we go wrong?
Older Maramu 1981, hull #94