Engine blues - volvo penta

[Manana5]

Hello, knowledgeable sailors! We have been struggling with engine problems since we purchased our first boat this summer. I made one post about it before, however I felt like I have to start a new one considering the latest developments. This forum has always given me lots of perspectives and ideas, hoping for the same now.

Background: our engine is Volvo Penta D1-21 from 2007. Upon buying the boat, the survey deemed it perfect, it was starting instantly and running smoothly. We bought the boat in France and had to take it over to North Aegean this summer. We started experiencing problems a few days into the trip - in certain conditions we heard gurgling noises and the overheating alarm would go off. Mostly this would happen when we try to motor sail and the boat is heeled, or when there are bigger waves. In calm conditions the engine ran without a problem, sometimes for days.
Some things we did initially as precaution and/or later to try to find the issue: change oil and oil filter; clean fuel tank with antibacterial detergent; change impeller.

Eventually we reached a point where we couldn't go on due to weather (strong Meltemi in the Aegean) so we left the boat in a port near Athens for 1 month. Prior to this we opened and cleaned the water filter.

After 1 month there was a weather window and we returned to the boat with the intention to sail north. Only 20 minutes after taking off, the overheating alarm went off, even though conditions were very calm. We couldn't start the engine again without overheating, so we had to be towed back to port. Back there, we suspected air in the cooling system, so we tried to get it our by adding more cooling liquid and water, squeezing the hoses, etc. Also, at the advice of a friend, we moved the expansion tank higher than the engine, so the air would escape through there. In spite of all these attempts, the engine continued to overheat after about 30 minutes of running. We also noticed at this point that we seem to be losing cooling liquid.

The next morning we had a mechanic come to look at it. When we attempted to start the engine, it went CLICK and died completely! The mechanic said there's water in the pistons. So we ended up taking the boat out to the dry dock and taking the engine apart by ourselves. We suspected a faulty head gasket, however once we were able to reach it, the gasket seemed fine - no holes or rust visible. There is no visible damage anywhere in the head components or pistons either, though they were indeed full of water. It was fresh water/cooling liquid, not salt water.

We are getting frustrated and desperate, not being able to figure out what is the problem and where the water is entering from. Also I cannot figure out why the engine was running fine for the most part, then suddenly something changed after staying idle for 1 month? The local mechanic offered to do a full overhaul of the engine for a huge price, which for the moment is not an option for us (at least without being sure it is necessary). I turn to you once again for any helpful ideas or experience.

[mikeod]

I'm no expert but I think you found the problem. Unless the head gasket went bad after the overheating. Gurgling? Was it boiling over. Possible bad thermostat.

[Manana5]

Originally Posted by mikeod

I'm no expert but I think you found the problem. Unless the head gasket went bad after the overheating. Gurgling? Was it boiling over. Possible bad thermostat.

But the gasket seems fine and not damaged - this is why I am puzzled
The gurgling sounded like there's air in the system but we never figured out exactly what causes it.

[Paul L]

The overheating could certainly cause the head gasket to leak or the head to warp and end up with coolant in the cyclinders. The cause of the overheating might be a blocked heat exchanger, either from corrosive build up or parts of old implerers. Have you removed the heat exchanger and flushed the cooling system?

[Manana5]

Originally Posted by Paul L

Have you removed the heat exchanger and flushed the cooling system?

We did remove the heat exchangert but we were not able to open the freshwater circuit, as the bolts were too tight. We did open the salt water part - there was some salt deposits but it was not blocked. We have taken the heat exchanger (as well as the head parts) home for further investigation.

So are you saying that overheating can drive water in the cylinders even if the gasket is not damaged? We did switch off the engine every time the alarm went off, we have not run it in overheated mode for more than a few seconds at a time.

[Paul L]

Originally Posted by Manana5

We did remove the heat exchangert but we were not able to open the freshwater circuit, as the bolts were too tight. We did open the salt water part - there was some salt deposits but it was not blocked. We have taken the heat exchanger (as well as the head parts) home for further investigation.

So are you saying that overheating can drive water in the cylinders even if the gasket is not damaged? We did switch off the engine every time the alarm went off, we have not run it in overheated mode for more than a few seconds at a time.

I'm not enough of a mechcanic to say either way. Overheating can definately warp a head and cause a leak. Will you see the damage on the gasket always or not, I don't know. Have you done a compression test?

Maybe if you are lucky DougR will chime into this thread and offer some experienced advice.

[DougR]

A couple of thoughts:

- you said the overheating occurred when motor sailing and heeled over, or when motoring in big waves..... It sounds to me like the seawater pump was sucking in air and loosing its prime. If the seawater pump body or the cover is worn this can certainly happen, and cause an overheat. I have had it happen to me when racing and heeling heavily, and it can happen even if not heeling too much, depends on the water flow around the keel and the thru hull location. The pump is 12 years old......

- If you found coolant in the cylinders check:
- cylinder head for cracks or warped surface
- pressure check the exhaust manifold/ heat exchanger tank.....it may have cracked and allowed water into the cylinders via the exhaust ports

DougR

[CarlF]

Water in the cylinders sort of takes this out of amateur mechanic territory. Especially in a recent purchase of a first boat. With a ten year old engine that may or may not have been well maintained.

Whatever the initial problem(s) was, you now may have more. Multiple problems makes diagnosis extremely difficult. And you risk making things worse by guessing.

The fact that you had a good survey means little. As you say, it ran fine at the dock. Or at least it used to.

I would ask other locals for the best diesel mechanic in the area. Commercial fishermen are often a good guide. A full rebuild is rarely warranted but you need someone with the experience to make sense of this rather than just run up a big bill.

Yes, this will probably be expensive but almost every boat owner gets an expensive surprise that requires professional help once in a while. We’ve all been there

[MartinR]

D1-20A you mean?

I would guess blown head gasket, not always easy to see, or/and cracked/warped head.

The alternative, a cracked block would not be good. If I remember correctly these engines do not have cylinder liners.

As somebody else said, maybe the motor sailing caused the engine to overheat, due to sucking air into the salt water system. The intake might be placed too high up.

These are actually not Volvo Penta engines, they are some kind of Japanese engines, marinised by Perkins, so if you can find out who made the original engine, you can probably save a lot on spares. The only thing Penta about these is the green color.

[MartinR]

I agree, you need professional help from a good mechanic.

[richard97]

Intake too high would be my first place to look

[t588143]

I am a mechanic. Water can ONLY enter the cylinders via a leaking head gasket or by backflow via the exhaust. I think that the water lift muffler is not working properly or fitted to low or the vacuum breaker in the seawater coolant line is plugged which has caused seawater to partly fill the cylinders. Starting an engine with water filled cylinders will always cause a head gasket to start leaking due to the excessive pressures that are caused by the engine trying to compress water. To determine if indeed the head gasket is now leaking I suggest the following line of action:
Put everything back together using the old seals and gaskets and fill the system with coolant. Fill it up completely. Now you somehow need to pressurize the coolant system to operating pressure via the cap on the expansion reservoir. A mechanic has a tool (pump)for this. Monitor the level in the expansion vessel. If the level drops (give it some time) it is the head gasket or the heat exchanger that leaks. To be sure check the cylinders for water. If it is indeed the head gasket you will need to have the head resurfaced. Just fitting a new head gasket will have zero success in the long run. Next you will have to find the primary cause of the problem. For this you will have to take a really good look at all the components of the primary (salt water) cooling system. make sure that the vacuum breaker on the high point is the system is working properly, the water lift is without obstructions and the injector elbow is not excessively corroded. I am pretty sure that you will find the initial cause of your problem without much difficulty.

[endlesspursuit]

Since you already have it apart I would send the head out to a machine shop and have them check it for cracks and warpage. How many hours on it? Valve job ,deck the head. See if they can come to the boat. there is a magnetic test the can do on the block to check for cracks in the block. If all good reassemble with new gaskets. Now you know what you have internally. As for the cooling see above comments, but make sure what you have for cooling before running it for very long. Don't want to ruin your hard work.

[redsky49]

Originally Posted by t588143

I am a mechanic. Water can ONLY enter the cylinders via a leaking head gasket or by backflow via the exhaust. I think that the water lift muffler is not working properly or fitted to low or the vacuum breaker in the seawater coolant line is plugged which has caused seawater to partly fill the cylinders. Starting an engine with water filled cylinders will always cause a head gasket to start leaking due to the excessive pressures that are caused by the engine trying to compress water. To determine if indeed the head gasket is now leaking I suggest the following line of action:

Originally Posted by t588143

Put everything back together using the old seals and gaskets and fill the system with coolant. Fill it up completely. Now you somehow need to pressurize the coolant system to operating pressure via the cap on the expansion reservoir. A mechanic has a tool (pump)for this. Monitor the level in the expansion vessel. If the level drops (give it some time) it is the head gasket or the heat exchanger that leaks. To be sure check the cylinders for water. If it is indeed the head gasket you will need to have the head resurfaced. Just fitting a new head gasket will have zero success in the long run. Next you will have to find the primary cause of the problem. For this you will have to take a really good look at all the components of the primary (salt water) cooling system. make sure that the vacuum breaker on the high point is the system is working properly, the water lift is without obstructions and the injector elbow is not excessively corroded. I am pretty sure that you will find the initial cause of your problem without much difficulty.

This sounds like a good approach to the problem.

[BruceS]

I'm not familiar with that motor but at present I'm working on a Mercruiser that has a hole eaten thru the raw water cooled manifold & into the exhaust passage. (inlet & outlet old log style 6cyl)