Need help ASAP with cracked Volvo penta 55

[kmacdonald]

I take it that the exhaust manifold is raw water cooled? Aluminum exhaust manifold and iron exhaust elbow----sounds like the problem to me. Be sure to change the zincs.

[DougR]

I'll take a stab at re-creating the failure mode here.......

Both of the engines here appear to be early model D2-55 engines, so they are at least 10 years old. The cast iron exhaust elbows have rusted thru, allowing sea water to enter the exhaust stream close to the junction of the elbow and the heat exchanger tank and probably drain to that location when the engine is shut down. (OP states water is entering the engine room when the engine is running.. ...indicative of faulty elbow)

Hot salt water on the aluminum exhaust manifold surface when running and lying there after running has corroded/eroded the surrounding material to the point of failure.

Remedy? Could be flushing as mentioned by Oz, or more frequent observation of exhaust elbow condition. Most concur that cast iron exhaust elbows are considered maintenance items. I think aftermarket elbows in stainless steel are available for the D2-55.

DougR

[kmacdonald]

I would be very concerned about the condition of the engine also. Seawater could have entered the exhaust valves. I agree with the above post.

[kmacdonald]

SS exhaust elbow: https://www.ebay.com/itm/V55C-F-Stai...-/231994385652

[DeepFrz]

The description of the flushing set up in post #13 concerns me. May be a language/description problem however flushing the raw water system has been discussed many times on CF.

Just put a y valve on the intake hose leading to the raw water pump. Run the engine with one end of the y inserted into a bucket of fresh water and then switch the valve so that the engine draws in fresh water and run it through the system for a while. Do this any time the boat is going to sit for a while and on a regular scheduled basis.

When you finish flushing make sure that the y valve is switched to the raw water intake. Also make sure that the anti siphon valve is operating properly.

[kmacdonald]

You might want to check and make sure the exhaust system was installed properly with the correct dimensions. Excessive cranking can cause salt water to back up into the exhaust manifold.

[redbeard1]

Hello all,

Great tips on preventive maintenance.

Just in case I run into this issue while buying a boat in future (and more importantly, for the OP checkbook today), can the hole in the OP heat exchanger be welded or is a new one needed?

Thanks in advance.

[DougR]

Impossible to tell whether the housing can be welded and remachined from the single exterior photo posted by the original poster. The housing needs to be removed and taken to a skilled machine shop for evaluation....
- can the base material be successfully welded?
- is the base material in the area substantial enough for cleaning up and building up?
- will the process be cost effective?

DougR

[Lepke]

If it's aluminum, it can be welded. Damage has to be ground down to good metal. Studs need to come out. Best if the casting is preheated, slowly cooled after welding, but much easier than cast iron. Leave it to Volvo to come up with a $3700 heat exchanger designed to fail.
If the area is water cooled, it's possible that high temperature epoxy could be used.

[kmacdonald]

I don't think it's a Volvo problem that caused this to happen. It was lack of maintenance. See post #17. The exhaust elbow wasn't checked and replaced when leaking causing the corrosion.

[Mitchell87]

DougR you we’re correct. The steel elbow rusted and allowed raw water to enter the heat exchanger. Raw water intact entered the engine as well. I had a mechanic from JAS Marine take the heat exchanger to his shop in ft lauderdale. They said I needed to replace it and I told them I think I can fix it.

I got some welders I know to come over and four hours and $700 later my heat exchanger is like new. A new heat exchanger would have cost $3700 so I saved $3000.

Furthermore, they were going to order a new elbow from Volvo for $680, but I opted for the stainless elbow on ebay for $390. In fact I bought two. I’m now waiting for the elbows to arrive and I’ll have JAS install.

[Mitchell87]

Here is a picture:

[kmacdonald]

Great!!!! Let us know how it turns out. Good you are replacing the elbow on the other engine also. Even though its stainless steel, they still need to be checked ever couple of years.

[jimbunyard]

Glad to see you got it fixed.

Was looking at this picture, posted by someone with a similar problem



and was curious. If the failure was caused by sea water pooling in the lowest point on shutdown, why is the corrosion pretty evenly distributed around the flange?

Not saying that it couldn't have been caused by seawater intrusion, but I'm wondering if someone has used a graphite gasket where perhaps they shouldn't have...

[OzDean]

As per Jim, good to see it fixed by welding. When mine broke I had asked if it could be welded but was told NO. Hey Jim, good question about the possible wrong gasket. I don't know. I purchased the boat in 2011 from an Italian fellow, it had a french flag, was lying at top of Croatia being sold by an agent in Slovenia. I have learnt a lot since then. One question that has arisen for me from this thread is looking a the picture again, I am surprised that my engine was able to run without leaking like Mitchell's. In any case, I have new heat exchanger and riser now and I will be inspecting regularly. Also re the question from DeepFrz re flushing the raw water system, I think was making it too complicated! Yes the y connector and bucket is a simple solution whether it be fresh water for flushing or coolant for winterizing. I was seeking to replace the bucket with a permant container. Cheers, Dean