New to boating, engine maintenance question about corrosion

camdunning · Mar 8, 2015

Hi TW -

I'm new to this site and new to boating generally, but I've poked around the forums here a fair bit and it seems like a great resource. Looking forward to any tips you all might be able to provide as I get up to speed on the world of boat ownership.

I have a pretty basic question about engine maintenance. Since I'm new to owning a boat I'm not totally sure what I need to be doing to stay on top of things, and want to make sure I'm not doing serious damage through neglect. For some background, I purchased a 1986 36' Nova Sundeck about 6 months ago and have been using it a liveaboard. My girlfriend and I are both students, so living on a boat has been convenient with location and monthly costs, and lots of fun so far. The boat has twin Volvo Pentas which both have low hours, but the starboard side has issues with seals on the heat exchanger. When the engines are running, I think seawater comes through the seals and gets in the engine compartment. Over the last 6 months I've seen corrosion start to build up on the engines, which I'm theorizing is from the heat exchanger issue, and has me a bit concerned. I'm planning on having the heat exchanger issue fixed as soon as I can get the diesel guy out here (and can afford it), but in the meantime I want to stop the corrosion from continuing. What's the best way to do this? I have some saltaway that the previous owner left me, can I go wipe down the engines with this to get the salt off? Or can you spray it down carefully with a spray bottle? Or am I way off base?

For what its worth, I've replaced 3 of the 4 engine zincs, but couldn't swap out the fourth because I think some of the old one broke off and is preventing the new zinc from getting in there. There also is always a little bit of standing water in the bilge under the engines which doesn't look great and smells terrible, part of the reason I need to get the mechanic out here.

Thanks in advance for any tips, sorry for the basic question but I'm just starting to learn the ropes!

DavidM · Mar 8, 2015

If you plan to fix the saltwater leak within a few months, you can limit the corrosion by wiping the area down and spraying with WD40 or similar.

When you do get the source fixed, wire brush the corroded area and spray or brush on matching paint.

You can try reaching in to grab your stuck zinc with a pick up tool, like this one- http://www.amazon.com/X-Long-Flex-C...&qid=1425837296&sr=1-16&keywords=part+grabber

But the broken off piece of zinc is probably swollen so it won't come through the hole. The only choice is to remove the end cap and reach in and pull it out. Replace the gasket and tighten the screws back up.

When you do replace the zinc, tighten the zinc where it screws into the brass nut with a pair of pliers. Also change them before they are half worn to limit the chances of breaking off.

This operation is essentially the same as what you need to do to stop your leak. But the leak may be caused by corrosion so you will have to deal with that.

To deal with your smelly bilge, dump a pint of hydrogen peroxide in and let it swish around to neutralize the source of odors.

David

bayview · Mar 8, 2015

Usually it is obvious how to remove end caps and fix the leak yourself. Don't let it keep dripping or the salt water will cause something else to go bad.

Post a clear PIX for more detailed suggestions.

Old zincs can be pulled using the proper sized threaded rod connecting nut.

eyschulman · Mar 8, 2015

Keeping your engine compartment free of moisture especially salt water will go a long way to protect your motors. Many put a source of heat in the engine compartment. Sometimes even a 100W light bulb helps others use real heaters or a external block heater on a timer or thermostat even better. If you have salt water from any source in the compartment the first thing you must do is trace the source and stop it otherwise all other measures will be wasted. Common causes of salt water intrusion are leaking packing glands-leaking raw water pumps-loose hose clamps-leaking seals-leaking overhead engine room hatches. There may be more than one source. Good luck.

ancora · Mar 8, 2015

We have owned the same year and model boat for 15 years and as a DIYer have "been there, done that." I would remove the heat exchanger end cap for a look see to find out where the water is comin' from. Be advised, that Volvo does not support those engines due to their age.

psneeld · Mar 8, 2015

Also don't panic...having some "green" corrosion around end caps of HEs isn't all that abnormal after a few years. If the HE is of reasonable quality, it should be looked after but not something to really bother you.

Now if you can see a drip or liquid moisture...it is getting time to get serious.

I have had my HE on the replacement list for 3 years now because it is of unknown age...the green loose buildup on the ends has been there and it hasn't leaked a drop in over 4 years. I do keep up with the zincs...maybe this summer she gets retired.

Depending on where your boat is in relation to a surf bound coast...like mine is...almost impossible to keep the salt air out...especially is you use the boat and salt spray slaps the side of your boat all day. The only cure for that is to completely wash your engine room every day. Not happening on my tire old boat.

FF · Mar 8, 2015

Shop vac and suck the bilge dry.

Heat exchangers usually leak at the end seal or O ring, not a hard fix.

camdunning · Mar 8, 2015

Thanks all, this is all super helpful. I'll get in there tonight and wipe off the built up rust (on things like the engine block and motor mounts) and spray it down with WD40, and do a full scrub and repaint hopefully soon. I should be able to figure out getting the end cap of the heat exchange off to get the old zinc out, thanks for those tips. I think there are other issues going on besides just the seals though, they originally thought there was coolant getting into the oil but did a test to see if exhaust was coming through the manifold, and it came back clean (although I'm a bit suspicious).

Its a good point that the water might be coming from other (or multiple) sources - I know our dripless needs to be serviced, and there could be leaks from other areas. There is always a couple of inches of water in the bilge, which I hear is normal, but please correct me if I'm wrong. It doesn't increase much that I can tell, and its far from clean, so I want to get checked out. I'll try the hydrogen peroxide trick for the smell though, thanks @djmarchland.

Also, the PO had block heaters installed, which he recommended that I leave on, and I have. I'm not sure they're working correctly though since I don't feel much heat down there.

Thank again, this has all be very helpful. I'll try to post some pictures tonight for context. And apologies in advance for the million other questions I will probably have for this forum over the next few months!

Wxx3 · Mar 8, 2015

FF said:
Shop vac and suck the bilge dry.

Heat exchangers usually leak at the end seal or O ring, not a hard fix.

Buckethead comes to the rescue.

I got it at Home Depot for $25. I even used it to clean up my fuel tanks.

http://www.amazon.com/Bucket-Head-W...425844718&sr=1-1&keywords=buckethead+shop+vac

RT Firefly · Mar 8, 2015

Greetings,
Welcome aboard.

tegdesign · Mar 10, 2015

Hello Camdunning, I bought my Nova 36 in November last year. I'm sure have the same engines (TMD41A) with a little over 1000 hours and have spend a lot of time in the ER trying to figure out all that's going on down there. So far I've changed both raw water impellers. The Stbd side was made more difficult because the metric bronze machine screw that keeps the cam in place was broken and the end stuck in the cam! I finally found the right replacement screw and and bored the end out for the fix. I've also been spending a lot of time really cleaning the bilges since it seemed the PO didn't like doing that job. I like the hydrogen peroxide tip! I will get a big jug. I haven't figured out where the engine zincs are yet. Where did you find them?

tegdesign · Mar 10, 2015

Also, I wonder if you have the same fiberglass tubs under each engine that I have. They catch any oil that might drip so it doesn't go into the bilge water. They are very clean so I don't think I have any leaks but I like them because I can see if any leak starts happening.

ancora · Mar 10, 2015

Puttin' in those fiberglass pans under the engines was a good idea. I also like the forward sump that collects any liquids in the bilge. I plumbed my shower to dump into the sump 15 years ago and have had no problems.

camdunning · Mar 10, 2015

I have those fiberglass pans as well, they look pretty clean but I don't think they're catching the water from the heat exchangers, which I'm hoping isn't dirty because oil is getting in there somehow.

My zincs are on the heat exchange cap and and underneath in the oil cooler, couple of pictures below. Also included are some pictures of the corrosion (last one is upside down).

tegdesign · Mar 10, 2015

Ancora, I was wondering about plumbing the shower into the main bilge sump. I figured once the ER has been completely cleaned combined with the engine pans, there should be no oil to worry about raising eyebrows if the pump were to kick on in the marina.

I have yet to actually take a shower on-board (have you ever seen a bigger shower on a boat that's not at least 20ft larger?) But was removing the crud and water from the PO from the shower sump (YUCK) and got to the bottom and discovered some weep holes. As soon as I got all the water out these weep holes would allow a trickle of water into the sump. I don't know were the extra water is coming from but I've managed to remove it all. Any idea what these weep holes are for or where the extra water could have been coming from? I wonder about plugging them.

ancora · Mar 10, 2015

When we first bought the boat, I found the shower sump pump located under the house batteries. I removed the shower sump pump and noticed some water seeping up from a screw hole in the hull on top of where the keel is located. I used some underwater epoxy to seal the hole and plumbed the shower to the sump.

tegdesign · Mar 10, 2015

camdunning said:
Hi TW -

I'm new to this site and new to boating generally, but I've poked around the forums here a fair bit and it seems like a great resource. Looking forward to any tips you all might be able to provide as I get up to speed on the world of boat ownership.

I have a pretty basic question about engine maintenance. Since I'm new to owning a boat I'm not totally sure what I need to be doing to stay on top of things, and want to make sure I'm not doing serious damage through neglect. For some background, I purchased a 1986 36' Nova Sundeck about 6 months ago and have been using it a liveaboard. My girlfriend and I are both students, so living on a boat has been convenient with location and monthly costs, and lots of fun so far. The boat has twin Volvo Pentas which both have low hours, but the starboard side has issues with seals on the heat exchanger. When the engines are running, I think seawater comes through the seals and gets in the engine compartment. Over the last 6 months I've seen corrosion start to build up on the engines, which I'm theorizing is from the heat exchanger issue, and has me a bit concerned. I'm planning on having the heat exchanger issue fixed as soon as I can get the diesel guy out here (and can afford it), but in the meantime I want to stop the corrosion from continuing. What's the best way to do this? I have some saltaway that the previous owner left me, can I go wipe down the engines with this to get the salt off? Or can you spray it down carefully with a spray bottle? Or am I way off base?

For what its worth, I've replaced 3 of the 4 engine zincs, but couldn't swap out the fourth because I think some of the old one broke off and is preventing the new zinc from getting in there. There also is always a little bit of standing water in the bilge under the engines which doesn't look great and smells terrible, part of the reason I need to get the mechanic out here.

Thanks in advance for any tips, sorry for the basic question but I'm just starting to learn the ropes!

I wonder about using a product like Osfo to treat the rust on the engine and mounts before painting? I don't know if it's an old wives tale, but I put a little block of camfor next to each mount. It's supposed to inhibit rust.

Rsysol · Mar 10, 2015

Don't use Osfo, my PO did this all over my steel boat. I spend my weekends grinding the rusting Osfo crap off back to steel and repriming and painting.

YMMV

tegdesign · Mar 10, 2015

ancora said:
Puttin' in those fiberglass pans under the engines was a good idea. I also like the forward sump that collects any liquids in the bilge. I plumbed my shower to dump into the sump 15 years ago and have had no problems.

Rsysol said:
Don't use Osfo, my PO did this all over my steel boat. I spend my weekends grinding the rusting Osfo crap off back to steel and repriming and painting.

YMMV

So just brush/grind to fresh metal and paint? Or...?

Rsysol · Mar 10, 2015

tegdesign said:
So just brush/grind to fresh metal and paint? Or...?

Grind, sand, prime and paint would be my choice. You'll need special primer/paint for the engine block, check your manufacturer for the proper product/color.

New to boating, engine maintenance question about corrosion

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