White smoke from seawater outlet

[crieders]

engine running fine at 160 or so says the temp gauge. water coming into raw water filter and out to engine again, impeller pump working, water coming out of outlet in back of boat...so why white smoke? Thanks for any suggestions or thoughts.

[Ron Hill]

Cliff : Is it smoke or steam???  Watch how it dissipates!!   Did you get a blast of hi humidity and cooler air???

Steam or water vapor will rise and clear fairly rapidly!!  Smoke tends to stay closer to the water and takes longer to dilute.

A few thoughts

[Jon W]

Cliff, Per Ron's response, make sure you have steam and not something else. If it is steam, I had the exact same situation recently. After motoring for about 1 hour at 1800 rpm, steam would begin to appear from the raw water exhaust. Engine coolant temperature was fine. I have a 1987, with M25XP, 1/2" seacock for water inlet, and 5/8" hoses.

There was water exiting the discharge, but not enough water to cool the exhaust properly so the water turned to steam.

Check the thru hull is not clogged, the strainer is clean, and you have all the blades on the impeller.

Check that your hoses and HX are not clogged.

I changed to the Oberdorfer brand impeller. I found the blue Globe impellers didn't deliver as much flow.

Check that the injection nipple on the exhaust riser after the vented loop is not clogged. The ID should be around 7/16" to 1/2", but at least 3/8".

I changed my raw water pump from Oberdorfer N202M-15 to a N202M-16. In my opinion, and now experience, the -15 is too small for a M25XP.

Each of the steps improved water flow, and I no longer have any steam.

Hope this helps.

[Ron Hill]

Cliff : Jon made a good call!!  One of the things that C34 owners usually fail to check is the inside of the raw water face plate. The wear groves will hinder the pumps ability to move water - not a good seal!!!!

Check Jon's suggestions and your face plate before you purchase anything new!!

A few thoughts

[crieders]

i have an oberdorfer pump
i checked the impeller before I put the boat in
i did replace the strainer with a Vetus, as someone did on this page.

[Ron Hill]

Cliff : The question still remains - Steam or Smoke???

A thought

[Jon W]

Which Oberdorfer? A -15 with its' 3/8" NPT ports will barely work.

Check the ID of the hoses to and from your HX are not clogged. Remove one of the end caps on your HX. If it looks like this photo it's time to clean it, and may be the source of your problem.

Check the ID of the injection nipple on the elbow of the exhaust riser with a drill bit. Be very careful not to drop the drill bit into the hose/muffler. If you can't stick at least a 3/8" drill bit in there easily, the ID needs to be opened up to let more water through.

[scgunner]

Jon,

When it looks like that you can soak it in vinegar overnight then use pipe cleaners to open it up.

[Jon W]

I took it off the boat and soaked it in Barnacle Busters premixed solution. Cleaned it like new. It says you can use it in place so I added an hour soak to my annual maintenance.

[crieders]

The engine is running at 160 degrees and I have had that Oberdorfer for long enough to know that it does an adequate job. the day was cooler than usual and very humid but what worried me is that I motored out and back down the channel and when I tied up to the mooring, was still getting the white "steam". and water was coming out of the boat as per usual.

[waughoo]

It sort of depends on how much you are talking about.  I pretty much always have some steam on my M35 with an Oberdorfer that I installed a while back.  It is a very small amount of wispy steam that looks a bit like what you'll see off hot coffee or tea on a cold day.  In other words, not much.  The engine temp is at 165 and the general temps of the hoses and things I can touch all seem to be in spec, so I have just decided to leave it alone for now.  I still would like to try improving the general flow by removing the 90s off the inlet and outlet of the oberdorfer and actually removing the heat exchanger to have it boiled at a radiator shop (I cleaned it manually with barnacle buster and mechanical clearing while it was in situ).  But... that will be when I can find a "round - tuit" next time I'm out shopping.

[KWKloeber]

Hey Cliff

You nailed it.  Cooler / high humidity. It doesn't much matter whether you're on the hook or not - you will get steam if the conditions are right for it.  You would be cheap insurance to buy a laser thermometer and check the Hx, Muffler, and exhaust hose temps.


You may have a blockage in the Hx or in the exhaust injection riser nipple, but there is no sense playing Whack-A-Mole.  Troubleshoot, Troubleshoot, Troubleshoot what you MIGHT need to do and save yourself some time.

Have you serviced the Hx since the 2015 install?  If not, it probably needs attention. 
It should be on your annual maintenance checklist to check its condition.  If its cooling drops, it can lead to the deposits/reduced flow/eventual blockage at the injection nipple.

I endorse about changing the hose barbs -- I tell EVERY customer to do that.  Change the inlet to a straight -- and both straight if you can, or at least a sweep 90 on the pump outlet. 
 
-Ken

The engine is running at 160 degrees and I have had that Oberdorfer for long enough to know that it does an adequate job. the day was cooler than usual and very humid but what worried me is that I motored out and back down the channel and when I tied up to the mooring, was still getting the white "steam". and water was coming out of the boat as per usual.

[Ron Hill]

Guys : I've had great success using "Lime-A-Way" to clean out the Heat Exchanger!!

A thought

[Noah]

Lime-a-way worked well for me too. Removed the exit hose from my water pump to HX and poured it through the hose into my HX using a funnel. I kept the hose elevated and let it sit for an  hour or so in the HX. Then I hooked hose back up and ran engine.

[Ed Shankle]

Noah, do you also drain the HX, so the LimeAway can advance throughout? Otherwise I would think it's just backed up in the hose?
Regards,
Ed