WHite Vapor in engine exhaust....

[michelsecurity]

OK folks, I'm finally frustrated.  I had a VERY large amount of white smoke (cloud) which smelled strongly of anti-freeze come from the exhaust as soon as we left the marina in the earlier part of the season.(first cruise)...Crept back in at idle, and diagnosed (with supposed weekend mechanics, of which I'm one) that the head gasket had blown......3 weeks to get it!...along with all of the other upper end gaskets, etc.

Replaced the head gasket, checked valves (they look new), installed new seals, gaskets, etc. on intake, exhaust...had a shop check for warpage, and they stated the obvious, it looked almost new and was in good shape (aside from a little outside rust)....Also rebuild the salt water Oberdorfer pump and used the run-dry impeller.... Replaced thermostat...Checked water flow to the heat exchanger, it was good....  Bypassed the through-hull fitting, (to monitor the fact that the raw water pump was working consistently, with a 5 gallon bucket....

Ran the engine for a 15 minute warm-up, then under load (in gear)....and...the water vapor returned, and gradually got worse! ......What the H--- am I looking at?

We did run the boat for an hour initially, to season the head gasket, and re-torqued the bolts...
There has never been any water in the oil...
Temperature is about 180 once it warms up...

Why else would I be getting a vapor trail after doing all of these seemingly obvious repairs?

[Craig Illman]

Have you considered the heat exchanger? Fresh water (coolant) leaking into the raw water before it's passed out through the exhaust?

Craig

[michelsecurity]

Craig;
Yes,... today before the run, I pulled the heat exchanger, replaced the end gaskets and o-rings, new zinc,....I can see clearly through the tubes, they are not obstructed.
Steve

[Gary]

Michael,

Two simple thoughts.  Did you verify that the thru hull was not blocked? Sea weed, plastic bags etc.  Take your water line off the thru hull and you should see daylight and a lot of water come in. If not use the many recommended methods to clear the thru hull.  Dinghy pump pressure or a 1/2" x 8" wooden dowel to poke out the obstruction.

Second, over time the many fittings from thru hull to engine sometimes need tightening and RENEWED teflon tape.  Even a small air leak may not show a water leak but can allow air entry and loss of vacuum. 

Gary

[Craig Illman]

Steve - I wasn't implying an obstruction, but a leak. You probably need to pressure test the coolant system. I rented a radiator tester from a local rental firm. I then removed the zinc and pressurized the coolant tank. As I suspected, but didn't want to learn, coolant was leaking into the raw water side of the HX.

You may have a crack somewhere else.

Craig

[michelsecurity]

Craig,Gary;

Again, thanks guys....This forum is SO helpful for us dummies!

This heat exchanger was cleaned/checked last year....I did pressurize the engine collant side todaywith dock water to check for leaks, and there were none...Since that side wasn't leaking, I saw no reason to go further......
Also, I'll clarify that this seems only to be when under a load, (in gear at the dock)....and after at least a 5-15 minute run.

Steve

[Ron Hill]

Steve : Contrary to some of the written publications that I've seen, the internal coolant flows thru the tubes in the inside of the HX.  The raw water flows around the outside of the internal tubes.  Especially look at the tubes near the Zn to see if there might be an internal leak. 
If you have a coolant recovery system and the bottle level has remained constant - disregard what I've said !!

BTW : "White exhaust smoke" is usually unburnt fuel that can be caused by excessive fuel or poor combustion.   A thought

[michelsecurity]

Thanks Ron;

I think it's time that I stopped being so damn cheap and hire a good mechanic......the season's almost over for us.

Steve

[Stu Jackson]

Replaced thermostat, right?  What temp. thermostat?

What is your engine operating temperature under load?

[michelsecurity]

Everyone....
Thanks soooo much for your help....
The thermostat was the one reccommmended (160 degree).
When warming up, everything is fine, then as soon as I put it in gear under load, it starts to overheat gradually..... I've always shut down before 180 degree mark.....
Tomorrow, I'm moving the sea water intake to the adjacent 3/4 inch through-hull (new strainer also) because the loss of vacume idea sounds logical.
Here's hoping....If this doesn't work out, I'm bringing in the mechanic!
Steve

[Ron Hill]

Steve : If you have an over heating problem when under load, you have a restriction in your raw water flow. 
Start at the thru hull & strainer and work yourself thru the raw water pump to the heat exchanger.  Could be something as simple as old broken impeller blade/s in the outlet elbow of the raw water pump ?! 

[Hawk]

Steve,

White smoke in the exhaust can mean over heating. I know as my raw water intake plugged twice in the last two weeks..temp rose quickly toward 195 degrees and visible white exhaust. As Ron says start by opening the lid on the raw water strainer. When I did it nothing happened. Thats bad, as with the sea cock open there should be water pouring out of the top of the strainer.
But thats also good because it means your problem is likely the blocked raw water inlet. I duck taped my high pressure dingy pump to the hose after removing it from the strainer ( that can be the hardest part). That idea came from Ron or Stu. A few swift pumps and all cleared.

Hope its that simple for you.
Hawk

[Stu Jackson]

Dinghy Foot Pump clearing of raw water intake:  see Reply #2 here: http://c34.org/bbs/index.php/topic,4635.0.html

No duct tape required...

[Peter Lewis]

Hawk must frequent the same kelp, algae, and eelgrass infested anchorages that we do.  This is a common enough occurrence that we usual notice the change in exhaust color now even before the temperature gauge registers a change. 

Along these same lines, our temp gauge consistently climbs up to the 160-162 operating range during warmup, but never runs above 162- even when the white indicator exhaust starts to appear.  Is it possible that following an intake blockage we could be getting white vapor in our exhaust while still in the 162 temp range (we always shut down immediately and clear it, rather than wait for the temp gauge to go up) or is it more likely that the temp gauge is malfunctioning?  I recall that the first time this happened several years ago, we didn't recognize the significance of the white exhaust until the exhaust sound changed and the temp gauge was reading over 180.  Is it possible to test the gauge by putting the sensor in boiling water or something?

[Stu Jackson]

Is it possible to test the gauge by putting the sensor in boiling water or something?

The engine manuals are available on our website. http://www.c34.org/manuals/index.htm

Yes, you should be able to do this.  See page 23 of the manual, PDF page 3 of the second part of the engine manual, here:  http://www.c34.org/manuals/Operators-Manual-2of2.pdf

It shows the location of the temperature sender.  Remember that if you take it out to test it, you will need a ground wire, since the sender is grounded right to the engine when it's screwed in.