Milky Exhaust Water

[Mart]

When I started the A4 engine on my boat this weekend I noticed the exhaust water was white. This is the first that I have seen. The engine started right up and ran smoothly. The coolant in the FWC system was down. As I was engaged in repairing sail handling rigging I did not start to trouble shoot the issue. My first thought is that the head gasket has failed. I have not checked the oil nor have I pulled any plugs to check the condition or ran a compression check.

I usually check the exhaust when starting the engine. It seams that there has been a blue smoke until the engine warms up. Two previous times it looks like there was a discharge of black carbon.

I want to ask the list if any one has any suggestions as to what is the cause of this anomaly.

Mart

[Mo]

Might be something...might be nothing

Hi Mart,
A few things to check out first. Doing this will give you a good idea of what is going on with the engine. So lets back up for just a bit...it's a good idea to check a few things right away even though we think we know where the problem is.
-was the boat lay-up or winterized and was there oil put in the cylinders for winter.
-top up the FWC reservoir with premix coolant...50/50 should be good.
-now pull each plug individually: only remove one wire at a time and one plug at a time...you will replace each and wire plug after completing the following before moving on the the next one: take a note pad with you to write it down.
-take a digital pic of each plug if you can
-put your thumb over each plug hole while plug out and turn engine over...if it pops thumb off while holding down briskly you have adequate compression. If you can get you hands on a compression guage all the better. You are looking for decreased compression on cylinders next to each other.
-see if one or more plugs look unusually clean or water drop beaded on them...gas does not bead...water does.
-clean each plug after you have taken a pic
-check the gap
-check the plug itself for spark.. while out ground the hex part on the head and turn engine over...look for spark from plug tip that would be in combustion chamber.
-re-install plugs...ensure you don't mix up wires when doing this ...doing one at a time will help that from happening.
-next check the oil and see if there is any evidence of water in the oil. It may look greyish or white foamy if water present.
-now start engine and see what happens on the exhaust side of thing. Initially watch the exhaust:
-how much
-smoke? what color and when it occurred or changed (also tell us what the outside temp is)
-look inside boat and around engine for any noticeable leaks from the exhaust.
-keep an eye on the temp guage and see how long it takes to warm up. If it goes up to 180 in the first few minutes I'd shut it down....othewise run it for about 20 minutes or so.
-shut the engine down and let it cool...have a beer here.
-after about 30 minutes check the FWC resevoire again and see if it went down....the wait is so you don't get burned.
-check the oil again to see if evidence of water in the oil.
-check plugs after you ran the engine to see if there is water beading on one or two or any major change from your install above....

Do this much and get back to us. There are some things like T-stat and circulating pump that can cause problems...but a combination of things can do it also, fuel mixture too rich can cause black sooty leaving a sheen on the water..a dead plug could dump raw fuel in the exhaust also..I think a simple systematic approach will help you sort that baby out. Let get a good look at her.

[CalebD]

Sheen at exhaust?

Is there an oily sheen on the water by your exhaust pipe?
Milky colored oil is an indication you have water in the oil. The same would be true with your exhaust cooling water that would show up as a rainbow of color on the waters surface from oil. Perhaps more likely is there is an anti-freeze leak in your HX to the raw water side - if no sheen on the water.
Others will know more.

[Mart]

Maurice,

Thanks for the rigorous protocol. I will check it out this weekend when I get out to the boat. For the record the boat has been docked for the winter. No freezing weather here on the lower Columbia River. The FWC system is filled with 50/50. I am out to the boat regularly to do work, start the engine, charge the battery, and heat up the cabin. New plugs last spring with about 30 hours on them. With the FWC system the temp gauge is showing ~160. With the heater on the temp is a little lower.

Last month I ran down to the fuel dock and filled the tank. Marine fuel here in Oregon is high octane, no alcohol. I have had some worry about octane rating and the A4 compression.

Thanks for the feedback. It give me something to focus on.

CalebD,

No oil sheen or rainbow color on the water. That is something I am looking for. The discharge was chalky and dissolved into the water. No soot this time but heavy soot a week ago and before that.

Thanks all, I will check back in next week.

Mart

[Carl-T705]

Mart, High octane has no effect. Think of high octane as " anti knock for higher compression engines. High octane will not burn valves or give you more power in a low compression engine. It will cost more for something you don't need. High octane keeps high compression engines for pre-igniting the fuel on the compression stroke. Actually the lower the octane the more explosive the fuel. For the most power you want to run the lowest octane rating that that your engine will run on WITHOUT preigniting on compression. This doesn't change for a lowly A4 or a supercharged race engine, it's just the way it is....... Although it does go against most conventional thinking.
Your problem may be as simple as moisture has settled in your exhaust system over Winter. I would run the engine up to operating temperature and let it run for 30 minutes or so to see if it clears up. The low coolant level combined with the white milky smoke does indicate a coolant leak though. Good Luck

[Mo]

"No oil sheen or rainbow color on the water. That is something I am looking for. The discharge was chalky and dissolved into the water. No soot this time but heavy soot a week ago and before that".



Hi Mark
That really sounds like a dry exhaust. Did you happen to shut the water off before that to throw most of the water out of the engine. Mine throws some soot every spring at first start. Give it a good check anyway and if all seems to be OK check that FWC fuild level frequently to see what is going on there.

[Mart]

All,

Yesterday, I ran the trouble shooting procedure suggested by Maurice.
Compression was 95 psi plus or minus a point. Plug gap was correct. The plugs were covered in black soot. No rust or ash was observed. As I recall from when I did my own auto maintenance, black plugs indicated to rich of a fuel mix. That indicates a carburetor issue. This may also be the cause of the soot discharge?

I removed the oil and found no evidence of water. It was just dark brown to black.

Back to the milky exhaust. Saturday, the exhaust cleared after running for about 20 minuets. Yesterday, the exhaust water was gray. Then milky then cleared.

The FWC system continues to require additional mix. I have not identified any leaking hoses or connections.

The temperature was in the fifties both Saturday and Monday.

The engine fired right up both days. No smoke was noted on either days.

There did not appear to be any antifreeze in the bilge.

The through hull water inlet was open when the engine was started and in the past.

From what I have seen the head looks ok. I am thinking a leak in the exhaust manifold?

Thank you,
Mart

[hanleyclifford]

Sounds like your exchanger is compromised. Antifreeze is leaking into the raw side and appearing in the exhaust.

[edwardc]

I agree with Hanley. If you're adding coolant mix, and its not leaking into the bilge, it's going somewhere! And with the grey/milky exhaust, the HX is your prime suspect.

Has the zinc been changed regularly in it? At least once a season?

[ILikeRust]

I third Hanley and Ed. When you said your FWC is requiring more coolant to be added, that combined with the description of the discharge, makes me think your heat exchanger core has rotted through.

[Mo]

yup

I'm on board as well. Sound like the heat exchanger is rusted through or sustained a crack for what ever reason. The guys above, Hanley for sure, have played extensively with FWC and would be an excellent source of info....as many others would be. I don't have one so I'd just be stating other's experience.

[hanleyclifford]

The only way to know for sure is to pressure test the unit, doesn't matter which side. My understanding is that the copper can be attacked internally by the solder which is more noble than the copper itself, hence the recommendation for zincs.

[Mart]

All,

On the question of a zinc. Are you stating the need for an additional zinc in the raw water line or the need for one some where on the boat? I have a zinc on the prop shaft.

Mart

[ArtJ]

The heat exchanger itself should have a pencil type zinc installed, normally
this is in the salt water side.

Regards

[hanleyclifford]

The zinc is actually in the exchanger itself via a 1/8" NPT fitting.