Yanmar Smoking and Making Oil

[Highlander40]

So, did you get a probe into the exaust pipe to check back pressure?
Would be a bummer to swap out the engine and find a rat in the muffler!

[Northeaster]

I sure it is somewhere in the earlier posts, but what is your hull speed?

I still say that you gained 500 rpm by changing the pitch, and the engine is smoking as it is still overloaded at that point.

I am not a mechanic, and I am not trying to spend you money foolishly but .. You mention that you could reduce the pitch to zero... Ok, let's take the sillyness out for a minute. I am not saying going too low, but if you can depitch by 1 or 1 1/2 more inches and make lets say 8 knts at max rpm (4000), and cruise at maybe 7 kts (let's say 3200 -3400 rpm or so) with no black smoke and a happy engine, would that not be a decent thing.

I feel for you, and it's too bad that you have paid big buck for the new turbo, but hopefully you can sell it to someone soon ,and recover even 50% of the cash.

Best of luck!

[never monday]

IP = injection pump

preferably from the side

[Gnitfar]

On smaller Yanmars, such as the 3GM, the mixing elbow (exhaust riser) becomes rusted internally over time and begin to restrict exhaust flow resulting in lost power and thick black smoke coming out of the exhaust.

[Navicula]

have you checked the timing belt, to see if it lined up

[Tspringer]

The engine will currently cruise at around 6 knots at 2500rpm.... but she is throwing plenty of black smoke and sooty exhaust water while doing so. I am really not inclined to ignore this and just head out long term cruising with what is an obvious major engine problem. If I did not get billowing clouds of reeking black smoke and a trail of black water behind the boat at cruising rpm then I would probably just ignore it. I am not a diesel mechanic.... but I am reasonably sure that simply running the engine in this state will wreck it if it is not wrecked already.

I will get a picture of the injection pump. I do not know if I can post it here or now but I can email it to you regardless.


Terry

[Gene :^)]

I agree that the prop is just compensating for low power output of the engine.

I still think it is because we are not getting the proper turbo boost.

However, we have determined:

1. It is not the intake side (no restriction).
2. It is not the Turbo bearings (replaced).

So the next major cause would be exhaust restriction...

This is something you could do yourself:

-Go to the auto parts store.
-Get 1/8 inch brake line tubing (about a 3 foot stick).
-Get an engine vacuum gauge (make sure it reads both vacuum and a small amount of pressure, most do. You are looking for 1 to 3 psi, they usually go higher for measuring fuel pressure).
-Cut one end of the brake line tube off and remove both fittings (slide them off).
-Loosen your exhaust hose and feed the line down into the hose as deep as you want (your book had the distance for a good reading).
-The exhaust hose may leak a small amount where the tube won't let it seal but it should be ok for a quick test.
-Attach your vacuum/pressure guage and see what you get at various RPM.

I would hope to see no more than 2 psi.

Note: if you can not get the tube to fit and still put the hose on the exhaust outlet. Maybe you can just install the hose about 1/4 to 3/8 inch on the manifold (so it is barely on there) and clamp it good at the edge. Then you can make a small hole in the hose for your tubing to be inserted. After the test you just slide the hose all the way onto the manifold and the small hole won't make a difference since it will most likely be under the clamp anyhow.

[Tspringer]

two shots of the injection pump.


Terry

[GeoPowers]

I've been watching this thread for a while, hoping for your success!! I know the last thing you need is another armchair mechanic, but I can't help thinking what I'd try if I were you. When I was building houses, I had to get the plumber to do video inspections of the clean-outs to the streets. The same equipment could tell you quickly whether there were any obstructions on the exhaust side. Here's what I'm talking about:



I'd expect about $100 in cost. Good luck!!!!!!!!!!!!!!!!!!

[Gene :^)]

I have been thinking about this and researching online all day...

Everything I have read (and I have burned up google today) points to only a few things and I have listed them in the order I feel they should be checked... We have only absolutely ruled out 2 of 6 items.

1. Intake restriction (ruled out).
2. Damaged Turbo (ruled out).
--
3. Restricted Exhaust (I hope you will test this).
4. Bad Injectors (I hate to say it, but if all else fails we need to look again at the injectors. Maybe there was a mistake there.)
5. Injection Timing off (seems unlikely but was not checked).
6. Bad Injection pump (seems unlikely but possible).

Edit: Forgot to add, Air leak between the turbo and intake of engine causing a loss of boost. I am sure this would be loud and obvious so I left it out.

[never monday]

pull this hose off and see if it has air pressure / flow when your on boost.

while it's disconnected also see how the load test goes with smoke production / RPM's

[Navicula]

there you go......number 5. Injection Timing off (seems unlikely but was not checked). can we please ellminate the timing issue which includes the checking the belt, we know the engine has 4000 hours. On my TDI we change the TEE belt every 160,000k and timing is very important

[never monday]

Originally Posted by TACK OFF

there you go......number 5. Injection Timing off (seems unlikely but was not checked). can we please ellminate the timing issue which includes the checking the belt, we know the engine has 4000 hours. On my TDI we change the TEE belt every 160,000k and timing is very important

please stop post this disinformation. This Yanmar was not made be Volkswagen. It is not a timing belt engine.

[Gene :^)]

Just got off the phone with

Oregon Fuel Injection, diesel fuel injection pump, turbo, injector and diesel performance product specialist.

in Eugene, OR.

Their service guy says that even grossly overfueled we should see full turbo boost. He says that if the intake is clear, no boost is escaping or leaking from the hoses/clamps, and we have already replaced the turbo... it probably is the exhaust back pressure. He said back pressure should be measured with a manometer, but to get an idea of the pressure the test I suggested would work. He said no more than about 2 psi of back pressure.

[Laidback]

Terry,
By now you must be overloaded by advice on solving the problem of your engine not performing as it used to. I am sure everyone has your best interests at heart.
May I suggest the following from the service manual of your engine . These trouble-shooting extracts relate precisely to the
symptoms you have described so many times :
The very first is easy to test - run the engine without the air cleaner filter.