Yanmar 1GM10 - Smoke, No Power

[SkiprJohn]

Fuel injection timing? Or, was that already mentioned?
regards,

[Tellie]

Originally Posted by billmcc

Chief: We removed exhaust hoses, looked through them (about the only light at the end of the tunnel!) blew through them and hosed water through. Removed and washed out water trap. I am not sure about the elbow - it has never been changed. I will whip it off next week, and if in doubt will test with the elbow off my friend's boat. Blocked elbow would tick all the boxes! Will let you know how I get on. Thanks again.
Bill.

Wait, you haven't checked the elbow? Even when you had the head off? Surely the Yanmar mechanic checked the elbow way before he started yanking parts off the engine. I hope it is that simple for you. But if this turns out to be a bad elbow you just went through a lot of needless expense.

[s/v 'Faith']

Any updates?

[billmcc]

Next Saturday is the day. I have booked the mechanic for 10AM and we will spend the day getting to the bottom of the problem. Due to work and family stuff, I only had a brief visit to the boat this week, but I took the opportunity to remove the exhaust elbow which unfortunately is clear and unblocked.
Bill.

[Tropic Cat]

Originally Posted by billmcc

........
Anybody: Does anybody know what the spec is for compression on 1GM10? Is 40 bar enough?

I'm late to this thread but can at least answer one of the questions asked. From the 1GM10 Yanmar DIESEL INBOARD SHOP MANUAL ONE, TWO , THREE CYLINDER ENGINES


Compression Gauge
An engine with low compression cannot be properly
tuned and will not develop full power. A compression
gauge (Figure 37) and adapter specifically designed for
diesel applications is required to measure the high cylinder
compression pressure (390-470psi [2700-3300kPa]).
If these specialized tools are not available, refer compression
testing to a qualified technician. See Chapter Three.

I have the manual in PDF format. I believe it was Gord who posted the url to download it. You might ask him to post it again?

Also from the same Yanmar manual:

Black Smoke
Black exhaust smoke results from excess fuel (rich) that
forms soot when burned. Either excess fuel or insufficient
air can cause black smoke. Some possible causes are a defective
fuel injection pump, poor injector spray pattern,
low injection opening pressure, clogged air intake, restricted
exhaust system or low compression pressure.

The fuel injection pump is common to your various configurations, however you describe classic clogged elbow symptoms. I have two of these engines in my boat and they are very solid engines.

[chihuahuas]

Run the engine with the alternator belt off. See if it runs normal. Probable will. Reconnect belt and problem shows up. Check temp on alternator after run 2 -3- minutes. See if it is real hot. May have a short on one of the stator windings causing the alt to run flat out. This extra load will do what you have..

ALso run with cover off. Sometimes exhaust leaks in and starves the engine for O2.

[s/v 'Faith']

Originally Posted by chihuahuas

Run the engine with the alternator belt off. See if it runs normal. Probable will. Reconnect belt and problem shows up. Check temp on alternator after run 2 -3- minutes. See if it is real hot.....

From Bill's first post;

black smoke and oil under any kind of load and I can only get 2.5Kts (plus 1 Kt if alternator belt disconnected) instead of my customary 5Kts.

Hope it goes well today, maybe the 'new' mechanic will find the problem.

Good luck

[Tellie]

That's right, todays the day. Pins and needles.

[billmcc]

Exhaust elbow is clear of blockage, but it has an internal hole in the water jacket so water is entering the exhaust very high up and so could conceivably have run into exhaust port and caused the hole in it's side wall. Saturday we put on a different elbow, front exhaust and water lock from my friend's boat. No improvement. Put on rocker cover from his engine in case my breather was faulty. No improvement. Checked spill timing carefully - it's exactly on the mark. Connected clean diesel supply to lift pump ard ran engine on that for some time. No improvement.
Engineer in UK said remove head and check piston is 22thou proud of block on TDC. Con rods bend easily in these engines say if water got in combustion chamber. Suppose I will have to try it, but can't really buy the idea when compression is so good.
Chihuahuas:Thanks for your tip, but I am leaving alternator belt disconnected until I get engine running ok. Will address potential alternator probs then. All tests done with engine cover off.
To summarise: engine now seems to run pretty well out of gear. Put in gear and open throttle and you get clouds of diesel smoke and no power.
Next plan??? Will get diver to check folding prop again. Will speak again to the diesel specialist who overhauled my injector pump - could he have made some error? Perhaps I should try the injector pump from my friend's boat?
Mechanic could only spare me 3 hours on Saturday, but he has no better ideas.
I feel really stupid over this; there must be something obvious we have missed!
Bill.

[John Pestana]

Before going any further since it seems you just about covered any mechanical causes. The fuel itself is where I would look which has been mentioned previously but not sure if advise was taken.

[billmcc]

John: Thanks, but I ran it on a direct feed of fresh fuel yesterday. Road diesel from a filling station, not something from a tank in somebody's marina.
Bill.

[John Pestana]

Confusing why compression readings are so high. 100 psi above normal? Does engine revs freely and sounds good in neutral? Have you noticed any oil residue in exhaust?

[John Pestana]

Excessive oil in cylinders can account for higher compression readings. Higher readings is not the cause of your running problem but rather a result of the problem.

[billmcc]

John: No sign of oil from exhaust - just clouds of black smoke, and soot in the water being expelled when engine is under load. Engine starts easily and sounds good; problem only arises when you ask it to do some work! No rev counter fitted, so I can't be specific.
"Normal" compression may possibly refer to "minimum acceptable". I tested on cold engine just honed and fitted with new rings. Gauge used is an expensive professional model we use to test diesel car and van engines in our dealership.
Bill.

[Boracay]

Could the drive (chain) to the injector pump have slipped or jumped, or could the timing mark have moved?

THere is a discussion of a similar problem here.