Visit our Popular Forums

Mexico Mike · 22-01-2007, 18:47

Here's the story: My 40 horse 3 cyl. Izusu Pisces has always worked great and still does at lower RPMs, but has developed a rough sounding "missing" and/or "surging" kind of noise over 1500 rpms until after about an hour or so running, when you can inch up the throttle and it smooths out and behaves itself at 2000 like always.

Fuel filters are new, oil changed recently, air breather cap cleaned recently, and besides, if it was any of that stuff it wouldn't smooth out at all, I would think, plus not run smooth at the lower RPMs. No smoking at any RPMs, but tends to overheat over 2000 in this 80 degree water in Mexico.

My theory is my batteries are really sick (only 2 years old but boiled dry during their 1st off season) and the alternator is working too hard to try to charge them for that first hour or so. The alternator slipped recently and the engine ran perfectly. When I found the loose belt next time before firing up, and tightened it up, presto, problem back like before. Batteries keep their charge overnight since I installed the LED anchor light, but not much over 12 volts left in the am. The Link 2000 says 71% charge efficiency.

So, long story, but does this sound like I'm on the right track? (I'm going to Manzanillo tomorrow to buy 4 new deep cycle 6 volt golf cart batteries anyway, and I'll let you know if it solves the problem.)

Best,
Mike

OldSarg · 22-01-2007, 19:22

I think you would be better off checking the plugs to make sure they are properly torque'd in and maybe replacing your plug wires. It is also possible to have a craked plug, in this case. I have seen this problem when a wire or ground does not make until the metal expands with heat. New bateries, after having run them dry, would be a sound decision but it will not affect the running of the engine, except for being able to start it. So here it is; the smartest path 1. change plugs, plug wires, and gap and torque them to the manufacturers specs. Replace the batteries ASAP, your are on borrowed time with those. The first time they truely fail will be in cold wet weather when you need them. Oh yeah, it'll be dark too. I spent several years as a mechanic in the service and my brother was a pilot. He made thos same connections as you. So, are you a Pilot?

Mexico Mike · 22-01-2007, 19:37

Thanks for the response but I guess I neglected to say it's diesel, so the plugs and plug wires are really hard to find

I guess my real question is weather a normally functioning alternator could cause enough strain on the engine to make it sound like it's lugging or straining. Otherwise I'm afraid I may have alternator problems (again.) It's putting out 50+ amps when the engine first gets going but I'm wondering if bearings might be going out

No, not a pilot- too chicken. Not afraid of 3500 mile blue water passages in small sailboats tho.
Best,
Mike

**Alan Wheeler** · 22-01-2007, 19:49

Could be several possibilities, so the best is to eliminate one. I would check the Alternator drive belt. Ensure it is tight enough and in good condition that it is not slipping and grabing under load.
Do you have an Amp meter? If the alternator was intermitent or the load it is charging was intermitent, you would see the amp meter jump all over the show as the engine coughed. If the meter sits fine, then I doubt your problem is in the charging system. A 50A alternator isn't going to be much more than 1 or maybe 1.5Hp laod on the engine. For 40Hp, that isn't a great deal of load.
Failed bearings would sound bad. So you should be able to hear that.
I would be looking at the driving side of things. Like gearbox, shaft and such. But firstly the big one would be propellor. Is it clean and in good condition. Cavitation could be a good culprit. So as I said, many possibilities, so start by elimination of each.

delmarrey · 22-01-2007, 20:15

Did you release the parking brake???

Actually, I would consider checking out the injectors. When it's cold the fuel may not be vaporizing enough to run properly until it's warm........._/)

OldSarg · 22-01-2007, 20:17

"I guess my real question is weather a normally functioning alternator could cause enough strain on the engine to make it sound like it's lugging or straining." No, the alternator would not affect the load on the engine. To go back to your original concern about the “missing” could it be “Knocking”? With a diesel if your fuel/air mix ratio is off it can compress the air too much and the fuel/air mixture spontaneously ignites causing the “knocking”. I would look in that direction.

Mexico Mike · 22-01-2007, 20:37

Thanks again for responses.
Alan, I will replace the belt after I drop in the new batteries. It does look glazed and may not be riding up where it should on the pulleys. I do have an amp meter, but the (link 2000) panel was indicating a constant charge rate, only deviating an amp or less up and down. I did have a little trouble getting a shaft zinc to seat when I was hauled, and perhaps whacked it a little harder than I should have with the hammer, think a slightly bent shaft could cause a problem like I described? Cleaned and polished the Autostream prop with 400 grit so that's prolly not it. Problem really seemed to manifest after leaving the yard, though...
Delmerry, will have injectors checked if it's still bad when I get to somewhere a real mechanic might be able to do that.
OldSarg, no not a knock, more like a complaining, grinding/surging kind of noise, with lots of vibration. Makes me throttle back real quick. Also, when I did try to give it a bit more throttle just to see if it might stop, there is no more power forthcoming-almost like as if it were starved for fuel. I'm starting to like the injector theory alot, but will eliminate stuff I can do myself first as suggested.

**Alan Wheeler** · 23-01-2007, 01:25

Quote:

think a slightly bent shaft could cause a problem like I described?

Absolutley, but you would ahve to really smack it, so I doubt it.

Quote:

Cleaned and polished the Autostream prop

Arrr, back up the horses. Are you sure this is opening properly??

OK, let me put one important question in here. Does this problem happen when only in gear or when in neutral as well.
Del's suggestion of injectors and even the injector pump is possible, although you will have the issue in or out of gear. If the issue is only when in gear, Prop or shaft could well be a possible cause.

Mexico Mike · 23-01-2007, 08:28

OK, shoulda thought about that sooner- of course I tried it out of gear, to eliminate "downstream" stuff, and yes, it does it when out of gear also. Another clue for you- i finally did a couple of maintenance items that I had never done before, right before the problem manefested. One was change the oil in the governor, one was change the oil in the injector pump. This was supposed to be done regularly and I had never done it. Owner's manual said 30 wt oil in each, but when I drained the injector pump what came out was a very thin fluid that smelled alot like diesel. Since the POs had put ATF in the tranny which was supposed to use 30 wt, I just figured this was one more **'d thing, but now I wonder. Maybe now the injector pump has to get hot enough to make the oil thin down before it works properly? Maybe I should contact an Izusu person and see if there is something they can tell me?

delmarrey · 23-01-2007, 09:26

Oh Boy!!!!

**Alan Wheeler** · 23-01-2007, 10:18

Oil in the injector pump??? Oil in the governor?? I am not familiar with this type of Izusu then.
Pat, have you come across that?
Mike, usually the injector pump is lubricated with Diesel. Are you absolutley sure you have seperate oil lubrication?
I am not sure how you lubricated the Govenor. That is normaly an internal part of the injector pump.
I am a little puzzled on this.
What model engine do you have, as in a number not the name?

Mexico Mike · 23-01-2007, 14:14

Not absolutely sure of anything, Alan. Manual only says Pisces 40 for model number. Under Engine Maintenance section, after the stuff about crankcase lube, I quote: #5 The Injection Pump
The Injection pump oil should be drained and refilled at 300 hr intervals or at least once a season, whichever comes first. Drain the cam chamber through the oil drain plughole (see fig. 8B) on the lower part of the injection pump and refill through the oil dipstick hole with engine oil (see fig. 8A) <Figures 8a and 8b didn't look exactly like my engine, but there was a separate little dipstick and a plug to remove that did cause some fluid to drain out.>
#6. Mechanical Governor
The oil dipstick is located on the rear part of the governor chamber. See fig. 9. Every 300 hrs or once a season yada yada, drain the oil through the drain plughole on the lower part of the governor chamber and refill through the oil dipstick hole with engine oil. <once again pic was a little different, but there is another little dipstick and of course a drain plug, so I did what it said>
Both times there had been fluid showing on the dipsticks before I drained them, none when drained, and showing correct levels when refilled with a tiny funnel through the tiny dipstick holes. I was just trying to do the right thing, ya know? it's been three seasons and hadn't everdone it. Probably should have left well enough alone, I guess.

**Alan Wheeler** · 23-01-2007, 23:47

OK, that's a new one for me. Hey so I learned something today :-)
I don;t think you have done anything wrong. It is good you changed the oil. But are you certain you have the right weight oil? and is it filled to the correct level? That is the only thing I woudl think of. It could just be that the pump/gov needs servicing and putting the "correct" oil in it has shown up a fault.