Perplexing problem solved?

[mudnut]

Originally Posted by mudnut

I wonder who else knows that.Mudnut?PS.."Roll me over,roll me over,roll me over in the clover & do it again." Mudnut.

Question,How is the"Perplexing", problem "SOLVED".That is the heading of the thread isn't it.that is confusing.mudnut.

[Mexico Mike]

Mudnut- at the time I started the thread, I was pretty sure new batteries were going to solve the problem, just curious to hear if anyone had any other ideas. Still don't have the new batteries-had to be brought in from Guadalahara or somewhere, but now pretty sure that's not going to be the magic fix I was hoping for.
I did buy a workshop manual for this beastie last summer, wasn't sure it was the 3AB1, but glad to see I got the right manual. Just dug it out and it says the injection pump is "reformed Bosch, in line" and the governor is "all speed mechanical type" if that means anything to you.
Been reading the troubleshooting section and can't find anything that seems to fit my engine's problem except "engine lacks power while accelerating" and that mainly points to the injection pump and/or injectors. I just don't get why it works fine up to 1500 RPMs before the problem begins, and why the problem goes away after an hour or so of running.
It is good to know that if/when I need to get the injection pump or the whole engine overhauled, I have the manual to hand to the mechanic. Hope he'll have all the special tools required

[delmarrey]

Originally Posted by Mexico Mike

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?

Most injector pumps use the diesel fuel that runs threw them for lubrication. I know the bigger Isuzu's, the motor oil flows threw the pump and back to the motor.

I think I'd be looking at the govener a little closer. If the oil is too thick the counter weights may not be coming out until the oil thins down. Just a theory, but I'd check the manual real good to make sure you read right.

How many hours is on the motor???????????????

[Mexico Mike]

Del, the counter says 2391.1, should still be a baby, shouldn't it? I try to do oil changes religiously every 100 hours, and as I said, she doesn't blow smoke or use oil...
Believe me, I have quoted the manual verbatum in an earlier post, but the same manual also originally said to use 90 wt gear oil in the tranny and somebody crossed it out and wrote 30 wt, and the POs had ATF in there, so who knows?

[Alan Wheeler]

Ouch on the geabox. Any damage done?
Anyway's, 2400hrs should have had an injector check twice by now. Every 1000hrs is actually the extreme side of the dial for injector service. If they are poorly operating, that could be the issue right there. At 2400hrs, I would be suggesting the injector pump may need looking at. Especially if the oil has been deluted with diesel for sometime. So that may be another quite possible source of the issue. The problem with the ruff part is that not all cyclinders are likely firing, then when the pump speed raises enough to overcome the pressure loss of the injector, all cylinders fire and the engine runs smooth.

[delmarrey]

Yeah! 2000 hrs is fairly light for that motor. I think I would be trying to contact a marine Isuzu dealer to get the facts. Do you have the trany the manual says it has. Some one may have replaced the trany.

And trany's with multipule clutch plates usually run ATF, hard core gear drives take the 90W (Truck trans and differentials). 90W can gum up clutches.

Motor oil is more for hot applications where "ways" (sliding areas) need to be kept lubricated. And it is very seldom used in trany's unless they have bushings instead of bearings. ATF is used as a coolant and a lubricant like hydraulic fluid.

[Alan Wheeler]

Good point Del. Isuzu do use 30W motor oil in there Vehicle gearboxes. Mike do ensure you have the right box. If it is a hydraulic box, as many marine boxes are, it WILL use ATF.

[Mexico Mike]

Finally actually solved the perplexing problem. Found a knowlegable diesel guy who was willing to come aboard and just listen to the noise. Took him about 2 minutes to discover I had a broken motor mount bracket, and that godawful noise was just the sound of the engine rubbing on the mounting bed at certain RPMs. Found a local metal guy to fabricate a new L bracket, and the problem was solved. Now I can get to the other 999 things on my to-do list...
Thanks again for all the help.

Mike

[OldSarg]

You are a pilot.

[Mexico Mike]

I guess...thought I should 'fess up to my mechanical ignorance and hope someone might at least get a laugh out of it...gotta tell ya, though, the break was not obvious, it was down between the bed and the engine in a real tight area. The only way we could get the broken piece off without jacking up the engine was to cut the lower bolt with a hacksaw. The upper one must have been missing for quite some time. Also, the only way you could see any movement to indicate a break was when the engine was making that noise, and I never wanted to let it make that noise for long enough to see it. At least I'll know next time.

[SkiprJohn]

Aloha Mike,
Aren't you glad you didn't tear the engine and transmission apart for a rebuild?
Regards,
JohnL

[delmarrey]

So, how does a broken motor mount affect all this?

Originally Posted by Mexico Mike

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.
Best,
Mike

[Mexico Mike]

Ya know, I really don't know why the sound went away when the alternator belt was loose, if that's what you're asking. I really thought I had it all figured out at that point, and I didn't. Maybe the extra stress of spinning the alternator made the engine hit the bed a bit harder, who knows.
I did get some great info from this thread, and will most likely still have the injectors and pump looked at when I get back to somewhere where there are mechanics. That and adjust the valves, and I should be good to go on the infamous "Puddle Jump".

Regards,

Mike

[senormechanico]

Glad to hear you figured it out. I had a Yanmar 3HM35 in my old boat which I bought when it was only 1 1/2 years old. It ran like a clock, but when I shut off the engine it always had a "thump" at the instant of cessation of motion. I always thought that was normal, but after a few years when chasing another problem, I found a bad motor mount. The rubber was fine, but the adjusting bolt which supported the engine was broken and the engine was just sitting on it. The broken ends were smooth as a baby's butt. After replacing the motor mount, the mysterious "thump" was gone.

Steve B.

[mudnut]

Perplexing problem solved.Volkswagons have a different sound for everything also.Intriging situation.Mudnut.