1988 3.0L GM Stalls. Wassup?

[Bhamil]

My 3.0L runs fine for about 2 hours then loses power and eventually stalls as if the alternator wasn't charging. Had it tested and it takes a load. Batteries are charged, but, after it stalls it is hard to crank, even causes solenoid to click, like low battery. I can't duplicate the problem in the driveway; when running, oil pressure at 40-45 PSI, engine temp at 145-175, alternator output voltage at 2500RPM at 14.5VDC (I checked it with a DVM across the + to - battery terminals). I suspected the outdrive for seized bearings because I found water in the oil but, when I took the O/D apart, I found no bearing or gear wear. I'm snookered.

 

[Walt T]

Re: 1988 3.0L GM Stalls. Wassup?

Check basics, water in the engine oil? if so possibly its getting water in the cylinders. I'm guessing this is a Merc. Check the gimbal while you have the drive off.

 

[navigator336]

Re: 1988 3.0L GM Stalls. Wassup?

What's the battery voltage immediately after it dies? How long have you run it in the driveway? Have you ever changed the battery cables?

 

[cobra 3.0]

Re: 1988 3.0L GM Stalls. Wassup?

The fact that you can drive around for 2 hours trouble free makes me think it's battery/alternator related. How old is the battery? Check the terminals for tightness. They sometimes look tight, but are not. If the cables aren't corroded, I doubt that they would need changing.<br /><br />Do a load test on your battery. Some batteries charge up fine, but crap out after a few cranks/time. As mentionned earlier by navigator, keep your voltage meter handy. <br /><br />You may have a short somewhere that drains the battery, but I doubt it. Driving for 2 hours would normally keep it fully charged. Unless, the alternator has an intermittant problem like the one I had with my GM Van. I brought the alternator to an Alternator Rebuild Shop who checked it. During the check, his first remarks were " all seems fine" and a few seconds later "oops No it's not".

 

[Bhamil]

Re: 1988 3.0L GM Stalls. Wassup?

Thanks, all. It's too cold here to get out and try your recommendations but they all seem likely, and worth following up on. I have run the boat in the driveway for up to three hours at 2000RPM, then another 45 minutes at 3000RPM. Since I'm using a garden hose and the "ears" to supply water, I have tried restricting the flow to cause it to overheat and increasing the flow to rorce a leak; all to no avail. I agree with the idea that it's electrical, although a hydrostatic lock isn't out of the realm of possibility.

 

[edwardh1]

Re: 1988 3.0L GM Stalls. Wassup?

recent ( 99 or 00) merccruiser service bulletins say to only run an engine on "ears' at 1000-1500 RPM I think.

 

[Bhamil]

Re: 1988 3.0L GM Stalls. Wassup?

To Edwardh; that's probably true but it has to do with engine temperature and as closely as I've been monitoring the engine when it's running I don't think that's a problem. My engine is an older model 1988, 3.0L GM in-line 4 cylinder that uses external (sea/fresh) water to cool and I can regulate the temperature by the volume of water I provide via a hose. It would be better if I ran it overboard but, I can't simulate the problem, even pier-side. It's a head-scratcher, to me, anyway.

 

[DJ]

Re: 1988 3.0L GM Stalls. Wassup?

An overheating coil will make it lose power and die.<br /><br />Does it crank over slow?

 

[Bhamil]

Re: 1988 3.0L GM Stalls. Wassup?

To djohns19; Here's what happens - It starts and runs fine for about two hours. Then, it begins ti lose power, similar to what happens when an alternator goes dead on the car, draining the battery. after a few minutes the engine dies altogether and then turns over very slowly as if the battery is now dead. After a while )say 2 hours) it will turn over and run for a few minutes, then die again. If I wait, say 24 hours, it will start and run fine, repeating the process. I cannot cause it to happen under test conditions, however, and here's the kicker; After having the alternator rebuilt, I cleaned off all connections, and took the boat out last month. I ran about 45 minutes to the fishing spot, trolled all day (6 plus hours) and had no troube until I started back. Once I got the engine back up to speed (about 3K RPM) the problem started all over again. I do agree with the coil idea, however, and I suppose it wouldn't hurt to replace it. They're not expensive and it will eliminate it's potential as a trouble-maker. Thanks

 

[mrm]

Re: 1988 3.0L GM Stalls. Wassup?

Try rebuilding the starter. That fixed my some what similar problem.

 

[DJ]

Re: 1988 3.0L GM Stalls. Wassup?

Ben Hamilton,<br /><br />Hmmmm, interesting. The slow cranking speed, after a hot soak, intrigues me.<br /><br />I'm thinking: starter, coil, or bad connections. The last, is the cheapest.

 

[andrewgroup]

Re: 1988 3.0L GM Stalls. Wassup?

Random comments and Recs.<br /><br />Internal Combustions Engines require 3 things.<br /><br />Fuel, Spark, Air<br />The fact that it runs for a period of time rules out major or significant mechanical damage like no compression. Did I read you took the outdrive apart?<br /><br />Slow cranking problems can be eliminated by manually cranking the engine on the harmonic balancer before and after the problem begins. I suspect the engine will turn by hand just as easily before and after. If it cranks hard, remove the plugs and try again. Maybe you are picking up water after the exhaust manifolds heat up......this could be a bigger problem.<br /><br />If it turns as easily as beforem then the starter is having the problem.<br /><br />I insert sewing needles into the cables at various point so that I can get voltage drop reading on cables that I suspect may be contributing to failures. One close to the battery terminal, the Starter selonoid. When the thing is working properly document the voltages at these test points under idle, start and run conditions. I have found that corrosion within the cabling system itself occurs about every 5 years and I have a standard policy of replacing all heavy guage wiring at that interval. It cost about 30.00 for all of the cables but it's worth it never to have on-lake cable troubles. (I know my designated driver (SON) can't fix it and I might be in the mood to sink it if that ever happens. Ha)<br /><br />CRC makes electrical connector spray to coat these connections to prevent corrosion in humid conditions.<br /><br />Getting back to your problem, can you duplicate the problem on the muffs? NO you can't This appears to be load sensitive adding to the heat.<br /><br />I would run it on the lake with the Cover Off to provide more air....better cooling, Is the thermostat allowing the engine to run warm affecting the Carb.<br /><br />I agree with the previous posts that this is likely to be electrical so begin the process of documenting the various points when it all works correctly.<br /><br />Good luck once it warms up..

 

[mrm]

Re: 1988 3.0L GM Stalls. Wassup?

The starter on my 3.0 sits near the bottom of the bilge, very damp wet location. Water can easily get into the stater motor and corrade things up. Don't just replace the selonoid. Take the motor apart and make sure all four brush and brush holders are free and working properly. <br /> Getting home from a day at the jetties , Price-less

 

[Bhamil]

Re: 1988 3.0L GM Stalls. Wassup?

Hey, good comments, all! I apprecate the advice. I need the weather to cooperate a little so I can try these recommendations out! Thanks again.