140 mercruiser missing after it gets warm

[splatter]

Re: 140 mercruiser missing after it gets warm

I took the boat out sunday and it ran as it should. lane:No sputtering at the 30 minute mark . The only thing I did was I moved the ign coil away from the motor by mounting it on a piece of 6" all thread and insulated it with a beer coozie . I also noticed that the engine ran about 20 degrees cooler than it had been running before, even though it was a good bit hotter on sunday .
Of coarse I don't think moving the coil had anything to do with the engine temp changing .

I'm thinking that the whole thing was caused by the engine running hotter than normal and the coil being mounted right on the engine was causing it to overheat and break down . As to why the engine was running hotter than normal all I can come up with is that maybe the new outdrive was running hotter during the initial break in period . I'm about 7.5 hours into the 10 hour break in , Maybe things began to losen as they broke in and now its back to normal operating temp .
can't say for sure I'm just glad its running good again and I hope it continues to do so .
I'm still going to mount a couple of clam shells on the motor cover to scoop some cool air into the engine compartment .

Thanks for all the help guys especially MikDee whose given some great tips through all this .

i will give an update again soon just to let you know if its holding up . if it isn't I'll be back crying the blues:sour:

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

What I meant was, I know you must be getting 12V from the solenoid when starting/cranking, but if you take the sol. wire off the coil, and put the Pos. + probe from your meter on it, and the Neg.- probe from your meter to ground, with the ignition key on Run, are you getting 12V? or 0 volts? It should be 0 volts.

 

[dubs283]

Re: 140 mercruiser missing after it gets warm

break-in has nothing to do with an engine or drive running hotter/cooler

don't remember reading anything in this thread about engine temp, figured if there had been that is a big deal and someone would have mentioned it, its a long thread and i don't remember everything from it

that said, the temp difference could be a blockage in the cooling system that dislodged to simply a faulty guage - we may never know, but in future posts, keep in mind even the most seemingly arbitrary thing about your engine could be the key to your issue

glad you got it figured out and good luck

 

[emt29179]

Re: 140 mercruiser missing after it gets warm

break-in has nothing to do with an engine or drive running hotter/cooler

don't remember reading anything in this thread about engine temp, figured if there had been that is a big deal and someone would have mentioned it, its a long thread and i don't remember everything from it

that said, the temp difference could be a blockage in the cooling system that dislodged to simply a faulty guage - we may never know, but in future posts, keep in mind even the most seemingly arbitrary thing about your engine could be the key to your issue

glad you got it figured out and good luck

2nd page, next to last entry talks about temp. This whole thing has me scratching my head.

 

[splatter]

Re: 140 mercruiser missing after it gets warm

What I meant was, I know you must be getting 12V from the solenoid when starting/cranking, but if you take the sol. wire off the coil, and put the Pos. + probe from your meter on it, and the Neg.- probe from your meter to ground, with the ignition key on Run, are you getting 12V? or 0 volts? It should be 0 volts.

I get 0 volts ,did this after you advised me to check the solonoid

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

I get 0 volts ,did this after you advised me to check the solonoid

Thanks splatter, I'm still trying to get this clear in my own head, for future reference,,, One last question, is this wire coming off the right side of the solenoid "S" small terminal (as you're facing it), or the left side the "R" or "I" small terminal?

By the way, IMO, I've found the break in of a new outdrive, or engine, may cause it to run a bit hotter then normal. After rebuilding my son's 355 modified 74' Nova yrs ago, it ran hot for quite awhile till it was fully broke in. I almost bought a solid aluminum flex fan, but didn't need it after a short while.

 

[splatter]

Re: 140 mercruiser missing after it gets warm

I think it was the right side but i can't say for sure . I will have to look at it later and see

 

[splatter]

OK ,I installed 2 clamshell vents on the motor cover and now the missing is almost gone .Its really intermittent at this point . So basically the vents were a bandaid to help get some cool air to flow over the coil . For some reason my coil is getting hot and this is the source of the trouble . I can use the boat at this point but I would really like to figure this out

 

[James D. Evans]

Is the coil you installed a true 12 volt coil? There is a difference, a true 12 volt coil will handle 14 volts. If its just a standard 12 volt coil, there only rated to run about 10 volts ie like the stock coil with points ignition. NAPA IC14SB, Autozone LU800, and BWD E40P are true 12 volt coils rated to handle 14 volts. I installed the NAPA with my electronic ignition and had to add a ballast resistor to keep the voltage at the coil down below 14 volts. My electronic ignition requires 4 amps or less or it will fry. Voltage/Ohms=Amps. I ran an additional wire from the key just for the coil, to get steady voltage. I too, was having problems with coils overheating, and was seeing 13.5+ volts on the resistor wire also. My coil is still mounted in the original spot on the engine, and I put the ballast resistor over by the reset button in one of the pre-drilled holes. Ran like a champ yesterday, burned about a 1/3 tank of fuel without a hiccup.

How many volts are you getting at the coil measured from the coil + and where the engine ground wires are? Also what coil are you using?

 

[splatter]

Is the coil you installed a true 12 volt coil? There is a difference, a true 12 volt coil will handle 14 volts. If its just a standard 12 volt coil, there only rated to run about 10 volts ie like the stock coil with points ignition. NAPA IC14SB, Autozone LU800, and BWD E40P are true 12 volt coils rated to handle 14 volts. I installed the NAPA with my electronic ignition and had to add a ballast resistor to keep the voltage at the coil down below 14 volts. My electronic ignition requires 4 amps or less or it will fry. Voltage/Ohms=Amps. I ran an additional wire from the key just for the coil, to get steady voltage. I too, was having problems with coils overheating, and was seeing 13.5+ volts on the resistor wire also. My coil is still mounted in the original spot on the engine, and I put the ballast resistor over by the reset button in one of the pre-drilled holes. Ran like a champ yesterday, burned about a 1/3 tank of fuel without a hiccup.

How many volts are you getting at the coil measured from the coil + and where the engine ground wires are? Also what coil are you using?

I installed a "true 12v coil" when I upgraded to EI . When doing this I bypassed the resistor wire as stated on the instructions with the coil .

Just for grins I hooked the new coil up with the resistor wire the other day and it made the problem alot worse .

 

[splatter]

I found something yesterday that said incorrect plug wires can cause the coil to run hot .The plug wires I had on there were ordered over the net and were suppose to be for my boat . But I figured why not try it any way . so I stopped at the marina and got a set for my boat .(they looked them up by the boat serial #) I installed them and took the boat to the lake . I had things to do so I couldn't stay on the lake long so I don't know if this fixed it or not . I do know the coil still feels hot but I don't know how hot the coil would feel under normal conditions cause I never had reason to feel it before this all started happening .

Before installing the wires I checked the resistance in the old coil wire and the new coil wire(coil to distributor) . One was 6.53k ohms and the other was 563ohms . So there is a very significant difference . I can't remember if the new one was the lesser of the 2 or not . I'm thinking the old one was the smaller value but I can't say for sure . At any rate I definately had the wrong plug wires on there .

I will check back in a couple of weeks to post the outcome .

 

[splatter]

it still isn't fixed . Although it takes it longer to start acting up it is still doing the same thing

 

[boozer1966]

I have a 1984 Mercruiser 140 that does the same thing. It's definitely electrical. I have replaced the entire ignition system. It has gotten better with just about everything I have done. But after about an hour of normal running it starts to miss. I have about given up trying to cure it.

 

[Fun Times]

it still isn't fixed . Although it takes it longer to start acting up it is still doing the same thing

What year is your engine? Serial number handy?

Did it act up while hot or running the trim pump again? Next time it acts up, stay at the same throttle position and vent/remove the engine cover to see if it helps again.

Also check the condition of the main power and ground battery cables by giving them a slight bend to see if you feel/hear any internal corrosion build up. A voltage drop test while hot may be beneficial if the problem is electrical....Since things like running the trim pump seems to effect it while hot. Small battery cable size maybe? Aging battery?
Could also have an heat related internal alternator problem. The correct coil for the new ignition system you installed is important.

It would be best if you had an infrared temperature gun for your testings.

Is the flame arrestor clean?

Just some random thoughts to keep in mind as you do your testing! Hope you find it soon, good luck.

 

[splatter]

What year is your engine? Serial number handy? Did it act up while hot or running the trim pump again? Next time it acts up, stay at the same throttle position and vent/remove the engine cover to see if it helps again. Also check the condition of the main power and ground battery cables by giving them a slight bend to see if you feel/hear any internal corrosion build up. A voltage drop test while hot may be beneficial if the problem is electrical....Since things like running the trim pump seems to effect it while hot. Small battery cable size maybe? Aging battery? Could also have an heat related internal alternator problem. The correct coil for the new ignition system you installed is important. It would be best if you had an infrared temperature gun for your testings. Is the flame arrestor clean? Just some random thoughts to keep in mind as you do your testing! Hope you find it soon, good luck.

cant find anything wrong with the cables. Yes using the trim still makes it worse. I've checked and rechecked the grounds. What's a flame arrestor?

 

[splatter]

I'm going to try a new alternator ,don't think it's gonna fix it but it's all I have left

 

[kart74]

I have the exact same issue, and have done all of the same things as you including the new alternator. Is it hard to start when hot? I haven't put in a new battery or new battery cables yet, but I may give that a try as well. Do you have the Mallory distributor or the Delco? I was hoping it would have just sank last weekend as well. Sure hope someone finds the issue. Sure is frustrating.

 

[splatter]

I have the exact same issue, and have done all of the same things as you including the new alternator. Is it hard to start when hot? I haven't put in a new battery or new battery cables yet, but I may give that a try as well. Do you have the Mallory distributor or the Delco? I was hoping it would have just sank last weekend as well. Sure hope someone finds the issue. Sure is frustrating.

i have the delco distributor . Dont bother with the new battery . Mine is new .My cables are good but im gonna change them anyway . I also gonna change the distributor cap again just because . Im about to sell mine cause Im about done ouring money into it