Overheating and diesel if problem

jtim108

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Jun 29, 2020
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29
First time posting in this forum but I’m hoping to get some good information...I just bought a 1984 sea ray seaville with the mercruiser 140 and aloha 1 gen 1 out drive the boat has been very well taken care of and has only been in the water for 5 years of its life, and is a 1 owner boat, however we’ve ran into some issues

first time out the boat started to over heat so we shut it down let it cool for a while then brought it home, after some looking we found the thermostat was rusty and seized open which wouldn’t cause the over heat but the impeller wasn’t pumping so we replaced that went back out and it was good for most of the day then started to over heat again, got it back home and found the water pump on the engine was worn out pretty bad and found the water passages on the riser and the spacer to be completely gunked up however had good water flowing out of the exhaust manifold before those spots took the boat out after and real good clean and was out for about 7 hours tubing and such and at the end of the day temp climbed to about 185 and we shut it off for a bit....so that’s our first mystery we are thinking more debris came up stream and clogged things up again or the exhaust manifold wasn’t flowing water as good as we thought it was so my question is is it possible to use that marine flush that’s meant for eating away corrosion and gunk inside the cooling system to flush out the passages?

second issue was when we were last out the boat was shutting off very weird it was gurgling and trying to stay running several seconds after shutting the key off then once we restarted we found that the boat didn’t want to go under load it was just dying out, when we got home we found a little dibree in the fuel screen and the filter itself was crushed, also found some people saying run 93 but we’ve been running 87 octane, could the filter and the low octane gas be the hole problem we are having and what else should we look at while we are at it?

the boat was originally ran in salt water but was flushed and winterized every year with documents to show us what shop did it however we run the boat in freshwater now

any help would be greatly appreciated!
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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47,307
first, welcome aboard

second, with any new to you boat, much less one that is 37 years old, you need to do all the maintenance to it prior to using it.

Third, service your points. your timing is off which will lead to run-on. that last little gasp as the motor dies is the motor running backwards and sucking in water from the exhaust.
 

jtim108

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Joined
Jun 29, 2020
Messages
29
first, welcome aboard

second, with any new to you boat, much less one that is 37 years old, you need to do all the maintenance to it prior to using it.

Third, service your points. your timing is off which will lead to run-on. that last little gasp as the motor dies is the motor running backwards and sucking in water from the exhaust.

Thanks for your response it’s funny you say that cause last time we were out and it kept running after the key was off for a second the motor ended up getting hydro locked in cylinder 4 and we had to remove the plugs crank it and then change the oil when we got home and replace the fouled out plug so on top of the fuel issue from the filter we need to replace or clean the points and check timing?
 

alldodge

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Yes, check timing
Other things that can cause it to diesel; if its running rich and if idle is to high.
 

jtim108

Cadet
Joined
Jun 29, 2020
Messages
29
Yes, check timing
Other things that can cause it to diesel; if its running rich and if idle is to high.

It idles around 1000 rpm sometimes a bit lower around 900...and it seems to run a bit lean the plugs are showing more white in color then black and I think it’s running lean from the possible timing problem
 

jtim108

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Jun 29, 2020
Messages
29
Also as far as timing I’ve read I’m looking for 8 btc but not sure what my dwell should be on my points and I’m also not sure how to do the timing on this engine I was reading that I have to jump the spark interrupt plug when I check my initial timing?
 

Alumarine

Captain
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Feb 22, 2005
Messages
3,684
Idle speed should be 650-700 in gear.
Dwell 28-34
Timing for the 140 is supposed to be 6 BTDC.
As far as I know there's nothing to jumper on that era of motor.

If you provide your serial number(s) it would help.
 
Last edited:

jtim108

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Jun 29, 2020
Messages
29
Thanks for the info my timing was set at 2 atdc and found that the fuel trim for idle air mix was pretty lean only about half a turn out changed that to 1.5 turns as a base line until I get on the water, set idle at 850 since it’s out of the water and will drop a bit once it’s in the water and got the timing pretty close to 6 btdc and changed out my fuel filter that collapsed it started up faster then it has since I owned it and ran real smooth we will see how it goes on the water tomorrow
 

jtim108

Cadet
Joined
Jun 29, 2020
Messages
29
Idle speed should be 650-700 in gear.
Dwell 28-34
Timing for the 140 is supposed to be 6 BTDC.
As far as I know there's nothing to jumper on that era of motor.

If you provide your serial number(s) it would help.

The serial on my engine is 6805225

is there a website I can put these serial numbers into to get all of these specs?
 

Alumarine

Captain
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Feb 22, 2005
Messages
3,684
The serial on my engine is 6805225

is there a website I can put these serial numbers into to get all of these specs?

Not that I know of but you could get Mercuiser Service Manual # 3 part no. 90-95693 it has all the info you need.

If you put your motor and drive serial number in your signature it would help going forward.
 

Rick Stephens

Admiral
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Aug 13, 2013
Messages
6,118
You can read service manual #3 online at www.boatinfo.no .

Like to reenforce the point Scott made earlier that a new to you 37 year old boat needs all the maintenance gone through. The problems will keep adding up and you will find some things that are expensive if left until they fail. Not to mention the part where you have to walk back or the boat sinks.
 
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