Volvo 4.3GL Run on, run on, run on

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
My 4.3 Vortec (carb) runs on sometimes. Would switching to colder plugs make any difference?<br /><br />One mmechanics suggested reducing the idle speed but that doesn't seem like a fix to me. Any opinions?<br /><br />Another guy suggested just letting the engine idle longer.Any opinions?
 

Massawippi

Cadet
Joined
Jun 6, 2004
Messages
10
Re: Volvo 4.3GL Run on, run on, run on

My 4.3GL does the same thing. It's pretty much brand new (got it this season and it onlu has 23 hours on it). I talked to my dealer about it and he said just let it idle a little longer before shutting it down. So far that has worked every time. <br /><br />It's a bit annoying when you want to pick up a skier and you want to be safe and turn the motor off but oh well, I can live with that. <br /><br />Does anybody else with this motor have this problem? If you have this motor and you don't have this problem I'd love to know why not?
 

whickety1

Cadet
Joined
Aug 2, 2004
Messages
9
Re: Volvo 4.3GL Run on, run on, run on

I once read that when an engine runs on, it actually fires on the wrong stroke and run spinning backwards. This is caused by a hot spot in the combustion chamber(wrong heat range on a spark plug maybe)<br />I think I remember it being harmful, like excessive pinging. Over time it may bite you.
 

Dunaruna

Admiral
Joined
May 2, 2003
Messages
6,027
Re: Volvo 4.3GL Run on, run on, run on

Its lovingly referred to as dieseling, fuel is ignited by a hot combustion chamber, not the spark plugs.<br /><br />The problem is always heat related. Could be caused by wrong plugs, idling to high, wrong timing, coolant overheating, high underbonnet temps, carbon build up, fuel octane ratings can sometimes be an issue......the list goes on. <br /><br />Letting the motor idle a bit longer before shutting down allows the combustion chamber to to cool down (ever owned a turbo). Reducing the idle speed may fix the symtoms but not the cause.<br /><br />First step: Do a regular tune using correct plugs. Check cooling temps. <br /><br />Aldo
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Re: Volvo 4.3GL Run on, run on, run on

I''l check those plugs this weekend
 

cpjxh7

Seaman Apprentice
Joined
Jul 5, 2004
Messages
43
Re: Volvo 4.3GL Run on, run on, run on

Just swithching to 89 octaine help my situation.<br /><br />Check out this link: http://www.marinemechanic.com/volvo/sb-34-2-10.htm <br /><br />Here is a clip:<br />Volvo Penta has received several reports that 4.3 GL/GS engines running on 87 AKI fuel develop an audible knock on hard acceleration. This audible knock occurs when the ignition timing is set to 6" before top dead center (BTDC). The timing is set at 6" under the assumption that an owner will be using 89 AKI gasoline. Ask the owner if 87 AKI fuel was being used when the knock developed.<br />To eliminate the knock, you must reset the ignition timing on the 4.3 GL/GS to 1" BTDC (see instructions below.)
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Re: Volvo 4.3GL Run on, run on, run on

that's a coll web site. Is it a mechanics aid?
 

Wart T

Petty Officer 2nd Class
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Aug 1, 2004
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102
Re: Volvo 4.3GL Run on, run on, run on

Dieseling causes:<br /><br />Idle speed too high<br />Ignition timing advanced too far<br />Engine overheating<br />Gas Octane too low<br />Incorrect spark plugs<br />Internal engine damage (pistons or valves)<br />High compression engine/low fuel octane<br /><br />I have found that some dieseling problems can be helped by installing an extra blower in the engine compartment and making sure fresh air is constantly drawn in.
 

dmorley

Petty Officer 3rd Class
Joined
Mar 1, 2003
Messages
97
Re: Volvo 4.3GL Run on, run on, run on

Oldbaldfatguy summarizes exactly what a Mercury service bulletin said about the run on issue with their 4.3. I had the same problem and when I ran a compression check two of the cylinders were at about 65 pounds of compression. The machinist who rebuilt the motor showed me where small amounts of water had leaked in and created a kind of metal flake around the valves and valve seats. Once that happened I had "glow" plugs that created a diseling problem that nothing short of a valve job would cure. In my case the problem was exaserbated by the one piece mercury manifolds. Do a compression check and if it's bad you should be able to get away with just a valve job unless you have significant wear on the rest of the engine.
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Re: Volvo 4.3GL Run on, run on, run on

Hey Blk-n-Blu<br /><br />How did you get that Merc bulletin?<br /><br />Where can you get the same thing for Volvo Penta's?
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Re: Volvo 4.3GL Run on, run on, run on

Blk-n-Blu?
 

KM2

Chief Petty Officer
Joined
Oct 15, 2003
Messages
556
Re: Volvo 4.3GL Run on, run on, run on

my 4.3 gl volvo is now dieseling a little after coming down from high rpm quickly and shutting down. I'm also running 89-90 octane gas for the first time. (high gas prices) Alway ran premium before going back to 92 next tank of gas and see if that helps. I'll post back my results.
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Re: Volvo 4.3GL Run on, run on, run on

Anyone know how I can contact Blk-N-Blu?<br /><br />Also, how do you insert *.gif files?
 
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