WON'T IDLE

boatmoter1

Cadet
Joined
Sep 13, 2005
Messages
16
I hope that theres help for this problem ..<br /> 1978 evinrude 140hp/ crossflow.. <br /> will not idle below 1100 rpm's,just shuts off.. responds well to throttle, have replaced intake gaskets,spark plugs,coils, tried a known good set of carbs.. <br /> had the timing checked,tried hi test unleaded..<br /> NOTHING I have done has changed the symptoms at all.. <br /><br /> compression test>> three cylinders have 105 to 115 >>and the other has 85// is the compression the problem??
 

dolluper

Captain
Joined
Jul 19, 2004
Messages
3,904
Re: WON'T IDLE

Wecome to Iboats<br />That reading would be a problem <br />You could try a decarb but I think it's a little more serious
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: WON'T IDLE

A big welcome your way - - - A couple of things -<br /><br />First forget the hi test - these engines are designed for 87 octane. I agree with dolluper on the decarb. You might try it a couple of times.<br /><br />One other possibility if the compression comes up is to see if the thermostats have been removed. These engines do not like to idle if run cold. <br /><br />Else pull the heads & have a look see.
 

boatmoter1

Cadet
Joined
Sep 13, 2005
Messages
16
Re: WON'T IDLE

Thanks for the comfirmation.. looks like Im gonna just rebuild it and be done with it...<br /><br /><br /> Thanks...
 

Pony

Rear Admiral
Joined
Jun 27, 2004
Messages
4,355
Re: WON'T IDLE

make sure you figure out why that cylinder went bad so you dont have the same problem after rebuild......don't want to have to rebuild it again for the same reason....JMHO (If it turns out that a rebuild is necessary of coarse)
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: WON'T IDLE

A compression reading of 30 psi difference between the highest and lowest reading indicates a rebuild might be required, but first remove the cylinder head to inspect the gasket, sealing surfaces, piston, cylinder walls, etc.<br /><br />That'll tall the tale.
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: WON'T IDLE

Are we jumping ahead too fast? A rebuild?<br /><br />Try the decarb and see if that brings up the compression on the ailing cylinder. Also, like capt. Reeves mentioned, a blown head gasket can give you a can of worms.<br /><br />I am a mercury guy (so I may need a little slap in the right direction, but...) but I know (at least with old mercs) that worn reed valves will not let you engine have a low RPM idle. Have you inspected them? Also another classic poor idle culprit is too much air intake. Are the carbs properly sync'd with the throttle.<br /><br />Just throwing stuff out there<br /><br />-andy
 

boatmoter1

Cadet
Joined
Sep 13, 2005
Messages
16
Re: WON'T IDLE

I removed the powerhead and removed the heads and intake, all 4 cylinders are 0.30 over, there is 0.35 clearance bettween the walls and cylinders,the other 3 have .020 clearance..<br />there is some scoring in 2 of the cylinders,<br />I did not find the clearance spec's in my book..<br /> whats my next step to determine if the sleeves are keepers??
 
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