Stalling wth engine cowling on

[ttriebler]

Interesting one this....<br />I have a 115hp inline 6 (1976) and have done the carbs, new dizzy cap and plugs, fuel system etc.<br /><br />I tuned the idle jets so that the motor finally goes from neutral into gear and doesn't stall.<br /><br />Install the cowling and she stalls when going from neutral into gear. I guess there's not enough fresh air getting to the carbs. Take the engine cowling off andshe goes perfectly again.<br /><br />I spoke to a marine wrecker who said it was the "top mounts" (what are they) being worn out and hence the engine is sucking in exhaust gas. These mounts would be difficult/expensive to replace. His suggestion was to just drill some holes into various areas of the cowling thus allowing more fresh air to enter.<br /><br />Anyone had experience with this situation and can explain and possibly provide some advise?

 

[Hooty]

Re: Stalling wth engine cowling on

Sounds like exhaust ok but I'm not sure what he means by top mounts either. I'd check the exhaust cover and adapter gaskets. I would not drill holes in anything.<br /><br />c/6<br />Hooty

 

[jim dozier]

Re: Stalling wth engine cowling on

Yeah, ixneh on the drilling holes. You either have an exhaust leak on the exhaust cover gasket or an exhaust leak on the powerhead gasket (where the powerhead bolts to the outboard). You should see some evidence like black soot around the gaskets where its leaking. Find the source and fix it, don't drill a hole to fix a leak.

 

[dilligafda]

Re: Stalling wth engine cowling on

The "top mounts" that are being referred to is where the exhaust is coming from. The source is a leaking exhaust plate gasket. Replace the gasket and check the upper motor mount rubber for deterioration from the heat and replace as needed.

 

[ttriebler]

Re: Stalling wth engine cowling on

Thanks for your responses. OK NO HOLES to be drilled.<br />dilligaf could you please explain the upper motor mount rubber. I have looked through the manual and don't understand what/where this part is. Exhaust gaskets should be easy to replace.

 

[dilligafda]

Re: Stalling wth engine cowling on

The exhaust plate I'm referring to is also called the adaptor plate and gasket replacement requires powerhead removal. The motor mount rubbers are located under the adaptor plate. The steering arm attaches to it. Look in the service manual (depending on which one) under the driveshaft housing and you should find the motor mounts. Keep us up to date on the repair!<br /><br />dilli<br />

 

[Walker]

Re: Stalling wth engine cowling on

If she idles with the cowling on and stalls when you put it in gear I don't think its an exhaust leak problem. Sounds like you'r running too rich with the cowling on. A 1976 motor could very will have erosion in the idle jets.

 

[mellowyellow]

Re: Stalling wth engine cowling on

agree sounds like exhaust, but a chance it's<br />flooding maybe? does gas leak out of carbs when<br />you squeeze the primer bulb? when u rebuilt the<br />carbs, did you install new check valves?<br />good luck,<br />M.Y.

 

[ttriebler]

Re: Stalling wth engine cowling on

Gas doesn't leak out of the carbs when I squeeze the primer bulb. I didn't install new check valves when rebuilding the carbs.<br /><br />Wow powerhead removal to replace top mount rubbers and adaptor gaskets. Don't have the garage facilities to do that right now and I guess it would cost me thousands to have the shop do it.

 

[mellowyellow]

Re: Stalling wth engine cowling on

maybe you can try to do a de-carb and get some<br />carbon build up removed from exhaust ports.<br />slim chance, but cheap...<br />good luck,<br />M.Y.

 

[Gold Bear]

Re: Stalling wth engine cowling on

toddski <br /><br />Glad the idle mixture sugestion worked well for you.<br /><br />This new? problem about stalling with the cover on is a puzzle.<br /><br />When you accelerate from an idle speed, to up on a plane does the engine stuble at all? If so, open the idle mixture screws a bit more and try again until acceleration is smooth, with no hesitation.<br /><br />Look around under the engine cowling and make sure there is nothing unusual such as a spark plug wire with a bad spot in the jacket - that shorts out when the cover is on, but is not a problem when the cover is off.<br /><br />Look around the area of things that move under the cover, and see if anything is hitting the cover once the cover is in place, and is not a problem when the cover is off.<br /><br />You can check the condition of the spark plug wires by spraying them with a window cleaner such as Windex. With the engine running, the Windex will make any bad spots "spit" and you can see the problem.<br /><br />Once you are satisfied with the idle mixture, look around the engine for anything that changes when the cover is on, as compared to off.<br /><br />I suppose the exhaust thing may be the problem, but before I pulled the powerhead, I would like to feel that something positive was actually going to be accomplished by all that work!!<br /><br />Good Luck,<br /><br />Gold Bear

 

[DHPMARINE]

Re: Stalling wth engine cowling on

Toddski,<br />This is a long shot,but I saw it happen once or twice.If the exhaust is plugged the motor will act the same way.If it can't get out...air can't get in.One time was a rodent nest in the exhaust leg (just above the lower unit).Another was a Johnson right after a waterpump job.Someone put the prop shaft bearing housing in upside down,and the zinc anode was cutting off the exhaust.Not a problem on Merc's,though.Keep us posted.<br /> DHP

 

[ttriebler]

Re: Stalling wth engine cowling on

Gold bear, (and others) thanks for your feedback.<br />Without the cowling on the boat goes very well from idle speed (in gear) to full throttle. I've managed 40mph out of her so far so I think we're ok there.<br /><br />I wouldn't mind doing a de-carb and seeing if something's a bit clogged. Then will also check just to see if the cowling is somehow sticking or rubbing on something that is causing this strange situation. <br /><br />Boat is in storage now for about a month so it will be a short while before I get back to you with an update.