unable to idle

[ALAG3]

Re: unable to idle

I stopped in my Mercruiser dealer yesterday to pick a few things up and asked them about my engine problems. I explained to them it recently began intermittent overheating problems along with an inability to idle. I also told them about the fuel pump vent tube filling up with gas, and that I replaced it to stop that problem. The guy at Mercruiser says that anywhere from 5-7 years, the exhaust risers begin to deteriorate and that a common symptom of a bad riser is a rough idle. Do you guys think this could be my problem? I am guessing to check it, I must remove it, but what am I looking for? Thanks!

 

[KaGee]

Re: unable to idle

An inspection of the spark plugs would give you an idea if water intrusion is your problem. Pull the plugs and see what they look like. If you have water, you might actually see water droplets on the plugs. Or, the plugs may look super clean... literally. Or, they may appear a little rusty.

 

[Stinger313]

Re: unable to idle

A new manifold and riser would be a good preventative investment.The heating problem you described is a clogged riser.1998 and you never replaced them,trust me its time.Pay now or pay alot later.Good luck

 

[ALAG3]

Re: unable to idle

Well, I think I may have found my problem with overheating, just wanted to "ask the experts"! I pulled my lower unit to replace leaking seals and found the following pieces of metal around the outside of the water pump housing. Even I know they aren't supposed to be there and suspect they are from the riser, but am not sure...all of the pieces in the below pics are metal and are rusty.<br /><br />

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[KaGee]

Re: unable to idle

That would be a good assumption. <br /><br />Although, check your flapper... they may be ready to self-destruct and the particles are from them. Probably not, but they should be checked out when you pull the manifold and riser.

 

[Don S]

Re: unable to idle

Those look like burned rubber pieces to me. Several possiblilities of where the came from.<br />1. The previous or present impeller.<br />2. Exhaust Shutters<br />3. Exhaust hoses between riser and transom exhaust tube.<br /><br />The only reason for the shutters or hoses to get burned (Charred) like that is due to lack of water. If the impeller has never been bad, a partially plugged riser will not allow water out in certain places. Then just the exhaust gas from the engine heats the rubber hoses or shutters till the burn and flake off. <br />If you are running in salt water, like your dealer said, 5-7 years and the manifold and risers are probably due for replacement.

 

[RandyJ]

Re: unable to idle

As for the over heating problem I'd suspect rust blocking passages in cooling system or manifold exhaust jacket. As for the fuel pump problem, I'm wondering if the correct fuel pump here is not the one in the carbureator(some times referred to as the "accelerator" pump) which squirts fuel into the carb when you pump the throttle for a cold start. As for excess fuel and flooding at the base of the carb I'd bet on a float valve not seating for whatever reason. If the fuel pump which supplies fuel to the carb is not leaking but is sending adequate fuel to the carb then I'd say there is no problem with that fuel pump.

 

[ALAG3]

Re: unable to idle

Thanks for the input...these pieces are definitely metal, and I plan to pull the riser off tomorrow and have a look. I'll post what I find there.

 

[MRS]

Re: unable to idle

I found the same metal pieces in my lower drive when I pulled it 120 cruiser they looked like they came from the inside of the exhaust manifold. When I drain manifold at end of every summer season a few tiny metal pieces come out of manifold and look the same but are alot smaller.

 

[ALAG3]

Re: unable to idle

Well, today I pulled the riser and exhaust/intake manifold off of my engine and here is what I found... ...Probably explains ALL my problems, huh? I am in the process of locating replacements. <br /><br />

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[ALAG3]

Re: unable to idle

I have ordered the parts to replace the manifold and riser, but I have another question. Since there is alot of rust present, do I need to flush the engine itself too? I am worried that there may be more rust somewhere else that will cause problems after reassembly. Any advice would be great. Thanks!

 

[rbezdon]

Re: unable to idle

Since you have it apart, flush it as much as you can. Of course there are rust clumps in the block if there are rust clumps in the manifolds, Since you have some of the engine dismantled you may have access to some of the freeze plugs. If you do these ae fairly easy to R%R and one of the best ways to get access to the block internal water passages. Remove which ever ones you can get to and flush through there. After your done make sure you drain everything from the crankcase and put in new oil. It is fairly easy to get some of the water during this kind of flushing to splash up into some palces it should go. Maybe put rags in the exhaust ports etc.