dir dobbers in exhaust

renee338 · Apr 1, 2013

i am recently getting an old 1976 evinrude 35hp running that has been sitting for 5 years outside. it seems to have dirt dobbers inside where the prop is but have no idea how far they went. i am soaking the foot in a big bucket of water to see if i can soften it up. i realized this once i got it all ready on the top end, but when i crank it without the plugs it starts fast and good but once the plugs are in it turns really slow like a tenth of the speed with plugs out. so i put my air hose to it and blew it out and some black bug pieces came out with some dirt so im guessing dirt dobbers are my problem. what should i do from here anyone have an idea?

GA_Boater · Apr 1, 2013

Re: dir dobbers in exhaust

How fresh is your battery? Leads to slow cranking more often than bugs.

renee338 · Apr 1, 2013

Re: dir dobbers in exhaust

GA_Boater said:
How fresh is your battery? Leads to slow cranking more often than bugs.

all i have is my truck with cables but to achieve amperage i start the truck so it cranks well. plus my question is how to clear dirt dobbers cause i know they are there so they are a problem.

GA_Boater · Apr 1, 2013

Re: dir dobbers in exhaust

Hook up muffs and flush until the water runs clear.

renee338 · Apr 2, 2013

Re: dir dobbers in exhaust

GA_Boater said:
Hook up muffs and flush until the water runs clear.

nvm thank you tho. but i dont think you understand. the prop exhaust does not connect to the water cooling supply. so muffs do nothing.

GA_Boater · Apr 2, 2013

Re: dir dobbers in exhaust

Then you don't have a problem. Bugs can't go very far if you don't have through prop exhaust. If you do have through prop exhaust, exhaust gasses and water exit the motor through the prop. One of us is confused.

gm280 · Apr 2, 2013

Re: dir dobbers in exhaust

Being how this engine has been setting up for five years, you need to take it apart to change the water impeller anyway so clean all those pesky dirt dobbers as well while you have it apart. Because after five years of not running and setting in the yard in all types of weather that impeller has taken a set and won’t pump right. So one way or the other that LU (lower unit) is coming apart... I am guessing your outboard does not have the exhaust going through your prop. My 1976 Johnson 40 HP doesn't either. And at the same time you can clean out the upper section (or mid section as it is called) also. And I would look over any small opening that they could have sealed up on other parts of the outboard. They can find the smallest opening and make it their own so quick causing such problems...

71Windsor · Apr 2, 2013

Re: dir dobbers in exhaust

What is a dirt dobber? Is that like a mud wasp? Sorry I've never heard of one of which your calling it. I'd go with soaking the entire leg then pull your lower unit and see how far they have gotten. It's your engine so if you don't want to remove the lower unit I'd soak it for a few good days maybe try agitating everything with some air in between soaks.

cajuncook1 · Apr 2, 2013

Re: dir dobbers in exhaust

If, I were you, I would drop that lower unit and inspect completely. You need to change the water impeller anyway. If, significant mud dauber nest have been made, then you want to clear them out. They will restrict your water intake and restrict the exhaust coming out and that will lead to very poor running.

Here is a example of what mud daubers can do!! I had a chance to revive a low hour 1955 Evinrude 15hp Fastwin that look dumpster bound. After cleaning it, it had 115psi/120psi upper and lower. She looks like hell but she is a low hour motor. The previous owner stated that when he bought some property years ago, the motor was already in there sitting in a corner of the barn where I removed it from.

Here are some pictures, it will give you an idea what mud dauber can do.

BB9A88E3-4411-4249-A393-714D9E450485-4951-00000B29C7D57288_zps730085cb.jpg

48B90323-6EAE-45C6-BDFE-668616533010-4951-00000B29D40F6B1F_zps76c9563d.jpg

FAEAF9F6-C9A1-46DC-83AE-A8E513A5B81D-4951-00000B29DD68BB7A_zps29f48183.jpg

glenn property of pam · Apr 2, 2013

Re: dir dobbers in exhaust

we see slow cranking motors that will crank fast when the plugs are removed in at least 3 threads a week and 99% will be cured by cleaning the connections on the leads or rebuilding the starter. if you think that mud dobbers are the cause then remove the lower unit as it has to come off sooner or later to have the water pump serviced and you will be able to clean the inside off the lower. putting water backwards up the exhaust is a bad idea. a easy test is to make sure its not in gear then get someone to crank the motor with the plugs in and see if you can fell the airflow coming out of the exhaust. if you can then its not that plugged that it would slow a starter motor.
im fairly sure that you could plug a exhaust on a 2 stroke and it wouldnt slow a good starter. It would stop the engine from starting but shouldnt slow the cranking speed

cajuncook1 · Apr 2, 2013

Re: dir dobbers in exhaust

http://i737.photobucket.com/albums/xx19/photocajun/1955%20Evinrude%2015hp%20Fastwin/15hpEvinrudeFastwin006_zps6c948611.jpg[/IMG

[IMG]http://i737.photobucket.com/albums/xx19/photocajun/1955%20Evinrude%2015hp%20Fastwin/15hpEvinrudeFastwin009_zps20a860d7.jpg

71Windsor · Apr 2, 2013

Re: dir dobbers in exhaust

Glenn is right stopping or slowing the exhaust ports on a 2 stroke wouldn't really slow your starter, not enough to notice any way unless your cranking it for a long while. There's to much cavity to create the back pressure to slow or stop the engine. There's a good sign out of all of this though. You know atleast your getting a nice tight seal between Piston and piston wall so that's a bright side to look at lol.

71Windsor · Apr 2, 2013

Re: dir dobbers in exhaust

Good god I've never seen anything that bad. I've had my run ins with them but that is insane.

RogersJetboat454 · Apr 2, 2013

Re: dir dobbers in exhaust

cajuncook1 said:

Now that's just flippin nasty...

renee338 · Apr 2, 2013

Re: dir dobbers in exhaust

GA_Boater said:
Then you don't have a problem. Bugs can't go very far if you don't have through prop exhaust. If you do have through prop exhaust, exhaust gasses and water exit the motor through the prop. One of us is confused.

well mine IS thru prop exhaust so if you cannot answer my question for what im asking then don't post my crap. just butt out and aggravate someone else.

cajuncook1 · Apr 2, 2013

Re: dir dobbers in exhaust

After some clean up, which took some hours!!

Just thought I would give you guys a laugh, but I also wanted to impress upon the original poster to the need to drop the lower unit and inspect the exhaust and water cooling system.

Good luck!! Fyi.... that old mud dauber motor runs pretty sweet!!

renee338 · Apr 2, 2013

Re: dir dobbers in exhaust

glenn property of pam said:
we see slow cranking motors that will crank fast when the plugs are removed in at least 3 threads a week and 99% will be cured by cleaning the connections on the leads or rebuilding the starter. if you think that mud dobbers are the cause then remove the lower unit as it has to come off sooner or later to have the water pump serviced and you will be able to clean the inside off the lower. putting water backwards up the exhaust is a bad idea. a easy test is to make sure its not in gear then get someone to crank the motor with the plugs in and see if you can fell the airflow coming out of the exhaust. if you can then its not that plugged that it would slow a starter motor.
im fairly sure that you could plug a exhaust on a 2 stroke and it wouldnt slow a good starter. It would stop the engine from starting but shouldnt slow the cranking speed

thank you very much all i have is my truck and jumper cable to start it cause its electric start and a pain to crank by cord. i guess i need to find a shorter connection to start it off my truck. sometimes it starts fast with plugs in but it dont do it often. fyi i rebuilt the starter last week.

nwcove · Apr 2, 2013

Re: dir dobbers in exhaust

renee338 said:
well mine IS thru prop exhaust so if you cannot answer my question for what im asking then don't post my crap. just butt out and aggravate someone else.

:facepalm:

GA_Boater · Apr 2, 2013

Re: dir dobbers in exhaust

renee338 said:
well mine IS thru prop exhaust so if you cannot answer my question for what im asking then don't post my crap. just butt out and aggravate someone else.

I'm sorry you feel the way you do.
I'm only responding to the info you have posted. As in "the prop exhaust does not connect to the water cooling supply. so muffs do nothing. " and "well mine IS thru prop exhaust". As I said one of us is confused. But you don't want to listen, so good luck. I'm done.

nwcove · Apr 2, 2013

Re: dir dobbers in exhaust

cajuncook1 said:
http://i737.photobucket.com/albums/xx19/photocajun/1955%20Evinrude%2015hp%20Fastwin/15hpEvinrudeFastwin006_zps6c948611.jpg[/IMG

[IMG]http://i737.photobucket.com/albums/xx19/photocajun/1955%20Evinrude%2015hp%20Fastwin/[/QUOTE]

geez....i was thinking that was a special noise suppression option offered by omc back in the day!!! ;). dont have them dobber bugs here, but they can obviously make quite a mess!

dir dobbers in exhaust

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