Vent for Motor Cover?
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=6104
Printed Date: November-30-2024 at 5:54pm
Topic: Vent for Motor Cover?
Posted By: Siveck
Subject: Vent for Motor Cover?
Date Posted: March-25-2007 at 11:09am
I am considering a permanent modification to my '75 Nautique. Almost any problem that I have ever had with reliability has been heat related. I plan to dril or cut some holes or a slot on top of the motor box near the highest point. I will cover this with a rectangular louvered vent. The louvers will exit towards the stern. We all know that heat rises and this should considerably lower temps under the cover to prolong the life of the ignition system and such.
What do you think? Will this affect the existing bilge ventilation system? Any problems that I am not forseeing here?
Thanks for any replies.
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1975 Ski Nautique
"Small Letter Boat"
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Replies:
Posted By: TRBenj
Date Posted: March-25-2007 at 11:18am
The older style motor boxes had vents, so I dont think theres much harm in adding them.
Heat really shouldnt cause any engine troubles though- these motors only run at 160 degrees. I believe heat soak issues are usually carb related.
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Posted By: 8122pbrainard
Date Posted: March-25-2007 at 11:19am
It's not original! If the venting was required, then all boats would have them.
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/diaries/details.asp?ID=1622" rel="nofollow -
54 Atom
/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
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Posted By: MaddMarxx
Date Posted: March-25-2007 at 2:35pm
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rex marine and livorsi sell a vent that goes under the handle of the motor box that you cant even see, thats what im going to put on mine for better air flow! http://www.rexmar.com/page26.html - Look
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Posted By: eric lavine
Date Posted: March-25-2007 at 3:05pm
make sure all your vents are working as they should, a good way is to put a shop vac on one end and see if the other is sucking
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"the things you own will start to own you"
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Posted By: boat dr
Date Posted: March-26-2007 at 8:40am
Eric, Oh Man of Great Wisdom,one more use for a tool we all have in our shop.
Will not tell you of the weather here,but can you spell shorts and a tee shirt.................80s all week
boat dr
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boat dr
/diaries/details.asp?ID=4631 - 1949 Dart
/diaries/details.asp?ID=1533 - 1964 American Skier
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Posted By: 79nautique
Date Posted: March-26-2007 at 9:40am
kind of a waiste of time if you ask me if your having heat issues then your still going to have them, A vent in the motor box isn't going to help draw in more or less air in or out than it currently does, fix the heating issue, you have a weak impellar, clogged tranny cooler,wrong type of hose,( non-wire reinforced where it should be), wrong circulation pump or the wrong t-stat. you should be able to run wide open and not see the temp go above 10-15 degrees higher than the t-stat you have in it.
I have a 145 and never seen mine go over 160 and that's after running 90% full throtle for well over a half hour straight.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: JoeinNY
Date Posted: March-26-2007 at 9:43am
Add timing to the list of possible problems Chris lists above that can cause some overheating problems...
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http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001
1967 Mustang 302 "Decoy"
http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video
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Posted By: 8122pbrainard
Date Posted: March-26-2007 at 10:17am
I don't think that a "billet" style vent would look good on a 70's boat. Wouldn't that be "bling".
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/diaries/details.asp?ID=1622" rel="nofollow -
54 Atom
/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
<
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Posted By: Siveck
Date Posted: March-26-2007 at 6:58pm
I never see water temperatures over 170 degrees. However, it sure does get hot under the cover where the distributor is located. There is no telling what the air temperature is inside the top of that box. I see alot of ignition related posts. I would think that our wiring, coils, ignitions, and whatever would last longer if this heat had a way to escape. My ignition module is shot and I think it is from the heat. I'd rather not cut a hole, but if it makes my boat more reliable, then I'll do it. Has anyone driven without the motor cover?
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1975 Ski Nautique
"Small Letter Boat"
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Posted By: 87BFN owner
Date Posted: March-26-2007 at 8:28pm
Yes I have and it is very noisy and not very safe if you have passengers and ski equipment in the boat. I did it on a test run after I changed the impellar when the boat was empty of equipment and only had one passenger. I would recommend it. I like noise, but ony from the exhaust.
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Posted By: p/allen
Date Posted: March-26-2007 at 10:57pm
I would try to run your blower all the time . That will be bringing in fresh air from the bow and sending it out the back . I really wouldnt think that hot air under the hood would creat a problem . Think of a black car out in the sun in 110 degree heat with . I wouldnt guess there would be a constant problem with these , otherwords there would be no black cars in Arizona. My .02
Pat
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Pat
http://i175.photobucket.com/albums/w146/72ccfan/100_5977-1.jpg - My 72 Skier
Rock River
Dixon,ILL.
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Posted By: Siveck
Date Posted: April-02-2007 at 12:15am
I have the final answer. I went to a boat show and met a guy who works on the assembly line at Correct Craft. He has been there since the early 70's. He told me that adding a vent would mess up the "Flow Through" ventilation.
I replaced my thermostat with a new 140 degree unit. Maybe that will help as I had been seeing water temps in the 170-180 range.
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1975 Ski Nautique
"Small Letter Boat"
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Posted By: reidp
Date Posted: April-02-2007 at 2:41pm
That sounds good and logical to me. Along those ilnes, let me share this air flow phenomenon: When we bought our '63 Classic, the original owner had added a neat and "somewhat original" looking fiberglass hood scoop, which resembles something from a '55-'57 Tbird. The scoop is/was an actual Ford Motor Company piece based off the Fomoco emblem molded underneath, which lends no credibility or plausibility, just observation. Regardless, I thought it would provide additional air to the big 390 engine and when polled, all my buddies said leave it when we installed new vinyl last year. But I'm here to tell you now that it doesn't suck more air, as was witnessed by the severe case of blow-by this engine had. The faster you went, the more and more smoke came barreling out that scoop right over your shoulder. These older boats came only with a forward and aft facing scoop on either side of the top deck just aft of the helm with a pipe that led down under the floor. Nothing on the front or rear decks. PO had added an elec blower to one side.
To more address MMs plan of adding some type of intake vent, (I didn't see actual pict yet) you may have to duct it directly to the carb if that's where you want the air to go, as opposed to it ending up as an exhaust like mine is. When my engine goes back in, I may investigate some means of concocting a gasket under the scoop/engine box, that only lets the flame arrestor pop thru. I'm not anticipating any more smoke, but the engine noise right there in your left ear, aided by solid lifters, was also a little annoying.
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ReidP
/diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang
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Posted By: 87BFN owner
Date Posted: April-02-2007 at 7:56pm
Siveck my BFN runs right around 160 degrees crank it up and it will see temps of 180. Back of the gas and after a minute the temp comes right back down to 160. I had to change mu t-stat two falls ago before winter lay up because it wasn't getting up to propper temp.
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