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Uh Oh!

S

snookstalker

Well-known member
Well, I finaly got my boat all done (14 1/2 X 7 1/2 Combee w/ 500 Caddy DD) and took it to Kissimee for a trial run. Everthing was going great-handles nice, plenty of power, even climbed the hill(well the short end-didn't try the steeper part) then it started blowing oil out the dipstick! I managed to baby it back to the ramp. Any chance this is anything other than a cracked ring? yeah, yeah--I know what AIRBOAT stands for!
Was really hoping to make it to the run to meet some of you guys. The knowledge and experience on this forum has been a HUGE help to me in getting this (my first) airboat built. Thanks to all. Now somebody please tell me I didn't tear it up the first time out!!!
Dan
 
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did you notice a loss of power before you noticed the oil.do you have a signifigant amount of blowby from your exhaust or did your motor seem uneffected. and was the oil coming from the tip of the dipstick or near the block. any account of what happened to make you notice the oil would be helpfull. meaning pinging noise,los of power ect. not that these examples pertain to you just what got your attention.
 
first noticed when I did a u-turn and smelled the oil burning on the headers. Saw that the dipstick was pushed up out of the tube. Started losing oil pressure and power as it blew out enough oil. Luckily I took an extra quart with me and got back on that. It did seem to make some popping noise out the exhaust a couple times. Shut it down and waited a few minutes and fired it back up. Ran a short distance until it started to lose power again. Repeated this a few times to get back to the ramp. I have not done a compression test yet, maybe tomorrow
 
Man, I don't know anything about Caddys, but I hate it for ya'
Hope it's something real easy to fix.

BF
 
You need to do a compression test on the motor and when you pull out your spark plugs look for a wet one. Hopefully it is from your rings not sealing yet but it sounds like blow bye to me.
 
It was a used motor. Realy don't know it's history. appears to be all stock. If I find low compression on one cylinder, is it ok to replace just that one ring or would it be stupid not to do them all. Please forgive my ignorance, I am handy but not a mechanic.
 
honestly it would be a great waste of effort to just replace one set of rings,and i dont even know if you could just buy one set.i'm with waterthunder on this one do a compression check see if you have a week cylinder.but if you have to and decide to go into the motor before i put it back together i would check many parts out before reassembly.i know you are excited to get on the water and i'm sorry for what has happend.but don't rush this motor back together if you decide to do anything i would atleast to attemp refreshing most of the motor while it is down.a 25 plus year motor can yield you many problems. this of course
is just my opinion. but once you do a compression test let us know the results.
 
It just counts on how fast your looking to get on the water. Of course it would be better to do the whole motor.
 
Of course I want to get it back on the water yesterday (did you guys know these things are addictive?) but I also don't want get back out there just to break again. I will have my wife and kids with me most times (they are hooked too) so reliability is important. If it has to come apart, what are the main things I need to check? I'll let you know what I find as far as compression.
Dan
 
it just depends on how tight you want your motor te be with tollerances.
and dependability and budget,and importantly how long you can stand being land bound and not on the water.
 
SS If you need some help some one just north of ya ,in palmetto across the river ! Let me know !Sorry about your setback Its just a minor one :DGot a friend he has a shop just putting mine togather!Just rebuilt your motor the only way to go !That way you no. You got lucky that time !Its always a good day when you make it back to the dock!With all the parts floating :shock:
 
Unfortunately, at this point in this project, budget has become a big concern, however I don't want to not do something that needs to be done. Especially something that might cause problems and cost more $ and down time later.
 
SS Cant use budget and talk about a airboat in the same paragraf ! :cry: You are looking at a 25 year motor They are killer motors. All the shiny stuff wears out ! The blocks never hardly give you problems just the stuff that spins !I bet you got a val sticking crack your piston when it cools it sort of works until it gets hot ! I know a used motor that sits up the guides get sort of galled up ! Not much clearence Just a geuss you said poping loss of power ,bent push rods if the lifter is coming out to far of the galley would give the loss of oil presure ! Just look at it closely! :D
 
Sorry about your luck :cry: . You have to realize that these motors are at least 29 years old :shock: . Rebuilding correctly is a really good thing to do. If you do not do it right, you WILL be doing it again. Your timing was probably incorrect and it detonated itself to death. I have done it too!!!:cry:. I know how these boats get out of hand, but breaking down is no fun either. Pull the compression and see what broke then let us know. Have fun,this kind of thing adds to the experience :wink: .
 
I've tried the route of getting by and it is a lot more expensive! I rebuilt my caddy twice. In my case I had broke ring lands and rings on two cylinders, replaced all pistons, rings, bearings but didn't replace oil pump. Two hours of run time after reassembly and I had two spun rod bearings. I thought I had cleaned all the junk out of the pick up tube....wrong! So the second rebuild included a crank as well. Then I had the idea of swapping a set of 76cc heads on it to get around 12:1 compression. The higher compression did not make much difference on a direct drive and a broke timing chain took out several valves about a month later. I replaced the heads with my 120cc heads and all was fine. All of this was done in about an eight month period. I am currently in the middle of swapping from direct drive to reduction drive and have been building another 500 for the reduction setup. Crankshafts are getting hard to find so be careful not to ruin yours! Moral of this post is do it right the first time and you'll save tons of money, won't feel like an idiot later, and you'll have an impressive boat that lasts. BTW, it is a good idea to balance the rotating assembly if you change any part of it since there is not a damper on these engines.
 
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