Ski Boat Forum
Repairs and Maintenance => Engine Repair/Maintenance - All Ski Boats => Topic started by: 11.50fox on February 09, 2014, 01:27:49 PM
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my motor is a 87 351 in a advance
I ran it hot after a faulty water pump let go. I ran it up to 270 degrees{I know wow}
but I check oil and all everything is good. ran the boat and I would run and ski fine.
all though it had a small miss, so I changed the plugs and haven't ran it since. but I have
noticed when cranking in the yard it was hard to start normall before the running hot issue
it was never a problem to crank even when dead cold, 2 turns of the motor and it was running
now I have to give it almost wot to get it to crank. after letting it run 2-3 min I can shut it off
and it cranks perfect. until I let it set for 3-4 hrs and its hard to start again.... any advice is
wanted.... thanks
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"Small miss" is the key words- When we have an overheat issue the first things that go are wet exhaust parts that are now running dry & hot, like exh. hose, fiberglass mufflers, etc. Next is engine "hard parts" like heads. I would closely monitor the oil for milkyness and do a compression check on all 8 cylinders, if you find a low one you will find the cause of your miss, (hopefully a simple blown head gasket) this will also cause hard starts as well.
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Ron, my AS developed a hard star too. Sounds the same as fox. I went from easy starting with no throttle assist to one day out of the blue, no start. I too have been WOT to start and then after heat, easy start. It was the end of summer so I just put her in the garage. I wow
I was gonna tune her with plugs, plug wires, fuel filter, new gas and see how she goes. After that, you have my attention with the heads. Since I'm an internet mechanic, I'm sure I can find a compression tester at a parts store (unless you have a recommendation) and what does Ron suggest I should see on each cylinder?
I appreciate the help!
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Unless you overheated yours it would only be a coincidence that you have the same problems. Compression PSI per cylinder on an old engine is not as important as the "balance" make sure each cylinder is pumping up within 10% of each other. Buy the thread-in style tester not the rubber tipped taper kind that you hold against the spark plug hole.
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Ok will do. I did run her hot, but after the hard starts. Sometimes I'm a Dumb@$$. After she cooled I fixed my intake line and she ran like a champ.
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just a update...... I changed plugs at the end of last summer. the small miss I gone. but the hard start is still there. and I have noticed that my battery will run down in 1-30 sec of spinning. I took the batt out of my truck and put in, just to make sure the batt was good. and it will run it down super quick. I was thinking I had a bad cell in my marine batt. so I took the one out of my truck and put in. my truck batt. is a regular truck batt. not a marine batt. last year I had a problem with the key switch running batt down. my marina said it was fixed. it wasn't hard to start before I ran it hot.
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you still should ck. compression. does starter or battery cables get hot after trying to start ( high amp draw ) most parts stores can ck. starter for you if you bring loose starter to store. does engine turn over by hand. should turn easy with spark plugs removed. ck. batt. cable connection, at batt, starter & ground. hope it is not engine damage. good luck.
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going to do a comp. test today.
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Their is a difference between a slow cranking engine & a hard starting engine. The common causes for slow cranking would be poor battery, battery cables, cable connections, and the starter motor itself. I define hard starting as: the motor cranks over with a normal rotation but will not start, will crank like this for 20-30 sec. without starting.
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Batteries: A/S boats use "cranking batteries" not trolling motor batteries, our application is no different than an old pick-up truck. The "Marine Cranking Battery" claims to have better constructed cells that are designed to handle rough riding conditions. I have never taken them apart to see if their is a real difference. I do believe the following is true:
1) Ski boats in general (unless the battery is in the transom area) are brutal on batteries, try replacing your drivers seat cushion with a piece of plywood then cross a few wakes at 35mph, see how you back feels. Compare that to a vehicle with suspension & tires that absorb dynamic shock loads.
2) Ski boats have dormant periods, 3-6 months of doing nothing. Batteries that are cycled regularly seem to live longer.
3) I have not seen a ski boat battery last more than 3 years, where my little parts truck is going on 6 years with the same battery type/size I use in my ski boat & it is going strong.
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comp. test........
left bank...
107,110,109,123
right bank 117,110 9.5 126
now got to pull the head and see if its a burnt valve, burnt piston, cracked head on exhaust side or bad rings.........
being im am going into the engine, can I up grade the cam being in will be in the motor. I also have a set of trickflow heads from a old race car I had. thinking about putting the heads and aluminum intake and a nice tow cam in....
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Think of it this way, your on the cutting edge of marine technology with cylinder de-activation. My $$ is on a valve/pushrod/rockerarm/cam problem, my fingers are crossed for you.
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thanks brother...my wife is happy about it...lol j/k.....
what you thing about running trickflow heads and a rv cam or some kind?
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It takes a lot of HP to make ski boats go faster, on an advance hull expect 43-45 mph on 240-260 HP, Our late model Lazer's (same hull) were a little lighter but had 300HP & ran 48-49mph.
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yeah not looking to go faster, I just sold my 21" hydrostream 2.5L......over going fast on the water. I just want more low end grunt for pulling. my boat is normally weighted down with 5-6 people and 1100lbs of added weight. so any extra power would be great. I have a 4 blade prop already. just thinking since im already in there now. would it be worth it to put them {trickflow heads} street heat models and a rv cam in to give it a lil more ummmff... looking for 300+ hp
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ohh yeah sorry, when I took my heads off today and flipped the over the number 3 cyc. the exhaust valve was super clean looking and the others were black/carbon looking. is that my burnt valve? cause my number 3 cyc. was 9.5 comp.just wandering. it really dosent look that bad just at a glance. I am taking the to machine shop tomorrow....
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In that case go for it! Most calls I get are about increasing top speeds just to keep up with the neighbours boat, I tell them if you want to test an American SKier tie them pylon to whatever they have & play tug of war, sterndrives & outboards lose every-time.
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what would be a good cam to get to match the heads and a dual plane intake??
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heads are at the machine shop. valves were not burnt or bent. having the checked out and a valve job done on them now. what else could be my problem?
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Call Comp Cams and give them your info, check into one of their extreme marine cams........ Let them tell you how big you can go that way there is no mistakes.
There are quite a few variables, but they will help you out.
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is the combustion chamber & top of piston clean? if so had water leak into cyl. any sign of a leak at head gasket? if only exh. vale was clean I'm not sure what that could be. any sign of piston or cyl. wall damage? not normal from overheat unless piston burned & than you would have had a large misfire.
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the exhaust valve was a lil cleaner that the others. but not like a burnt valve would look. the piston looked just like the other 7.
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heads are back....not warped or anything.......... had to be a head gasket?
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In that case go for it! Most calls I get are about increasing top speeds just to keep up with the neighbours boat, I tell them if you want to test an American SKier tie them pylon to whatever they have & play tug of war, sterndrives & outboards lose every-time.
I always wondered if people have tried this..
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it would have to be a large head gasket leak to have 10 psi compression. only other thing i can think of would be a stuck open valve. you should have done a wet test on that cyl. before tear down ( sqirt oil into low cyl. & recheck comp. if comp. higher = ring fault). but I doubt worn or broken ring would cause that low reading.
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Batteries:
2) Ski boats have dormant periods, 3-6 months of doing nothing. Batteries that are cycled regularly seem to live longer.
3) I have not seen a ski boat battery last more than 3 years, where my little parts truck is going on 6 years with the same battery type/size I use in my ski boat & it is going strong.
Agree Ron with the following caveats:
Move someplace where you can use it year round and you won't have that problem near as much or get an Optima Red Top.
I had a Red Top that I bought for the boat back in WI before I moved to FL. A couple years ago I started having some starter issues and I thought that the battery had lost some of it's cranking power (which can in turn weld starter relay contacts) so I replaced it with another Red Top. After all, it was now 11 years old. The new Red Top I got online so I didn't have a core return. I had that old battery sitting on my garage floor (on a rubber pad) for over a year and never touched it.
The battery in my truck died and just for the hell of it, I measured the voltage on that old battery seeing as it was just collecting dust now. It looked good so I put it in my truck. Been in there for the last year working fine. It's now 13 years old and still works great. It does definitely loose it's charge pretty quick if you leave lights on or a door open, but it still works.
I know that Optima batteries aren't cheap but when they last 11 years in a boat, sit on the floor for a year, then spend a year in a truck still getting the job done, they're worth every penny.
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a batt. that is discharged will lose some of it cranking power & will not fully recover. the best way to store a batt. is with an automatic charger/ maintainer to keep batt. fully charged. I store my batteries in crawl space & charge every 2 - 3 mo. had a delco batt. that was a warranty return & used it for 8 years. high heat is also harder on batt. life than cold temps, but batt. will loose cranking power when cold.
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I too have a hot start issue with my 90’ 454. I did run it with a shotty impeller earlier in the season (water was >50 degrees), and ran it up to 270 degrees. However, according to my owner’s manual overheating isn’t an issue until 180 degrees. The boat has been difficult to start since I bought it in November. I didn’t think much of it, just figured I had to get the “feel” of the boat. I am not used to carbureted marine engines. I always assumed that I have flooded it out and needed to let it rest, before attempting restart, because it has eventually turned over. I plan on doing a tune up (oil, plugs, and wires) before I get it wet again. Any other suggestions, I can do easily myself, that may help my issue? If this is a common problem what is the most common fix? It’s seems to be near impossible to research issues for the 454.
-Corey
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No problem with support here, yes 180 deg. is MAX, 270 tells me you had fire breathing down the exhaust tubes! Sounds like a total tune-up is in order plus some very careful cooling system inspections. Glad to help you when need it.
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My fault *270 degrees was a typo. It should of read *170 degrees.
After reading through a metric ton of threads on here, web searches, and talking with anyone who will listen, I think my problem may be vapor lock. It matches all the symptoms; solid cold start, fails to start hot, but after I have the hatch up poking around and not really doing anything it fires right up. I'll be back home next weekend to thoroughly troubleshoot the issue.
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I personally think that vapor lock is a myth in these boats but I'm certainly no expert. I've never seen it myself and every hard starting issue I've ever heard of had a logical remedy that was nothing even close to vapor lock. Just my .02
Start it up, get it warmed up and remove the flame arrestor. Shut it down and look down the throat of the carb and see if there is any gas leaking into it. I'll bet there is. It's basically flooding itself out as soon as you shut it off. The fuel dumping into the carb will eventually stop as soon as the bowl is low enough on fuel or even empty. Then the raw fuel either evaporates off or washes down the cylinder walls and you can start it again (i.e. poking around and not really doing anything).
It's either a dirty needle/seat or a float that as become saturated and too heavy so it doesn't close the needle/seat or it's just adjusted too high. I'm guessing a carb rebuild is in order if you have no idea when the last time it was ever done.
By the way, if this is the issue, you should be able to hold the throttle wide open to help it start when hot but it may take quite a bit of cranking to do that.
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Mechanical fuel pumps & carbs. rarely vaperlock if ever, next time out before you shut down open the hatch, remove the spark arrester, turn off the engine & see if fuel continues to dribble down the carb throat, this is a very common problem and will cause hard starts like you have described. If this is the case a simple fuel system tune up and carb re-build will take care of it.
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I was afraid it was carburetor related. Unfortunately I have never rebuilt one. I’m no slouch with a wrench, but I am far from a mechanic. Anyone know of a good “how to” video that would be similar/identical to our carburetors? I ordered an engine and trany manual, but I am not sure it will be here in time.
Big thanks to RonT and backfoot100 for the help so far!
-Corey
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It's pretty easy to do. I can't help you on a website but you can get a book by Dave Emanuel called Super tuning and modifying Holley carbs. It has a step by step in there for rebuilding one.
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I just ordered ‘Super Tuning and Modifying Holly Carbs’ from Amazon. I also picked up the ‘Holly Haynes’ manual just in case. I’ll post back after this weekend and let you know how it goes. Can’t wait to dive into this project.
-Corey
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Confirm the problem before you rebuild something that might not need it. Rebuilding a carb isn't rocket science but troubleshooting a problem to verify the carb needs rebuilding is the first step.