help my as is hard to start

[11.50fox]

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

[RonT]

"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.

[Messer]

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!

[RonT]

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. 

[Messer]

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.

[11.50fox]

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.

[shyskier]

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.

[11.50fox]

going to do a comp. test today.

[RonT]

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. 

[RonT]

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. 

[11.50fox]

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....

[RonT]

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.

[11.50fox]

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?

[RonT]

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.

[11.50fox]

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