1989 454 hydrolock questions
 

1989 454 600 hours

No sooner do i figure out my over heat on my starboard engine...my port motor hydrolocks...i was out one day ran great...when to start it the next and starter makes an awful grind

symtoms...

just starbord bank of cylinders...all filled with water..
with riser and manifold off water leaking out of cylinder 8 and 6 valve holes i dont know if its becuase the motor leans back that its toward the back cylinders

what ive done:

taken exhaust off starboard side...pulled all plugs...disconnected all water lines...drained motor of oil...had some water in it...even though it was not run...never got milkshake. i refilled the motor with oil...left off all water lines..sprayed fogging oil into the cylinders and poured some oil into the carbureter...turned the motor over on the starter for about a minute to recoat all walls and make sure nothing would rust...

whats next...im assuming head gasket or cracked head...is this correct or could it be something else...i will begin teardown as soon as i hear anything from you guys...id would like to try and save the motor and get a few mor years out of it...i just can't afford a new motor...right now...what do you guys think

First suspect would be leaky riser / manifold, especially if run in salt water. And yes, that would tend to fill the rear cylinders first. Compression or leakdown test will probably confirm if it is a leaking head gasket. Take a close look at that riser and manifold first, though - that is the #1 cause of hydrolocked motors.

with the manifold and riser out...i have water coming out of the number 6 and 8 exhaust ports...if i just leave the manifold on...i can watch it fill with water and leaking into the front two cylinders as well through the manifold...will do a compression test tomorrow...but would love whatever else information you guys here have for me

I wouldn't waist the time with a compression test. If it leaking water you won't have any compression. Spend the time pulling the head off and you will know what your problem is. The faster you get it apart the quicker you can clean the water off and prevent rust. The biggest question is, did the hydrolock hurt the bottom end?

It is possible the head has just rusted on through

from what i hear big block heads don't like raw water cooling. they rot through way before the engine blocks. in the sportfish world there are NO raw water big blocks. get a pair of heads. the other one is just as bad-just hasn't popped yet...

ok i will pull the head and skip the compression test...I'm hoping I didn't hurt the bottom end...o never ran since it hydrolocked

drain oil, or at least bottom quart or so if oil is brand new to get the rest of the water after you are done pulling heads. that block is tough. you didn't hurt it. what heads, peanut (330 hp) or square port (365 on up hp)?

ok i pulled the starboard head...the head gasket looked really good...as well as the head...the valves have some surface rust on them so i will take them to a shop along with the intake to be cleaned up....i don't get it everything seems really good...the only thing i didn't love was the intake manifold gasket...could that create a problem only on one side?

i do have one question though and maybe its just new to me(big block) what the passage for on the inside of the head...in the middle, along the intake runner. i count 4 exhaust ports and 4 intake ports but there is a square one in the middle that i can see a valve? maybe im wrong and i wonder if this could create the problem

(peanut port)

That is the exhaust heat riser passage. It takes some of the hot exhaust and circulates it under the intake to warm the charge for cold weather operation. It can be useful on a car, but not needed in a boat. If you look at your gaskets, you should see a metal blockoff plate to keep the exhaust from circulating.

It could be as simple as an intake manifold gasket leak, but the heads should be closely checked, along with the intake manifold and exhaust manifolds / risers. If those risers are more than 4 years old running in salt water, they should probably be replaced.

+1
Take the head to the machine shop and have it mangifluxed and if it's good, get a valve job to clean it up. It sounds like you may just have a bad intake gasket, I would use a felpro gasket to replace it.

I am willing to bet that a 365 magnum head that has been on a boat since 1989 is going to be rusted out. Fresh water,salt water,brackish water it dont matter, if it didnt have antifreeze in it ,like in a closed cooling system, to curb the corrosion it will be rotted out. 23 years is a long time for anything on a boat.

it was a rot...water flowed into the exhaust port...pulling the other head tomorrow and having them both changed

as long as you are buying heads, don't get more peanuts. go square port. your intake is about to rot through anyway...

I don't know what you exactly found out but I just solved a similar issue with my engine. Was getting water in the oil as well as the exhaust manifold. Pull my hair out for a week. Turn out to be leaking exhaust valve guides. Magnafluxing won't find them only pressure testing will. Also DON'T use rectangle ports on a 330 engine, they're way to big and will also require a new intake. You can most likely get yours repaired at reasonable price.

Wow, that's a new one...you want to repair peanut port heads???? I thought once they came off they were boat anchors ;)

Rectangle port (or large oval port) and a good and matching intake with the right mild cam combined with a slight compression bump is about the oldest 454/330 performance upgrade ever. I wouldn't just bolt on rectangle port heads without matching the combo, but keep it below 4800RPM and 400 hp is pretty easy to do, and pretty reliable too.

Maybe you are saying don't put them on just by themselves???

What I'm saying is that 088's are to big for a 454 mag, which has a bigger cam and .75 more compresson. Adding only a set of rectangle port heads IMO would be a very poorly matched combo. A lot of guys have wedges installed to decrease the runner size. 400 hp out of a 330 with just heads isn't going to happen. A merc 420 has Gil exhaust, bigger cam than a mag (way bigger than a 330), much better intake, higher compresson. In addition to all that, he has two engines which would mean he would have to change everything.

the water is pouring through his heads. they are too rotted away for use as boat anchors. means his intake is likewise rotted away. i believe his boat is a 206 formula. 3500 lbs with big block. i think boat will do ok with a little low intake air velocity at 2200 rpms. you buy a set of peanuts, you are locking yourself in at 330 hp. i am assuming he will be considering more upgrades in the future.

boat is a 272 with twin 7.4's i have to update my profile...im just repair this one motor for now...i got cheap peanut ports and all the valves were ok...shop is changing everything over to the new ones this week...intake seems great. hoping the othe rmotor holds out...can't afford to tear into both of them right now...

in the future i would like to rebuild these 7.4 330s not mags...to about 400 hp each...i guess i should start collecting parts for that

and first thing you need is better heads...check the underside of the front water passage on intake for signs of drip-through.

intake looks great...shop had replacement heads for 100 they are going to move all my parts over to the new ones...hopefully this gets me going again this year...we will see how finance is next season as i am getting married in 2 months...can't afford to go crazy yet

FWIW - My 7.4L leaked at the valve guides as well. Hydro-locked the same way as yours did. Happened on the port side rather than the starboard side like yours. Same story though, lots of water building up in the exhaust manifold. I believe mine bent a few connecting rods as water was getting into the cylinders.

I ended up selling the boat as a fixer-upper.