Block full of sand???

[riverbound]

I removed the freeze plugs last night and found that my water passages were FULL of sand. It wasnt just a little bit they were full. What damage would this have caused? Is there anything I can do to prevent this in the future? Does anyone else have this problem?

[Taylorman]

I can't imagine this would hurt anything. It may restrict the water flow throught the block some. Since all the sand settles to the bottom of the block, you will have to pull the freeze plugs out to flush it out.

[Wet Dream]

For starters, don't drive over sandbars, don't use reverse bucket off of sandbars or sandy beaches. You'll blow all the crap right up into the pump and into the engine.
To clean out my block, I have petcocks that I can open in the side of the block to flush out the block. These go in place of the pipe thread plugs.

[riverbound]

I never do drive over sand bars or reverse off the beach. I am just in the process of rebuilding the motor and discovered this. There is so much sand in the motor that I dont think the rear cylinders were getting water to them. If they were getting water it was only at the very top of the cylinder. When I pulled the freeze plugs out I couldn't see the cylinders just solid sand.

[JayBee]

Sounds like my 396 was when I got my boat. I had to rebuild the engine because the previous was an idiot - running car oil pan and high flow oil pump in a boat - and had hammered several of the rod bearings completely out of the rods. When I pulled the freeze plugs I found the water jacket was full about 2" up the cylinders all the way around! Scary part is he claimed he didn't have many hours on the BBC - he had just had the olds swapped for it not long before. And, it was a rebuilt engine, too, so it was all his doing.
The lake he ran the boat on tends to be very crowded and muddy at times - I wondered if the mud and silt were coming out of the water when they hit the hot cylinder walls. This is also why I have been thinking a lot about a closed coolant system with a heat exchanger. Seems like it will always be a problem to some degree when running raw water through the block...

[OMEGA_BUBBLE_JET]

sand in the cooling jackets can RUIN a block. because the water can not reach the full extent of the cylinder they develp 'hot spots' near the bottom that ruins the integrity of the metal and the block becomes scrap at that point. Remove your freeze plugs once a season and flush with water thorughly. It will take about an hour but save many heartaches down the road. Just because your temp guage reads normal does not mean there is not a cooling problem in bottom of the cylinders. It is important to remember these engines were designed for closed cooling systems in automobiles and do not tolerate cooling system contaminates well. Good luck and better check your cylinders for hot spots.
Omega

[riverbound]

What about a sea strainer? We run them on all our other boats. why not on a jet?

[Wet Dream]

Is it really that big of an issue? How does a block efficiently cool when you're running a blower and you grout the bottom of the block?

[riverbound]

Originally posted by Wet Dream
Is it really that big of an issue?
I don't know that is what I am trying to find out.

[Wet Dream]

I wasn't trying to imply that you were running over sandbars or reversing, but that can trigger it. Sand, silty lakes will allow the residue to settle faster than it can escape the block.

[wet77]

I use replaceable neopreme plugs that you can pull out easily and remove any sand in the spring or fall:D
They have a nut on the outside that you tighten to install them, and when you want them out loosen the nut take a flat screw driver and there you have it, instant sand removal;)

[Taylorman]

I recently added a water strainer that water goes through before going to the engine and headers.

[spectras only]

Originally posted by wet77
I use replaceable neopreme plugs that you can pull out easily and remove any sand in the spring or fall:D
They have a nut on the outside that you tighten to install them, and when you want them out loosen the nut take a flat screw driver and there you have it, instant sand removal;) Riverbound , wet77's suggestion is a good one. Also installing brass male gardenhose fittings in place of the rather small draincocks will allow you to reverse flush the block frequently.The problem with sand buildup in the block could become a problem for the main caps/bearings too. An oil cooler added would be a good idea while you're at it;) .

[riverbound]

Originally posted by spectras only
The problem with sand buildup in the block could become a problem for the main caps/bearings too. ;) .
afetr tearing down the motor I did notice that ALL of my bearings were shot with the worst being towards the back where the most sand is piled up.

[drysumpjet]

I have seen sand in the blocks of many jet boat motors over the years, but on mine each Fall, I remove the bottom 1/4" block plugs and flush out the sand with house water. This may be important as the sand may hold enough water, that if it does not run out of the drain plugs, may cause winter freeze damage.
As a side note, my past experience with jet boat spark plug readings indicates that the rear cylinders typically run hotter than the front. In an attempt to correct this, I silversoldered 3/8" hose barbs to the rear most brass freeze plugs to split up the incoming water. I also tapped the intake manifold rear water blanks to split up the outgoing water from the heads (also 3/8" hose from each side). Although not a perfect approach, this seems to even out the water flow thru the entire engine, and has resulted in consistant spark plug readings.
The point of this is the improved water balance, to my surprise, almost eliminated the sand I would observe coming out of the bottom block plugs during the "Fall flush". This may be attributed to that the water velocity is consistant and high enough to prevent the sand from "settling" and/or that introducing a portion of the incoming water at a lower point of the block (at the freeze plug level) prevents sand settlement.

[LVjetboy]

I think a sea strainer would work on a jet. Extra weight but not nearly as much as a closed cooling system.
Where and how you run makes a difference. I flush the block through the drain holes at the end of the season and rarely get much build up...seems to work fine. 12 years on my old 454 and no lower cylinder heat problems. But I normally boat deep lakes. Tho guilty of beaching time to time...and running onto the trailer. Not good practice.
This season I've run 12 lake/river days on a new build and after the last trip (Big River) I drained the block. There was minor sand buildup at the petcocks but not much.
I wonder if a cooling system that feeds water through the drain holes (or out the holes) in addition to front water feed would work? Not volunteering for that experiment.
jer

[LVjetboy]

Drysump, just read your post. We're thinking the same? But how does changing block cooling flow design affect the heads or the engine as a whole? I think there's a better way but for me the cost of failure from trial and error too high.
jer

[drysumpjet]

Hey Jer,
I think I already did your experiment suggestion, results are great, at least for me. I'm adding water a bit more rearward thru the rear freeze plugs. I like your suggestion on the sea strainers but didn't have the room. On mine I run 2 brass 1/2 "Y" plumbing strainers, 1 for header water, other for oil cooler to the block.

[rivercrazy]

Sea strainers will not stop sand.....They are designed to for larger debris.
To me they are beneficial for outdrive setups because there is a small source of water to feed the belt driven water impeller pump at startup. If you run them dry at all, see ya.... But on a jetboat, that water supply problem is non-existant.

[drysumpjet]

Jer,
I can't type fast enough! Yes we are thinking the same. My best guess is that this modification shouldn't have any negative effect on block cooling, as water is entering the cylinders and leaving at the intake manifold side of the heads...just in more places! Since I am running the Banderlog valve which doesn't like preheated engine water, all water exiting the heads are unrestricted, so the block pressure is minimal. Result has been all good for me.
Now here is an experiment not for the faint of heart...REVERSE COOLING, like many newer high performance cars. Benefit with this concept is cooler water at heads result in less detonation issues meaning we could get away with more boost, ignition timing, compression, and the "preheated" water would be more suitable for the cylinder area.
My concern with this concept in a jetboat is the reverse flow of water would not push out the air at the bottom of the block, leaving air pockets at the heads. I would like to try this someday but I am afraid of my boat turning into a bad science project!

[LVjetboy]

Rivercrazy, I've never run a strainer and don't know screen filter specs...not listed in Rex's catalog. When I first read this thread I questioned that too. I also checked online and reports said it can fill with sand. They mentioned a nylon metal mesh? I was thinking a drilled SS plate. No doubt there's different filter designs.
I think someone here runs a strainer or could've been RJB? Anyone know what particle size strainers typically handle?
jer

[LVjetboy]

Drysump, you're right. That's the problem with reverse flow or any modified cooling design. The potential for hot spots and engine carnage. As you go up in power and $$$ the risk is more. We know the original design works ok, could it be better? Most likely. Who's brave enough to try? Not me.
:D
jer

[riverbound]

I do run a thermostat kit on my motor so doing different types of water flow will not work for me. :( I do about 90% of my boating in Parker and the other 10% at elsinore. So my only solution would be just flushing out the block once a year?

[LVjetboy]

River, I think the best solution is to avoid sucking sand in the first place.
When I beach I shut it down well before I get there...and push it out before startup. Just because we don't run a prop doesn't mean 007. If I trailer at a muddy or sandy shallow ramp I walk it both off and on well before the pump sucks sand. At the river I watch for the jet kicking up mud and if I see that it's time for deeper water or wait for the level to come up. Most of the sand buildup will happen close to shore depending on how you boat. Reversing off the beach or off a trailer in the shallow is not good...you just shoot bottom junk right up your intake. The added benefit of avoiding is you save your wear ring and maybe a pump rebuilt.
For me, avoidance 90% the rest maintenance...regular flushing. Flushing won't remove all the sand but it seems to work just fine over the long haul. And the extra weight of a strainer or closed cooling is not an option for me.
jer

[OMEGA_BUBBLE_JET]

It really is not that big of a deal. I usually incorporate it with the oil change. I have wondered about the reusable freeze plugs and I might try a set next time.:)
Omega

[riverbound]

Originally posted by LVjetboy
River, I think the best solution is to avoid sucking sand in the first place.
When I beach I shut it down well before I get there...and push it out before startup. If I trailer at a muddy or sandy shallow ramp I walk it both off and on well before the pump sucks sand. At the river I watch for the jet kicking up mud and if I see that it's time for deeper water or wait for the level to come up. The added benefit of avoiding is you save your wear ring.
jer
I do all that stuff now, so this sand must mostly be from the previous owner.

[LVjetboy]

Yep.

[American Turbine Man]

Up here (Pacfic NW) we use sand traps. They are like sea strainers except they swirl the water and the sand drops to the bottom where it can be drained.
ATM

[rivercrazy]

I looked over 5 or 6 different sea strainer units before settling on the Teague unit. All have similar screen sizes that all will pass sand.

[canuck1]

I guess that I do everything wrong.
I drive on and off the trailer, I drive through real shallow/sandy water in forward and reverse, I drive over the odd sand bar with my foot barried in the pedal, I don't cover my intake on the road, all my blocks are cement filled, I run a car pan, I only flush the motor when I pull them from the boat....DAMM.... they still run:cool:

[Rexone]

Our sea strainers won't trap sand, holes are too big.
I'd see what ATM uses and get one of them.
Normally sand buildup like this is from running shallower river areas, not necessarily beaching although that certainly can contribute. When beaching just push the boat off into deeper water before firing up. And don't idle around in real shallow areas, sandbars etc.

[Squirtcha?]

Originally posted by canuck1
I guess that I do everything wrong.
I drive on and off the trailer, I drive through real shallow/sandy water in forward and reverse, I drive over the odd sand bar with my foot barried in the pedal, I don't cover my intake on the road, all my blocks are cement filled, I run a car pan, I only flush the motor when I pull them from the boat....DAMM.... they still run:cool:
Too funny canuck. You'd better knock that crap off!
I had a set of the rubber freeze plugs and spit one out at about 60 mph. Man did that bilge fill up quick!

[LVjetboy]

Crazy canucks. Why worry about sand with bigger things to do like cleaning beaver out of your pump.
:)
jer

[LakesOnly]

Another issue that was only lightly touched on is that with the recuced cooling capacity of the lower end, oil temps shoot up. And in jet boats, oil temp is already high to begin with. This is of course also true with blocks that have been hard-blok'd...
In terms of more even water coolong, Blown472 has his water lines entering into his block though the drain plugs on each side of the cylinder bank...I think he tapped oversize to the next size NPT fitting. Water enters from the very bottom of the block, in the center of each cylinder bank.
LO

[drysumpjet]

Lakes,
I was thinking of introducing cooling water in the block drains too but my 502 block has siameased cylinders thought that it would be better if the added water feeds are placed further rearward. I know my approach isn't perfect but introducing supplemental water thru the rearmost freezeplugs results in the feed for the left bank is between cylinders 5&7, and for the right bank, between cylinders 6&8. Note I am still also suppling water in the stock front locations too.
Maybe someday I will take temperature readings with an infrared thermometer on my "cooling modified" engine and other typical "cooling stock" jetboats while underway. Might be interesting, especially getting chewed up by the blower belt, then getting more jet boat merit badges from the headers!

[quiet riot]

I used to use a sandtrap like amer turb man said but found that I didn't drain it enough when running rivers anyways so it still went through the engine so I just removed it and started flushing the cooling after running shallow water.
On the new motor I built a self draining aluminum heat exhanger that seems to be working pretty good so far. Haven't run rivers yet as I'm still tuning in the new motor but I think the sand and debree thing (as well as saltwater and corrosion) will be taken care of for me now.
The sand trap would prob work well for you guys that just occasionally run over shallow stuff or beach things, as long as you drain it after each incident.
jd