99 7.4L MPI\Bravo 1 Sand Packed?

[TXDONZI]

Went out Sunday and beached 2 or 3 times I was running a bit hot 175 after the first time but it seemed to clear up. It normally runs about 155-160. Then after the third time same problem it got up to 185 - 190. Stopped at a place to eat and when I got ready to leave the motor sounded louder than it normally does. I just thought it was because the exhaust was facing under a dock. It ran about 150yrds. and stopped like it ran out of fuel. Paddled back to the dock and the motor was pretty hot to the touch. It acted vapor locked but after a while it started and ran funny (missing, cutting out) then cleard up and set off the buzzer in about 2 minutes. I went and got the trailer (hr or so) and loaded it on the trailer with the motor.... hot again maybe 4 minutes of running.

Today I removed the hose going to the cooler from the water neck and flushed water bacwards and put it back. Then with flush muffs and water on started motor and no flow from tips.....removed the hoses going to the risers... with flush muffs and water started the motor and no water flows from the water neck (1-2 mins maybe).....
TRASHED IMPELLER? It was replace last Sept.......
WHERE IS THE SAND? How do you get it out?

It sounded fine today and the oil looks good and clear. Only ran long enough to get to normal temp. before I shut it down.

Tt

[gcarter]

It'll probably take awhile to clear everything, but a good solution is a transom pickup and seawater strainer.
The hose fittings through the gimbal is only about 1/2" in diameter although the hose on the inside of the transom is 1 1/4" diameter. I'd probably look there.

[MOP]

Fine sand can get well into things plus like you say the pump may also be trashed. For starters remove the hose coming from the drive to make sure that section is cleared out using the muffs. The oil cooler and lines need to be flushed out, this means you need to get the hose of the outlet of the sea pump so you can back flush them. Once it flows clean you should be Ok except for maybe needing a pump job!!

Phil

[MOP]

George I think it is a Bravo setup, the gimble inlet has a 1-1/4" barb unlike the wimpy Alpha setup.

[TXDONZI]

Look at this picture for what I did.

[Tony]

Been there, done that. I tracked the water route, undid every hose connection there is, and backflushed each individual section. My hose squeeze nozzle has a rubber head that just happened to fit the 1 1/4" exactly so that I could get some real good pressure through the lines.

I felt that in my application the oil cooler and power steering cooler were especially restrictive, so be sure to flush them well. Also, like Phil so sagely suggests, inspect and replace your impeller if necessary.

:beer:

[TXDONZI]

I am using a 3/4"x1" conduit (RE32) reducer and the hose end in the small hoses. I have a water well and get 45-65 psi with fairly good flow.

[gcarter]

George I think it is a Bravo setup, the gimble inlet has a 1-1/4" barb unlike the wimpy Alpha setup.
Phil, from what he says, the drive is open, but, the short "S" shaped hose inside the gimbal is about 3/4" diameter and it has plastic fittings inside the ends that are about 1/2" diameter. Take a look at this microfiche; http://www.dougrussell.com/partscatalog/components/index.cfm?fuseaction=viewparts&colid=04&coldesc=BRAVO%20I%2FII%2FIII%20%20%20%20%20%20%20% 20%20%201996%2D1998&index=1943&block=160&BlockNumberList=180,150,120,130,200,190,80,60,70,5 0,220,230,250,240,100,90,160,110,310,170,280,270,3 20,0,330,300,290,340,360,370,380,350,40,20,30,10,1 40,260,210 and notice #15, and #16, this is the most severe restriction in the entire system. This is what you eliminate when you install a transom pickup.

Since the engine is cold, you may have to remove the thermostat because it will be a restriction in the system.

[BigGrizzly]

Also check the water pump housing for cracks too. Seen this happen even if not on a sand bar. what happens is the motor runs fine on a hose but doesn't pump. I am eith George on the transom pickup. all of my boats have them.

[TXDONZI]

Shouldn't there always be flow out the two connections going to the manifolds regardless of engine temp. and t-stat status? I am starting to think the pump impeller and/or housing are shot. I will try flushing from the top again and look for a leak in the bilge. Also if I am seeing flow down through the system how does water get past the impeller if it is not missing veins? After pulling the boat out on the trailer I always remove the plug while on the slope of the ramp. There was very little water that came out the bilge.... less than usual really but it was a short day that day with very little on and off boarding.

Does someone have a diagram of the cooling system showing direction of flow?

Oh..... I also placed a bucket under the drive when I flushed and did not see anything but water come out the intake grates..... No sand what so ever!!!!

Also does the right side manifold always run a bit hotter than the left? I have always had a differential between the two 5-10 degrees or so?

[glashole]

remove the plugs at the bottom of the manifolds

I did this (read mechanic did this) at the last winterizing and i had a bunch of sand come out of the drain

I go though alot of low water areas where it was likely to have picked up the sand

this is probably not the issue with yours as mine never ran noticably warmer, but you might want to try and do it :)

also it has neen my experience that water will run past the impellor without it moving

take off the housing and put in a new impellor kit including a new housing

you can see how the water will run around it once it is off

[gcarter]

[QUOTE=TXDONZI;458772]

Does someone have a diagram of the cooling system showing direction of flow?

I bet if you owned a Mercruiser manual, even one of the inexpensive ($25.00) Clymer manuals, it would have a cooling schematic.....in fact I know it does. Available from most local book stares and Merc dealers.

[RedDog]

Also does the right side manifold always run a bit hotter than the left? I have always had a differential between the two 5-10 degrees or so?

That is normal

[MOP]

Phil, from what he says, the drive is open, but, the short "S" shaped hose inside the gimbal is about 3/4" diameter and it has plastic fittings inside the ends that are about 1/2" diameter. Take a look at this microfiche; http://www.dougrussell.com/partscatalog/components/index.cfm?fuseaction=viewparts&colid=04&coldesc=BRAVO%20I%2FII%2FIII%20%20%20%20%20%20%20% 20%20%201996%2D1998&index=1943&block=160&BlockNumberList=180,150,120,130,200,190,80,60,70,5 0,220,230,250,240,100,90,160,110,310,170,280,270,3 20,0,330,300,290,340,360,370,380,350,40,20,30,10,1 40,260,210 and notice #15, and #16, this is the most severe restriction in the entire system. This is what you eliminate when you install a transom pickup.
Since the engine is cold, you may have to remove the thermostat because it will be a restriction in the system.

George you need to quit thinking Alpha! Made me get my calipers out! I went out in the rain and did some good measuring!!!

Bravo gimble hose 1-1/4" OD, Alpha hose is just shy maybe a 1/16" of 1" OD and 5/8" ID so you are correct on about 1/2" out the Alpha barb.

George part#20 is a 1-1/4" barb, I have 1-1/4" hose going to my strainer from that barb with no bushing. The connecting hose is not an S on the Bravo and is way bigger then the Alpha, the flow comes into the gimble on the stbd side and then is routed to the port side where the gimble hose fitting is. The hose goes forward then up and over to the fitting eliminating the Alpha S, it is near impossible to kink a Bravo hose but almost a sure thing on an Alpha. I kinked my Alpha and did what I did to several of my customers boats, I put wire wound in it's place. My Alpha shield is now on my kids boat and still had no hose problems. I had my new Bravo transom shield on the bench for a few months and did some good looking over, I moved the gimble in and out several times watching very carefully to see just what the supply hose did, it does not even try to kink unlike my Alpha which kinked very easily that was part of the reason I did not bother with a transom pickup I could easily see there would be no problems with flow. I like all other Bravo owners suffer from too much water/pressure at speed! I measured the Oring in the Bravo mount kit it is 1" it sits in a land with a very thin inner lip. As you know 7/8" will flow about double the amount of liquid then 1/2". The bravo is 7/8" from end to end!

Put the muffs on with the inner gimble hose disconnected from the pump not he shield barb as that is easy to crack, turn the water on and run the drive up and down a time or two the line will flush out. Once it up and running the block drains should be left out and the engine run on the muffs, there is enough water to do this with plenty coming out of the exhaust while flushing the sand out of the block. The circulation of the engine running helps to get rid of most of the sand. I have flushed quite a few engines over the years, the bottom of the block catches quite a bit and just lays there if you don't stir it up.

I had nothing better to do then write a dissertation its raining outside!!!!!

Phil

[gcarter]

Phil, I'm not sure why you keep talking about an Alpha....that Microfiche is for a mid '90's Bravo and the interconnecting hose diameter is way less than 1 1/4", in fact I just went out to the shop and measured mine (#15) and it is just under 3/4"...the little plastic inserts (#16) are smaller yet and I think they are about 1/2". I would measure them but I threw them away already. So anyone thinking they have a 1 1/4" hose running through their gimbal is missin' it.

[cutwater]

So anyone thinking they have a 1 1/4" hose running through their gimbal is missin' it.

I think that's right. My Cobra drive (which I've heard flows much better than an Alpha) still only has a 1/2" or 5/8" ID connection through the housing. In fact, the OMC setup I had was 1/2" almost the whole way until it reached the Tstat housing!

Glashole made a great point - instead of an elaborate flush scheme, first just pull the plugs on the bottom of the manifolds and the block. A moderate amount of debris can be normal, just take a screwdriver and poke through the clog. But if it is really packed in, you will know it.

[MOP]

Phil, I'm not sure why you keep talking about an Alpha....that Microfiche is for a mid '90's Bravo and the interconnecting hose diameter is way less than 1 1/4", in fact I just went out to the shop and measured mine (#15) and it is just under 3/4"...the little plastic inserts (#16) are smaller yet and I think they are about 1/2". I would measure them but I threw them away already. So anyone thinking they have a 1 1/4" hose running through their gimbal is missin' it.

George like I said there is a 1-1/4" OD hose from the gimble to the shield and 1-1/4" ID off the shield to the strainer with the water passage through the gimble and shield of 7/8". The measurement in the prior post are correct. Like I also said Bravos at speed have way more water then they can use, that is the reason when mine first went together I had high a pressure water leak at the strainer cap requiring a special gasket. The pressure was caused by the drive as the strainer is before the pump. In the Doug Russel diagram the hose is 1-1/4" OD Item #16 is the barb on the gimble which the 1-1/4" OD hose goes on to. Beat it with a stick you are wrong on this one!

Heck we have a few Merc parts guys here on the board all they have to do is to pull the barb off the shelf and measure it like I did!

[gcarter]

Phil, tomorrow I'll take a picture of the gimbal hose w/my calipers stuck in the end of it w/a reading of .72" diameter.

[TXDONZI]

Good flow through every hose and the motor too. I now know all the hose routes and their directions of flow. I found sand in the lower portion of the block and flushed it forward & backwards several times till I felt no sand coming out. I did feel small exhaust pulsations coming in and out of the right side manifold cooling hose but not the left side. This was done while the engine running with the hoses disconnected. Is this normal? Could this possibly be the source of the differential temp? I feel on the manifolds and the exiting water from the tips? I am guessing the impeller/pump housing needs replacing. SUCH RELIEFE!!!!

The motor sounds normal and the oil looks like it was just changed yesterday. The guy I bought it from last September had it serviced and impeller changed the week I bought it. He gave me the receipt for the service showing the computers scan with the hours. It had 197 hrs. and now has 229. Can sand trash one or both of those items that quickly? I have parked on sandy beaches every time I use the boat and have had the sand issue a few times but it always cleared up quickly.


I found several of the manifold bolts in a corroded state and one has the hex head all but gone. Other than the mentioned bolts heads everything else looked good. The two fittings going into the PS cooler looked a bit rusty and the PS pump had rust on the housing. The motor mount isolators are rusty on the threaded area and nut. There were no signs of the head gaskets weeping. I guess this winter I have a few projects to take care of.

It looks like time for a nice set of EMI's or SS marine manifolds.

[BigGrizzly]

Sounds like normal maintenance to me, your doing fine!

[Air 22]

IMO...add to that list a..Sea Strainer...:smash: :wink: Save yourself some headaches....changing your impeller and housing once a year is a good idea especially if you boat in sandy area's...ask me how I know this.:doh:..:nilly::smash:

Its cheap insurance:wink:

I've added a sea-strainer 2 yrs ago.... u would be amazed what they keep from going into your motor:eek!:

Good Luck....

[TXDONZI]

That’s the plan..... I will do the sea pump stuff now and over the winter I'll get all the other stuff along with the strainer and possibly manifolds.

What you all think of the manifold differential temp. and exhaust gas pulsations I am seeing in the cooling hose on the right manifold but not the left one?

[gcarter]

Just so everyone knows how big their Bravo gimbal hose is, here's a picture of it. Unfortunately, the glare prohibits you being able to see the dial, but it's .75" diameter. The inside of the plastic inserts that go inside of the hose is about .50".

But it ain't 1 1/4"!!!:smash:

[MOP]

Well had to make a trip out east to do a favor which gave me the opportunity to go to my buddies Merc shop. Again having better access to a transom shield the OD or Outside Diameter as stated in the earlier post is in fact 1-1/4", the passage through the shield is 7/8" but has it's edge rolled to allow you to get the hose on. So for argument sake lets call the passage 3/4", click the link below and scroll down to chart #5. http://www.plumbingsupply.com/pluminfo.html It is very easy to see the 3/4" flows more then double that of 1/2", so us Bravo guys need not be scared! Sorry for the light photos maybe someone can clean them up in Photo Shop.

Phil