Hey all,

My 496 HO saga continues. Backflushed everything, oil cooler, ps cooler, heat exchanger, took them off and cleaned them thoroughly. Water pressure (fed via hose to dash gauge) is off the charts, goes way past the 35psi on the gauge. Started spitting water out the end caps of the heat exchanger and overheating.

I'm thinking the only thing left is the manifolds/risers (EMI Thunder) and/or the hoses that come off the bottom that have a poppet valve (not sure what the poppet does) I can tell water is coming out the back, but I know you can't really tell if it is the right volume etc.

How can I test or check the manifolds. I took the risers off and they look good and can look inside the manifolds which look ok??

Hi Titan,

3-15-21

just went Through something similar, I have twin Mercruiser 496 HOs. Long Storey short , motors were pulled to find transom Assembly raw water tube / That comes through the lower unit was 80 % clogged ..

lower units have to come off to see it

ZUSH, would that cause low WP to?

ON my 2002 496HO I don't have overheat issues but WP is near 40PSi WOT(rinda monitored). No faults, been like that for 2 summers, freshwater with just over 200hrs. HE is clean... so if oil cooler isn't the issue what could cause high WP after the HE. BTW, checked PS and it's OK along with new WP sensor.

Hey Woodchuck,

it’s Possible !! Mine had high numbers also, but also went into Guardian and shut done a couple times !!

it’s easy to pull the lower unit OFF .. the Inlet Tube / Hole is east to see at that point .

that may answer your questions. My Formula is a 2008 with 350 hours !! Flushed and washed and waxed after every use ... but that Fitting still closes up ! ITS Called Bravo Itis

utube has a lot of Videos .. Ck them out ..

My bill was almost like buying a car ..

Bravo-itis.

The opening in the transom where the inlet hose comes through corrodes and compresses the hose. Aftermarket repairs use a stainless insert to prevent the problem from returning. Why Merc hasn't done this from the get-go, who knows?

I like thru-transom pickups and strainers for that very reason.

https://www.hardin-marine.com/p-7405...epair-kit.aspx

I've repaired a couple of transom assemblies using this.

Rookie question: So the raw water pickups under the boat feed the raw water pumps that cool the engine and exhausts, correct. Is this hose an additional pick up point?

Traditional Bravo picks up water through the drive. Water is the. routed through the drive’s transom assembly to the raw water pump (belt driven). From there it goes to the oil coolers and then to either the thermostat housing and into the engine or to the heat exchanger (if using closed cooling). Exit is through the exhaust.

Inboard is similar but uses pickups at the transom or on the hull bottom.

Alpha drives have the pump built into the lower unit; a raw water pump is not used.

Run 50/50 muriatic and water from raw water pump out the back thru the drive. It will eat it out fast.

[QUOTE=TomZ;4781856]Traditional Bravo picks up water through the drive. Water is the. routed through the drive’s transom assembly to the raw water pump (belt driven). From there it goes to the oil coolers and then to either the thermostat housing and into the engine or to the heat exchanger (if using closed cooling). Exit is through the exhaust.

Inboard is similar but uses pickups at the transom or on the hull bottom.

Alpha drives have the pump built into the lower unit; a raw water pump is not used.[/QUOTE

Gotcha. Since I have pickups in the bottom of the the hull, this crushed hose is not a potential problem for me I take it. Thanks.