Gnational

94 American Offshore 2600- 540 Ateco 700hp motor, Bravo One with XR Gears- running great but overheating. Got into some sand first time out and boat is now overheating. Low water pick up on the nose cone, then short hose to upper outdrive, hose into seawater pump, out to oil cooler, up to a cross into the block with a bypass above the thermostat, out to water jacketed headers. I have back flushed from the short hose back through the low water pickup, flowing freely. backflushed from the pump inlet back out the short hose, flowing freely. Backflushed from the oil cooler outlet to the seawater pump outlet, flowing free. Flushed from the seawater pump outlet through the oil cooler to the block, flowing freely. Flushed from the seawater pump outlet through both block plugs, seem to be flowing freely. Motor runs fine on garden hose at low rpm, no heating up at all. Even in the lake it will cool at idle to 170, but any significant motor load and the temp shoots to 200 and I shut it down. I ran the 140 thermostat in hot water and it opened right up. I installed a new seawater pump yesterday, no help. The flow out the headers is usually OK, but sometimes the flow seems reduced to the starboard header. I installed a water pressure pickup in a plug on the intake manifold before the thermostat, and I have no/1-2 psi water pressure at the gauge under any condition. Previous owner says ran fine at 180 for him, he thought the thermostat was a 175, but he never had sand trouble. Originally I did backflush some sand out the oil cooler, but not much. The block plugs are picking up small amounts of debris, nothing notable. Seems something is restricted - ideas?

MOBILEMERCMAN

Gnational- did you replace your water pump. sand probably ate up your pump body. The 140 stat is the right one. if your header is restricting out flow it will make it heat up. You said you have next to water pressure it should be around 20 lbs at speed. Get a pump kit with housing.
Jim

Gnational

Jim - I replaced the Housing and Impellar yesterday, and the belt is not slipping. I don't think the header is plugged as I have had good flow at times especially out the port one, heres a twist though, I ran it with no thermostat and the starboard one had great flow and the port flow diminished, further confusing me. Thanks

baja bailey

Be sure to let us know what you find, as I have very similiar issue with temp problem after sucking up sand.. Mine has been backflushed twice new raw water pump and 2 new thermostats. The temp used to be rock steady on 175 before, now it fluctuates between 175 and about 200 all the time...

rangerrick63

I did the same thing on my Donzi at the beginning of the season. I had to remove every hose & cooler & flush completely. Luckily I was able to do this on the water, or it would've been a long tow home. I started with the hoses, & discovered that each cooler was packed with the sand, so the coolers had to be flushed. I did get lucky, nothing got past the T-stat, but I did remove all my block & manifold drains, & flush completely when I got home, & of course new impeller & t-stat, & switched to a transom mounted pick-up, & now I have no worries, temps are actually about 10 degrees cooler. Bottom line, flush, flush, remove everything & flush again....& change the impeller...

oldandtired

I have run into this many times and have it down on my boat. The easiest way to deal with it is to disconnect the raw water outlet from the pump and the raw water inlet to the thermostat housing. I then blow into the hose at the thermostat as hard as I can. Gets it every time. I have had to do this on the water alot. In order to be sure where the problem is, squeeze each one of the hoses with the engine running in the water. The discharge hose from the seawater pump will be pretty tight (high pressure) if you have a flow restriction. Mine always clogs up at the inlet to the oil cooler and gets hot on the starboard exhaust first as well. Get a strainer to help reduce your problem. The nose mounted pickup isn't helping either.

Rene

Scarab28

Has anyone attempted to convert their LWP to a dual water pickup or even plug the lower pickup after converting? The LWP's are horrific at even the sight of sand!

rangerrick63

After I installed my transom pick-up, I kept drive pick-up (LWP) as is, & ran the hose from the 1 1/4" barb fitting to a 45 degree dump fitting (Stainless Marine). This dumps on top of the outdrive, & it dumps alot of water.
I did this because I couldn't get definitive answers as to whether or not I had to keep water going thru the drive. So, I look at it as good insurance, water still goes thru the drive, & it dumps right back on top to keep the top cool.
Oh, & since the water is only going thru the drive as a result of the boat moving forward, if I bump bottom, no sand will enter....unless I'm moving pretty fast...then I'll certainly have a few more issues to deal with....