www.iFourWinns.com

My boat's engine overheats withing 2-3 minutes (on idle) after I connect it to the garden hose. If apply power power, it overheats in 1-2 minutes. Water flow appears to be normal.

The engine does NOT overheat while cruising in the bay.

Does anyone know why it overheats so quickly while attached to the garden hose?

Do you have the hose pressure up high enough? Which drive?

_________________


Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Mike,

Even though the boat is approx 30 ft away from the spigot, the water pressure seems to be high.

It has an Alpha drive

Howdy,


What year is it,

Which engine,

salt or fresh,

how old is/are the manifold(s) and riser/elbow(s)

and when did you last change the raw water impeller??



regards,

_________________
1987 Four Winns Liberator 211, formerly OMC 460 King Kobra powered, replaced in 2006 by a 1997 Mercruiser 454/Bravo III

They sell water pressure gauges at most hardware stores. They're inexpensive. Get one and check your actual water pressure. When the engine is above idle it pulls a LOT of water. If your pressure isn't up to it you'll starve it for water and it'll overheat. Around here at the house we get EIGHTY pounds of water pressure. At the marina out on the docks it's only around thirty. Both seem like "a lot" when it's coming out of a garden hose, but in reality they're quite different.

Also consider whether the hose is collapsing. If the pressure is marginal it's entirely possible for the engine to pull enough suction to collapse the hose.

_________________
-Bill Kearney, 2005 348 Vista

Just some further input .....

I run our boats off the garden hose, which is about 100' (on a reel). We have a well and the pump runs between 40 and 60 lbs. At a constant draw from the hose, it runs about 40 lbs and can go down to 30. I never have any trouble running any of our boats on the muffs (at idle and with short revs, if whatever I'm doing requires it). It takes quite a while to get the engine up to temp at idle, certainly longer than a couple of minutes.

When the boat is in the water, there is unlimited volume of cooling water available, with no input pressure. All of the water is draw in by the raw water pump. If the raw water pump were bad, you'd have trouble with it getting hot when it's in the water. This is not to say that you may not have a worn pump impeller that should be replaced anyway .... I just don't see this as a root cause of the issues you're having.

If the engine circulating pump (which, with a few exceptions, either works or does not work at all) were at fault, the engine would overheat fairly quickly ... be it on muffs or in the water. Kind of like you are seeing while on the muffs.

If you had corrosion build-up in the exhaust riser(s), this should cause problems with either the muffs or in the water, since this impedes the flow of hot water exiting the engine.

Thermostat? Can't really see this making a difference between the muffs and in the water.

The only thing that I can see that would cause the temp to go up as quickly as you have noted, would be a stuck (closed) thermostat, blocked risers or a faulty engine water pump (like, all the impeller blades corroded off .... rare, but can happen). None of these really should make a difference when running muffs or in the water. Unless your hose flow is just WAY too low.

If the only problem were low hose flow, I still can't see it getting that hot, that quick.

Perhaps this will generate more thoughts from others .........

_________________
Gordon Arnold
New Hampshire

2003 268 Vista ..................................................................Prior: 97 245 Sundowner

Thanks to all you for your replies.

The boat is a 2004 four Winns
260HP Mercruiser engine
Alpha drive
It has less than 200 hrs
I have only used it in salt water
I have never replaced the manifolds, raw water impeller or the risers/elbows.

I bought it in 2005 and have been the only owner.

The boat has been doing this since I bought it, but since I was (and continue to be) a rookie I thought that was normal.

I am venturing to do the maintenance myself. Since some procedures require that I run the engine for more than two minutes using the water hose, I though about checking around about this issue before doing so.

It doesn't overheat in the water but it overheats on the water hose, eh? Well I'd get a nice heavy set of dual feed muffs that put water to both sides and use a 3/4 in diameter hose, I use a length of automotive heater hose instead of garden hose. With that I never have an overheat condition on the muffs.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Be careful that the hose is not being sucked closed when running above idle. I have seen cases where running above idle has enough suction to suck the hose pinching off the water supply

_________________
Bridgewater, PA
2008 Vista 318

As I suggested earlier. And Lou added the suggestion of using a better quality hose. Your "garden variety" hose (sorry, couldn't resist), coupled with less than FIREHOSE levels of water pressure will certainly collapse under the pull of an engine at anything above idle.

Check the water pressure, get a (much) better quality hose. The pressure gauge and a hose are certainly going to cost a LOT LESS than replacing the engine due to overheating.

_________________
-Bill Kearney, 2005 348 Vista

It's very possible that you have picked up something that may be blocking or reducing water flow.

With 4 years and 200hrs on the boat, you should replace the raw water pump.

Mercruiser recommends checking it any time you suspect a restriction in sea water flow. Some dealers and marine mechanics like to replace it every 2 years or so....Since it's an Alpha, you'll have to pull the "lower" to check it. I would never put one back together with a used impeller, (the impeller kits are fairly inexpensive) so if you take it apart you should replace the pump.



While you can probably get away with letting it go longer, you should replace it at least every 2-3 years when using it in salt water. They'll go a lot longer in fresh water. And maybe longer in salt if your boat is trailered and flushed with fresh water after every use.

If it only does it on "muffs" it may be due to the "cups" not sealing completely and sucking a little
(or a lot of) air.

_________________
1987 Four Winns Liberator 211, formerly OMC 460 King Kobra powered, replaced in 2006 by a 1997 Mercruiser 454/Bravo III

Rick,

I am not familiar with the water pump on an Alpha, but does the actual pump really wear out and need replacing every 2-3 years? Or do you mean the impellor needs changing every 2-3 years (like I do on my VP pump)?

The first VP impellor kit I bought (wrong one as it turned out!) included, for want of a better word, a " wear plate", so clearly at one point pump body wear must have been an issue on VP pumps. Now if that occurs, the whole outer pump housing would have to be replaced, not cheap I am sure!

Graham

Hi Graham,

A lot of times you can get by with just replacing the impeller, plates and gaskets like this from eBasic Power:


All the raw water pumps are somewhat similar for OMC/Volvo/Merc, in that they use a rubber impeller, a (usually) stainless steel wear plate(s) and a stainless steel, plastic, aluminum housing (sometimes with a stainless steel "cup" inside).

The rubber impellers can get a "set" if left in there too long and they of course do wear out.

Depending on which repair kit you get, you can buy just an impeller, or complete kit that includes the housing, plates, gaskets, bolts, etc like below.... (I think the OEM Merc kit comes with bolts)

For an Alpha, the lower unit must be removed to replace it. this one is a GEN II so the following kit would be appropriate if he needed to replace everything.

From eBasic Power:



Anytime there's a cooling issue you must consider the raw water supply. (pump or blockage) Blockage can be either at the inlet or the manifolds/risers if they are old and have been used in salt.

Sometimes it's the thermostat but most of the time it's the raw water pump.

The raw water pump or "sea water pump" is lubricated and cooled by salt or lake water.
If it's run without water for even a min or so it could fail or be damaged enough to cause an overheat.

If it fails and you replace it you MUST locate all the pieces (impeller remnants) that broke off to prevent them plugging up your oil/power steering coolers, heat exchangers and thermostat housings.


Cheers,




Oh, btw, it appears that you might be the second owner? if it's been doing it since it was new it's also possible that someone before you ran it dry and damaged the impeller. The Gen II impeller is pretty tough though.........regardless. If it's never been replaced you should do it.

If you don't have a service manual you should get one. (NOT a Clymer/Seloc)

Go here for an online manual---> http://www.boatfix.com/merc/Servmanl/14/14cover.pdf

_________________
1987 Four Winns Liberator 211, formerly OMC 460 King Kobra powered, replaced in 2006 by a 1997 Mercruiser 454/Bravo III

Hi Rick,

Thanks for the information; I think I'll stick with VP and their engine mounted pumps !

As a matter of interest, does that Alpha impeller turn at engine speed, or at the speed that the reduction gear in the outdrive gives?

Graham

Being a former Apha owner, never had a bit of trouble as indicated. I replaced the impeller every two years, because of operations in silty water can wear it rapidly. Understand, my boat had only that and the engine mounted H2O pump. Not the "added" pump that my present boat does. The raw water pump is coupled to the drive, and turns at that RPM. This dilema really has me scratching my head. If I were in your position, I'd do all the normal maint items, such as replace the pump, as well as the T-stat, and check all the hoses and anything else posible for blockage/debris. When running on the muffs, a non-contact thermometer is a great too to have to check the riser and effluent temps. Maybe even try hooking up a garden hose and run water through the PS cooler backwards. Chances are it's something failrly simple, just elusive.
Good Luck!

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.