350mag A1 overheating under load

[Limeyguy]

Hi guys, OK I have done a search but has this happened to anyone so they know whether its manifolds+risers or impellor or thermostat etc?<br /><br />92 350mag Alpha 1 on 24' Regal cruiser<br /><br />Fine on idle, fine all the time EXCEPT when under way, 3500rpm+ temp starts rising until overheats.<br />BUT if I shift into neutral, rev 2-3,000 rpm temp immediately comes right down to 150.<br /><br />Risers not too hot to the touch. Starboard side is a bit hotter, can keep my hand on for a few seconds.<br /><br />Would like to know what this is - it's VERY expensive here in the UK to replace everything!!<br /><br />Thanks very much hope someone can help!

 

[Haut Medoc]

Re: 350mag A1 overheating under load

Welcome to iboats. .......If you don't know when the impeller was replaced last, by all means replace it now. That's where I would start. Easy and relatively cheap. You don't say if you have closed cooling or raw water cooling....Change that impeller & post back.....JK

 

[Limeyguy]

Re: 350mag A1 overheating under load

Thanks. Boat's in a marina and a drive service inc impeller kit will cost about 750bucks here which is fine if it cures it. I've been offered some nearly new manifolds & risers for about half that which should be able to be fitted without lifting boat out of water. All I know is the option I choose will be the wrong one!<br /><br />Its raw water by the way, boat just arrived from Florida, don't know when impeller last changed, or the manifolds/risers which, as I say, aren't tooo hot and look good (from the outside).<br /><br />So which first - cheaper & quicker manifolds/risers or the more expensive and slower impeller? Thanks

 

[navigator336]

Re: 350mag A1 overheating under load

Did you say $750 (450 pounds)for a water pump rebuild kit? You could have one shipped by air from here for a fraction of that.

 

[bigbrownbuku]

Re: 350mag A1 overheating under load

make sure the water pump base comes up and the gasket beneath is replaced or you will continue to have problems. the gasket is in the kit.

 

[Limeyguy]

Re: 350mag A1 overheating under load

navigator. sorry that's what it'll cost for a liftout (no ramps here), service inc parts and gaskets, and a lift back in the water. That's a full drive service including bellows and pump kit. If the drive's geing pulled might as well do it all. Bit beyond my DIY capabilities once I've bought the right tools etc.<br /><br />One marine shop here reckons impeller, the other reckons manifolds/risers!<br /><br />What I want to avoid is doing the impeller, finding it hasn't stopped overheating, and then missing out on the cheap manifolds.

 

[tommays]

Re: 350mag A1 overheating under load

how old is the water pump ? if it more than 3 years its just good PM to replace it<br /><br />if the boat just came out of salt water i would be wary of the manifolds and risers <br /><br /><br />tommays

 

[Haut Medoc]

Re: 350mag A1 overheating under load

When you add the bellows in....$750.00 isn't that bad....You could do it for $100.00 in parts over here.....No ramps there?....And they say the British are civilized..... If the cost of the haul out is a considerable part of the cost 1/3 or so, I would bite the bullet and have the full service done....Bellows and all....'cause if they fail.....You've really got problems.....Unless you know the age of both the bellows and impeller, just just 'git er done'. Especially if the boat came from Florida where I'm sure it lived in salt water... Buy yourself a manual & take the time to familiarize your self with the impeller replacement procedure, while your boat is running good......It's very easy and requires very few tools.....And you will save big $ in labor bills.....I think changing the impeller will make your troubles go away......I would buy the manifolds too, if you can, just for spares....You only get 5 -7 years out of manifolds that are raw water cooled, esp. in salt water.......Good Luck..........JK

 

[Limeyguy]

Re: 350mag A1 overheating under load

I think that's all sensible advice - thanks a lot. I'll let you know what caused it when I find out. By the way there's nothing civilised about our gas prices either, now $7 a gallon!

 

[Limeyguy]

Re: 350mag A1 overheating under load

Hi guys, boat came out of the water for servicing and bottom paint. Impellor wasn't great thats now been replaced, but the thermostat wasn't working either, so it must have been this.<br /><br />Hope this might help someone save a few bucks in the future!<br /><br />Another problem solved was she could be difficult to start when warm/hot. A choke solenoid was the cause of this which has also now been replaced.<br /><br />Back in the water tomorrow she should be fine now ... until the next time!