Water flow to exh manifolds

On my Welly with a 350 Mercruiser I was experiencing a temp rise at WOT last fall and this spring I pulled the outdrive and did a complete pump replacement it was shot,then serviced the boat and put the muffs on it and fired it up and ran it to temp,there was plenty of flow coming out the thru hulls(that are baffled).But I noticed that one exhaust riser was fairly warm and the other one stone cold,I also noticed by squeezing the hoses coming from the top of the thermostat housing to the manifolds that on the side that was hot it felt like air surging thru the line whereas the cold running side felt like full flow,I have not yet had a chance to put the boat in the water and see if it changes it at all,what do ya think do I have another issue to take care of.Thanks Rob

Re: Water flow to exh manifolds

Slippery When Wet said:

...what do ya think do I have another issue to take care of.Thanks Rob

Click to expand...

Without know anything about the year or model of the engine or stern drive unit, or if it's an inboard, we have absolutely no idea....

Have a read of this -> http://forums.iboats.com/showthread.php?t=220416

Then come back with all the information we need to help you....

Re: Water flow to exh manifolds

achris said:

Without know anything about the year or model of the engine or stern drive unit, or if it's an inboard, we have absolutely no idea....

Have a read of this -> http://forums.iboats.com/showthread.php?t=220416

Then come back with all the information we need to help you....

Click to expand...

Sorry achris its a 1985 Wellcraft Nova XL 350 ci (5.7 litre) with a Alpha one outdrive,running a 19 pitch 14.25 prop

Re: Water flow to exh manifolds

Thank you... Assuming the engine is the same year as the boat, it a 1985 Mercruiser 260 with an 'MR' drive...

With those drives, getting hot at WOT, is a classic symptom of a leaking water pocket cover gasket, and it's completely normal for one elbow to run hotter than the other... The water follows the path of least resistance. If the boat is even slightly off dead level the water will naturally flow to the lower elbow, or if there is a slight amount of corrosion inside one, it will flow better to the other... But the water pocket cover, in the bottom of the top half of the drive, would be the first thing I would be checking.

To check for a water pocket cover gasket leak, just put a section of clear water hose in the line coming from the transom to the thermostat housing. Run the boat normally and observe the clear hose.. You see anything but a solid water stream, you have a problem. Running the boat 'normally' means out on the water under normal load conditions, not on the trailer with flushers, and not just sitting at a jetty with the throttle opened.

HTH,

Chris.......

Re: Water flow to exh manifolds

Thanks Chris good info,never thought about the use of a clear hose to check flow under way good trick I will set that up and see on the first outing,and yes the engine is a original Iam the second owner.Regards Rob