Cooling issues

Help be my head hurts. I have a 1990 Sea Ray 230 with a motor ( purchaced new and installed by a previous owner) 2001 marine power 5.7 efi closed loop fresh water cooled. I bought the boat k knowing it had a running issue. I took it to the lake the day I bought it to see what it was doing. It got hot, spit sputtered died. The next day I put it on muffs to see what was going on with it and it started fine ran fine for about 15 minutes until I fixed the idle air issue and the idle dropped down started to get warm spitting and sputtering etc. Starboard risers much hotter than port side but appeared to have good flow. Pulled lowerer unit, complete cooling system manifolds, risers all that. Only thing I found was the starboard matter shutter was half gone, same elbow looked melted at the riser joint. Manifolds looked very nice but sent them and the risers out to get hot blasted. Only ran in fresh water and has from what I could figure less than 100 hrs on it. The boat only has 257 hrs total. Obvious cultprit would be raw water pump but that looked almost new (replaced anyways) heat exchanger appeared to be good with no clogging, thermostat looked old so I have a new one. Haven't put I back together because I haven't located the other half of the water shutter and I haven't found a smoking gun as to why it got hot. Compression test showed 175# on all but 2 cyliders and the oil is fine and no back pressure in overflow tank. I have all but ruled out head gasket being the issue from the symptoms on the water and on the muffs. One thing I did notice was it has a blocked gasket between the manifolds and the risers and the coolant in there was brown ibrown ish while the rest of the coolant was bright green and new looking. Pulled and inspected the circulation pump and it looked new.

What 2 cylinders didn’t show 175psi and what was the compression in those 2?

3&5 both showed 150. Leak down test tomorrow to rule out head gasket 100% but my guess is not head gasket. No smoke, no moisture in oil, no signs of exhaust gas pressurizing cooling system.

Espos4 said:

What 2 cylinders didn’t show 175psi and what was the compression in those 2?

Click to expand...

Could all my issues be caused by the half of the water shutter I can not seem to find? Could that half be restricting my exhaust flow and water flow from the starboard side manifold? With the out drive off and garden hose ran into the y pipe water comes mainly from the holes at the bottom of my gimble it I do get some water from my center exhaust opening. Before I tore it apart running on muffs it would spray water from center if prop with majority of water coming from the holes on each side of the gimble housing.

Cast away nick said:

Could all my issues be caused by the half of the water shutter I can not seem to find? Could that half be restricting my exhaust flow and water flow from the starboard side manifold? With the out drive off and garden hose ran into the y pipe water comes mainly from the holes at the bottom of my gimble it I do get some water from my center exhaust opening. Before I tore it apart running on muffs it would spray water from center if prop with majority of water coming from the holes on each side of the gimble housing.

Click to expand...

lso the port side shutter was missing all of its rubber coating (they were aluminum covered in rubber style)

Most likely the missing shutter is lodged in the y pipe. I would gave a good look through the y pipeb with an endoscope or just use a plumbing snake from the top down with the drive up and bellows removed. If you don't find the restrction there you can try running it on the muffs again with the exhaust bellows removed and drive up out of the way . If the temperature is ok like that you will know that the restriction Is in the drive and it to need to get it out if there.

I've never taken apart or researched exhaust belows, is it possible to do this with everything attached? Will I need to replace the belows?

You probably have heat damage to the exhaust bellows given the damage to the exhaust tubes and shutter . It likely needs replacing . The drive can remain attached for this but needs to come off to do the impeller for your water pump if it is an alpha 1 . Most peopkendo the water pump exhaust and shift cable belliws as well as lowershift cable as a msintwbance item every 3 years or so . You said the raw water pump was done icam thinking you might be mistaking the engine circulating pump with the raw water pump... more reading up on your systems will go a long way in determining what your cooling issue is ... Good luck

I pulled the lower unit and changed the raw water pump already, the pump and impeller looked almost new with no cracking on the impleller and no wear marks on the housing. I pulled the upper portion of the out drive to look for the broken shutter. I flushed with water from the top of the y pipe, used 175psi of air to try and blow it out, stuck the hose from my rainbow vacuum down to try and suck it out, used a grabber tool and was able to get 1\4 of the rubber and the half of flap I dropped in on accident. I will try to get my hands on a scope today to look for the rest before pulling the bellows as like are very soft and appear almost new also. So you think this could in fact be causing my heat issue?

Yes any restriction on can definitely be the cause also remove and inspect all ripper cooling lines some will have deposits cracks or collapse under suction . I did a post in here about that job when u did it this year different motor but same principal . You could always flush the block too

Is there a way to pull the y pipe with the motor in still? I planned on doing a coolant flush on the block when I put it all back together. Currently everything is tore apart so I can find my issue. I hope it is a restriction issue and should have results from a leak down later today.

Look at the small hose from the lower unit to the transom, if it's too long it will link and restrict inlet water to the heat exchanger. It's worse at low rpm, increasing revs pushes more water thru. You need to get that piece of shutter out. Try a shop vac with a thin hose in the nozzle and shove it down the y pipe and suck it out.

I will look at the hose to check for kink or obstruction. I have a scope now so I'm going to look for those pieces.thanks

As far as the shutter, I change my last year and found 1 out of 4 shutters missing half the shutter, I want crazy looking for it finally after pulling the drive and putting a camera in there and trimming up the drive as if you were planning off the boat you can see a 3/4 in gap that the shutter can fall out.
I never found my, I am 100% sure it fall right out the exhaust.
Don't have the boat with V drives anymore

Okay put a scope to it and found three pieces, one rubber one aluminum and a steel rod. No other obstructions found. Just cooked the old thermostat and it didn't open all the way until 185 degrees. I'm going to start putting it all back together tomorrow and see what happens. Thanks and I will keep posted.