Checking Manifold and risers requires new gaskets?

[eavega]

I probably know the answer to this one, but I'll put it out there in case I am wrong...

I have a carbureted Mercruiser 3.0L (Circa 1988). I've noticed the motor is running a little warmer this year than it has in the past. Still within "safe" range (gauge reads about 160-ish where it used to read slightly abouve the 140 degree mark), but definitely a little warmer. I keep forgetting to to bring my non-contact thermometer when I'm out on the lake to verify the temps. I've also noticed the tendency to run on a little when you shut it down after a longer run (say solid 10 minutes of pulling tubes, or a long run back to the dock). I'm not sure if its just a combination of the lake being very warm (water temps are close to 90 degrees) and air temperature being very warm (its been 90+ degrees here for the last 3 weeks or so), or there is actually some problem with the cooling system. I checked the impeller at the beginning of the season and it was in good shape, I had serviced the water pump at the beginning of last season but didn't use the boat more than 5 or 6 times last year. I'd next like to remove the manifold and riser to check for any restrictions, so my question is; do I need to replace all the gaskets if I pull the manifold and riser for inspection? Also, what else should I be looking at in terms of the "slightly warmer than expected" condition? I replaced the thermostat two seasons ago and have really only put about 30-40 hours on the motor since then (last year was not so good for boating. This year is much better).

Any help or suggestions you can provide would be appreciated.

Rgds

Eric

 

[Bondo]

when I'm out on the lake

Ayuh,.... Rust, 'n corrosion is pretty much a Non-issue on sweetwater boats,.... It's the Brine that kills exhaust castin's,.....

I'd blame it on higher water, 'n air temps,......

 

[crazy charlie]

New gaskets for sure.Since you will have the mani and risers off you may as well try cleaning them out as much as you can.Start with some high pressure water into the internal water passageways and take note if anything comes out like rust chunks/chips ,muddy looking gunk etc.You can use a gun cleaning kit if available.you can also try poking a wire coat hanger as far as you can trough the passageways.When it wont go any further,clamp it with a locking pliers and hit the pliers with a hammer to force the wire to go further.Take note of the size of the passage opening inside the riser.They tend to corrode a lot at the opening so pick at it with a screwdriver to make sure it isn't closing up.I had one that was the perfect shape opening but it was only half a large as it was supposed to be.A few hits with the hammer and a screwdriver and the hole opened to the size it should be.Charlie