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83' 270 need advice please about cooling

C

capnandy

New member
Hi all, I'm Andy and I just put my 31' Silverton in the water. Twin 270's.On port engine I have decent water coming out only one exhaust port. little is comming out the other. And the one with little is very hot to touch exhaust manifold. I think if impeller is bad I wouldn't have water coming out either. Any advice?
 
Welcome Aboard!

Sounds like the hot elbow isn't getting enough water. Risers and elbows have finite lifetimes and those may be due.

Impellers are also routine maintenance items. Your thoughts on the impeller are correct.

Is this fresh water cooled or raw water cooled?

any info on age of current exhaust components?

Last time the raw water impeller was changed?
 
Thanks for responding Mark. Raw water. Checked impeller last summer. Mostly all original parts. Here in Franffort Mi. shallow water in the marina I was suspect of being clogged with sand and silt. Any way to blow out if its clogged?

Andy Odette
Intimidator Charters Frankfort Mi.
 
If the elbow is clogged with sand, you can bet the impeller is worn. most pump data sheets will tell you annual replacement, some every other year.

If the exhaust cast iron is original, you may want to start funding the replacement budget, you are at 25+ years so they could go at any time. If you book is filling up this summer, I'd encourage you to replace the risers and elbows now, while you still have bye days.

You could disassemble the elbow/riser from the manifold to try to blow them out but I'd expect them to be clogged with cast iron 'parts'. With that age, I'd expect the thing to be 'rotten' on the inside - in other words, it will start disintegrating when you start poking the rust parts with a coat hanger, etc. Another option is to take them to the radiator shop and have them boiled (dipped in the hot tank).
 
I have a world of experience boating on the Mississippi River in the Memphis area. The thing in common with your river in Michgan is the sand in the water. By the way, my son lives in Grand Rapids. I found that sand will grind the body of the water pump so that there is a clearance between the body or wear plate and the impeller. This lets water short circuit and the pump looses considerable capacity. The impeller can look good but the pump will not deliver. I just chose to replace the pumps as they wore. I believe they can be rebuilt. I fould at low flow from the pump one exhaust manifold got more of the water than the other.

I would work on the pump before tearing into the exhaust system. My engines are 1984 454 CID raw water cooled in fresh water service with 1400 hours.

Chuck Hanson
 
Before pulling the impeller, check the plumbing system before the raw water pump for blockage and air leaks--a tiny bit of air leaking in will raise hell with cooling.

Jeff
 
By disconnecting hoses I was able to flush manifold system with garden hose. Came out the back fine. Also back flushed from ahead of pump through v drive and no restrictions. Impeller looked ok but probably isn't. In the upper thermostat housing there is a spring loaded water relief that seems to let water flow to exhaust manifolds. What are the chances it's bad. Seems fine. Just found this site. You guys are awsome for sharing knowledge!
 
Like Chuck said. It's not just the impellor that wears. The metal cam and the cover plate wear as well, especially if an abrasive is present. If these pumps have not seen a major rebuild in the last 10 years, now is the time.
 
You are right Mark. Sometimes we skip the diagnostics and go right to the difficult stuff. Ockham's razor comes into play here somewhere; the simple solution is often the correct one.

I concur; measure the output of the water pump. If it is low, I would check the pump first on a fresh water engine used in a sandy river.

Chuck Hanson
 
The chart i have from Sherwood (pump OEM) shows a 'normal wear' impeller will deliver between 5 and 8 gallons/minute, with the engine at 1000 rpms. The difference is due to head pressure (0-15 psi). If you run an open hose from the pump outlet fitting into a bucket, I'd expect to see 2 gallons in 15 seconds. Much under that means it is time to service the pump. if needed, both Sherwood and Jabsco have 'troubleshooting" info available on the www.
 
I recently discovered numerous chunks of impeller in my transmission oil cooler which was slowing water flow through my system. If you have an oil cooler plumbed just after the raw water pump you might check to see if there's anything in there. Mine was blocked so badly that the prior owner actually removed the thermostat from that engine in an effort to cool it down (well done eh?). After I replaced the oil cooler and installed a new raw water impeller I'm running at 160 degrees again.
 
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