87 PCM Chevy inboard temp / water pump issue

[steelers7]

You seem like you know what you're talking about, ill trust your advice. But I still cannot understand the difference between the method I'm describing and how a fake a lake operates... unless I'm watching people use fake a lake the wrong way.

Out of curiosity, the other method I have seen to run an inboard out of water is to connect the hose directly to a water inlet hose, like the hose right off the water pickup. Have even seen people connect garden hose right to impeller inlet hose. Thats how my old man did it for years (and still does it) and how I did it before I read that this was wrong and could lead to pushing too much water into engine, and to use the bucket trick instead.
Is this method any wrong too?

 

[steelers7]

Bucket method video link, anyway

 

[Scott Danforth]

A fake lake looks like a toilet plunger with adjustable handle with a hose attachment and forces water at 50 psi or more to the water pump from the pickup under the boat

Trying to suck water into a bucket is a fools errand and will always result in a burned up impeller

No matter how many time you post it, it is wrong as it will never prime the pump

The process your father has will also work, however is harder than a fake lake

 

[Scott Danforth]

FAKE-A-LAKE

Whether you need to flush, tune-up or winterize your inboard engine, you can easily run your boat engine at home and out of the water with the Fake-A-Lake.

skidim.com

 

[steelers7]

Thanks a bunch, will let you know how it goes

 

[steelers7]

Pulled impeller, it looks okay, although I don't know exactly what to look for short of missing rubber. Rubber was all there though, no missing chunks or anything.

So I tried again with the garden hose jammed directly into the hose from transmission cooler to water pickup. Garden hose only on for a second before water started coming out the other end. Ran for about 10 seconds a few times, no water out the exhaust at all.

I tightened tension on raw water pump belt and watched that it is definitely spinning... definitely spinning with a good impeller but no water pushing.

Could the raw water pump itself be the problem? Could trans cooler be clogged and causing a blockage? Guess I could just take the hose off water pump inlet and see of garden hose gets water out that end.

 

[Scott Danforth]

If you haven't found the missing pieces of your first impeller, they could be blocking flow

 

[steelers7]

I guess I'll just start at the back and move forward...
Any particular spots that are more likely or unlikely to catch debris

 

[Scott Danforth]

Start at the thermostat housing and work to the pump. If not there, start going towards the exhaust manifold

 

[Scott Danforth]

BTW, make sure you have the raw water pump plumbed correctly. If mounted to the crank, the upper port is the inlet. Follow the arrows on the front cover

 

[steelers7]

Just an update.

Pulled tstat housing... ports are pretty wide throughout, but still dug around as much as possible, didnt find any impeller pieces.

Have it soaking in some rust removal stuff right now... maybe something is stuck in there where I cant get to and hoping loosening any rust might let me get to it. Thing is pretty rusty anyway, but I put the hose to it and did get water through all 5 ports (thermostat, 2 exhaust, 1 from raw water pump, 1 from water circulation pump).

With the tstat housing off, put the garden hose on the water pickup line and cranked a few times... water coming from raw water pump outlet as expected. That would seem to indicate to me that there isn't a blockage anywhere between water pickup and raw water pump, no?

I also think I should be able to eliminate exhaust from potential blockages since its a v8 with 2 separate exhausts, and it would seem unlikely they both got a clog at the same time. Even if 1 was totally blocked, i'd still get water through the system, albeit only through 1 side, right?

 

[steelers7]

Another update

Cleaned up the thermostat housing as good as possible. Also pulled raw water pump and cleaned it up.

Put it all back together, fired engine. Water shot from an exhaust outlet from the tstat housing. I forgot to put the hose back on one side. But great though, plenty of water getting there.

Reconnect that line from tstat housing to exhaust... and nothing. No water being moved anymore.

 

[Scott Danforth]

Your exhaust manifolds may be plugged

 

[steelers7]

More details...
Pulled risers on both sides
Rust in water ports, no rust in exhaust ports
There was a chunk of rubber on 1 side, looks like gasket maker, not impeller. enough to clog the port

The other side was free from impediments, but I did knock some rust away with a screwdriver

Got it back together, fired engine again
No water movement again

Shut down, this time pulled the other exhaust hose between tstat housing and exhaust mani, from the exhaust mani, and fired again, expecting to see water from that hose.

I did not, but I did see water bubbling out of the exhaust mani inlet