2005 ZR6 no water flow in raw water side of cooling.

[Providence]

Hey Guys,

I have a 2005 210 with ZR6 800 hours. Last season I noticed water leakage from the mainfold/riser gasket. Also was getting increased engine temp at higher RPM. I replaced the exaust manifolds, and risers this spring. Also my temp gauge failed. I replaced the temp gauge (works). I also drained and replaced the coolant. Upon start up on the lake last week my risers approached 200 after a minute or so. Back to the garage I built a T junction fake a lake with garden hose and 1" hose from garbage can beside the trailer into intake. Changed the impeller and checked the water pump (seems like bearings tight and serpentine belt tension good (it seems to be spinning fine). After reading all the posts here about cooling issues I checked the suction side. I checked the clear water strainer (and gasket), redid the elbow joints, checked the transmission cooler for blockage. Started boat on garden hose/bucket but still no water exiting the exahust and no suction from bucket and high riser temp on the temp gun (approaching 200). I haven't yet put a garden hose on the outflow side of the RWP and start to see if water is flowing to the risers. I am now pulling the heat exchanger to check for blockage and clean.

Questions

1)Will a properly functioning RWP suck fine from a bucket on the ground beside the trailer? 10' hose supplemented by garden hose at T?
- can an airlock prevent water flow?

2) how can you tell if raw water pump is unservicable?

3) I am currently removing the heat exchanger (very dirty) I opened the drain plug labled 'fresh water drain' and coolant came out??? (engine coolant as I stored the boat in heated garage this year I didnt add RV antifreeze to the raw water side). Is this a source of a heat exchanger failure? Or indicative of some other problem?
The PCM manual shows this , but my heat exchanger is labled like this?



EDIT* upon inspection heat exchanger is pretty clean. Thinking the stickers were misplaced, as it seems to me the drain is for the coolant that flows between the water pipes in exchanger.




Engine temp remained around 170, so guessing it has nothing to do with the thermostat. I will clean the heat exchanger, reinstall and try to run the garden hose on the outflow side of the RWP to see if flow is making its way to the mainfold. What should max temp of risers reach? Any thing else I should be checking before I replace the water pump? Any advice is desperately appreciated.

Many thanks,


Kris
604.671.2665

[Scooter G]

Thinking out loud, you may be creating yourself a lot of unnecessary work. How are you measuring temps at the risers? It wouldn't surprise me for these to be in the over 200 range, or right there-in. If I remember right, limp mode hits around 235/250 depending on fresh draw or a closed system. If you bypass the pump/impeller with a hose, and run it for any length of time you are jeopardizing your impeller. You need to get some water pressure on that system either through an in-line hose attachment or a real fake-a-lake under water pressure, available at most Marine shops, or next day on your door step. No water out the exhaust = No good.

[Providence]

Thanks Scooter. Snap, you are probably right, making more work for myself seems to be my M.O.
Just can't figure out why the RWP is not sucking. New impeller, housing and bearings spin freely, and tension is spinning the flywheel. I was thinking about running water into both the impeller and disconnecting the outflow and feeding water there also. I may be over thinking this whole thing. Think the RWP should suck through a 10' one Inch hose at idle? Maybe I need a bit of RPM to prime the system as everything else looks good??!!

I will try to find the max riser temps and give the system a bit more time to prime. Always thought you should be able to touch the risers when running, but maybe they just run hotter than I thought!!!

Appreciate the thoughts brother!!!

Kris

[jpwhit]

I don't know the answer to how high the raw water pump can draw water. But it may not be that high. But you could also have an air leak on the suction side of the raw water pump. That would be a leak anywhere between the pump and the seacock in the hull of the boat where water enters. Typically includes the strainer and the transmission cooler as well as all interconnecting hoses. All of that side of the raw water system is at a negative pressure. So water won't leak out, air will leak in and displace the cooling water.

Ilmor / MasterCraft uses clear 90 degree elbows on their water strainers connections. It's super helpful because typically the output elbow on the strainer is the last connection before the raw water pump. It makes it super easy to see if there is an air leak because you can see if it's all water still at that last elbow. I like it so much, that I always install one on the output side of the strainer on all my Nautique / PCM boats.

[Scooter G]

When the boat is in the water, imagine where the water line is relative to the pump, there is very little negative water draw, system just needs to prime. Water should come out the exhaust regardless if the boat is running or not, with a few exceptions. I like the way you think MacGyver Kris, but sucking water from a 10' hose is not going to do the trick and not enough volume to keep the system at proper temps. There is more than one way to skin a cat, but the quick solution is going to be a fake-a-lake. It will pay for itself over and over again. You need positive water pressure on that system, not time to prime.

[Providence]

Hey Jp and Scooter,


Thanks for the advice. Really appreciate the insight. Fake a lake enroute. I may have found the issue while re-doing the elbow joints on the strainer. This connection with the red hose leads to the back of the boat. It was found open ended yet with a pipe clamp on loosely doing nothing. . It seems to have been to this back outlet (maybe a heater adapter, but comes from the cool fresh water inlet upstream of the strainer), The outlet on the rear of the boat has always been busted since the Original owner. If open hose I'm guessing this would draw air not allowing the system to get the vacuum pressure required. (unless there is some fancy one way check valve in this plastic housing, but I doubt it.

I have capped the end air tight, and will re-jig with a fake a lake and report back. think this is the issue?

Thanks gents, slightly out of my comfort zone with all this but I'll never surrender!

Kris

[jpwhit]

That's some kind of aftermarket flush adapter. The fitting on the back of the boat originally had a garden hose connector before it broke off. Personally, I'll never install one of those on a boat, because most of them are of poor quality. If it were my boat, I'd remove the whole thing including that white fitting near the strainer that is partially circled in red. I'd replace the hose from the strainer where that fitting is installed, and the hose was cut to insert it.

[Scooter G]

What the? That's crazy! And thru the hull, that's going to be a fun fix.
That should of leaked like a sieve when in the water, no?
At the end of the day you'll still be glad you've got the fake-a-lake on the shelf.

I've got my eye on this one from NP, much higher quality. Just need to have $375 burning a hole in my pocket with nothing else to spend it on, nothing.
https://nautiqueparts.com/fresh-wate...rves-nautique/

[Providence]

Thanks guys for the direction. I hooked up to the input on the RWP and slowly pulled hoses to eliminate a blockage. Pump is sucking good out of bucket when any downstream hose is disconnected. It seems the flow stops at the risers. I had installed new exhaust and risers a few weeks ago so I will pull them off and hope to find maybe a plug I missed to remove or a blockage in the exhaust maybe. I am assuming the water flows to the exhaust manifolds then up the "jackets" in the riser and out the exhaust?

Will update my findings.

[Providence]

So I pulled the risers, and maybe found the problem. When I removed the riser, turn upside down and fill up the water jackets on the riser with a hose, there is nowhere for the water to go. It is like a bowl, just fills up. Shouldn't the water flow out the back of the riser?

I am correct on this? Could this be a casting issue? Called dealer and there is only one riser that fits zr6.....

[jpwhit]

Yes, water should flow out where you have arrows on the 2nd photo.

On the first photo, the water could flow through those small round holes. But the water passages must match up with the water passages on the exhaust manifolds. And on some risers, the gasket intentionally blocks certain holes depending on which way the riser is installed. So you need to pay close attention to how the gasket was oriented on the original riser and which water passages were open.

[Providence]

Think I found it. This must be a riser with an optional 'riser temp' or something. There are 2 plugs on the top of the riser, and between them where my finger is, is an internal wall. basically dividing the front half of the jackets to the back, as in the only way for water to flow would be out the first plug and back in the second plug. Ever see something like this?

[Scooter G]

Something is not right, those should just be plugs, or there was an optional temp sensor which you may not have or need.
You should still have water bypass.
Are you experiencing this same thing with the other side?

[Providence]

Well that was fun. So turns out from PCM there were a few shipments of risers in 2021 (when I bought them) that has no water flow. Why, cant say. Essentially the wrong risers were shipped. My local Nautique dealer was dealing with PCM and is shipping me the correct risers. Until then ground test serviceable in my driveway thanks to home depot!

Thanks for all the help, I certainly know this cooling system on an intimate level now!

[Scooter G]

That is wild!
You'll never get those 16 hours of lost sleep back, lol.
That just seems an odd design, I don't like it, I wonder who's brain child that was?