Overheating 210 SAN (Hot booded Python?) can't find reason

[alalor1]

Hello, I'm writing to see if anybody here can have some idea of what's going on with my engine.
1999 Super Air Nautique 210 with the 8.2L 502 Python engine stock, no mods, ran fine for the 3 years I owned it until now.
The steering cable broke, and to replace it, I disconnected the hose that goes from the transmission cooler ot the raw water pump, so the suction side. After I put the new cable in, I forgot to connect this hose. When I took the boat to the lake, it overheated, of course, it ran about 4 minutes before we realized and stopped it. I put a new impeller in since I always carry a spare and connected the hose. Ran it and saw a lot of water coming out of the circulation pump. So we took the boat out of the water.
I changed the gasket on the rear plate of the circulation pump because it looked like it had failed. I also took out some impeller pieces that had made it to the pump, though the majority seemed to be in the V-drive cooler, which I cleaned too.
Ran the boat at home with a garden hose, no problem, took it to the lake, and the circulation pump was still leaking and the engine overheating. Back home, installed new circulation pump. Back to the lake and a few minutes later, overheating again. Hose from the circulation pump to the thermostat developed a leak. Hose not in stock anywhere, found that Marine Parts Guys had more leverage than I did with PCM and had them make a hose for me. Very dissapointed with PCM, I had 8 PCM engines over many years, first time they let me down. Put a new thermostat since I was at it.
Go to the lake, idling fine, temp came to normal, start pulling, overheating again. Just to test, I took out the thermostat to see what happend, nothing changed. Overheating again. I started disconnecting hoses and testing, raw water pump pumps water; circulation pump seems to run well, both pumps are new. New J hose, I can't find any clogging anywhere.
I am really confused as to what could be making my engine overheat, I came up with these options:
-Broken impleller blade bocking some very important passage I don't know, anybody knows if there is one that could cause this?
-Blown head gasket that lets compression escape to the water jacket but no water goes into the oil, big enough to do this but small enough not to be detected by a compression test, is this possible?
-Spirit of dead wakeboarder jealous that we can still wakeboard interfering with my engine.
-Most likely, something else that could cause this and I didn't notice.
Any ideas are welcome.
Thank you for your time reading this.

[Quinner]

For sure check anywhere and everywhere for broken bits and pieces from the old impeller, assuming it came apart in a big way.
Tighten everything on the intake side using a nut driver not a screw driver, also make sure your strainer gasket is in place and all good.
Sounds like an air leak to me, first place I would start.

[Skidave]

Is the temp sensor bad? Are ypu getting water to the exhaust?

Maybe the sensor did not like the overheating and now it is just bad. Long shot, but possible.

[alalor1]

Thank you for your replies.
Quinner, I will check all hose clamps again, with a socket and a drive, not a screw driver. And I will take out the thermostat housing again, that's where parts are most likely to collect.
Skidave: You might know better than me, but I think these engines have two temperature sensors, one that sends a signal to the dashboard, and one that sends a signal to the computer, that when it kicks in, sends a signal to the red light on the dash and also makes the computer switch to limp mode. Wouldn't it be too much coincidence for both sensors to fail the same way at the same time? I really appreciate your input, but given the behaviour of the gauges and sensors, I don't think they both failed at the same time.

[alalor1]

Well, I never found out what it was but after doing the following today it ran fine:
-New impeller (was destroyed from running without water)
-New Circulation pump (it leakedd a lot)
-tested without thermostat (still overheated)
-New J hose (circulation pump to thermostat housing, sprouted a leak), still overheated in the lake
-Compression test: 135 psi on all cylinders except cylinder 3 (as per GM numbering) that had 155, Should have repeated this cylinder.
-Pressurized water intake and looked for leaks, none found
-connected the water intake to a bucket, sucked all the water from the bucket in a couple of minutes with no issues.
-Ran water on circuit from raw water pump to thermostat (through v-drive cooler) , passed, no obstructions
-Ran water on hoses from thermostat housing to exhaust manifolds, passed, no obstructions or back pressure (started the engine right after to clear any water that could have gone the wrong way due to lack of engine flow during the test)
-Ran water from top of block to end of j-hose , no problem. Tried it backwards, same thing, no noticeable obstructions.
The temperature went slowly to 175 and stayed there, ran the engine 45 minutes non stop. Watched the gauges continuously, every once in a while I would bring it down to idle and check exhaust manifolds with laser thermometer. Port exhaust always read 15 to 25°C (depending if it was manifold, raiser, elbow or close to the hose) hotter than starboard exhaust and when testing on the driveway, at idle, the starboard exhaust always puts out more water. I had never tested this before, so I don't know if that's an issue to address.
But the Python did its job flawlessly today, at 2400 rpm, usual wakeboarding speed, and during the 10 minutes I ran it at 3000 rpm.
So, problem apparently solved, but no idea how or why.

[s_kelley2000]

Got any pics of your boat?

Are you saying you run at 175 all the time? If so are you sure you have the correct Tstat in there? I have the same boat/motor and I run right at 160 all the time. After hard barefooting runs it will heat up to about 170 when I first come back to idle but then quickly goes back to 160. I don't think 175 will cause you any problems if it stays consistently there and doesn't go higher but I just wanted to give you another data point as I know there aren't many 502s out there.

[alalor1]

Hello Shawn, I didn't have any pictures but I took some yesterday.
I took the boat out 4 times already and it always does the same, sits at 165, when pulling goes up to 175 and when you bring it back to idle, in less than 2 minutes it's back at 165. I still think there's something not allowing all the water to cool down the engine at higher RPM as it should. But I can't find it anywhere.
Here are the pictures, on one or two you can see the hump on the sundeck they had to add to fit the engine under it. Poor boat needs new upholstery, but I will wait for the winter, I don't want to put new vinyl to have it ruined by the hot Texas sun.

[alalor1]

Hello
I want to give an update to all those who helped me when I was having the overheating problem. The good side is the boat is running.
The bad side is that it still running the same way, even not that the lake temperature has gone down from 90°F to 76°, start it, takes a while to warm up, longer than before, temperature settles at 165°, then when we start pulling, it goes up to 175° in less than a minute, and when the rider falls and we go back to idle, engine water temperature goes down to 165° again. The behaviour has been very consistent, now that the water is slightly cooler, I can see some steam coming out of the exhaust flappers when I'm riding, but I used to see some before too, so I don't think I should worry too much (or should I?). We must remember this boat doesn't have muffler like the small bock engine boats, there's no room for it.

[DW SD]

I'm guessing you might have a slightly blown head gasket when it overheated the first time. Still, 175 isn't enough to be concerned about. some T-stats will have an operating range of several degrees F, even 10F.
Have you checked the oil? Continue to make sure no water is getting in your oil. It would be one thing for combustion gases to sneak in to the cooling system, a whole another issue if you are getting water in to your oil, as you pointed out.

Thumbs up for the Hydrophase unit. A great product from Justin!

Good luck!

[ohiowake2]

Not sure if you boat is like mine or not. I have an 01 with the GT40 engine. I have the closed cooling on mine and it run about 175 like yours. Could it be that the closed cooling system runs a bit warmer with the antifreeze staying in the block and the lake water cooling the exhaust and and coolers.

[DW SD]

I do get steam from mine, too, at the exhaust. I don't see that as worrisome. Check the oil often for evidence of water. Pulling the heads isn't a huge job. It might be worth that effort to make sure you don't lose the whole engine. You would bring them to a machine shop, have them checked for flatness and overall checked and then reinstall with a new head gasket.

[core-rider]

Unless you ran the engine for an extended period of time with no water flow I doubt you have a blown head gasket. Your OP you mentioned about 4 minutes, so I think you'll be okay there.

I would be suspicious of the strainer cup gasket not sealing well as I had a similar issue and kept eating up impellers until I replaced my strainer assembly a few years ago. If you see ANY air bubbles in the strainer cup while the engine is running that is a dead give-away of air leaking by the gasket. I would also try to back-flush the entire cooling system with a hose. Taking some of the hoses loose to let any potential pieces fall out during the flush. Pay close attention to v-drive heat exchanger and oil coolers as debris will most likely collect there first. Make sure you have correct tension on the raw water pump belt and that it isn't slipping under load. It sounds like you may have a bit too warm of a thermostat installed, but 175 compared to 160 isn't anything to worry about at this time.

Look for the simple stuff first as that's most likely where the problem is... Don't get bogged down looking for major issues like head gaskets just yet.

[DW SD]

Jason has good ideas. It occurred to me that impeller blades might have gone downstream. Could they get lodged in the head? A bckflush may get them out. Removing the engine's water pump and pressuring against the normal flow might unlodge bits.
I now might bet on Jason's theory that impeller bits partially block the raw water coolant stream. Hopefully.... upstream of the heads

[alalor1]

The mystery is solved. The new impleller had failed for some weird reason, it was in really bad shape, disintegreated into so small pieces that I couldn't find any remains on the v-drive cooler or the thermostat or anywhere else. WIth the new impeller in, the temperature stays very stable between 160 and 165F Probably the impeller had spent too much time on a shelf or something like that.

[charlesml3]

The mystery is solved. The new impleller had failed for some weird reason, it was in really bad shape, disintegreated into so small pieces that I couldn't find any remains on the v-drive cooler or the thermostat or anywhere else. WIth the new impeller in, the temperature stays very stable between 160 and 165F Probably the impeller had spent too much time on a shelf or something like that.

Wow, that was quite the trip. It does sound like that impeller was defective when new. Glad you got it sorted out and THANK YOU for posting the resolution. This helps all of us should we come across another on exhibiting the same symptoms.

-Charles