Startup Engine Heat (343) ?

[ZachD]

I'm a newbie and would really appreciate some seasoned veteran insight here....I recently purchased a 2008 SANTE 210 with the PCM 343. A few days ago, I had it out and was getting some higher than normal engine heat at startup and low speeds which made me think it was in need of a new impeller. At higher speed the engine cooled down and ran great, however idling later in the day and back to the dock, the engine temp began to climb again. I immediately replaced the impeller (the old one was in bad shape when i removed it) with a new one and have had it out twice since. Both times, upon startup, the boat engine heat climbed more than it should initially - enough that the SEE DEALER light was on and beeping at me. Then, after I turned off the engine and waited a few minutes, I started back up and immediately increased the speed some. The engine cooled down immediately and ran great. Even at idle speeds later in the day and returning to the dock both times (with the new impeller installed), there were no engine heat issues whatsoever. It was almost as if the new impeller needed to "seed" or "break in" a bit both times...
3 questions -
1. Anyone seen this before?
2. Is my assumption the new impeller needs a chance to be "broken in" accurate ?
2. If my assumption is accurate, how many times out will I need to do this before the new impeller gets working immediately upon startup?

Any insight is greatly appreciated.

[ronskal]

You were correct in replacing the water pick-up impeller. You say it was in bad shape, were there pieces missing that could have gone down stream and cause an obstruction? If so my hunch it is that.
Are you sure you put in the correct impeller? they are a real tight fit by design to self-prime to pull water up to the engine.
An impeller needs no bedding-in at all.
Based on what you say, the higher speed equates to higher pressure helping the impeller do its job. Make sure it is not leaking also at the cover plate.

[ZachD]

Thanks - I definitely put in the right impeller.
So if a part of the old impeller made it downstream into the engine, anything I should be doing in particular?

[rcazwillis]

May be the thermostat sticking. If you are checking for debris in the housing, put a new one in. Cheap insurance

Sent from my SM-G900V using Tapatalk

[Paxdad]

You are describing what sounds like to be a thermostat issue (thermostat is delaying opening). Be sure to check your sea strainer and make sure the through hull valve is full open.

[lucky7t]

Thermostat

[jbach]

Startup Engine Heat (343) ?

Tighten all cooling hoses with a 5/16 nut driver to seal any air leaks and change the thermostat.

[Nordicron]

Do like jbach says and tighten all the connections. Also make sure your strainer is screwed on tightly with the o-ring in place, very important. Sounds like along with bad impeller I could be getting some air in system at slow speeds. I don't really think it's a t-stay thing it's either open or closed and as u increase engine speed heat would build up even worse on a closed t-stat. U can change it too for good measure but check those hose connections and strainer for airleaks.


Sent from my iPhone using Tapatalk

[s_kelley2000]

I think jbach and Nordicron are correct. Heating up at idle but cooling properly at higher speeds are typical of an air leak because at higher speeds there is enough water flow to overcome the air leak. Checking each hose with a nut driver is key because you can seldom get them tight enough with a screw driver. Also the strainer not being tight enough or the gasket not being present or seated correctly are very common sources of air leaks. If you look at the strainer at idle and see air bubbles then you can start checking hose clamps from the intake to the strainer first and see if that solves the problem. It's always a good idea to check all of the clamps and hose condition at the beginning of the season to spot issues before they get worse.

Although if there were fins missing from the original impeller then I would also look to see if it got lodged in the T-stat housing or the transmission cooler.

[xrichard]

Sounds like you have a small leak before the water pump. In my experience with Nautique, the most likely culprit is the seal on the raw water strainer. Replace the o-ring and make sure the plastic canister is tight and I'll bet money your problem goes away. If you see ANY water around the strainer or its fittings, then you will likely see overheating at low rpms.

[ZachD]

Thank you everyone for your help here. I took off the impeller cover and realized that the housing (giant washer looking device) wasn't set flush against the casing when I replaced the impeller the first time. I think this caused my air leak and a drip which explained the subsequent serpentine belt squeaking after I had replaced the impeller. I also checked all the hoses and removed the sea strainer and O ring and then reset the O ring and screwed it back in. I've had it out twice since then and the first time, experienced a little more heat than i would've liked to have seen during the initial startup (got to about 185) before it began to drop, but it was better than before. After it began operating at normal temperature, I also shut off the engine and floated out on the water for a half hour and then restarted without any problems. No issues at all, even idling. Then, the second time back out, I had no issues at all with the engine heating up, even at startup......maybe a sticking thermostat that was coupled with an air leak initially? Took care of the air leak now (I think), but a new thermostat might be good insurance as some folks have said above...? thanks again for the expertise

[ZachD]

I've got to re-open this thread.....So I replaced the thermostat this evening and tightened hose clamps with a nut driver and I'm still having the same issue. Upon startup the engine begins to run hot. The manifolds begin to heat up like there is not water rushing thru them. The only way I have found to get the engine to operate at a normal temperature is to create some water force by getting on the throttle right away. I've replaced the impeller (ensuring the casing is seated correctly), tightened multiple hose clamps with a nut driver, and replaced the thermostat. I've checked the sea strainer for bubbles and screwed it in a couple times to ensure it wasn't cross threaded or leaking air. The O ring here is in good shape too. Once the engine begins running at a normal temp, I've found that it's fine the rest of the day and never heats up again, even if I turn it off for a couple hours and float....any thoughts? Could there be something (like a flap or something) blocking the intake to the impeller or causing some sort of vacuum that significant water pressure overpowers or eliminates? any expertise is greatly appreciated!

[jbach]

Classic air leak symptoms. I'd go through and make 100% sure you don't have any impeller pieces downstream of the housing. Usually they'll get caught up before the trans cooling hoses. Relighted all clamps with the bit driver. A flat head will not do the job. You can then do a bucket test to make sure your rwp is sucking enough water.

[Paxdad]

The T-Stat housing is two pieces with the bottom piece having a bypass port for initial water flow to the exhaust manifolds etc. Then once the water is heated the T-Stat does its thing (open) and provides additional cooling for the motor. If the T-Stat was replaced at some point and the incorrect gaskets were used it could be restricting the initial waterflow and causing your elevated start up temp until the T-Stat opens. Nautiquehunter and I pulled mine apart last night and this just struck me this morning that that could be your problem.

[ZachD]

The thermostat that I removed appeared to be the original one from the factory. I am the second owner and the previous owner did not have an issue (as fas as I know). I removed the thermostat last night, carefully scraped the old gasket and then replaced it with the thermostat and new gasket I bought off Nautiqueparts.com so I should be good there. I didn't see anything in the housing when I removed the old thermostat. Given that I still have the same problem with a new thermostat installed, I am inclined to think it's something else... maybe air leak somewhere I haven't found yet. I'll likely try tightening every hose I can get a nut driver on tonight. Are there any that I should be particularly looking for or making an effort to get to that are difficult to reach? Any other thoughts? thanks guys!