Engine Heating Problems - Please Help!!

[brent.jp]

Any help is much appriciated with my problem!!!
Here is the situation:
Dropped the boat in the water last weekend and as I was leaving the launch I noticed the temperature raising fast. I was able to keep the temperature below 200F by keeping the boat at low speed and hatch open and made it to the dock.

Went for a nice spring swim and unblocked the water intake (or so I thought). Took the boat out again and I was able to get up to plane (was not able to do this without reaching 200F) but the tempature was still high. Went full out on the engine and the temperature spiked to high alarm limit, obveously I backed it off instantly and the temperature dropped to the 180's or so.
I got two high alarms the whole time I was out but was able to drop the temperture down in a few sections by slowing the boat.

Alarm codes:
SPN110 FMI 15 - EngCoolant Temp
Data Valid but above normal range
-This code is still active but from what I read think it will stay that way until the boat goes through 3+ warmup cycles

SPN3266 FMI5 O2 2/2
Current below normal or open circut
- not sure what cause an O2 code but its inactive now.. I bought an new O2 sensor so I might replace it if this keep coming up.

Went for a second swim and discovered there was still some blockage on the intake which I then removed. After this I replaced the raw water intake impellar and took it out for spin.

Motor runs nice and cold now, but wont get up to temperature. Maximum temperature I get up to is around 95F. When I a crusing around the lake the temperature actually drops about 5F.

I thought it might be a failed thermostat so I replaced it with a brand new one. Same result, engine wont reach temperature. I tested the old thermostat and it opened and closed at 160F as expected.

I have done some basic checks on the ETC (temperature sensor) and the resistance value matches what the temperature guage is reading based on a cross reference chart i found for a similar boat (same brand but newer).

I am going to do some more checks with my DMM today to see if I can trick the ECM to thinking the engine is hotter (jumper ETC with a fixed resister), do some grounding checks, etc. But I am at a lost for what could be causing this.

Engine: 2010 Indmar MCX 5.7L (date of manufacture)
Boat MasterCraft X2 2011
Hours: 450 or so.

Thanks for your time!!

 

[alldodge]

Unsure if Indmar uses a analog temp sender and a digital temp sender for the ECM like Merc/VP. You mentioned verifying resistance values with chart (gauge checks) ones so I will assume it does.

Use an IR temp gun and measure temp at the thermostat housing at the sender locations. This will verify if its a sender issue or gauge.

 

[brent.jp]

Hey alldodge,

Indmar uses and RTD for the temp sensor (is there a difference between a sender and senor??).

I disconnected the temp sensor and jumped two different resisters accross the terminals and the temperatrue on the dash corresponded to the temperature I was expecting for the resisters used (470ohm = 158F, 680ohm = 140F). Based on this I think the wiring harness is good and most likely the ECM.

Next I pulled the sensor and placed it in some hot water ~160F and measured the resistance accros the RDT (temp sensor) and the value was in the range of what I was expecting.

So thermostat should be good, Temperature sensor appears to be ok and the link between the sensor and the dash is ok (assuming that means the ECM is ok too).

I will have to get in IR gun from someone to check to see if the block is getting warm...I am not sure what else to look for.

Is it possible that the cold lake water ~55F is just keeping things to cold??

 

[alldodge]

Is it possible that the cold lake water ~55F is just keeping things to cold??

IF the thermostat is working and shutting off cold water from coming in until it opens, the no

 

[brent.jp]

I did not think so...I wish I had a good cooling water diagram of the engine. It looks like the cold water goes into the water circulation pump on the motor but then I don't know its path from there. I am assuming it goes into the block. This is way I asked the question. I don't see anything from preventing the cold water from entering the block. I am going to draw out the schematic later tonight and I will post what I have been able to figure out so far. I am a rookie engine guy which is not helping the situation.

I am a bit at a loss with what is happening. I dropped the sensor back in and I have an RTD that I can measure the block temp with but I need to calibrate it first before I fire up the engine again.

 

[brent.jp]

I just fired up the engine and let it idle for about 5 to 10 minutes. I was able to place my hand pretty well anywhere on the engine (beside thermostat, side of engine block, on top of exhause risers, beside manifold, etc.) I could leave my hand there all day! Its barely warm. Engine is running smooth had no power issue the other day when I took it out..

 

[alldodge]

Been looking around and found a 2013 5.7 and it doesn't have much info on the cooling, but does show hose routing
http://www.nautiquespain.es/shop/img/cms/Monsoon 5 7 411344E Combined 01-07-2014.pdf

Everything running cool to touch sounds normal with the water temps your in. The thermostat housing only needs to be about 125* or so to not want to keep your hand on.

Exhaust risers will be different temps normally. One side will be slightly warmer then the other and having them cool enough to keep your hand on is normal, even more so with cooler water temps

There is a possibility the engine is running normally but just paying more attention now due to what previously happened. I don't know for sure because Indmar doesn't come up much

 

[brent.jp]

Its an odd one for sure...I was thinking that too but someone else on the lake has a malibu with an indmar engine about the same age and its running at 165F.

 

[brent.jp]

I have drawn out the cooling water circuit based on what I can tell from looking at the boat and the various reference information I can find (very little). I am not sure which line to the exhaust risers actually exhaust the water, but I am assuming its the one closet to the actual exhaust.

 

[alldodge]

Your sketch looks close to what is shown on pages 10 and 11 in the pdf. Water comes into the Tstat and with Tstat closed water goes to the exhaust. The circulation water pump tries to move more water into the block but with Tstat closed nothing moves.

Think your Tstat will have a hole which feeds water up to top section to feed exhaust

 

[brent.jp]

I am starting to think that the cooling water manifold might have a crack in it which will allow water to flow. There is a small hole in it but I am wondering if there is a bigger crack somewhere. Stupid me did not check the manifold when I had it apart!

And yes my sketch matches your diagram, the only difference is I have a one peice cooling water manifold and the ones you provided are split into two sections. Following the flow path it looks they the pretty much function the same, which they should.