2005 496 mag ho running hot
 

my apologies if this has been talked about but cant find anything on it. background, i bought the boat may 2015, every since then
the boat runs 190 degree and borderlines alarm status. i have changed seawater pump last year to the stainless hardin marine.
all the hoses were flushed out and clean. did not see a big difference, this year, same thing, had a thru hull water pick-up installed
because the plastic tube in outdrive was in bad shape. also, the hoses, heat exchanger all the coolers have been cleaned twice this year.
a few weeks ago, my thermostat stuck closed, when it opened, again to 190. i am in the process of changing thermostat and water temp gauge
sender. hoping this fixes it. However, here are my questions. if i use a heat gun to take temps off the motor, water, or ??? where do i aim the laser
to get the most accurate reading. and 2, should i change out ECT sensor and the Exhaust manifold sensors too? i know these will also go in alarm.
i dont have the scanner and trying not spend another 1500 dollars and not running the correct temp. i was hoping the wrong thermostat was the problem,
but a 160 degree was in place. thanks for the help!

1) Go ahead and buy the scanner. It's only $500 and it will be the best $500 you EVER spend on the boat. www.rinda.com
2) What boat is it? Do you have a fresh water flush fitting (to hook up a garden hose)?

hello, thanks for responding. its a 2005 baja outlaw 25. yes it has the garden hose hook up. that was part of the thru hull water intake installation.
and yes, i do plan on getting a scanner, hope im not chasing the wrong thing because i dont have it yet

The flush fitting has a Tee in it that goes to your Sea Water Pump. Inside that Tee-fitting, there is a spring loaded check-ball. Take this Tee fitting apart and remove the spring and ball. It's not needed, and actually is a huge liability as I have seen this assembly gum up with seaweed and debris on more than a few Bajas; that have all had persistent overheating problems.

I'm curious, what is it installed in?

I've noticed that if I run mine for a long time at higher RPMs the heat will start creeping up but if I crack the engine hatch on my Donzi 35 ZR, it will immediately drop back down.

Also as Sydwayz says, get the scanner...I needed the scanner to verify one of my gauges is full of it. It always says it is 10 degrees higher than it actually is.

Ok, thank you. I will look when i get from work.

2005 baja outlaw 25

do you have smartcrat gauges ? They are pretty darn spot on especially with temps

saltwater app ? anytime ?

condition of heat exchanger, oil cooler and impeller housing ? condition of water circ pump and coolant ? condition of all groments and end cap seals thru out the cooling system ? Condition of the T stat and its related items.

Important ****** condition of check valves / balls - this is often missed for cooling related problems ,

Inlet water hoses kinked external side and or internal one

water jackets in the exhaust riser and exhaust manifolds not restricted at all ?

loose and or worn serpentine belt ?

Any leaks of water and or coolant ??

Clear hose method of testing for air bubbles in the cooling system

Volume water flow testing output - this will tell if in fact you are pumping enough volume of water to keep a specific engine app properly cooled.

Might want to find a really good tech that works on 496 's. That would include myself in the mix here.
A scan tool is not going to tell you where your problem is - unless your temp is off at the dash and compare that value. Water pressure values can be monitor but that really is not going to pin point your problem.

Heck you can test your temp gauge in various ways - one simple example is with a hand held temp gun and shoot it at the temp sensor to see what that temps reads then compare it to the temp at the dash. Also ohms test the temp sensor itself and while you heat it up. The same goes for the T stat testing,

Location of your boat ??

Holy moly, not sure about gauges, i know they say livorsi. Yes, saltwater boat now, bought it in Dallas. It gets flushed everytime, dont stop until water is hot.
Heat exchanger and coolers are good snd clean, seapump was installed august ladt year. Hardin marine stainless pump.
Circ pump??? Dont know yet
Coolant, i suspect its old, gotta change.
New thermostat i am installing today
Also new watertemp sensor
Where are the check valves, dont see anything like that.
Hoses are good, good flow
The manifolds and risers, dont know, praying they are ok.
Belt changed last year
No water or coolant leaks
Never checked for air bubbles, dont know how?
Water flow was good when new seapump put in, told everything good.
Thanks for the info, gonna try and work on tonight after work

Texas Gulf Coast


do you have smartcrat gauges ? They are pretty darn spot on especially with temps

saltwater app ? anytime ?

condition of heat exchanger, oil cooler and impeller housing ? condition of water circ pump and coolant ? condition of all groments and end cap seals thru out the cooling system ? Condition of the T stat and its related items.

Important ****** condition of check valves / balls - this is often missed for cooling related problems ,

Inlet water hoses kinked external side and or internal one

water jackets in the exhaust riser and exhaust manifolds not restricted at all ?

loose and or worn serpentine belt ?

Any leaks of water and or coolant ??

Clear hose method of testing for air

Volume water flow testing output - this will tell if in fact you are pumping enough volume of water to keep a specific engine app properly cooled.

Might want to find a really good tech that works on 496 's. That would include myself in the mix here.
A scan tool is not going to tell you where your problem is - unless your temp is off at the dash and compare that value. Water pressure values can be monitor but that really is not going to pin point your problem.

Heck you can test your temp gauge in various ways - one simple example is with a hand held temp gun and shoot it at the temp sensor to see what that temps reads then compare it to the temp at the dash. Also ohms test the temp sensor itself and while you heat it up. The same goes for the T stat testing,

Location of your boat ??[/QUOTE]

So your in Texas ? and or the boat is currently ? Where did you buy it or from in Dallas ? If in fact was bought in Dallas probably repo boat and from the auction.
\
Salty dog internal cooling systems will have to be checkout very closely. I'm in DFW TX.

Im in the clear lake area, so i go out in galveston bay, texas intracoastal waterway, sometimes the Gulf. I bought the boat from Casey at Legend Marine Group. I did one day see on the boat that once had a sticker from a used boat dealer in Oklahoma.

good luck with it. If you end up pulling your hair out completely and parts change half the engine in which can break the bank and problems still exist. I'm half the day road trip away.

Thank you! Really appreciate it. Im almost to that point. Been fkn with this since may 2015.

You are guessing..you need to confirm it..that motor needs to be scanned..that processor with give you exact temp that motor is running.stop guessing..second reason to scan that motor is you can take a water pressure reading and depending on what seriel number engine you have ( because of water pressure sensor locations) you can clearly see under a load if it's higher than spec whether you have a restriction anywhere after the sensor or if the pressure drops under a load Wether you don't have enough water getting to the raw water pump.it takes minutes to diagnose where your issue is..keep in mind that you will never find a 496 to have exact same exhaust temps so do go by feel on the elbows..not that you need to change the emct sensors but depending on the seriel number you prob have the old style plastic sensors..you should upgrade them to the new brass sensors which you will need to drill and retap the manifold.

yes sir, i am guessing. i am gonna get a scanner next week. i realized when i see multiple problems with same alarm, its very confusing and frustrating to figure out what it is.
thanks for reply!!

What is boarderline alarm status ? do you have an actually alarm taking place or just going by that phrase cause your temp gauge reads 190 without having a real live alarm going off ?

The T stat being 160 degrees is completely not the same style / model as what a 454 / 502 big block take here from 2000 and back. You better make sure it is the correct T stat installed for a 496.

Like I said you can verify your dash temp gauge with a hand held temp gun - 30 buck tool, to rule in or out for if in fact it is reading correctly. Do you have warning horn going off and engine running in a form % of guardian mode. (restricted / limiting rpms) I say this because EMCT sensors are not going to lower your temps at the dash nor will changing the water pressure sensor - if those faults are taking place you will be in a % of guardian mode. So what rpms can you reach while running full rpm range at WOT ?

Just putting forth the question - Scanning for water pressure - if you monitor with the scan tool what are the proper specs for PSI ? If you do not know those specs how does one know if it is low water pressure especially without a current fault ? and if you have low water pressure, the scan tool does not pin point any mechanical cooling issues. What is the plan if you have low water pressure readings ? just asking not being a smart azz but curious. Not dogging you.

hello, yes it keeps going in and out of alarm. rides 190 but as soon as it goes over the 190 mark, it alarms. gonna use one of those temp guns to get temp. im gonna be honest,
i am not a mechanic, just trying some things to see maybe its something simple. i do plan on getting a scanner but i dont know pressures like you say. tach says about 5100 ish wot

So your temp rises and alarm comes in at 5100 rpms and goes away -- does the alarm ever happen at rpms say at 4800 and below ???

if the alarm ONLY happens at say 4900 rpms and or above - that is not alarm for overheat as I THOUGHT with the statement of boarderline. That's an OVERSPEED alarm. Hence why I asked to get very clear about.

A OVERHEAT alarm will not come and go You have a overspeed alarm at 5100 rpms. lower your rpms with the correct running rpms - 5000 K is max recommended for WOT / 496 HO MAG --- 4800 rpms for an plain 496 Mag.

the coming and going alarm is overspeed alarm.

Still verify your temps to see how much your gauge is off and or running a hotter than normal spec. You can temp shot with gun at the t stat housing and at the coolant temp sensor to see what the readings are compared at the dash.

if your alarm was an overheat this PCM 555 496 would never reach 5100 rpms NEVER for an overheat alarm. AGAIN NEVER to stress that issue. Guardian mode would set as soon as the first hundredth of a second sound of an alarm, limiting the engine to 5 % to 90 % available power depending on how hot the engine was getting.

PLUS overheat alarm is a continuous horn fault set. Its called ECT Overheat as a fault.

Overspeed alarm is an alarm that can come and go even by a hair push back of the throttle as it still can bump off the rev limiter.

So does your temp gauge creep back down or stays at or above 190 ? How much temp swing does the gauge show thru out rpms ? So when the alarm goes away what is the temp reading ?

i dont always do WOT, the motor gets too hot. here lately i cant even get to 4800 rpms. just cruise at 40-45 mph.

3 weeks ago, didnt even make 1.5 mile from ramp, temp showed 220, no gaurdian mode, i shut it down instantly, sat for a little bit, then thermostat opened up, temp dropped, the rest of the day, 190.
i will verify with temp gun. where do i take the temp at with gun?

220 and no fault / warning horn and NO guardian mode nor limiting rpms ? could you rest your hands on the exhaust risers at that gauge temp reading ? You have problems if in fact you were at 220 degrees and still able running above 1500 rpms

temp gun - exhaust risers and t stat housing and coolant temp sensor and heat exchanger areas

alarm was going off,radio was too loud. i shut it down immediately, did not touch risers, but the hoses were pressured up. i have been in gaurdian mode before
so i know what its like. like i said before, im just doing what i can do, if this doesnt work, then off to the shop it goes. i am changing thermostat, new water temp sensor,
change out coolant, was gonna change any other sensors if i needed to. pretty much everything else has been in the shop.

ok, last question i promise, i am in the process of putting it all back together. after tightening the two bolts for the thermostat housing, the heat exchanger doesnt feel like its sealing. once the bolts are tight, is it normal to be able to pull exchanger off? what did i do wrong?

There are two large hose clamps that go around the entire heat exchanger and crossover. That's what holds It down. They are mandatory.

Also, before you refill and button it up, replace the grommets that the heat exchanger fits down into. They are a very common leak/failure point.

thats exactly what i was referring to, before i put the hose clamps on, is it normal for exchanger to have wiggle room, or have any play in it?

i just thought it would be a tighter seal

Replace the grommets. It will be tighter which is crucial.

yes sir, the first thing tomorrow morning going to get some. thank you so much!!