Exhaust temp gauge 350 mag mpi.

[Jayo02]

Well finally got the boat back on the water after the impeller went and overheated engine. It took several sensors, the exhaust boots and flappers, shift cable and caused the head gasket to blow. The only good thing that came of it was I learned that the engine I thought was a 5.0 turned out to be a 350. ( thanks alldodge ) Lol. But that happening also has me wondering if there is a mercruiser exhaust temp sensor that I could possibly run with smartcraft. When the impeller went; it never gave smartcraft an alarm. In fact the engine never actually overheated the temp sensor that feeds the ECU. So while I was cruising around all my parts were melting away. As I watched my temp gauge that read Normal. As you may understand i Have a little PTSD from this.

is there a good exhaust system monitor some of you guys use ? What do you guys recommend?

thanks in advance.

 

[Scott Danforth]

you dont need to monitor exhaust. that would be pointless

you need to monitor temp and possibly add a water pressure gauge. a water pressure gauge will monitor your raw water pressure. that would be the first indication of something to go awry long before your gauges would even flicker. that is a mechanical gauge and no, you cant tie into smartcraft without the ability to re-program the CAN, find an open address, re-flash the ECM, etc.

 

[Jayo02]

you dont need to monitor exhaust. that would be pointless

Seems to me that monitoring the exhaust temp would have alerted me that there was a problem with the raw water system. Eg. no water reaching exhaust = much higher temps. Smartcraft does monitor engine temp and water pressure and sent me no alarms. Even after the damage was done. But I will look into your suggestion. Thanks.

 

[Scott Danforth]

the water pressure sensor used by Mercruiser is garbage and if you test yours, you will find it most likely doesnt work, especially if you in salt water. its an oil pressure sender used in a water application. the inner workings of the sender are not water friendly

you wont find an EGT sensor that will live in a wet exhaust

I am talking a nearly bullet proof mechanical bordon tube pressure gauge.

such as one of these. https://www.iboats.com/shop/boat-mo...tation/gauges/boat-water-pressure-gauges.html

BTW, the Sierra gauges are made by VeeThree who makes many of the OEM gauges out there.

 

[Jayo02]

the water pressure sensor used by Mercruiser is garbage and if you test yours, you will find it most likely doesnt work,

What is the PSI supposed to be ? I want to check into that. Thanks again.

 

[Rick Stephens]

the water pressure sensor used by Mercruiser is garbage and if you test yours, you will find it most likely doesnt work, especially if you in salt water. its an oil pressure sender used in a water application. the inner workings of the sender are not water friendly

you wont find an EGT sensor that will live in a wet exhaust

I am talking a nearly bullet proof mechanical bordon tube pressure gauge.

such as one of these. https://www.iboats.com/shop/boat-mo...tation/gauges/boat-water-pressure-gauges.html

BTW, the Sierra gauges are made by VeeThree who makes many of the OEM gauges out there.

Finding the gauge is easy - what about the sensor/sender?

 

[Scott Danforth]

What is the PSI supposed to be ? I want to check into that. Thanks again.

about 15-20 psi is what the raw water pump generates

 

[Scott Danforth]

Finding the gauge is easy - what about the sensor/sender?

not sure on the EGT gauge sensor. most of the ones that people buy for monitoring EGT's in boosted car/truck applications use a really inexpensive thermocouple with a fairly thick sheath. the issue with the type K or N thermocouple in a wet exhaust environment is the probe will crack after repeated heated/cooled cycles. they usually last about a week or two.

however for the pressure gauges, they are a mechanical bordon tube type. uses the same pitot tube hose as mechanical speedo's. they connect to a 3/16" hose barb.

 

[Rick Stephens]

however for the pressure gauges, they are a mechanical bordon tube type. uses the same pitot tube hose as mechanical speedo's. they connect to a 3/16" hose barb.

I don't see a way to do EGT on a wet exhaust except at the head end, which would not tell anything. No, what I was asking was more detail on the mechanical bordon tube sensor. I've never seen one, didn't know what it looked like and no idea where to find one.

 

[Scott Danforth]

I don't see a way to do EGT on a wet exhaust except at the head end, which would not tell anything. No, what I was asking was more detail on the mechanical bordon tube sensor. I've never seen one, didn't know what it looked like and no idea where to find one.

all mechanical pressure gauges are a bordon tube sensor.

the ones for measuring outboard water pressure just happen to be the right pressure rating for all rubber impeller raw water pump applications (and you can get them in the same series as the other gauges to match the other gauges)

 

[Rick Stephens]

all mechanical pressure gauges are a bordon tube sensor.

the ones for measuring outboard water pressure just happen to be the right pressure rating for all rubber impeller raw water pump applications (and you can get them in the same series as the other gauges to match the other gauges)

Gotcha. Have to make or find an inline proper sized hose fitting with the proper port T'd into to screw the sensor. Look just like an oil pressure sender. I was making too big a deal out of it.

 

[Scott Danforth]

you are thinking electric gauge and not pure mechanical gauge

there is no sensor, just plumb a hose from the gauge to a tee or a port in the cooling water after the raw water pump, however before the thermostat housing or heat exchagner

I modified a hose sleeve and I read mine in the hose between the raw water pump and the heat exchanger

 

[Rick Stephens]

you are thinking electric gauge and not pure mechanical gauge

there is no sensor, just plumb a hose from the gauge to a tee or a port in the cooling water after the raw water pump, however before the thermostat housing or heat exchagner

I modified a hose sleeve and I read mine in the hose between the raw water pump and the heat exchanger

Got it..... finally. Slowing up in my decrepitude.

 

[Scott Danforth]

no problem Rick.....

 

[kenny nunez]

I mounted the pressure hose fitting on the top of the thermostat housing. There is a 1/8” pipe plug that I used. The gauge usually reads 1–2 lbs at idle and went up to 12-15.
As far as I am concerned the only thing the “Smart craft” accomplishes is a more expensive engine and headaches later.

 

[Scott Danforth]

As far as I am concerned the only thing the “Smart craft” accomplishes is a more expensive engine and headaches later.

exactly, boat manufacturers now need a set of gauges that costs 5X what they did prior, and they are not any more accurate, in fact, for example, on the smartcraft water pressure, they are less accurate

 

[QBhoy]

Hi. Not only should or would the smart craft send you an alarm for overheating, but more fundamentally, the alarm on the dash does too. Not sure what’s went on here. You should have had an alarm of at least one form. Was the gauge not showing high either ?

 

[Timbolex]

Stirring up old post, but just bought 2003 with 350 mag mpi
Temp gauge reading high, but IR thermometer reading lower, is it guages or sending unit