engine overheat. 350mpg 5.7 ltr bravo 3

[joe piscatelli]

Hi, any help on this . my engine runs around 170+ at idle speed, but when i speed up to plaining speed the engine starts to go higher on the temp gauge to about 185-190. no alarm sounds. i changed the raw water, water pump last year and just changed the thermostat thinking that it might be defective. help!!!! thanks joe:smt100

 

[srdancer90]

A slow speed increase in temp may indicate that the exhaust manifolds and risers are cloged. when was the last time that they were changed?
2004 320 DA t5.7 mie

 

[surfinjoe]

Remove the thermostat and run the engine and see if it is within normal range. My 350 MAG runs about 160 deg. at all times.

Hi, any help on this . my engine runs around 170+ at idle speed, but when i speed up to plaining speed the engine starts to go higher on the temp gauge to about 185-190. no alarm sounds. i changed the raw water, water pump last year and just changed the thermostat thinking that it might be defective. help!!!! thanks joe:smt100

 

[joe piscatelli]

I bought the boat in 2009 ,and have never changed them. what is the procedure to check them and how involved to change them?

 

[BUSTMUP]

My 2003 350 MAG runs at +170 at idle. I see 175 - 180 when at 3000 to 3500 RPMs and maybe +185 at WOT, but it hard to tell because the temp gauge doesn't have much resolution. I have a brand new impeller installed this Spring.

 

[joe piscatelli]

Thanks for your input. it sounds like our engines are alike. have you had any alarms sound? my next step is to replace the impeller. hopefully that will help my problem!!!!!!! i agree the temp gauge does not have much resolution.

 

[joe piscatelli]

well,i have changed raw water pump ,thermostat,manifolds ,risers,temp sensors, and temp gauge!!!!!!! i had a mechanic[ sea ray tech] put his computer on the engine, and the temp reads 165on the computer but the gauge reads 185 to190 . any thoughts on this would be much appreciated..... joe

 

[Lazy Daze]

Well, the scanner is more accurate than an analog gauge, but let's take a look at this another way. With the engine running at a normal cruise (say 3500RPM), can you put your hand on top of the risers? If you don't have to immediately remove them, your fine. In that case, you likely just have a wiring issue between the sensor and the gauge causing a little more resistance in the wiring (hence, the higher temp reading on the gauge).

I'll share this, but it may not be of help... Does the needle "swing" up and down (correlates to the t-stat opening and closing) or does it just stay at the higher temp? I had an issue where it would swing up to about 190, then back down to just over the 170 line (one needle width above) - kept doing it as long as engine was under load. I found a piece of an old impeller lodged in the t-stat housing - removed it and now the needle stays at that spot just over the 170 line, which is normal.

 

[ardeprint]

I don't think you have a bad gauge for it would read wrong at idle too. I am assuming you have raw water cooling? Your risers and manifolds should be a concern. I would do all of the following in any order;

1- I would do a clear hose test to make sure you dont have air in your system.
2- change impeller. If damaged check all hoses and fittings for broken impeller parts
3- Check spark plugs and oil for water
4- open the risers and check for signs of water inside (Rust, scalling of walls, etc...)

After a good run, check your engine's temperatures at the manifolds (180 - 200), thermostat housing (160 - 175) and riser elbow (140-170) using an infrared thermometer ($45)

Temp should not go to 190 or above on a 350. That is a sign of a damaged cooling system and its the first signs of what could develop into more complex problems. I would not sit on this symptom. Let us know what you find.

 

[joe piscatelli]

thanks for your advice: my risers are new from sea ray, my raw water pump is new,just put it in.. thermostat is new. manifolds are new. old raw water impeller was like new when i changed it. no broken pieces. temp at t stat housing is 164. risers run cold. manifolds 170 checked with infra red gun.. checked engine with lap top computer and the temp stayed between 164 -166. thanks joe

 

[ardeprint]

Great news!!!
I see you did your homework. Just as a final precaution, if you are still in doubt, test using a different gauge from another boat. Maybe a buddy will lend you one.

 

[joe piscatelli]

Thanks for your help!!!!!!!!!! iam going to try to find someone with the same gauge ,and see if he is willing to let me try his gauge. not sure if it can be done. joe

 

[Bob & Sue]

I would definately find out why it runs at 190 as stated before it could lead to a lot larger problem, I have a 5.7l after it comes to temp it stays at 170 all day long even after trolling for salmon for 4 to 5 hrs. If you have an extra $20 buy a new cheap (inexpensive) sun pro gauge with sending unit and mount from amazon, you could just do a temp mount on the deck somewhere, here is a link to it. Good Luck

http://www.amazon.com/Sunpro-CP8201..._1?s=automotive&ie=UTF8&qid=1309877029&sr=1-1

 

[joe piscatelli]

Thanks Bob and Sue. i think that i might try the sun pro gauge ....... thanks for the info!!!!!!!!!!!!!!!! joe