Exhaust Temp Alarm -- Hatteras 52" 1990 with DD 8V92

[chalycuba]

I need help with my Exhaust Temp Alarm of my Port engine. The exhaust system I have are key marine raw water cooling (company that closed a few years ago).
The alarm goes out when I speed up to 10/14 Knots while at fishing speed the alarm does not go out.
I have changed impeller, clean the heat exchanger, check and substitute all raw water houses, review & clean intake, .... I have done all I can think off.
My question is that, can it be caused by the engine? meaning the port engine is producing higher temperatures at combustion and therefore at exhaust? Can it be caused by injector problem?
The exhaust does not show white or dark smoke, only water steam when hot, more than the starbord engine.
Another issue is that those exhaust elbows I have them custom made with stainless steel as the original ones but maybe there is a inside design on the raw water chamber that is missing and that might be the reason why the water is not getting to the temp sensor.
Last weekend I also tryed to close 100% the spillway on the port side engine so more raw water will get to the exhust but nothing.
I am starting to think that there is a engine problem instead of a exhaust problem or a raw water problem.
I have checked the flow of both engines and is very simillar, in less that 15 secods I got more than 5 gallons.
Thanks for your help.

Carlos

[Andy B]

Pick up up a non contact thermometer and check the differences in temps between port and stbd , and what temp its actually running could be a faulty temp switch.

[Glory]

Dito!!

[rwetherington]

Check you spray ring inside your exhaust the top of the spray ring may be stopped up and that is the reason that at low rpms you are not getting water to the top of the exhaust.

[Modman]

I ran into this same problem last Saturday. 1989 52C with 8V92's. Was running for about 2 hours going between idle and running on plane. After coming off plane entering marina, Exhaust Temp alarm sounded after idling for a minute or two. Ran down below, but could not see anything wrong. The next day started the engine and let it idle for five minutes. Went below and felt the stainless elbows coming off the turbos. One side was definately warmer than the other. Increased the RPM to about 1100 for two minutes and went down and felt them again. This time the temps were close (hot side had cooled). Bottom line is I think the diagnosis of a partially blocked shower head is correct.
The question is, how do you clean it out? Can I simply detact the raw water hose and reach in with a brush or does the whole elbow need to come off?

[Texastailboard]

I have been experiencing the same on my starboard engine, mine shows more steam on that engine while underway. H long is your boats steam trail while underway? By laser thermometer the starboard engine is a little hotter but not noticeable?I am interested to hear what yall do to check or service the spray ring.

[Modman]

I can never decide whether it is a steam or water vapor trail. Either way it is always s the same on both engines and extends 8-10 ft under all weather conditions.

[rmatt]

I had the same condition. Different engines but same problem. I pulled the riser and out
the 18 holes in the diffuser, half of them were plugged or partially plugged. I acid bathed them
with a diluted mixture of muriatic acid and water 5-1. No alarms since.

[sandspur1966]

Since, by your diagnosis it appears localized to the exhaust temp sensor, I'm with Roger on this, likely to be the shower and a muriatic solution will likely cure.

The infrared handheld suggestion will help you narrow it down more. i couldn't help notice that you ran through all the coolant piece-parts but didn't mention the intake side of the intercoolers... I usually have them serviced at the same time that I do any work on the exchangers because that is where anything that gets through the sea strainers tends to collect and pieces of a your raw water impellers as well.