Exhaust temp problem.

[Bill Root]

BUFFALO GAL has developed an overheating problem on the starboard engine. The alarm goes off after running for about 125 minutes above 1300 RPM. Shooting the heat gun indicates 165 degrees at the outboard exhaust temp sender. The sender on the inboard exhaust shows 110 degrees. The engines are 8V92 TA's. The engine heat exchangers have been thoroughly cleaned and checked. The impeller is new. However there is a heat exchanger for the stabilizers that is located in the water line that goes to the outboard exhaust. I'm inclined to think that exchanger may be clogged, since I have never cleaned it. We're in Marsh Harbor now with some decent wifi, so before I get involved in a mechanic here I thought I would reach out to the forum to see if anyone has another idea on what else could be causing the problem. Thanks for your help.

 

[bigbill]

can you bypass the stabilizer heat exchanger and run without the stabs on and see if that solves the problem?

 

[SEVEN]

Even though the impeller is new they sometimes Break a few blades for one reason or another. Check that first.

 

[saltshaker]

What's the engine temp? The exhaust alarm shouldn't go off under 180 or 185.

 

[kelpy]

All of the overboard water should not be going thru the stabilizer cooler. In any event, don't bypass the cooler completely for any length of time. The oil pumps are always running whether the stabilizers are on or not. (assuming the pumps are belt or gear driven off the main engine(s).)

165^ should not set off the overheat alarm. That is where the engine should be in normal operation at low RPM. What is the temperature of the thermostat housings?

 

[PeterK]

When I blew an impeller Bruce M. made sure I checked the fuel cooler, which was outboard on my port engine (not sure where it is on the starboard). A royal PITA as it has very little clearance to seperate and was right above the starter. Had to use a mirror and dental pick to clean it out...

 

[BOATER BOB]

Take sender out and swap with other engine if it cures that engine problem bad sensor.
Bob

 

[saltshaker]

Take sender out and swap with other engine if it cures that engine problem bad sensor.
Bob

Exhaust senders aren't that easy to swap. You'll have to cut the wires. Big question is what are the coolant temps.

 

[Bill Root]

Thanks for all the suggestions. Here's some clarification:

- Ed at Sams says the exhaust temp alarm is set to go off at 155 degrees. The senders are mounted on top of the exhaust riser just behind the turbos. The cooling water hose goes into the under side of the riser.
- Engine water temps are fine at 175-180 degrees
- When the exhaust temp alarm went off I shot all four risers at the the temp senders with a temp gun. The one with the stabilizer oil cooler in the cooling water line was the only one reading over 110 degrees.
- the problem occurs after about 15 minutes running above 1300 RPM, not 125 minutes.

At this point I guess I'll go ahead and start by cleaning the stabilizer oil cooler, check the impeller for damaged blades and check the exhaust cooling water supply lines for any obstructions. If anyone has further insights, I would sure appreciate hearing them.

 

[doc g]

so is the stabilizer heat exchanger in line before the shower head, IE does all the cooling water have to go thru that cooler before getting dumped into the exhaust?? IF not any clogging in that cooler would increase the flow to the exhaust not decrease it. My stab cooler on my 61 was branched off before the exhaust in line......Pat

 

[Scott & Malina]

Thanks for all the suggestions. Here's some clarification:- Ed at Sams says the exhaust temp alarm is set to go off at 155 degrees. The senders are mounted on top of the exhaust riser just behind the turbos. The cooling water hose goes into the under side of the riser.- Engine water temps are fine at 175-180 degrees- When the exhaust temp alarm went off I shot all four risers at the the temp senders with a temp gun. The one with the stabilizer oil cooler in the cooling water line was the only one reading over 110 degrees.- the problem occurs after about 15 minutes running above 1300 RPM, not 125 minutes.At this point I guess I'll go ahead and start by cleaning the stabilizer oil cooler, check the impeller for damaged blades and check the exhaust cooling water supply lines for any obstructions. If anyone has further insights, I would sure appreciate hearing them.

Bill,Check your spray ring on that side. Unfortunately, it's not an easy task if the bolts haven't been out in a while. If that is the case, you should keep an eye on the other ones as they will need cleaning soon.Good luck, keep us posted.Scott and Malina

 

[rmatt]

I had a similar problem with Cat 3208s. I found the shower head to be partially plugged
with what looked like crushed pieces of shells. I cleaned the shower head and the temp went down and
the alarm quit sounding.

 

[Bill Root]

so is the stabilizer heat exchanger in line before the shower head, IE does all the cooling water have to go thru that cooler before getting dumped into the exhaust?? IF not any clogging in that cooler would increase the flow to the exhaust not decrease it. My stab cooler on my 61 was branched off before the exhaust in line......Pat

All the water for that exhaust goes through the stabilizer cooler.

 

[Bill Root]

Bill,Check your spray ring on that side. Unfortunately, it's not an easy task if the bolts haven't been out in a while. If that is the case, you should keep an eye on the other ones as they will need cleaning soon.Good luck, keep us posted.Scott and Malina

OK. What's a spray ring!!??

 

[Avenger]

Also called the Showerhead. It's the water discharge in your exhaust elbow.

 

[Bill Root]

Also called the Showerhead. It's the water discharge in your exhaust elbow.

Thanks. I learn something new every day.

 

[Scott & Malina]

So....what did you find Bill?Scott and Malina

 

[Bill Root]

I haven't done anything yet. I took a header off the swim platform last week and injured my left shoulder, so I'm operating with one arm, which means I'm going to need help to do the job. The mechanic is away until after the 4th, and I have guests coming the week after the 4th. The first chance we can do the job is July 7th. Fortunately that's not a problem here because all the cruising around we have planned will be at 9 knots max. the plan now is to do the job on the 7th, then leave Marsh Harbor to begin the return to Florida the 8th. Once I find out if what we did actually solves the problem I'll send a report.

 

[Scott & Malina]

OK. What's a spray ring!!??

Bill, Here's a pic I snatched off a fellow Hatter here on the forum. This is a custom riser, but the point of the pic is to illustrate the "spray ring" or "shower head" as some call it. This begs to be checked if all else is good.Scott and Malina

 

[Bill Root]

Thanks so much, Scott. Looks very much like my exhaust risers.