D4 overheat

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bill46

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Joined
Jan 13, 2016
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509
Fluid Motion Model
C-302 SC
Hull Identification Number
FMLT3107F314
Vessel Name
Radio Active
We just returned from a 170 mile cruise and found our D4 in R31CB overheating over 3000 RPM. Stays at 185F under 3000 RPM, Still reaches 3500 WOT as when surveyed in January, delivered in Feb and Cruised in March to June in cooler water without overheating.
The water temp. yesterday was 88F, air 95F. might this be warmer water than this engine is designed for?

Bill46 on Radio Active.
 
Did your survey include all the fluid analysis ? mine did just to make sure no metal was found in coolant = intakes bad
When I bought mine second hand , I had everything checked. which led me down another 1200 dollar road.

also check your raw water impeller , Mine got chewed up 2 weekends ago and it would over heat , then cool down for a bit then over heat again .

Also changing that impeller sucks, pay someone else to do it.
 
Hello Bill,

Have you inspected the raw water strainer for debris? That is always my first check anytime an engine is overheating.

Thanks,
-Kenny
 
My d4 has always exhibited similar temperature behavior here in the Washington, DC area. Above 3150 the temperature will stabllize at 194F but below that rpm it will stay at 185. I have never been able to pull 3500 rpm. I top out at 3250 or so.

Corey
 
Our d4-300 never exceeds 185 degrees. We are in cooler waters here in Ontario. Having said that however, we don't often run over 80 percent WOT or 2800 rpm. I just changed the impeller and it was pretty straight forward and readily accessible. 6 bolts and the cover is off for inspection. Be sure to not have the little rubber disc fall out and go down under the engine when you remove the impeller cover. I guarantee that will ruin your day. There is enough room around the engine working from the top on the 31. I have wondered about the size of the sea strainer thru hull as it seems a little small to me. The hoses feeding the raw water impeller appear to be sized larger than the thru hull diameter. I did ask a local Volvo tech and he said it's not a concern...hmmm.
 
We check our sea strainer every time we dock and it always has stuff in it. We are in the Puget Sound. We always watch temp. We run around around 2200 rpm.
 
Thanks all
Sea strainer is clean, found some dirt in air conditioner.
Impeller replaced recently
wondering if it is just hot sea water
 
On the loop we ran consistently at 185 degrees in the cool northern water. Coming across the gulf we ran through miles of weeds and started overheating. I had to have the heat exchangers cleaned. This is a difficult job. The people at the local Volvo dealer tell me that 195 in Florida water is normal at high rpm. I believe you are ok. The sea strainer was ineffective in keeping the grass out.
 
Thanks Pourhouse, believe it might just be warm water - will observe next weekend and see if it will stabilize below 200F.Stays at 185 when warmed up to 3000 RPM.

Thanks Automaticman865. Great article. Still reaches 3500 WOT as recommended. overpropping can increase economy at lower speed and lower RPM, , underpropping reduces engine load and accelerates quicker.
 
We had a similar problem this weekend with an audible alarm indicating high exhaust temperature. Water temperature was at least 89 and I'm planning on an impeller replacement as a routine matter targeted and curing the alarm situation. I had plenty of water discharge prior to a short cruise with visible flow through the strainer. After 25 minutes at no-wake speed @ 700 rpm, engine kept its cool. The minute I bumped up to a 20 mph cruise speed in Naples Bay, I got the audible alarm. I found it interesting that I got an exhaust temp warning and nothing indicating excessive engine temp. Has anyone else experienced that particular phenomenon?
 
CaptainDavid":3bb9tjv6 said:
We had a similar problem this weekend with an audible alarm indicating high exhaust temperature. Water temperature was at least 89 and I'm planning on an impeller replacement as a routine matter targeted and curing the alarm situation. I had plenty of water discharge prior to a short cruise with visible flow through the strainer. After 25 minutes at no-wake speed @ 700 rpm, engine kept its cool. The minute I bumped up to a 20 mph cruise speed in Naples Bay, I got the audible alarm. I found it interesting that I got an exhaust temp warning and nothing indicating excessive engine temp. Has anyone else experienced that particular phenomenon?
Click to expand...

Hello David,

WELCOME to Tugnuts!

No, I have not experienced this phenomenon. I AM curious HOW you came to have an Exhaust gas temperature monitor, however. Did you install or a previous owner? Or, maybe factory installed?

Do you also have a cooling water flow sensor?

I would double check the exhaust temp with an noncontact IR temperature 'gun' and maybe start monitoring that as part of your routine checks whilst underway.

/dave
 
I can't recall what the sensor for exhaust temperature is set for, but perhaps with such high ambient water temperature you are getting a false alarm. As Dave said, what was your engine coolant temperature? Usually high exhaust temperature and high coolant temperature go hand in hand. However, a high exhaust temperature without high coolant temperature could have other indications regarding fuel burn, mixture and valves. It could also be a bum sensor.

Hope all turns out well. Keep us informed.
 
The Yanmar in my previous boat would frequently display hot exhaust temps after extended periods of low speed operation. While the fresh water system showed normal engine temps.

The Yanmar manual addresses this situation by stating that the reduced raw water flow during low speed ops can cause excessive heat build up in the exhaust system. The manual recommended cycling some increased engine rpm (in gear or not) occasionally to increase water flow.
 
Thanks for the welcome and the comments. I had been running slowly for 25 min or so just before I got the alarm at cruise speed. I can't find any reference in the Volvo manual re exhaust temperature monitoring or alarm code. Maybe I misread the fault screen since, as a pilot, I was used to exhaust gas temperature readings. I have to admit I was in disturbed mode as I was in heavy traffic and not happy I had a problem. It failed to mention that I just had a fresh bottom paint job and we all know that it's possible that the tape might not have been removed or some othe compromise could be at play with the raw water intake. The boat yard that did the painting was a good operation with whom I've had great experiences. The owner said today, "We could have done something to block your intake, even though my guys know better." He's going to put it in his travel lift and have a look so I'll let everyone know what we see. For the first time ever, I wasn't on site when the yard launched a boat I own. Note to self...don't do that again.
 
As a result, perhaps, of very low use by a previous owner, the exhaust temperature sensor was corroded and likely the source of a false reading. I replaced the engine impeller as a precautionary measure and to rule out one other possible source of trouble. Surprise, the impeller was 3 years old, was on an engine with only 67 hours, and was in perfect condition (until damaged upon removal). Perhaps I'll mount it as a souvenir.

I hope all is well. We'll find out for sure within the next two says.
 
This is a good news - bad news situation. We made a nice 20 mile run today with perfect engine and exhaust temps ( at least our new exhaust temp sensor worked withou an alarm). In addition to replacing the sensor and other basic engine PM, the boat yard pulled our boat and found that there was a bit if primer and paint partially blocking the raw water intake. The excess paint was removed and the intake was properly repainted. It was very comforting to have a boat operating within parameters and sensors that didn't give me false alarms.
 
Next Chapter - as the water around here cools, I find I can't run at WOT for any length of time without hitting engine temps above 202F. As that happened on Saturday evening, the exhaust temp alarm sounded. I find that my speed and rpms are governed by a 185 degree engine operating temperature. I'll be checking this with a lighter load to see if the Saturday issue was just a matter of having 6 adults on board.
 
I wonder if your raw water inlet pipe coming up from your pickup at the thru hull has growth growing inside the pipe? I noticed on our inlet it looked like some extra sealant squeezed into the intake area when it was installed. I think we might add a T where the current 90 degree elbow is located (above the thru hull) so we could pull the plug from the top of T and run a stainless brush down the pipe thru the valve to insure it had no growth build up from time to time. If your boat is used often this maybe not a problem. If the boat does reside in the salt water I would think the intake pipe could be prone to growth developing on the inside. I would also make sure your raw water pump's belt is in good shape with a properly functioning belt tensioner. Thinking if the belt was slipping that could effect water flow thus attributing to hotter temperature. I would make sure that your strainer has a good seal as if that was sucking air it might attribute to hotter temps also.
 
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