Running temperature

walkermar

hi all, quick query, my D4 Volvo Penta’s normal running temp is 85. I went out last night and it was 85 at 2000revs but when rising to 2500 revs it climbed to 94/95. Pulled back on the throttle to 2000 revs and back to normal. Clearly she water must be restrained at higher revs. Any suggestions on what to check first ? 

Liberty44140

Assume this is a diesel and obviously those Temps are C. My D6s inboards run at 185F no matter the rpm. Climb fo 185 F and never go down all day unless I turn the engines off and they cool a bit. 

95 C is too hot, if you run for very long that hot you could seriously damage the engine. I would make sure that everything is clear from the intake to the water pump, make sure impeller is new, strainer is empty. Also it could be just a bad coolant sensor. 

walkermar

Thanks Liberty, yes it’s diesel. I checked coolant levels today and SW strainers and both ok, I ran her up on the dockside but she ran ok. Will test her midweek under high revs to see what happens. Thanks for the swift reply👍

walkermar

Ok, so I ran her up this week after self isolating from Covid. Temperature still rises as it approaches 2450 revs to 91. However, no way I can’t get past 2500 so it feels like it’s being restricted but not sure if that’s the temp or is it the turbo not kicking in so then running hot!

does anyone feel it could be a sensor is sure as the turbo isn’t kicking in and I can’t get past 2500

Liberty44140

Can you hear the turbo? It’s a pretty obvious weeeeeeeee starting over 2000 rpm and stays on as long as you are on plane. Volvo turbos stay on continuously while running at cruise, they don’t cycle on and off like a Cummins. The sound of the turbo is obvious so if you don’t hear it you may have a turbo issue. Highly recommend getting on boatdiesel.com, much more info on diesels.  

walkermar

Thanks Liberty, you can definitely hear a change in the engine noise so presuming that’s the turbo as it does sound like a weeeeeeeeeeee noise. Will look at that forum as you suggest. 
Thank you

walkermar

Volvo Penta Engineer has suggested that the coolant system is quite crudded up and would benefit a flush through as one of the pipes is rock solid suggesting a heavy calcium build up. No faults found on the EVC so looks like that’s the next step 

walkermar

walkermar

Hi all above is a picture of the outdrive which I feel shows the real problem. Intake was overwhelmed with growth but the hull was fine. Problem pertained to using a poor quality anti foul and sprayed on instead of brushed on. Took the opportunity whilst out of the water to also flush the heat exchanger with brick cleaner and then managed to achieve 28knots ina 2ft swell sea at 2950 revs with a rock solid 85 deg C . 

Quick query is does anyone know know what the revs should be at cruising speed, say around 22knots ?

LaRea

Wow.  That's awful.  I hope you cleaned up the props while she was out.

Handymans342

Probably about 2000 rpm. I wanted to see a pic of a clean drive!

PickleRick

That drive looks awful.  Do you guys have divers you can pay to scrub the bottom and drives on a regular basis?

walkermar

I guess I could have access to a diver but felt I wanted to take it out for a proper look. Looking to invest in a snorkel and mask now for a periodic review. 

Liberty44140

My D6 has a wot rpm of 3620 so I cruise right around 3000. As I understand it D4 has the same rpm spec and as long as our wot is at least 3500 we are within Volvo spec for wot. 3620 is just when the limiter kicks in. 

Liberty44140

Looks like you should be wot 3500-3600. Cruise is always at least 10% less than wot but ideally more like 15-20% less. 

https://www.volvopenta.com/en-us/marine/products/aquamatic-sterndrive-diesel/aquamatic-sterndrive-diesel-engine-range/d4-dpi/#specifications

halifax212

My thoughts exactly

andyd

I pay my diver $65/month for the hull and the outdrive, plus zinc changes. Money well spent! I use Bare Bottoms Boat Cleaning Company. When I hired them my wife went WTF is this? LOL.

Andy