R-21EC VP D1-30F Coolant Fill

[Sheepdog012]

Hi Folks, So I just changed out the heater hoses on my R-21 as they were starting to wear at the point they pass through the engine liner pan on their way into the cabin. Pretty simple job and I am refilling the coolant per the Volvo-Penta manual...through the expansion tank. I have only been able to replace about 2/3rds of what I took out so far. The manual says if there is a heater attached to the coolant system that I need to vent that when filling. I looked all over the heater core and can't find any venting nipples. Anyone have any insights on how to vent it? Should I just start the motor and let it fill under pressure, while adding to the expansion tank? Any ideas would be appreciated! Thanks!

 

[Thatguy]

Hi Sheepdog,
I’ll start by congratulating you on your good decision making (preemptively changing hoses). We didn’t see the wear on ours - until the high temp alarm went off! Wore a pinhole right where you describe. We used some of the old heater hose to make a sacrificial hose guard.
As far as bleeding it - we first added the coolant with the trailer jack as low as possible; in other words, the front of the boat was pitched down. We ran the boat with water running into the strainer long enough for the thermostat to open, adding coolant as needed (cap off). Next we ran the boat in the water at the dock for 10 minutes, managed to purge a little more air. We ran it underway, until the level stabilized, put the cap back on and were all set for another hundred hours!
Good luck, I think you will be fine.
JP

 

[Sheepdog012]

Thanks JP!

I checked the old hoses after I had taken them off, and probably could have pushed my thumb through it where the wear point was. These little 3 cylinder D1-30s shake like heck at idle which can wreak havoc on the hoses and the MDI box. I was thinking about how to fill the heater lines and core and I had an idea I am going to try tomorrow. The heater hose that connects to the back of the heat exchanger is really long. I'm going to disconnect it and the heater hose on the front of the motor, then hold the rear line straight up high and use a funnel to fill the line which will be higher than the heater core, so it will fill the core then fill the other hose. When it starts to come out of the front hose I will reattach it to the engine then reattach the rear hose. That will fill almost all of the empty areas, then I will do what you did as far as running a bit with the cap off and adding as needed. Thanks for the info!

 

[Newf]

I replaced the same hoses a couple of years ago for the same reason. The boat was on the trailer and sitting level. Ran the engine with cap off the reservoir and kept adding coolant as engine came up to temp. Kept an eye on it for the first few runs after that and probable added an addition cup of coolant. Did not have to bleed anything. Did the same thing when I replaced the coolant with new.
NOTE: After a couple of runs I had to snug up the hose clamps on the heater as there was a bit of weeping at one of the fittings. Probably not snugged up enough on the first go around.

 

[Sheepdog012]

Thanks Newf!

I am going to try to to that today on land, if I can get enough snow out of the way to take her out of the boat shed. 😀

 

[Sheepdog012]

Anyone wanna guess what happens when you take the rear coolant line off? Yep, coolant bubbler! Anyway, After cleaning up from that fiasco, I refilled the expansion tank and started her up. Added about two expansion tanks worth over the first few minutes. Brought it up to temp and added a bit more. All set!

On the new heater hoses I slid a short length of flexible water line on them to protect them from chaffing again.

Now on to replacing wheel bearings!