Coolant Drain on M-25XPB ?

[SailFysh]

First time to service the coolant on my boat and thought as always I would lean on you guys... what would I do without you. My manual shows drawings of coolant drain for M-50B and M-35B but I see nothing for the M-25XPB. I did find a drain on the HX that looks like the M-50B drawing. I assume that is where I drain coolant? Also, I am concerned about bleeding all air from the system as I refill with fresh coolant. As always, thanks for your comments and tips.
Neal

 

[SailFysh]

Drain the coolant from the Heat Exchanger? Is that the best way?

 

[buddybear]

Not saying that is the best way, but that is the only way I could do it. The manual shows a coolant drain just above and aft of where the top of the oil drain hose is attached. I tried that but nothing came out. I would also be interested if there was a better way to do it. After draining and refilling I was able to burp the engine to get the air out. As I recall there are several posts on how to do it.

 

[SailFysh]

Thanks. I see the drain bolt you are referring to. My manual does not show this. I will try it this weekend.

 

[njlarry]

If nothing comes out of engine petcock it must be clogged. Try clearing it with an ice pick. I have not yet drained mine but the heat exchanger drain is the lowest so it may make sense to open that petcock too along with the engine block.

 

[SailFysh]

Thanks Larry. Yes the HX drain does look lower than the engine drain.

 

[marchem]

Is there a recommended schedule for replacing the coolant? Probably a good idea to do it every now and then...

 

[SailFysh]

I read 1000 engine hours... I am at 650 but thought I would go ahead and take care of it. Everything else has just been serviced.

 

[SailFysh]

Ok this is getting silly. I know experience is everything but these little engines and the manuals could be a little plainer for us simple minded sailors from Alabama. First of all my manual does not show a pic of coolant drain on 25mxpb engine. Through this forum I hear about drain on HX and one on engine block starboard side at front. Today I open the drain on HX. No coolant comes out... Raw water flows. So I guess the coolant is inside the tubes of the HX and the raw water flows around the tubes right? I open the drain on engine block and nothing flows. I don't think either of these is the place to drain the coolant. I will PAY for a proper manual. Even though I have the one that came with the boat it covers many different universal engines and obviously is not accurate with respect to my engine. Anybody recommend a manual? Thanks.

 

[marchem]

Which one have you got? I've got both a Universal #200550 (Feb. 2010) and #200494 (Apr. 1977) version that have good descriptions of the actual engine in our boats. I'm happy to send you either or both.

Also realize that things changed constantly during the construction of these boats. the 310 is much better in that respect than the 27 or 30, but still, I've seen at least 3 different thru hull locations for the macerator.

 

[SailFysh]

Thanks. I will check my manual when I go to the boat tomorrow

 

[KZW]

Manuals: I have the following:

Universal_Technical_Manual_200554_m-25xpb_m35b_m40b.pdf
34 MB

Universal-Parts-Manual_201021_M25XPB-M35B-M40B revision 2 final.pdf
6.4 MB

Universal-Deisel-Operation-Manual_Feb-2010
2.5 MB

Universal-Deisel-Parts-List.pdf
1.3 MB

I can post the parts list is desired. The others are too large for this forum. If you search the net, you can find them. That I how I got them, but I don't remember the URLs. The drain on the Heat Exchanger drains the cooling water, not the coolant
In the Tech manual, pages 54-55, coolant system service, there is no mention of a drain. The block drawing on page three doesn't list a drain. I gave up looking for one, disconnected one of the line going to the hot water heater from the pump, put in the hose from my oil extractor (manual pump), and gently (note the word gently) pumped the coolant out. It emptied the heat exchanger and the coolant manifold. Practical Sailor suggests using a high quality diesel coolant and changing every five years.

 

[KZW]

Try here:

www.c34.org/wiki/index.php?title=Manuals

 

[SailFysh]

Thanks! Really appreciate the tips.

 

[SailFysh]

I have Operators Manual Universal Marine Diesel Engines
Publication 200550
1st Edition
January 2000

 

[SailFysh]

Thank you! The service manual 200554 shows my engine. Thank you!

 

[buddybear]

I have the original Heat Exchanger hull#57 and the petcock next to where you install the zinc does allow you to drain the coolant from that point. Maybe you have a different Heat Exchanger which does not have that function, I do find that hard to believe that a manufacturer would not set it up so you could drain the coolant. Do you see coolant in the overflow tank?

 

[SailFysh]

Yes. I see coolant in overflow tank. I have a better manual now thanks to KZW and hope I can find a drain. If not I will pump it out via a heater hose. Thanks buddybear.

 

[njlarry]

So just to confirm. The heat exchanger petcock drains the engine coolant while removing the heat exchanger zinc drains the raw water?

 

[buddybear]

Yes the petcock drains the coolant I have done it several times. Removing the zinc does drain out raw water whether it drains out all of the raw water I don't know. I normally close the intake for the raw water before I check the zinc.