3.7 Mercruiser Water Pump Leak

[Old Yeller Boater]

so, since my old motor decided to make a big crack in the side of it's block, I found a new/used one, but the problem is it has a leak around the water pump housing. all three of the pieces there have been put on with red form-a-gasket over the existing gaskets, so my spidey senses are telling me immediately to replace. The motor is not in the boat yet, so perfect time to get it all done RIGHT.

From looking at past threads and the manual, it mentions removal of the bolts from the oil pan. in one place it said to replace the gasket, but another place I found did not mention more than the removal of the bolts (approximately 5). I just wanted a bit of clarification to confirm what needs to be done.

Second, while doing this, do the various seals have to be replaced as well? I'm thinking with the age, it's safest and best to go ahead and do it. I suppose I just answered my question. lol

Thanks in advance for the help!

 

[Bondo]

Re: 3.7 Mercruiser Water Pump Leak

so, since my old motor decided to make a big crack in the side of it's block, I found a new/used one, but the problem is it has a leak around the water pump housing. all three of the pieces there have been put on with red form-a-gasket over the existing gaskets, so my spidey senses are telling me immediately to replace. The motor is not in the boat yet, so perfect time to get it all done RIGHT.

From looking at past threads and the manual, it mentions removal of the bolts from the oil pan. in one place it said to replace the gasket, but another place I found did not mention more than the removal of the bolts (approximately 5). I just wanted a bit of clarification to confirm what needs to be done.

Second, while doing this, do the various seals have to be replaced as well? I'm thinking with the age, it's safest and best to go ahead and do it. I suppose I just answered my question. lol

Thanks in advance for the help!

Ayuh,.... That usually involves speedi-sleeves, 'n cam seals on the 470s,...

It's been talked 'bout in here, Search it up,...

 

[Bt Doctur]

Re: 3.7 Mercruiser Water Pump Leak

How does a block with A/F in it get a freeze crack?

 

[stonyloam]

Re: 3.7 Mercruiser Water Pump Leak

Yeah you will want to replace the two waterpump seals and the crank oil seal.

 

[Old Yeller Boater]

Re: 3.7 Mercruiser Water Pump Leak

I got everything apart this evening. The issue was with the oil pan gasket. Looks like the previous repair job was shortcut as the gasket was broken at both ends of the timing cover. they used form-a-gasket to try to seal it up. Ordering the pan gasket too. should be easy to deal with since the motor is still out. Seals all appeared to be doing their job, but I'm going to stop by a local shop and have them give me opinion about replacing them. I don't have the presses to do it, so think I'll just do a shortcut and have them do it. Since it's already off, they should be able to do it pretty quick. I'll have them look at the shaft to for the sleeve.

 

[Old Yeller Boater]

Re: 3.7 Mercruiser Water Pump Leak

How does a block with A/F in it get a freeze crack?

overheated and run dry by the previous owner. I didn't notice the leak because it had a bad head gasket backflowing the antifreeze out the overflow tube. it also had a serious leak in the transom. once I got both of those fixed, noticed the antifreeze.

On the plus side, I'm learning a LOT about the boat and motor.

 

[Old Yeller Boater]

Re: 3.7 Mercruiser Water Pump Leak

So, in doing some further analysis, I think my problem was the bolt in the coolant drain is cross threaded and was leaking. Do you think I can clean up the threads on the housing, or should I look to get a replacement? I'm thinking the right tap would work. thoughts?

 

[stonyloam]

Re: 3.7 Mercruiser Water Pump Leak

I would think clean it up and use a little sealant should do the trick. Not sure anybody ever uses that plug anyway lol.

 

[Old Yeller Boater]

Re: 3.7 Mercruiser Water Pump Leak

I thought the same thing. for one it's antifreeze. for two, I can pull the hose. the only negative is that there would be a little antifreeze in the lower area of the housing. I'm going to try to re-tap it though.

 

[stonyloam]

Re: 3.7 Mercruiser Water Pump Leak

Yeah and if that doesn't work I would just seal it up with some JB weld on the threads, but that is just me LOL.

 

[Old Yeller Boater]

Re: 3.7 Mercruiser Water Pump Leak

I ended up re-tapping the threads and the bolt went back in and sealed up fine. ended up replacing seals on the timing cover and also installed speedi-sleeves on the cam shaft. Replaced pan gasket too and got it all back together. Installed in the boat and been running it for two weekends now. works like a charm. Thanks for everyone's input guys!