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Old 15-11-2017, 21:24   #1
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Yanmar 3YM30 Raw Water pump seized

Hi, after a 6 week lay up, when I started 1 of 2 engines, the water pump">raw water pump appeared to be seized. It will not turn, even with a spanner on the end nut. The other engine is fine.
Any suggestions?
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Old 16-11-2017, 02:32   #2
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Re: Yanmar 3YM30 Raw Water pump seized

I assume you know for sure that it is the water pump and not the engine seized. There would then appear to be the following possibilities:
-Something has jammed between the belt and the pump bracket or the pulley and pump body
-The impeller has come apart so that something is preventing the shaft turning. Such as the impeller drive pin.
-The bearings on the shaft have broken up preventing the shaft turning. If this is the case then the usual reason is that seawater has penetrated past the seal and drip ring and stuffed a bearing. If you have had a water pump leak, that seems the most likely.

Either way, the pump has to come off with its bracket, although you can check the 2nd option in situ with enough space by taking the cover plate off. Providing there is no damage to the shaft, housing or impeller aperture, repair by replacing impeller, bearings and seal is cheap if you use non Yanmar seal and bearings
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Old 16-11-2017, 14:22   #3
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Re: Yanmar 3YM30 Raw Water pump seized

Thanks for the reply.
Engine runs fine. The separate belt that powers the raw water pulley is slipping. Nothing is jamming the pulley, so I suspect an internal problem.
Next issue will be to unseize the raw water shut off valve...
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Old 16-11-2017, 14:32   #4
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Re: Yanmar 3YM30 Raw Water pump seized

Quote:
Originally Posted by michaux View Post
Thanks for the reply.
Engine runs fine. The separate belt that powers the raw water pulley is slipping. Nothing is jamming the pulley, so I suspect an internal problem.
Next issue will be to unseize the raw water shut off valve...
take the hose of the pump and raise it above the waterline (or open the strainer)
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Old 17-11-2017, 10:45   #5
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Re: Yanmar 3YM30 Raw Water pump seized

Most common cause of this is from a leaking shaft seal that was un-detected in time to save the bearing from salt water. Then after sitting for a while the corrosion/rust locked it up.
Trying to force it or turning the shaft now will likely ruin the shaft.
Remove the pump and disassemble it.
You will need to probably tap out the shaft and bearing from the body. Be careful not to flare or burr the ends of the shaft by pounding on it with a steel hammer. Try a wood block on shaft end and then use hammer.
Then highly lube with something like PB Blaster and soak. Tap the bearing(s) of. Clean shaft with Scotchbrite pad. If no damage to the shaft get new bearing(s), seal, impeller service kit.
If the shaft is damaged might as well plan on a new pump as the cost of the rebuild kit and shaft will pretty much be close to a whole new one.
The key is to service the pumps immediately upon finding any slight water drip. The pump may run quite a while with the seal failed bur soon as the pump sets and drys out it all falls apart.
I heavily coat the inside face of the bearing with Triple Guard Grease (it is very stiff and waxy) because I have found it to keep the water out of the bearing pretty well for short periods of time and eliminate bearing failure.

As a side note I have made some custom water collectors that fit onto the bottom of my raw water pumps and let me know with a warning buzzer if a seal fails.
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Old 17-11-2017, 14:21   #6
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Re: Yanmar 3YM30 Raw Water pump seized

These are Johnson pumps and are not expensive. Replace it and buy a spare impellor whjile you are at it, unless you have time to spare fixing the damaged one.
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Old 20-11-2017, 13:31   #7
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Re: Yanmar 3YM30 Raw Water pump seized

Hi,
I have now taken the pump apart and one bearing had seized. Cause was the oil seal that was letting water past.
Poor design.
Single seal with 1 lip on the seal.
I am trying to source a better, triple lipped seal.
Freudenberg is my favoured supplier (we have used them at work for years and their seals are exceptionally good, but expensive)
I will post any progress I make
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Old 20-11-2017, 14:01   #8
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Re: Yanmar 3YM30 Raw Water pump seized

Quote:
Originally Posted by michaux View Post
Hi,
I have now taken the pump apart and one bearing had seized. Cause was the oil seal that was letting water past.
Poor design.
Single seal with 1 lip on the seal.
I am trying to source a better, triple lipped seal.
Freudenberg is my favoured supplier (we have used them at work for years and their seals are exceptionally good, but expensive)
I will post any progress I make
How many hours on it?

The lip seal (not oil seal) is $5, easy to change.
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Old 20-11-2017, 15:16   #9
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Re: Yanmar 3YM30 Raw Water pump seized

i get no more that 2 years out of them before a rebuild
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Old 20-11-2017, 16:56   #10
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Re: Yanmar 3YM30 Raw Water pump seized

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Originally Posted by Ram View Post
i get no more that 2 years out of them before a rebuild
Wow, 12,000 hours is a lot!
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Old 21-11-2017, 04:09   #11
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Re: Yanmar 3YM30 Raw Water pump seized

As others have said, it is the seal that causes nearly all problems with this pump. Once water starts to leak then you can get it thrown over the front of the engine rusting the pulleys and other bits. Given how easy it is to change the seal and it's low cost (if bought from a generic bearing and seal supplier), you can change the seal as a precaution so it never happens. You only need to remove the impeller and then you can prise the seal out and push in the new one. It seems so trivial in cost and time that I now routinely change the seal when I renew the impeller each year. I remove the pumps any way to change the impeller so it is little extra work.
You can replace the single lip with a double lip seal. Thanks to this thread and BobnLesley post for a comprehensive discussion on servicing the pump
Pump Rebuild
I run the raw water pump belt with low as possible tension to reduce the side load on the bearings as others have reported high belt tensions can lead to early failures. Given the large belt wrap and low torque required for the pump you need very little tension.
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Old 21-11-2017, 20:24   #12
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Re: Yanmar 3YM30 Raw Water pump seized

It sounds like the pump is totally unfit for purpose.
Specifying bearings that take high side loads and that can run for thousands of hours between failures (mean time between failure) is as easy as a phone call to a bearing manufacturer. Does the alternator fail as regularly as the raw water pump? I think not, but that is a Yanmar specified item with the correct bearings.
I will research further...
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Old 22-11-2017, 03:24   #13
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Re: Yanmar 3YM30 Raw Water pump seized

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Originally Posted by michaux View Post
It sounds like the pump is totally unfit for purpose.
Specifying bearings that take high side loads and that can run for thousands of hours between failures (mean time between failure) is as easy as a phone call to a bearing manufacturer. Does the alternator fail as regularly as the raw water pump? I think not, but that is a Yanmar specified item with the correct bearings.
I will research further...
2600+ hours, no bearing failure due to side load, bearings fail when soaked with salt water. The pump design is fine, routinely check the seal for leakage, change the impeller as needed, the pump lasts a long time. Itís a ~$220 pump.
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Old 22-11-2017, 06:31   #14
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Re: Yanmar 3YM30 Raw Water pump seized

The OP is right in that the sea water pump is not the best bit of an otherwise very reliable engine. In mitigation, the pump had clearly been leaking some time and the OP would have been wise to investigate earlier. However, it is what it is and there is no real alternative that is more reliable I know of without major re-engineering. Given that the seals are so easy to change, a bit of pre-emptive maintenance will keep the pump running for a long life. I suggest:
- Change the seal at the first drip or earlier. If you leave it the salt water will get to the bearings with the result they will fail. Better still, replace them yearly when you change the impeller.
-Keep the belt tension low to reduce the side load on the bearings. You do not need much tension to drive the pump. The alternator needs a lot more tension to prevent belt slippage as it transmits more power.

There are quite a few threads on the forum regarding this pump which would be worth perusing. You are not alone
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Old 22-11-2017, 09:10   #15
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Re: Yanmar 3YM30 Raw Water pump seized

Quote:
Originally Posted by Rapanui View Post
The OP is right in that the sea water pump is not the best bit of an otherwise very reliable engine. In mitigation, the pump had clearly been leaking some time and the OP would have been wise to investigate earlier. However, it is what it is and there is no real alternative that is more reliable I know of without major re-engineering. Given that the seals are so easy to change, a bit of pre-emptive maintenance will keep the pump running for a long life. I suggest:
- Change the seal at the first drip or earlier. If you leave it the salt water will get to the bearings with the result they will fail. Better still, replace them yearly when you change the impeller.
-Keep the belt tension low to reduce the side load on the bearings. You do not need much tension to drive the pump. The alternator needs a lot more tension to prevent belt slippage as it transmits more power.

There are quite a few threads on the forum regarding this pump which would be worth perusing. You are not alone
I normally don't blame a device for my own laziness with routine maintenance. That pump should be inspected periodically for seal leaks and impeller condition, both will last several hundred hours (I got 900 hours out of one impeller). The belt is so short that anything other than tensioning with your hands is too much, that seems so obvious. But, I also check engine oil before a day of motoring, maybe it's just me.
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