1GM10 getting hot

[conks01]

Hi.

I recently launched my Westerly pageant and during the trek down the river to the mooring (20 min journey), near to the end, a warning light came on and sounded which was water temp.

Prior to this I regularly ran the engine in the yard filling a bucket of water for the water pump to take from. There were no real problems and the sensor never came on although running time on idle was approx 5 - 10 mins.

Previously I had replaced the impeller and renewed bearings and seals on the water pump.

The setup is raw water seacock hose to strainer, then hose onto water pump.

The pump is not leaking. The strainer is clear although I'd need to check the hoses (which are brand new fitted by me).

The exhaust elbow was not rusted. I did check this when I purchased the boat in 2019.

When I ran the engine again today the sensor came on after 20 mins and I did think that it wasn't pumping well today also.

I've uploaded a video to YouTube taken from a few weeks ago showing the water coming out of exhaust port. https://youtube.com/shorts/Y59zciuxam8?feature=share

Can somebody comment whether they feel this is or isn't normal for a 1GM10 please and point me in the right direction. Maybe it's the sender?

 

[Ammonite]

Not normal. There should be a lot more water. At least double what you are seeing. Worth checking the elbow again
How to inspect a Yanmar GM exhaust elbow - Practical Boat Owner

 

[Gixer]

compared to mine I’d say that water does look a bit less.

Have you taken the water hoses off the front of the engine and inspected. Also check the thermostat housing, it’s only a small hole there for the water to go though.

 

[RichardS]

It certainly doesn't look like much water to me. I'm assuming that the engine is fresh water cooled.

Richard

 

[conks01]

compared to mine I’d say that water does look a bit less.

Have you taken the water hoses off the front of the engine and inspected. Also check the thermostat housing, it’s only a small hole there for the water to go though.

No but that was the next plan I think. Thanks

 

[conks01]

It certainly doesn't look like much water to me. I'm assuming that the engine is fresh water cooled.

Richard

Sadly not, it's in the Bristol Channel!

 

[tillergirl]

I rarely use my 1GM so last season I was getting low water output and overheating alarm. It was blockage at the small, nay tiny elbow into the block. The hose goes up from the pump to a small elbow which lets water into the block to cool it. If the thermostat is closed, water doesn't enter the block but travels upwards and onto the exhaust. I pulled off the hose and found that salt had blocked the entrance to the block so cooling water couldn't enter. A gentle screwdriver was sufficient to pierce the salt crust and flow was restored.

 

[conks01]

I rarely use my 1GM so last season I was getting low water output and overheating alarm. It was blockage at the small, nay tiny elbow into the block. The hose goes up from the pump to a small elbow which lets water into the block to cool it. If the thermostat is closed, water doesn't enter the block but travels upwards and onto the exhaust. I pulled off the hose and found that salt had blocked the entrance to the block so cooling water couldn't enter. A gentle screwdriver was sufficient to pierce the salt crust and flow was restored.

Thank you. Checking all the hoses was my next step so good shout.

 

[Tranona]

Yes, that will likely be the cause. However it is also worth replacing the sender for the overheat alarm. Found out the hard way that even if everything is OK and flow is good the sender can still trigger the alarm. Cured by a new sender.

 

[Adios]

I forget the specifics but there is a part which comes off when servicing the impeller that can be put back the wrong way around which greatly reduces the flow but allows some so you think its ok-ish... I would take off everything you touched and try to work out exactly what it does before putting it back. Sorry can't remember the details but I remember thinking it was a poor design to allow that.

 

[pioneer]

The senders do fail, as i found out, but first i'd check the impeller is correctly fitted, i.e correct rotation and vanes compressed against the cam

 

[conks01]

I forget the specifics but there is a part which comes off when servicing the impeller that can be put back the wrong way around which greatly reduces the flow but allows some so you think its ok-ish... I would take off everything you touched and try to work out exactly what it does before putting it back. Sorry can't remember the details but I remember thinking it was a poor design to allow that.

Thanks. Yes, that's the cover to the impeller which gets worn

 

[Sailing steve]

I'll second checking inside the flexible water pipes on the front of the engine. If you're taking them off for a look then for peace of mind on an older engine you might as well fit new ones.

Mine had a significant build up of crusty scale in them which once replaced noticeably improved water flow out the exhaust.

 

[andsarkit]

It is difficult to judge the water flow from the exhaust if you have a water lock, as the water will tend to come out in bursts. At tickover you won't get much water from a 1GM but what happens when you increase the revs? The water from the exhaust should only feel warm and you should be able to touch the exhaust elbow easily. I think the thermostat should be fully open at about 50deg C. The usual blockage is salt in the short pipe below the thermostat

 

[179580]

It certainly doesn't look like much water to me. I'm assuming that the engine is fresh water cooled.

Richard

It is a pity in your 50 years of experience as an engineer you never came across a 1gm.

 

[conks01]

I'll second checking inside the flexible water pipes on the front of the engine. If you're taking them off for a look then for peace of mind on an older engine you might as well fit new ones.

Mine had a significant build up of crusty scale in them which once replaced noticeably improved water flow out the exhaust.

Thanks and yes I did replace the 2 pipes at the front with new for peace of mind.

 

[JumbleDuck]

Can somebody comment whether they feel this is or isn't normal for a 1GM10 please and point me in the right direction. Maybe it's the sender?

From memory of my 1GM, that doesn't look completely wrong for water at tickover though perhaps, as others have said, a little on the low side. My first act would be to check the sender. These don't run at all hot to avoid salt build up, so any water pipe you can get to - the one to the exhaust elbow, for example - should be no more than pleasant bath temperature to the touch.

It also might be worth pointing an IR thermometer (this sort of thing) at various parts to see if anything is very hot. They aren't desperately accurate, but they will spot hot bits on engines nicely.

As I recall, the flow divides in two at the tee downstream of the pump. Some goes up to the thermostat housing and the rest takes the long way round through the block and head. When the engine is cold the closed thermostat prevents flow though the engine itself, so the water there heats up faster and the engine warms up. Then the thermostat engine and more, most or all water takes the long way round. I think there is a restriction in the thermostat housing to encourage this.

When I took my head off I found that the short vertical pipe to the thermostat housing was almost completely blocked with salt. If your is the same it might explain reduced flow out the back, though if the engine is hot the thermostat ought to be open with plenty of flow though the block and head. Have you tested the thermostat?

 

[conks01]

From memory of my 1GM, that doesn't look completely wrong for water at tickover though perhaps, as others have said, a little on the low side. My first act would be to check the sender. These don't run at all hot to avoid salt build up, so any water pipe you can get to - the one to the exhaust elbow, for example - should be no more than pleasant bath temperature to the touch.

It also might be worth pointing an IR thermometer (this sort of thing) at various parts to see if anything is very hot. They aren't desperately accurate, but they will spot hot bits on engines nicely.

As I recall, the flow divides in two at the tee downstream of the pump. Some goes up to the thermostat housing and the rest takes the long way round through the block and head. When the engine is cold the closed thermostat prevents flow though the engine itself, so the water there heats up faster and the engine warms up. Then the thermostat engine and more, most or all water takes the long way round. I think there is a restriction in the thermostat housing to encourage this.

When I took my head off I found that the short vertical pipe to the thermostat housing was almost completely blocked with salt. If your is the same it might explain reduced flow out the back, though if the engine is hot the thermostat ought to be open with plenty of flow though the block and head. Have you tested the thermostat?

Really helpful, thanks. I havent checked the thermostat so will look at that and all certainly clean out all hoses. Pleased what you said re the pump rate out of the back, makes sense to me. I would think that it could be a more recent build up in a hose as it was definitely pumping at a higher rate before I'm sure.

 

[Adios]

Thats the part that i was thinking of, the thermostat cover.

If its upside down it would restrict the flow to what you have. Seemed bizarre that they didn't make it so there was no way to install it up the wrong way.

Even at tick over there was a good big splosh of water coming out every few seconds not a dribble like you have.

 

[RichardS]

It is a pity in your 50 years of experience as an engineer you never came across a 1gm.

It has always been the case that some members of this forum know a thing or two about engines and try their best to help the OP whereas others clearly know very little so simply try to score infantile points as they are unable to actually contribute meaningfully to the thread.

Richard