Descaling a 18hp 2 stroke outboard

[Neil Hapgood]

Hi all, I am looking to flush an outboard with descaler. its a 2 stroke tohatsu 18hp, I have connected a hose pipe to the wash port with a pump to run the descaler. However as soon as I turn it on the water seems to just flood out the inlets below without circulating round the engine. Is it possible to do this or does in need to go round the engine first before getting to the inlets? Any thoughts, tips or advice would be great! Many thanks

 

[Ribtecer]

Have you started it up with the water system you've created running?

 

[vyv_cox]

I know nothing about your engine but is it possible to invert it and pour the descaler in?

If using Rydlyme or similar it is mostly hydrochloric acid. This attacks some grades of aluminium, so do not leave it in too long and flush thoroughly afterwards.

 

[Neil Hapgood]

thanks so much both, I've got it working now by removing the lower unit and attching a hose from the pump running the proflush straight to the pipe the water pump attaches to and it seems to be running fine, coming out tell tale etc well. I'm guesing the flush port is blocked, I suspect its never been used the previous owner didn't seem to look after it very well!

 

[Graham376]

Assuming the flushing method is the same as the T9.8 2 stroke - cover the normal inlet grids with gaffer tape, connect the hose and run the engine.

 

[VicS]

thanks so much both, I've got it working now by removing the lower unit and attching a hose from the pump running the proflush straight to the pipe the water pump attaches to and it seems to be running fine, coming out tell tale etc well. I'm guesing the flush port is blocked, I suspect its never been used the previous owner didn't seem to look after it very well!

Remove the thermostat or you will not get a decent flow around the engine, only though part of it and out of the tell tale.

.

 

[Neil Hapgood]

Remove the thermostat or you will not get a decent flow around the engine, only though part of it and out of the tell tale.

.

Thanks Vic, I removed the thermostat as you suggested and got the pump running. At one point I lossened the 2 bolts for the thermostat housing to see if I could see water flowing and as soon as I lossened them water came leaking out so there was a lot of water being forced up. Would this suggest that the water wasn't flowing properly beyond the thermostat or is this to be expected even if the channels are clear throughout?

Many thanks

 

[GunfleetSand]

Some folk leave in a bucket with chemical of choice (citric acid or radiator flush) with pea stream diverted back into bucket. works best when engine warm

 

[Neil Hapgood]

Some folk leave in a bucket with chemical of choice (citric acid or radiator flush) with pea stream diverted back into bucket. works best when engine warm

thanks Gunfleet, yes that what I did, I left it cyle with a submerisble pump for a couple of hours, hopefully its done something!

 

[VicS]

Thanks Vic, I removed the thermostat as you suggested and got the pump running. At one point I lossened the 2 bolts for the thermostat housing to see if I could see water flowing and as soon as I lossened them water came leaking out so there was a lot of water being forced up. Would this suggest that the water wasn't flowing properly beyond the thermostat or is this to be expected even if the channels are clear throughout?

Many thanks

With the thermostat removed if you are not seeing a good flow of water from the engine, other than from the tell tale it probably means that the cooling passages in the cylinder head are blocked. If the cleaning solution cannot get through you will have to remove the head and clean it by hand.

 

[Neil Hapgood]

With the thermostat removed if you are not seeing a good flow of water from the engine, other than from the tell tale it probably means that the cooling passages in the cylinder head are blocked. If the cleaning solution cannot get through you will have to remove the head and clean it by hand.

Again thanks so much Vic, with the immersible pump running there was water coming from hole in the centre at the back directly below the cover and also running down inside the main leg as well as tell tale, are they good signs?!

 

[VicS]

Yes they are good signs. The descaling solution will be able to get through and do its job.